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Gaps/Holes in the 3D Print walls
I'm new to 3D printing, I bought an Ender 5 Pro just recently. Trying to print with 1.75 mm PLA, but the results are very bad, unfortunately. When I got after bed leveling I got a decent result from the demo dog and started to print small things, where the quality was acceptable. Then I tried to switch to bigger items, but the printing failed half-way due to not enough adhesion.
There were other quality problems too with this print, and you can already see that in the walls there are holes:

I did another round of bed leveling and Z alignment to make sure the adhesion is good and a test print came out quite fine in all corners and the center. The one layer rectangles and not perfect, in some places the lines separate, but they are mostly fine. But now I have a different problem: all the prints are very messy, less clear, they are not as strong as before and also there are big holes now in the walls.
The same statue base (as I had to stop after getting messy earlier) looks like this now:

Another try failed after a few hours (like printing stopped and was printing nothing in the air), but also there is the holes/gaps problem even more visible:

Finally as a test I printed an object with the same G-code as previously used and the result is much different. The object on the left is the new one. It is weak, you can feel by pressing that the walls are not solid, they bend. The rectangle "eyes" are also not clear:

There is a difference though, I changed the extruder's nozzle between, the new one was also in the Ender package, it is also 0.4 mm as the original should have been, I changed to try with a new one.
Because of the last test with the same gcode, different result, I think the problem might be in hardware adjustment as well, not only software. Anyone has an idea what I'm doing wrong?
EDIT 1: after calibrating the extraction amount and reducing the print temperature from 200 C to 190 C, now I get the below result. The values used:

Bed temperature: 65 C initial, 60 C for the rest
Print temperature: 200 C initial, 190 later
Print speed: 80 mm/s
Wall speed: 40 mm/s
Retraction: 10 mm
Retraction speed: 80 mm
Wall thickness: 0.8mm
Layer height: 0.2 mm
Initial layer: 0.2 mm
Line width: 0.4 mm

EDIT 2: Based on the comments, some changes were made and here are the results.
XYZ cube,

print speed reduced to 60 mm
layer height 0.12 mm
Z Seam Alignment is Sharpest Corner
Infill density 30 %
Retraction distance 8 mm
Retraction speed 40 mm

It looks good, the layers are visible though, some ghosting right to X and Y.
The sizes are not correct though: X = 20.07 mm, Y = 20.03 mm, Z = 19.84 mm

Are X/Y acceptable? What should I do with Z, increase steps/mm ?
Finally here is the 3D benchy too, although looks mostly fine, there are some bumps in the walls and small strings in open areas. This was printed earlier and with different settings though:

Layer Width 0.2 mm
Print speed 80 mm
Retraction 10 mm
Retraction speed 80 mm
Z Seam Alignment is set to Random

EDIT 3 I tried now to print the PolyPearl, that has thin curving lines. The first try failed after 2 hours, a knob developed on the nozzle that ruined the print. This was printing with 190 C. I gave a new try and printed with 200 C, and amazingly it completed the job. See below the pictures, here are my settings for it (changes for Cura 4.6.0's default Super Quality):

Layer height: 0.08 mm
Initial layer height: 0.12 mm
Wall thickness: 1.2 mm
Z Seam Alignment: Sharpest Corner
Print speed: 60 mm/s
Infill acceleration: 1000 $mm/s^2$
Print acceleration: 300 $mm/s^2$ (default is 500)
Print jerk: 8 mm/s (default is 10)
Retraction distance: 8 mm
Retraction speed: 40 mm/s

The model sticks well to the glass plate even without glue or hair spray, maybe a little too well. I see some problems though, not sure how normal they are:

outside area of first layer is not nice
there is some oozing, thing lines on the surface and between the columns
the top end of the tower is somewhat messy and there is a horizontal line attached to it (sure, can be removed easily)
the bottom is very smooth, I can see the glass' texture (the Creality glass top is textured) and the texture of the very first failed print, when I didn't take into account the extra height of the glass after leveling, and the print head hit it hard and the nozzle got completely damaged. Beginner's fault.

Here are the images: https://photos.app.goo.gl/ZfuMFFedL171eLeM7
Are this problems normal/acceptable?

hmmm, looks to me like... ringing or ghosting? to make it easier to analyze, please print a cube with 2 flat sides and 2 with indented X and Y.  As a second test print, I suggest a cylinder and one with a cut in the outer shell.

Unfortunately I was not clever enough to save the whole project for the tries, only the gcode, so getting the setting is harder.
I read around and found the under extraction can be a problem. Indeed for some reason instead of 100m it extracted 95mm. After a lot of calibration now I'm close to 100m and generated a new gcode for the same slime (cube) model. The result now is close to the original one. The surface is not clear enough though. I will ammend the original question with the values used for this and a pic.

ok, I see one parameter that might result in the pattern: "Print speed: 80 mm/s" - can you try slowing that one to 60? Also, the massive underextrusion in some intermediate prints might be a clogged nozzle - cleaning might also be in order.

I would bring the temperature up, for better bonding and to make the PLA more fluid (easier to extrude) and reduce by 1-2% the extrusion multiplier (see that on the top layer there is too much material and the nozzle left a line on the top right?)

Also, try linear advance to reduce blobs in the corners (where there is significant deceleration) or reduce acceleration overall by 500 mm/s^2. Printing time won't be affected much but you'll get better quality

Thanks for the hints. I have printed the XYZ cube and the 3D benchy, I will upload those two. It is definitively much better, not sure if something can be improved still, or this is how it is. Details will be in the edit.

The Z steps/mm must be ONLY calculated, not adjusted to compensate. Check your Z screws and that's the value, I think 400. If the cube is smaller, maybe the first layer is too thin (bed too high?) or something else. However, given the bottom surface of the Benchy, the bed is fine, since you can see the different extrusion tracks

Measure the vertical size of the Benchy features. Are they correct or too short, like the cube?

The top of the box is about right (15.48 mm instead of 15.50 mm), the whole height is a little smaller 47.88 mm vs 48 mm. In general the measured sizes are smaller with about max. 0.2 mm, but this was printed with a 0.2 mm layer height, if that matters.

0.16 sounds like you lost one layer thickness... hey, is the first layer thickness 0.2 or 0.24? if it's the latter, it does not add the needed last layer.

For the cube, the initial layer is 0.12 mm, for the benchy I used 0.2 mm.

If vertical sizes are offset by a fixed amount, not "scaled", then clearly that's a proof that the Z steps/mm should NOT be changed. In fact, it never needs to be calibrated. Never.

Ok, I did not change them, I changed only the extruder steps.

try a simplified version of the cube: 0% infill, 0 top and bottom layers, 1 shell. All layers - including first 0.2 mm. That should be rather fast and should come in to less than 5/100th of a mm difference.

BTW, I highly congratulate you on providing us with enough picture material and settings to properly troubleshoot with you!

The cube with those settings (0.2 mm, 0& infill, no top/bottom layer, 1 shell) gave interesting results: X = 20.00 mm +/- 0.01 (0.02 is the caliper resolution), Y=19.90 mm, Z=19.85 mm, so Z/Y got smaller, Z is the same as with the finer settings.
Thanks for all your help, and I hope all this discussion and my post is useful for other beginners too.

Forgot to add: for X there is no ghosting with these settings, the only strange thing is a line at the Y/opposite X corner, with the height of the Y character, you can even feel it is a bumb along the edge.

Let's see what kind of errors I see (accumulated from what I commented):
Underextrusion
The legs seem rather underextruded. This could be a clogged nozzle as much as too fast printing or too low a temperature as well as too little pressure (e.g. miscalibrated extruder). Try a cleaning or a fresh nozzle, other playing with the parameter can wait after you fixed the next big issue.
To fix the under extrusion if it persists after fixing Ringing, experiment with the following settings:

Check the mechanical system. Make sure that the extruder

has no defect. I had seen a lot of under extrusion when my extruder lever broke. The gear turned but did no longer push the filament.
does press the filament well with the idler bearing into the hobbled gear.
is properly calibrated according to the physical parameters. Use the Extrusion multiplier to account for different materials.

Temperature. If extrusion comes bad, increasing it in 5 °C steps can help.

Ringing/Ghosting
The cube with the indentations shows it best: There is a massive ringing happening. This is an effect that happens when the printer changes directions fast - the printhead can't accelerate and decelerate with infinity, as it has momentum, and as a result oscillates around the new path a little, like a sinus ring. This creates a "ghost" of the preceding path changes on a flat face, which is why I asked to print a cube.
To fix Ghosting and Ringing, there are 2 software fixes:

reduce print speed.

this comes at the cost of longer print times

work out better maximum acceleration and jerk

Reducing the maximum acceleration some (down to between 500 mm/s² to 1000 mm/s²) can massively better the quality at little to no effect on total print time, and keep your print speed up.
Jerk is the derivate of acceleration; finding out the two values that might be best for your printer setup can be a lot of experimentation.

There is also a hardware design way to reduce it in many designs by shaving off weight from moving parts or stiffening up the construction:

Get a lighter printhead

remove unnecessary addons
swap for a lighter printhead design
changing to a Bowden design
in CoreXY: use lighter rails

Stiffen the construction

Adjust the mounting of the carriage in such a way that it is better constricted
change out bearings and bushings for ones with tighter tolerances
bracings can massively stiffen a portal and cube design

Height inaccuracy
This could stem from any of several sources. In descending order of likeness:

the first layer is not a multiple of the actual layers (e.g. 0.12 instead of 0.2 mm) leading to a partial layer at the top being cut. in the example this would result in a fixed negative error about 0.08 mm.
a miscalibrated first layer. Depending on your leveling skills, this can account for a fixed error of up to 0.1 mm for a bad calibration to 0.025 mm for a really good calibration. This error can appear both positive and negative.
Z-Axis inconsistencies from a misaligned leadscrew, a sticky leadscrew, or insufficient Z-stepper voltage. Both would usually create a systematic error - as in printing a given percentage loss of height. Such inconsistencies can be fixed by solving the mentioned issue: check orthogonality first, then gently oil the screw with light machine oil (not WD40!), finally increase motor voltage slightly. Only if your results are massively out of whack, you should check if your steps/mm are set correctly. But I don't see the need in this case.


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Ender-3 Pro - PLA mid-layer warping (layer separation) - salvageable?
I just got into 3D printing with an Ender-3 Pro. The test dog printed great, some custom small/thin objects printed good, and now I tried my first big object.
Designed in Tinkercad (link to my (updated) design), exported to .stl, sliced and printed using Cura 4.5.0 with the default 0.2 mm profile (3 layers wall thickness) and 100% infill (for strength), with the extruder at 200 °C and bed at 50 °C. Ambient temperature had been 25-ish °C.
The filament is a brand-new Spectrum Premium PLA (Arctic White). On its box it says it prints at 185-215 °C.
So I got this:

The top (thinner) sections look OK-ish (there are some visible lines, but meh), but the transition from the bottom sections (thick) to the top has terrible layer separation and warping problems. One side of the base is actually barely holding together when I'm holding it. There is also a smaller problem mid-way at that side of the base, but it's not catastrophic.

Why did that happen? What did I do wrong? How can I print it again and get it nice and strong?

2) I have a handheld "3D print pen". If I use it to fill the gaps manually, how strong will the part be? The part is meant to "hug" the iPad charging port, so that you can hold the iPad in the bed while charging, without pressing the cable on your body and damaging it. nvm that

Using wall thickness of 4, layer height 0.16 mm, 30% infill and 205 °C extruder, this is my (successful) result.

I also repaired that broken part. Did it for the aesthetics, but it feels quite strong.

Good deal on the successful print!

One hundred percent infill is not necessarily stronger than lower values. By having such a high infill figure, the forces on the model as it cools are magnified and not in a particularly good manner.
Consider that you could use twenty to thirty percent infill to get the strength you require for this application, saving filament and time for the print. You've not noted how many wall layers used, but for increased strength, four to five would make for a very strong model.

Thanks! There's a "wall line count" setting, I'm assuming this is what you mean "how many layers". The default (which I used) is 3. If increasing wall layers count increases strength, how is that different from infill? If I use 10 wall layers, for example, so that the whole mass is "walls", wouldn't that be the same result as using 100% infill?

@Stratubas - Yes, technically it is true you could increase the wall line count to get to this, but rarely ever would come into play. One of the problems with 100% infill is you are retaining a LOT of heat within the print itself. Because of this, it isn't able to cool correctly or quickly enough to setup. It doesn't surprise me your print pulled apart. What I'm surprised about is it didn't pull apart more. Using a 30% infill will most likely cure your ills ... you could probably go down to 20% and still get the same strength and rigidity. Way more than what you need, IMHO.

@Pᴀᴜʟsᴛᴇʀ2: Not only are you retaining heat, but if the extrusion is even slightly over the nominal amount of material desired, at 100% infill there's nowhere for the excess to go and it will necessarily exert forces that warp your print (usually even causing slop to extend upward and collide with the nozzle, resulting in the print getting knocked off the bed).

The reason for this sort of error might be either
1) a clogged nozzel, try doing this
2) disturbed bed level,resolve this issue
3) poor filament quality,

source: Stack Exchange

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

sort: votes


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Hotend on a Neutron printer: E3D vs MK8
I own a Creality Ender 3 printer, and have been printing on it for about a year.
I thought it might be fun and instructive to build a Neutron printer (https://cobyhuang.com/ATOM-Neutron) using my Ender 3 to print the parts.
The Neutron printer can use either an E3D hotend, or an ATOM 2.5 MK3 hotend.
I think that the E3D hotend is more common, so I think that is the one I'll go with.
It occurs to me that the heater block for an E3D hotend uses an M6 thread for the heat break and the nozzle. Likewise, my Ender 3's heater block also uses M6 threads.
Here is my question, it is possible to replace the heater block and nozzle on an E3D hotend with a heater block and nozzle from an Ender 3? Not that I'd disassemble my Ender 3 mind you, but it would be nice to have one set of interchangeable parts.

Welcome to 3dPrinting.SE!

Yes, but...
Technically, you can reuse your old heater block and nozzles and just buy a new heartbreak and cooling body or the other way around. However, you might run into problems under working conditions, especially if you install the heater block together with its native heating cartridge and thermosensor. Installing a thermosensor to which the printer is not adjusted to can lead to all kinds of problems - Firmware update is a must!
Another source of trouble could stem from not taking care in the change itself. The Makerbot MK8 seals the hotend by pressing the liner against the nozzle, which itself is seated against the heartbreak, just like the e3D lite6 seals itself. On the other hand an all-metal e3D v6 seals itself by seating the heartbreak against the nozzle on a larger area. If the seal is imperfect, the Makerbot Mk8 style tends to leak out through the top. Such a leak can leave plastic in the threading which has to be removed carefully before reusing.

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/


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Can you help me improve my Renkforce RF1000 print quality?
I've got a Renkforce RF1000 which should be a good 3D printer. I got it second-hand for my birthday one year ago. I've got no way of contacting the old owner.
I spend a good amount of hours fine-tuning the slicer settings last year but at best got mediocre prints. Between September and a week ago I lived somewhere else and didn't touch my printer.
Now here's what I don't know:

I don't know what parts are replaced
I don't know what my nozzle size is
I don't know if the limit switches are calibrated correctly

Though I think they are. This doesn't seem to be a problem. I did re-calibrate the Z-axis

Here are some important details:

I use 3 mm Renkforce PLA filament which I print at 190 °C on a bed heated at 60 °C. The PLA is over one year old now.
There's a fan on the motor on top that isn't connected to anything.

Here are some of the problems I've got:

I've had multiple prints failing due to the extruder not working properly. The motor keeps on spinning but the "feed knurl" remains stationary
I can't seem to get the right extraction settings
I can't seem to get my prints to consistently stick. It tends to work when I heat the bed to 60 °C and use glue and get lucky.

Feel free to give any thoughts you've got. These are the most important questions I've got:

Should I replace the nozzle with this one so that I know what nozzle I've got and so I'm sure this isn't a problem?
Should I replace the filament with new 1.75 mm PLA? If so, why?
How do I fix the extruder?

I tried getting the "feed knurl" off but can't seem to do this easily. I've got some super glue I could try to put in there but something's telling me this might be a very bad idea...

Is the unconnected fan important and if so: what do I do with it? There's no remaining wire to connect it to.
How tight should the 4 screws that hold the filament between the extruder and the rolling disk be?

For now, these are all hardware problems. I can post my Slic3r settings too but I believe the hardware should be fixed before going into slicer settings.
Here are some pictures showing the problems:

This is the extruder. The feeding mechanism can be seen in front. It shows the "feed knurl" of which the inside spins while the outside remains stationary (question 3). Next to it are 4 screws which determine how tight the filament is held against the extruder (question 5). On the back it shows a black fan, this got placed by the previous owner but isn't connected (question 4).

This image shows the unconnected fan (question 4) to the right. Behind it is the motor that's connected to the extruder. The motor works but the extruder doesn't spin with it. The extruder has a little black hole on top.

This shows the extruder from the front. The inner layer spins, the outer layer doesn't (question 3)

These are some of the prints when the extruder was still working.

Nozzle and print bed (question 1)

If the stepper spins, but not the extruder gear ("feed knurl"), you need to tighten the grub screw.

How would I do this? The gear has a small black hole on top but I can't find it's use. The manual only says this about it:
"Push the feed knurl onto the axis of the actuator and attach
it with the threaded pin. Apply threaded pin with threadlocker
varnish. The motor axis must end flush with the upper edge of the feed
knurl."

That "black hole" on top is the grub screw ("threaded pin" in the Chinglish instructions). It can be tightened with a hex key to lock the drive gear to the motor's shaft.

Be careful with Z calibration: just like the other ones, it's better if you just calculate the theoretical value and stick to it. Also, I use 5 years old 3 mm PLA (after drying it in a silica filled box) with no problems, it only tends to snap if left stretched for a while, so I remove it from the extruder when not in use

Nozzles are consumables. If you don't know the age (in "spools") of the old one, don't even ask and replace it.

Would PLA snapping when left in overnight be a sign of bad or expired filament? It's connected like this (forgot to add this detail earlier)

it can, but it also can be a bad filament path with a sharp bend.

@Stefan it's filament from over 4 years ago... and once dried at too high temperature. It prints fine, but there are likely microcracks which make the filament snap when stretched.

Should I replace the nozzle with this one so that I know what nozzle I've got and so I'm sure this isn't a problem?

It appears the default nozzle size is 0.3 mm. The linked nozzle is a direct replacement.

How do I fix the extruder?

The "feed knurl", usually called the extruder gear is attached to the stepper shaft using a fine grub screw ("threaded pin" is a bad choice of words...). The black hole you mention is the hole of the screw (it should be in there, usually an allen key or flat screwdriver should be used). Position it so that the screw is tightened against the flat spot on the stepper shaft.

Should I replace the filament with new 1.75 mm PLA? If so, why?

If the PLA has been open for a year and not stored properly it could have taken up moisture, I would buy a new spool (3.0 mm) of filament, not 1.75 mm.

Is the unconnected fan important and if so: what do I do with it? There's no remaining wire to connect it to.

The fan doesn't look as if this is a default fan, this fan is mounted onto cooling fins probably put there by the previous owner to cool the extruder stepper. Maybe the printer has been enclosed and used to print ABS at elevated temperatures. For Printing PLA cooling the extruder stepper would not be necessary as it doesn't require an elevated print temperature.

How tight should the 4 screws that hold the filament between the extruder and the rolling disk be?

The 4 screws need to be tight enough for the extruder gear to leave indentations on the filament, but not too deep.

Thank you! Where'd you find the default nozzle size? The manual on the SD card says the nozzle diameter is 0.5 mm. Would the wrong nozzle size in the slicer show significant differences in the results?

@Stefan yes - the nozzle dameter dictates directly how the print is configured. 0.5 mm in the setting with a 0.3 mm nozzle gets you a different print than having the same settings, your prints should be lacking stability.

You'll see the difference when printing. Make that a new question then. :-)

Should I replace the nozzle with this one so that I know what nozzle I've got and so I'm sure this isn't a problem?

That is not really necessary. The exact nozzle size does not really matter.

Should I replace the filament with new 1.75 mm PLA? If so, why?

No, there's no reason to do that. Going from 3 mm to 1.75 mm filament usually requires replacing the entire extruder.

How do I fix the extruder?

Tighten the grub screw (the "black hole") with a hex key.

Is the unconnected fan important and if so: what do I do with it? There's no remaining wire to connect it to.

The fan appears to be cooling the stepper motor. This shouldn't really be necessary, the stepper should be fine without any additional cooling. People tend to "upgrade" their printers by adding unnecessary bells and whistles so it is possible the original owner added this fan just because they wanted to, and not because it is necessary.

How tight should the 4 screws that hold the filament between the extruder and the rolling disk be?

Tight enough that the extruder grips the filament and is able to extrude it consistently. If it is too tight it might deform the filament too much which could cause printing problems but it should be obvious if this is the case. There is a wide margin here so don't worry about this too much.

If the stepper fan is not used, the fan should be better removed to improve cooling


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Raised lips on sharp vertical corners
I have an Ender 3 with a lot of mods.  Of note, a cheap direct drive kit, linear rails for the Y axis, an upgraded "silent" mainboard and TH3D's firmware. But this issue goes back a long ways, yet I've not seen any really good examples of this particular issue in various faqs.
All of my vertical edges, especially when they are 90°, have raised lips in a very precise, repeated fashion. It's small, maybe a quarter millimeter in diameter, so it rarely is a problem, but occasionally it messes with the dimensionality of a print with tight tolerances.
I had suspected the problem might have been related to using acceleration/jerk settings, but I disabled them for the print below and got a perfect example case.

Other things I've tried:

calibrating E-steps (I've done this many, many times, only to find the E-step number changes with speed and temperature anyway).
Deliberately underextruding.  This actually doesn't help.
Slowing prints way, way down.  Also doesn't seem to have an impact, at least down to 20mm/s.
changing slicers. This problem happens with Cura, Simplify3d and PrusaSlicer.
replacing my nozzle with a fresh one, which should have cleared up any existing clogs or leakages from a worn nozzle.

After a lot of searching on the subject, I found this bug report for Marlin, the first case of over-extruded corners I've found that look at all like mine. What I find especially interesting is that changes to Marlin around version 1.1.8 have introduced the issue for some people who previously didn't have the problem.  This seems to suggest it's not necessarily a hardware issue, but a bug in software.  I'm considering testing out a downgrade to a 3-year-old version just to see if that alone makes a difference.

If the amount of time spent by the head near the corner is significantly longer than what's spent per unit time elsewhere, you will get more extrusion at the corners and thus this effect. High print speed combined with low acceleration/jerk limits give you this effect.
Using a lower print speed should make it go away because it takes very little time to accelerate up to (or decelerate down from) a low nominal print speed from (to) the max cornering speed allowed by acceleration/jerk settings.
Using (much!) higher acceleration/jerk limits can also make it go away, but can cause other print quality problems and even layer shifts.
The Right Fix for this problem is upgrading your firmware to a version of Marlin with the Linear Advance feature and calibrating it. Then the printer automatically compensates for this issue by varying the pressure at the nozzle to get consistent extrusion rate regardless of changes in speed. I've had very good luck with this on my Ender 3, with a calibration constant K=0.6 for PLA and significantly larger ones for flexible filaments (the constant is essentially the spring constant of the filament for the length of filament path between the extruder gear and the nozzle).
If you don't want to replace the firmware, though, increasing acceleration and jerk limits and lowering speed should work ok. Your machine should be able to handle 3000 mm²/s acceleration on X and Y axis, with 10 mm/s "jerk" (the units of jerk are weird because it's not actually jerk; see my question on the topic).

I have flashed my own firmware (see above) and would enable linear advance, except it doesn't work with the creality silent board.  Searching on that topic lead me to believe this is a bug introduced in marlin 1.6, unrelated to linear advance.  I'll add that link.

Added another note about a bug report for Marlin which suggests the problem might be firmware-related.  Oddly, it's users who have enabled linear advance who reported the issue, though disabling it didn't change it.


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Partially missed / dragged layers
I'm trying to diagnose a print issue that looks like a missed layer (sorry, first-time printer here)

and

Specs:

Printer: QIDI Tech X-Plus (direct drive).
Material: PLA.
Extruder temp: 200 °C.
Bed temp: 60 °C (70 °C first layer).
Print speed: 60 mm/s (actually 48 mm/s on non-infill because of min_layer_time).
Retraction distance: 2 mm.

Started from a new printer: I was getting imperfect prints (lesser version of this, functional part) and contacted QIDI support. They eventually replied that my bed was too low but I had since lowered the bed on a misdiagnosis. They supplied a slightly modified G-code but that also failed in a similar way.
Since then, I've been raising the bed bit by bit to try to fix this issue. I don't care about the little whiskers much, but the solid "connecting lines" are a problem.
Questions:

Is this actually a bed-leveling/height issue?
What is this defect called (whatever the cause)? I've been googling but can't find something that looks like this.
Is there a better way of fixing bed height issues than just printing->tweaking bed height->printing?

I'd appreciate any help diagnosing this issue - even if it's just the name of this problem. I have no experience disassembling/looking at hardware but I could always give it a shot.
Update
As per comments I took a look at coasting and ran some tests. I first re-leveled the bed manually (I'll call that height=0). I don't want to add tons of pictures so I'll show the baseline, and "bad" refers to similar failure as above.
+--------+--------------+------------+-----------------------+-----------------+--------------+-------------+
|        | Combing      | Coasting   | Retraction distance   | Extruder temp   | Bed height   | Results     |
|--------+--------------+------------+-----------------------+-----------------+--------------+-------------|
| Test_1 | infill only. | off.       | 2.0 mm.               | 200 C.          | 0.           | Baseline.   |
| Test_2 | infill only. | off.       | 2.0 mm.               | 200 C.          | +0.05 mm.    | ~ Baseline. |
| Test_3 | off.         | off.       | 2.0 mm.               | 200 C.          | 0.           | Bad.        |
| Test_4 | infill only. | off.       | 1.5 mm.               | 200 C.          | 0.           | Bad.        |
| Test_5 | infill only. | off.       | 2.0 mm.               | 190 C.          | 0.           | TBD         |
+--------+--------------+------------+-----------------------+-----------------+--------------+-------------+

(+/- 0.05 mm height achieved with clicks of "fast leveling")
Test 1 external view:

Test 1 internal view:

Update
I think I've confirmed an under-extrusion problem. Here is a top layer printing I stopped partway through.

This looks exactly like Simplify3D's Guide. So I manually pushed through, removed, and re-inserted the filament - and cleaned the nozzle with a brush.
I then ran a new print and noticed a clicking sound in the extruder (I don't know if it's new or if I simply noticed because I was focused on under-extrusion problems) - the print failed in the same "dragging" way as above, but the top layers were slightly better.
I'm now going through the list of possible causes of clicking extruder + under-extrusion.

It looks like the layer wasn't missed but failed to adhere and instead got dragged around until it stuck in the wrong place. This might be due to underextrusion at the start of the wall line, due to having lost (oozed) material elsewhere just before starting it. You say your retraction is 2 mm. Is your machine direct drive or bowden? If bowden that's way too low; minimum is around 5 or 6 mm. Also "combing" can cause this problem.

@R..GitHubSTOPHELPINGICE it's direct drive (as per the printer specs). If combing is the same as coasting then it is enabled. Slicer coasting: coasting replaces the last part of an extrusion path with a travel path. The oozed material is used to print the last piece of the extrusion path in order to reduce stringing.. I think they're different?

No, combing is not the same as coasting, and coasting is a very harmful option and probably the cause of this. It inherently causes underextrusion (total extruded material will be less than the nominal mass of the object). Turn it off. If you have stringing it means your retraction settings are wrong, not that you want to underextrude to compensate for it.

I was just reading https://3dprinting.stackexchange.com/questions/5276/combing-and-coasting based on your first comment and was just about to give it a shot without coasting...which does seem very problem-prone. I'll update once I have a new print underway.

I re-leveled the bed to run some tests. 1st test is combing + no coasting, it already looks much better. I'll try no combing + no coasting next and then play with bed height if needed...I'll update once I have a few tests done in case other newbies come across this.

I managed to get one much better print with: combing (infill only), no coasting, otherwise same specs. But since then it started having the same problem with every variation of parameters I try (no combing, retraction distance 1.5 mm, bed height + 0.05 mm) - any other ideas apart from coasting? I was thinking maybe turning off retract after layer change?

I don't follow - with same settings, it went back to producing bad results? BTW you never answered if your printer is bowden or direct drive. That makes a difference to recommendations for this.

@R..GitHubSTOPHELPINGICE I've updated the question with results, that'll make more sense! It's direct drive.

I managed to confirm the dragged layers were mostly due to under-extrusion.
I had a faulty extruder (clicking sound) and once I swapped it out it was greatly improved.
It's worth noting I also had a slight z-wobble issue so that could have played a role.
Hopefully this can help somebody out as I hadn't seen this kind of symptom in any of the print quality guides.


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PET-G grid print problem
My supports 'grid' prints with empty spaces (after stoping extraction over perpendicular lines)
(BTW. I have checked the direction when it appears and it has nothing to do with coastig)

(the end result is: extra filament sticks to nozzle forming 'big bomb' and end up with screwed printout due to layers shift)

Printer: Qidi X-Plus
Slicer: Qidi Print 5.3 based on CuraEngine 2019/09/24
Retraction: 3 mm, 30 mm/s
Filament: PET-G Spectrum
Temperature: 220 °C
Bed temperature: 80 °C
Speed: 60 mm/s

What could be the reason? This is particularly evident on PETG.

this seems to be a result of bad slicer settings. Please tell us: what printer, which slicer variant (YES, we need to know who made it), what filament type at what temperature, what retraction length and speed you use.

Printer: Qidi X-Plus
Slicer: Qidi Print 5.3 based on CuraEngine 2019/09/24
Retraction: 3mm, 30mm/s
Filament: PET-G Spectrum

Please update the question by [edit] and add even more relevant data like print temperatures, speeds, printer brand and model, etc. Without such information it might not be possible to solve this question. After editing, we can reopen the question.

what's the print Temperature? I strongly suggest to use proper Cura instead of the Qiditech reskin - it is impossible to know which version and derivate really was used and which bugs to steer around

You mentioned coasting. Absolutely make sure that's off. Coasting inherently extrudes less material than what's needed to print the model correctly, and this underextrusion will accumulate. PETG is really sensitive to underextrusion because it doesn't self-adhere well without a lot of effort to get things right (temperature, speed, etc.) and unless/until the amount extruded is enough to adhere well, it'll just get dragged by the nozzle.
Also 220°C is way too low for PETG, and low temperatures will exacerbate this kind of problem. I'd consider 230°C the absolute minimum for PETG, and 240-250 preferable. Ignore what the filament manufacturer or vendor advertises about lower temperatures being okay; this is normally a marketing ploy to ensure they can sell to users with printers that don't recommend high temperatures or have hard limits in firmware and users who are worried about PTFE off-gassing when operating at higher temperatures (not a real issue at or below 250°C, and probably not even up to 260-275, but still common FUD). Even if they don't want to be deceptive they're competing with other vendors who do.
Further, make sure fan is off, or at least set to very low speed. Rapid cooling will completely mess up PETG adhesion. PETG is still very viscous at printing temperatures (unlike PLA) so there's no need to start cooling it right away to ensure it keeps its form.
Finally, PETG is just a real pain to print with. At first I thought it was a nice material, because it holds shape well and can stand up to fairly high temperatures (which are still true), but there are lots of gotchas and it's really hard to tune your settings to get good adhesion and strong parts. Be prepared to do a lot of experimentation beyond the things I've written in this answer to get good results if you want to keep using it.


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Inconsistent printing results using same settings but different calibration models
I've got a second-hand Renkforce RF1000 which I've gone into more detail about in this question.
The extruder works however, I get some inconsistent results. First I printed a calibration cube and noticed huge gaps in the bottom layer. Because of this, I increased the extrusion multiplier to 1.05. I noticed there still were some gaps but also other issues, I then printed one with the extrusion multiplier reset to 1.0 and a negative Z-offset. The results are shown below. In every image, the left cube has multiplier 1.0 and the right cube has multiplier 1.05.

Then, for a better idea about the consistency, I printed a hollow pyramid. This shows some heavy stringing. However, when printing a retraction test I barely get any stringing.

Does anyone know what could cause these inconsistent results? I assume some hardware tweaks might be needed, not just slicer settings. Any help is appreciated.

I use Slic3r
I use 3 mm PLA printed at 190 °C on a 60 °C bed with some glue (doesn't stick without). The first layer is 200 °C with a 65 °C bed.
After three layers the fans are enabled.
I have a negative Z-offset, it probably isn't calibrated 100 % correctly
I don't know the nozzle size (a new one is being shipped) but use a size of 0.5 mm in the slicer
retraction length 2 mm & 60 mm/s
minimum travel after retraction 1 mm

Print settings:

EDIT:
After the recommendations I've changed the following:

All belts have been recalibrated
The e-steps have been recalibrated through this method. Couldn't do a wall measurement due to a lack of precise tools.
Changed first layer temperature to 210 °C and other layers to 205 °C
Added two top layers

I printed two new cubes. One without glue and with a Z-offset of 0.05 mm and one with glue and with a Z-offset of 0.15 mm. The results are quite comparable to the original ones although slightly better. Any recommendations?
I'm aware of some cooling issues on my prints. Once a new nozzle arrives I plan on printing the current cooling system again. It's not really blowing air right effectively now.

First of all, I would try printing a little bit hotter, let's say arround 210 °C. Secondly, due to how the X and Y letters are being printed in the sides of the cube I would suggest to tigthen both the X and Y belts.
Regarding the gaps, I would first try a flow rate test. You could use a cube like this one.
Using:

extrusion multiplier = 1
layer height: 0.2 mm;
layer width= 0.4 mm ;
wall count= 2.

Then measure the walls with a caliper and you should have 0.8 mm walls. Do a couple of measurements, get the average and divide  0.8 by it  and multiply by a 100 (100*0.8/average). That's your new flow rate.
I would also try to add 1 or 2 top layers to the print.
For the first layer, I would definitely get a glass bed and use hairspray. The bottom of the pyramid doesn't seem to be sticking well. Apart from this, I'm not really fan of using Z-offset. Just try leveling a couple of times manually with a paper to get it right.

Also, for stringing try changing the retraction length to 5 mm and ~30 mm/s. See if in your slicer you can turn on the 'Combing' option

" to how the X and Y letters are being printed in the sides of the cube". How do you recognize this is printed incorrectly and the belts need tuning? Also I've got a heated ceramic bed, shouldn't that suffice? I don't see why a glass bed should be needed

Okay keep the ceramic bed, but try changing glue for hairspray, I really got better results... For the X and Y letters there's an artifact called ghosting/ripple. Here you can see what's about: https://www.youtube.com/watch?v=KaFp6Eqk0QI
Anyways, I think your main issue is flow rate... Try calibrating both this and E-Steps and send new pictures

Thank you but due to the bed being in an enclosure and being connected by wires I prefer to stick with glue as long as it works. I've uploaded some new prints with the other recommendations in place. Could you give your opinion?

I think it's much better, first layers and side walls are looking nice. Anyways, you will have to do a flow rate calibration (See the blobs in the X and Y letters)... Get a cheap caliper, it will worth it
I think you're getting close to solving the problem. You'll just have to find the right slicing settings which is not that easy. Try printing a little bit slower

The problem got worse now that I've got a new nozzle and filament. It seems to be caused by the extruder. I've dedicated a new question to this problem. Thank you for the feedback, it did really help in improving the other problems and slicer settings.


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Getting a programatically-controlled, constant 12 V from one of the motor outputs
I'm building a device that requires five 12 V valves to be programmatically controlled as a switch. So far, I have been able to get outputs from the heated bed, extruder, and fan to be controllable through Marlin, by defining "SENSITIVE_PINS" to be an empty array. I can now use M42 to switch these pins on and off, allowing for programmatic control of 3 of the 5 valves.
For the other two valves, I'd like to control these directly from the 3D printer board somehow. I noticed the A4988 driver will rapidly flick a 12 V output on and off according to the microstep setting (https://lastminuteengineers.com/a4988-stepper-motor-driver-arduino-tutorial/). But this type of flicking is not really good for controlling a valve, because I want the valve to remain open until I say  "stop".
What I would like is to be able to use the M42 to command to administer a 12 V output on or off from the motor section of the usual boards. The A4988 driver takes in inputs like Enable, Step, and Dir from Arduino pins. Is there any way I can "hack" the A4988 driver to provide a constant voltage, similar to a relay switch? Alternatively, can I remove the driver and do something with the female pins that are normally used to connect to the A4988 driver?
In researching this I have noticed that when removing the driver, you expose some more 12 V female and GND pins on your board, which can provide an easy connection to a third-party relay or h-bridge. But ideally, I would be able to do this without adding any new hardware to the board.
This question is on-topic because it has to do with 3D printer boards that are currently on the market and because it is ultimately a device that is used to 3D print something.

Use the enable pin, you can solder a wire directly to it. You control it by giving any movement command and by disabling that stepper output. The same applies to the direction pin: give a movement in a direction to turn it on, send a movement in the opposite one to turn it off

@FarO The enable pin doesn't give out 12V so that doesn't address the problem. You can also just use M42 to address the pins directly.

It is easy. Leave the driver in. Connect to the first two wires usually used by the motor output. I.e. this is usually where the nema 17 motor goes. The first two wires are your output to the valve.
Use M42 to control the ENABLE pin. Bringing the pin high creates a 0V output. Bringing the pin low creates a 12V output.


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How do the MAX endstops work?
I’m building my new 3D printer and I have a doubt. I’m using limit switches on the 3 axes, but only the MIN switches. I also have another three switches which I want to use as MAX switches. How can I do that? I mean, if I insert a specific measure of the plate in Marlin and than the extruded stops before of the limit of the plate due to the MAX endstop what will happen? What should I do, upgrade to MIN and MAX endstops or only keep the MIN ones?

Most boards lack contacts for MAX.

You should see MAX endstops similarly as MIN endstops, or as an additional option to protect the printer:

Similarly seen as MIN endstops, you would define in the firmware that you are using them to set a reference point at maximum values, your offsets and bed dimensions would be calculated from the MAX positions;
You can configure the MIN endstops and have additional MAX endstops set beyond the bed size dimensions. If the printer would encounter a layer shift causing the nozzle to go beyond the printer (MAX) boundaries, the printer shuts down when the MAX endstop is triggered.

Ok, thanks. So i can’t use both of them in one axis? I think i’m going to use only the MIN ones

@Valeri0S As explained in the answer under 2. You can use them both. But don't put them at exactly at the maximum axis positions according the bed size, put them a little further, then they will act as safety stops in case of layer shifting occurrences.


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Enable pins with RAMPS and M542T stepper drivers
So, I've been building a very sturdy 3d printer (also in the future hopefully a cnc router), strongly based on this: Arduino Controlled CNC / 3D Printer Hybrid
I'm using a RAMPS (1.4, will upgrade to 1.6 in a few days), M542T drivers and NEMA 23 motors, I got everything to work pretty well already, but so far, I haven't connected the motor enable pins from the RAMPS to the drivers. But, I don't actually get what they are good for, I think I know what they do, when a signal is sent to them (sort of lock or unlock the movement of the motor), but the printer looks to be working fine. Still, I wanted to connect them just to have everything made properly.
I found a problem, when I tried to connect enable pins, I'm not using stepper drivers which plug into the RAMPS, so I have to run cables between them. When the X/Y/Z_ENABLE_ON in marlin are on 0 (active low) are set, everything works, well as it should I guess (or inverted I'm not sure if the M542Ts need high for enabling the motors or low), I connected the pins and when I try to move any axis, it doesn't, when I disconnect the cable the given axis moves, so I was thinking that they need high signal to work. Went to marlin, se enable_on to 1 (active high), went back, had everything connected, everything moved. But, I tried to disconnect the individual wires to see if it works as it should (when disconnected the motors shouldn't turn when given a signal I thought). The X axis moved when enable was connected or disconnected, Z also, Y one motor was moving regardless of enable connection, 1 behaved even weirder, moved in only one direction. I have pul+, dir+ and enable+ connected to 5V, pul-, dir-, enable- to the RAMPS as in this:
https://3dtoday.ru/upload/main/b03/%...%B0%D1%802.jpg
Tho I have also seen it the other way somewhere, like this:
http://1.bp.blogspot.com/-qvM7BrO1wE...mps_TB6560.png
(the M542Ts have 5V in parenthesis next to the pul+, dir+ and ena+ inputs, so I thing the way I have it right now I have it correctly, but I don't even know what could be wrong to be honest)
How would I get these to work correctly?
Can you better explain to me what they actually do? Also, could you perhaps help me a bit with the connections and Marlin settings to get them to work for the bigger drivers?

Welcome to 3dPrinting.SE!

Please check the links. You have supplied truncated (...) links which clearly will not work. I have (hopefully) fixed the first one and pointed it to the correct Instructables page. If people can't see your images then that will reduce your chance of getting a good answer.


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How to access BIGTREETECH firmware
I recently purchased a BIGTREETECH SKR mini E3 V1.2 and need to adjust some of the settings in configuration h to accommodate for my custom built 3d printer. In the past I've used the RAMPS 1.4 board and adjusted the firmware in the arduino IDE. What is the best way/recommended way to do this for the mini E3 V1.2.
Thanks.

Basics
Firmware can be distributed in 2 ways:

As a compiled file (for example as .hex).
As an uncompiled repository (as in a preconfigured marlin distribution) that needs to be compiled at the users' side.

compiled file
Compiled files can't be altered easily. The only way to change settings after installation is to send the correct commands via a console to alter the settings in the SRAM then save the new settings into the EEPROM via M500 from the M50X family of commands - and hoping that EEPROM was activated in the firmware to begin with.
uncompiled distribution
To alter an uncompiled Repository, you can follow the basic path in Updating Marlin Firmware - Step by Step Guide

The previous answer is good, but here's one specific for Bigtreetech.

Install platform.io. I use the command-line interface (CLI)
Modify your marlin files. You can clone existiing firmware for your board from the BigtreeTech Github for your board.
Remove microUSB card from your Bigtree tech board
Plug microUSB card into microUSB reader, and the microusb reader into the computer. You should be able to read your microUSB card
Enter the command in the root directory of your Marlin files: platformio run -e STM32F103RC_bigtree_USB. At least, this is the one for my board. You should have to run this in one folder before the Marlin folder.
It creates a file called firmware.bin in the directory .pio/build/STM32F103RC_bigtree_USB/firmware.bin. Copy it to your microUSB card, replacing and deleting any existing .bin. You can use the name firmware.bin.
Remove microSD card from computer and plug into board.

In your Marlin Configuration.h file, there should be a variable called something like MACHINE_NAME. If you make that name custom, then it will appear in the Octoprint terminal when connecting to your board, letting you know that you have updated the firmware.


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Empty patches with a very viscous resin
I have a Mars-like 3D printer, which so far worked very well with typical resins. Then I decided to print a mechanical part with Siraya Blu. I followed their recomendations of a "heavy" support, which means columns of a diameter of 1.2 mm minimum. The setting are 14 s (60 s) exposure, 60 mm/min (40 mm/min) lift/retract speeds, in parentheses the bottom layers.  Temperature 25 °C, the printer is leveled.
The object would have an even, well-defined resolution everywhere if there weren't some large "empty patches" directly below the support platform and of the height of about 1 mm, that damage the support structure, which in turn warps the printed object. The photo shows the problem. Everything prints very well apart of the inside of the blue patch, where the flat part of the platform is perfectly empty, no columns, no platform fringe, the flat part itself prints as it should (and sticks well to the build plate). The stray fragment of a column is a left-over after cutting off the platform with a knife.

The patch has crisp borders - outside, the columns are well printed and precisely round, inside the patch there is just the flat support part, followed by the object warped because of the momentary lack of support (the support shows again a millimeter or so later as round islands, the black arrow points to one). The object's layers gradually self-correct and print with the same high quality everywhere, inside the blue patch or not. So I assume the FEP film is okay, as the empty patch has only about 1 mm height and above/below it the precision is very good, as seen within the cyan ellipse. Also, other resins (all much more fluid, Blu is very viscous for the extra toughness) print with no problems.
There are 2 or three similar empty patches in this print elsewhere, but this is the largest one. Any idea what can it be? Trapped air bubbles? I did several tests with different settings, the problem persists. I increased the exposure time to 18 s and cannot increase it even more as this resin has a tendency of a "remote polymerisation" of overhangs. Changing lift/retract speeds does not help or help minimally, but I didn't go below 40 mm/min. Siraya Tech's recommendations are verbose but say nothing about the retract speed anyway. If these are bubbles, why the flat part of the support platform prints everywhere? To see if it has something to do with the bottom layers I tried different numbers of them, but the problem always starts exactly below the flat part, and not few layers sooner or later.


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Multiple objects on build plate
I'm new to printing resin miniatures for Dungeons & Dragons and most of my prints are successful, i.e. one or more miniatures print as expected.
However when I have multiple minis on the build plate the one in the middle works okay but the ones on the edges don't adhere to the build plate.
Should I limit myself to one or two minis in the center of the build plate? Or should it work and I just need to get my settings correct?
Note I'm using a Beam 3D Prism printer.

Welcome to 3dPrinting.SE!

You can definitely print full build plates of minis. You just need to find correct settings. If nothing sticks to the build plate - then you should increase bottom exposure time. Also check if the build plate is even. You can also sand your build plate a little bit to make adhesion better. Additionally, print with lower print speeds to increase success.
Finally, if your FEP is worn out and scratched or hazy, you should replace it.
I own a company producing 3D printing resins. We also write extensive printing guides from time to time. You can read more on finding correct settings in this article of mine.

Thanks for the comment. I'll update the answer to make my affiliation clearer.

Check the plate and be sure that it is level. Also, you need to check that your model is level.
The problem will be in the settings if everything is level.

You can fill the plate as much as you want, as long as the playing figure is not at the edge of the plate (can create problems).
The problem could be that the plate is too smooth or that it is not perfectly level.
If the plate is too smooth you could use some sandpaper to make it rough.

I regularly print multiple models on the build plate of an Elegoo Saturn. If your built plate is level and your tank is firmly fastened down you should have no problems.
What I have found is the my slicer (Chitubox) will sometimes corrupt the base layer if I print multiple models. With me this usually causes the bottom layer to be deformed, and to have jutting protrusions that were not on the original layer, or for the slicer not to recognize the base layer as being flat.
The second picture shows an example of how the skate or one model was deformed. The small pieces of cured resin are corrupted data and aren't part of any model or support structure. They were not visible in Chitubox unless I manually rotated the object view and saw little visual glitches.
I would advice that you check your sliced files.
See the example image:

sounds like an old version oc the slicer

No, it's the latest stable build. But it's not my thread.

Open your file in your slicer, and set it to only view the bottom few layers. Spin the view around several times and view it from different angles. Look for odd shadows or lines.
If it looks anything like the below image then the problem isn't with your printer, it's with the file that you've just sliced.

For some reason the slicer no longer sees its own raft as being flat, and it is creating floating geometry that sometimes breaks loose.
I've found that I can sometimes resolve this problem by reducing the size of the raft. About 105% usually does it for me. Otherwise the problem might be the geometry of the models that you're printing. I tend to print off models that I've made myself, so it's quite possible that it's something that I've done, or the way that I've exported the STL files.


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How to make a printer bed vibrate using g-code (heated chemical stirrer)?
I was just about to start using my 3D printers heated bed to warm a chemical reaction in a container and was thinking it would be great to be able to get the bed stepping back and forth to stir the pot.
Can anyone already up to speed in programming G-code walk me through a quick and dirty way to get the X-axis on my old Printrbot metal doing a couple of micro-steps either way in an endless loop? Or suggest some software out there that could achieve the same effect?

Basically you need to write a G-code file yourself. This is a plain text file with a .g extension.
You need to home the printer with G28, then move the Y axis all the way forward (for a Prusa style printer) with G1 F1500 Y{ymax} (where {ymax} is the length of the bed). Now raise the head with a similar command G1 F500 Z{zmax} (where {zmax} is the height of the printer volume).
Heating the bed is done with M190 S60 (set and wait to reach 60 °C).
You can now rock the Y axis by moving it fast, e.g. with G1 F5000 Y{ymax-5}, G1 Y{ymax-1}, Y{ymax-5}, Y{ymax-1}, etc.

Stefan from CNC kitchen already did it: https://github.com/CNCKitchen/3D-Printer-Vibration

Never mind, figured the quickest dirtiest way myself - created a tall thin cylinder shape model in Blender and positioned it in Repetier so the printer head will be clear of the table as it moves. Then just broke off the filament that was currently in the printer so it will stop feeding once the current piece gets to the end of the feeder wheel. - not an endless loop but should give me a good 10 or 20 minutes of agitation before I need to restart the print if necessary.


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How can I determine the current value of a #defined variable?
I previously set up my Ender 3 with a precompiled binary of Marlin that already had the correct X and Y offsets for the attached BLTouch. Now I'm compiling my own, and rather than measure for myself I'd like to just use the same numbers.
When I send M851 through the terminal, it gives me the current value for the probe's Z offset from the extruder. I know I can also use M851 to set the X and Y offset, but there doesn't seem to be a way to read the current values.
Is there any way to query the printer for the current values of X_PROBE_OFFSET_FROM_EXTRUDER and Y_PROBE_OFFSET_FROM_EXTRUDER? Or, ideally, for any other arbitrary variable?

"#define" is a feature of the compiler preprocessor and isn't a feature of Marlin. So there is no general way to recover the value of a "#define variable" (which isn't actually a variable at all) unless Marlin explicitly provides the option.
In the current version of Marlin M851 will report the X and Y offsets. It appears you have an older version which does not do this. In older versions there appears to be no option to recover the value.


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Titan extruder retraction noise
I am experiencing some retraction noises with my Titan Extruder. At first the noise was more of a clicking noise, and the gear was skipping. I didn't feel any backlash with my finger but I still followed the official troubleshooting guide on backlash and the noise has changed to some sort of buzzing, with print quality noticeably improving.
I should mention I recently upgraded my stepper drivers to TMC2208, extruder set to 1.31V. May be too much but I know the extruder motor needs a whole lot of torque, either way it doesn't run too hot so I'm keeping that for now. (If anyone knows how warm should a motor feel during normal operation let me know.)
I have two videos of the noise before and the noise after. I can't tell where this noise is coming from, I have never heard weird motor noises before so I can't tell if it's still the extruder or if it's the motor. I can't tell if it's normal.
I tried feeding filament in and out with GCode to find out the feedrate at which the noise goes away, and I found that anything above F2200 makes it do this noise, otherwise it's a pretty normal noise.
Before:

After:

I am new to 3d-Printing and am having my printer start to make the noise you display in the after video. If I understand your post, your saying that this is a normal noise and shouldn't be worried about? really appreciate any input! thanks!

Oh, oh no, do worry about this. My buzzing eventually was gone and never came back, returned to just clicking. And retractions started failing 90% of the time causing terrible layer defects and lack of precision. E3D refused to acknowledge this and claimed I was doing everything wrong, but I think they just didn't want to refund the defective extruder. Overall it's a poor design, it relies on the mounting bracket to properly assemble, even.
Switching to the standard extruder (which is cheap and crappy) yielded accurate printing again.
All of this was caused by stubborn gear backlash.

The question has been reverted to the original edited question, please answer in a separate answer below. Please try to be objective so that is doesn't come over as a rant.

@GuidoBelluomo It might be that a different current limit was needed for the extruder motor.

@Andrew Morton It was not skipping steps. The gears were skipping, backlash was confirmed by doing the gear wiggle test suggested by E3D.

After several email exchanges with the customer support, I was not able to find an answer. It was stated that it may have been my assembly and/or extruder mount, but I'm strongly against that after so many times reassembling.
Gear backlash ended up becoming permanent.
I ended up switching over to something else with a more self-sufficient design and less variables.


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How to interpret Trinamic driver continuous debug reporting?
In Marlin one can enable continuous debug reporting of Trinamic drivers with the command
M122 S1
This sends lines similar to the following over the serial connection:
X:93/28/0||    Y:35/14/-|IF|   Z:54/28/0||    E:176/25/0||

Each driver appears to report three integer values and some flags. I understand the F flag indicates an error state, for example the overtemperature pre-warn condition (OTPW).
What do the other values mean? How can this information be interpreted to debug printing problems or improve performance?

In the Marlin source code I found the function responsible for the report logs: report_polled_driver_data in Marlin/src/feature/tmc_util.cpp.
The values indicated appear to be:
<Axis>:<PWM scale>/<Current scale>/<StallGuard>|<Flags>|<OTPW count>

Where possible flags are as follows (where “debug” indicates that they only appear if TMC_DEBUG is enabled):

E: Error
O: Over-temperature
W: over-temperature pre-Warning
G: stallGuard (debug)
T: stealthChop (debug)
I: standstIll (debug)
F: otpw Flag


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Zortrax m200 skipping through menu options on it own and live print bed
Out of the blue I’ve noticed my m200 has been skipping through menu options as if someone is pushing and scrolling the control knob randomly. Then getting a print off today I got several small electric shocks off the print bed through the spatula. Does anyone have experience of this or to I have a £1500 paperweight?

This sounds really concerning.
Instantly remove the machine from the power and check EVERY wire if it might be broken!
Check if your power supply is properly grounded!
Check if the connectors of the bed are undamaged!

I have done and nothing is obvious. I might try it on a different power loop. I’ve only been able to find one other case online of the bed acting live but not the menu skipping.

@JamesB the buttons might be borked. Or your grounding line might be damaged - or not connected to the house ground.


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First 3D print made up of diagonal strands
Just got a Creality Ender 3 yesterday. Set it up and ran the dog test print. Photo below.
I used the sample filament that came with the machine. I'm not 100 % what kind it is, but assuming it is 1.75 mm PLA.
No matter what temperature I set the end and bed, when I launched the print, it would change to 200 °C hotend, 45 °C bed. Is that because the two temperatures are set within the gcode file? Do I need to set a higher nozzle temperature? And to do so, will I have to alter the G-code file?
Does the head need cleaned? I did try some blue ABS I bought, and didn't work, so I switched it to the sample filament. There was still some blue ABS in it, but seemed to be gone after a few seconds after the extrusion turned pure white. But might there still be some ABS clogging or slowing the filament?
EDIT: When I ran the test file with ABS, the material didn't adhere to the bed or itself, just created a jumbled bird's nest of spirals. Then I found something online that I needed to use the temperatures on the ABS spool. I set the temperature to 245C nozzle, 100C bed. But as soon as I ran the print, the nozzle went to 200 and the bed 45.
Is the motor that moves the filament moving too slow?
Is the head moving too fast?
Should I use a glass bed?

This is a very common problem lately, it is either related to wrong filament diameter (not in your case as is is a pre-sliced model) or the printer is set to volumetric printing. This can be changed through the display interface. See this answer.

When I go to Fillament, I get: E in mm3: On; Fil. Dia. 1.750

E in mm^3 should be off! That will fix your problem!

Based on your comment to the comment of 0scar:

When I go to Fillament, I get: E in mm3: On; Fil. Dia. 1.750

That's almost surely the problem. Unless the model was sliced for "E in mm3", this setting needs to be off. What it does is change how the printer interprets extruder moves in the G-code: rather than in linear mm of filament to move, as volumetric mm³ to extrude.
At 1.75 mm diameter, that's a factor of 2.4 mm³/mm, so you'll only be extruding 1/2.4 = ~41.5 % of the material needed. That extreme underextrusion will give exactly the effect you're seeing.

Thanks for answering! That is exactly what I was aiming to find. Lately, the "reasonably priced" Ender 3 printers seem to have caught this issue just out of the box...

sounds like they use a messed up marlin latey...


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Diagnosing why the left side of a print detaches from the board
I have and Ender 3 Pro, which I'm enjoying except for an intractable problem. No matter how carefully I level the nozzle and tighten the X belt, using this great guide, the prints seem to be tilting to the right, particularly if they're tall. I realize this is a common problem, but I'm at a loss for what it's called and where the problem is most likely to be.
The first sign of trouble in paradise is that, after two layers of a simple rectangular base for a Galton Board I'm trying to build that uses sand, the right side is clearly thinner than the left:

This is with a translucent Overture PETG filament, 1.75 mm.
For the board itself, which is about 15 cm tall and looks MUCH better if printed vertically, I notice after about 3-4 cm that the bottom of the left side is becoming detached from the bed:

This gets progressively worse as the print goes on:

The entire Galton Box takes six hours to print using the default PETG settings in Cura for a default level of detail, so I'd really prefer to find a way to diagnose the problem sooner. I know this is not a new problem, but I'd be grateful for any guidance on what it's called or links to how to fix it -- and how to determine if it's a hardware problem or not.
Also, out of curiosity: If the machine isn't PERFECTLY level on the table -- my work desk appears to slant by about 2° -- could that be implicated?

The level of the table top has nothing to do with the levelling of the printer, nor with the leaning of your prints! You're just having adhesion problems, use a specific print adhesion spray or a hairspray or glue sticks.

Thanks! Would that explain the uneven level in the first photo?

The uneven level is explained by the unfortunate choice of the printer manufacturer to not have a second Z lead screw. It is pretty difficult to level these printers, it is all a combination of the correct X belt tension and roller tension. The uneven level in the first picture is what is causing your print to detach, As can be seen you've got a lot of "squish" on the right side, but less adhesion (seen by the less transparent color) on the left, therefore it would fail on the left.
You need to:

level better,
fix the skew XZ gantry or
use an adhesive (and/or a brim).

Please note that the level of the table top has nothing to do with the leveling of the printer, nor with the leaning of your prints. You're just having adhesion problems as a result of an uneven bed/gantry.

Thank you! A combination of meticulous leveling, brimming -- actually, skirting, just to be safe -- and a gantry adjustment has improved this a lot. This YouTube video was a savior: https://www.youtube.com/watch?v=36u4gberzC8

On curious thing I noticed was that, when a fully tightened (lowered) each corner as a starting point, as the video suggests, the back left corner was about 4 mm higher. I noticed there's a piece connected to the adjustment rotator on this corner below the bed connecting a cable, but it's only being held in place and limits the freedom of the adjustment.


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BigTreeTech mini e3 V1.2 endstop installation
I recently purchased a BigTreeTech mini e3 V1.2 controller for my custom built 3D printer (as opposed to an pre-purchased ender 3). In doing so, I ran into the problem that the endstops I have been using have three wires: Power, Ground, and signal. The mini e3 V1.2 that I purchased uses endstop connections that only have two pins. This can be seen in the schematic below on the bottom right of the controller. I don't know where to buy endstops that only have two pins and have not been able to find anything online. If anybody knows where these can be bought or how the 3 pinned endstops are supposed to be wired up it would be much appreciated.

You do not need to connect the red (+) wire of the endstops. The controller board uses a technique to ensure the signal is 3.3 V or ground, see the top left schematics of this link (will insert an image later!). Specifics about this technology is found here and is explained as using a pull up resistor.
What happens is that the signal is always reported as triggered, unless the endstop connects the signal wire to ground.
This link shows that only ground and signal are required (will insert an image later!).


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Are stepper flex couplings important? How important?
TL;DR:
On my particular printer design, it definitely appears the company switched from flex couplings to solid couplings on purpose to improve the printer, and to prevent well-meaning users from adjusting the previous flex couplings. Whether or not this is a good design overall, is left for the reader to decide. It's certainly simple and cheap to use the motor itself as one of the leadscrew thrust bearings, but in the future I might add a micro-adjustable bearing block in place of the motor, and then couple the motor to the leadscrew with a flex coupling. That would be more typical of the way it's done on CNC machines, where the stepper bearings are isolated from any machine loads.
Original post: I bought a Artillery X1, supposedly the latest V4 version. It's my first printer, but I have experience with CNC machines. Although the pictures and YouTube videos all show the Z axis steppers connected to the leadscrews with flexible (spiral type) couplings, the printer I got has solid couplings.
I thought flex couplings were important to prevent binding, so I was going to buy some flex couplings. But as I look at the printer, it appears the leadscrews actually are supported by the stepper motor itself at the bottom...there are no thrust bearings, so the weight of the printhead is supported by the stepper motor directly through the coupling. Since the spiral flex couplings can compress slightly, is the use of solid couplings deliberate in order to make a more precise machine? If I install flex couplings, will it make my printer worse by introducing "spring" into the system? Is this a typical design, or do other printers have thrust bearings or "hang" the leadscrews from the top?
There are a lot of reviews and videos about this printer where people noticed the leadscrews were internally touching the end of the motor shaft inside the coupling, and people thought that was wrong, so they spaced them back apart. Now, I wonder if the shafts touching was a deliberate design decision, and maybe the company even switched to solid couplers to prevent people from adjusting the couplers back. Please help me solve this mystery of the solid motor couplings.
EDIT: I found a related application where the axial rigidity of the stepper couplings matter. In the following YouTube video the author deliberately jams together the lead screw and stepper shaft in order to eliminate spring from the flex coupling. This tends to solidify my theory that this printer uses solid couplings deliberately, and other printers with similar Z axes could potentially benefit as well. The X1 uses floating support bearings for the X stage to prevent binding, which probably helps.

Also, in this YouTube video the author describes how he deliberately decided to use rigid couplings on this printer to improve his Z axis and references other sources which come to the same conclusion.

Yes and No
Let's start with the obvious: Flex couplings or rigid couplings are a deliberate choice in designing the printer. Each has its benefits and drawbacks. So let's look into the 4 types of drive-train setups that I know to be possible:

Spiral couplings make it possible to operate the machine with a slightly misaligned motor to the shaft (<1°) but can add a measurable slop, which can be seen as a systemic error.
Rigid couplings have minimal slop but need to be much better aligned by the user in setup.
No coupling at all - direct drive to the shaft - has no slop at all, but is both more expensive and needs the most diligent work on setup.
Geared. You could couple the motor with the Z-Axis via gears, allowing to trade speed for detail and vice versa. It also can allow mounting the motor 90° to the printer, but it also adds some backlash and slop. Because good gears are expensive, this is really rare.

Using spiral couplers right
A spiral coupler can actually be used in two ways:
Keeping the leadscrew tensioned into a position.
This butts both parts together, it reduces the slop induced by the coupler to the minimum, but you need to forcefully make sure that the parts push together. You lose some of the misalignment-correction.
Decouple vibrations from one shaft to another.
This keeps a little gap between the two. The slop can be larger, but you get the benefit of the shafts on both sides not transmitting all the vibrations 1:1 to the other shaft and you get more self-realignment if the motor and shaft are not perfectly coaxial.
What is better?
Well, it depends. If you want the perfect drive, you'd go direct drive. If you want the finest motor control (by virtue of getting the steps to a much smaller rotation), you might use gears. But the spring-coupler allows you to do the setup easier for a consumer that might not be the most reliable in setting it up himself. Making the spring-coupler butted can increase repeatability and reduce slop to almost the same as a stiff coupler but not lose the ability to have a slightly crooked setup that still works.

authors: Дмитрий Бинат


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Using 2x CAT6 cable for 24 V hotend
I'm looking to replace the troublesome ribbon cable of my Duplicator 6 with a 2xCAT6 arrangement for all things extruder.

Are 4 26AWG wires (2 sets of 2 twisted pairs) enough copper for 50W heater at 24 volts?
Are 2 26AWG wires (1 set of 2 twisted pair) enough copper for the ground connection of the heater?
Can I consolidate ground connections of the low power fans/sensors to free up more wires?
Is it okay if I have some pins be 24 volt like for the heater and others be 12 volt for the fans?
Should I get a lower gauge CAT6 cable like 24 AWG? 23 AWG seems to exist too.

This question might be more appropriate at EE.SE. Why all the cables when a pair of AWG 18 or 16 will be enough?

Well the cat6, if only one is used, is already held together, without having to tie many cables. Of course if two are used, then no real advantage

Do not consolidate ground wires, use as many as the positive ones. In fact, use one wire of each twist for ground and one for the related positive, so that they balance each other.
Mixing voltages is fine, the CAT 6 cable will hold 24 V fine.
Concerning the number of wires, you should check the allowed current per wire and calculate the required number of wires.
Each pair can carry 0.36 A. 50 W is 2 A, you need 6 pairs for the heater.
You get two spare pairs, which can carry in total 0.7 A at the voltage you prefer. You could use two for the thermocouple and two for the fan, or two different fans.

Thanks for your answers! I added one more question that might be key. I think I designed the arrangement based on 23 AWG but when I went to buy them, found 23+24 AWG elusive.

Well you get the principle, you can check the current rating of 23 AWG and you can see it's twice as much. Then you have only a spare pair, so only one fan.


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Need sanity check debugging non-functional extruder
This is the same machine involved in this question: ender-3-pro-extruder-stepper-skipping-with-a-chunk-sound.
After reassembling the extruder, I discovered that the extruder stepper did not move, using prepare->move-axis. All three axis steppers did move normally.
The first thing is did to test was to exchange the wires to the extruder and X-axis steppers. After this the extruder stepper moved when I moved the X-axis but the X-axis did not move when I moved the extruder. Therefore, I concluded that the stepper is working.
I then opened up the main board chassis and exchanged the X-axis and extruder cables there (so the cables are exchanged on both ends). This restored operation to the X-axes (operated as such) and the extruder did not function again (operated as such).
From this, I concluded that the cables are also fine and I had somehow blown the extruder driver on the board.
I went on Amazon and ordered a "silent" Ender 3 Pro motherboard, rev 1.1.5 to replace my current rev 1.1.4 board. I just received the new board and, as far as I can tell, it looks like an authentic Creality product. The only visible differences between the old and new boards are the silkscreened version and the color of the PCB itself. Both are labelled "Ender 3 Pro" on the back.
I carefully removed the old board, marking where all cables connect and swapped in the new board. Much to my distress, everything acted exactly the same. The extruder stepper did not turn. Swapping the cables at the steppers restored functionality to the extruder (controlled as X-axis) and the X-axis did not move (controlled as extruder). Also swapping the cables at the motherboard restored the X-axis stepper (controlled as such) but the extruder stepper would not move (controlled as extruder).
I should add for Completeness that my printer was sold by Sain Smart (Creality OEM, I believe) and was labelled as such, both on the metal and on the LCD start screen. However, the motherboard was a Creality3D board, labelled as "Ender 3 Pro" and I believe the only actual difference is the text inside the firmware. With the new board in, the LCD identifies itself as "Creality Ender 3 Pro".
At this point, the only conclusion I can come to is that the new board has failed in the same way, which doesn't make any sense.
I need a sanity check. Does anyone see any flaw in my logic?
I should add that there is an oddity on the new board. The fan on front of the hot end seem to run at full speed and the hot end side fan and chassis fan run briefly at power up an then stop. Using control->temperature->fan-speed seems to have no effect on any of the fans. I never observed the chassis fan with the old board so I cannot say this is different but I did previously have control of the hot end fan.

The extruder motor will not turn unless the hotend is at a certain minimum temperature. This is a safety feature to prevent the extruder from grinding through the filament with a cold hotend. You can use the M302 command to control this behavior.

Thank you. I had just figured that out myself and was coming to post my own answer. I guess I’d never operated the extruder with the end cold before. Makes perfect sense and I’m kicking myself for not figuring it out earlier.


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Printer not processing G-code properly?
I have 3 printers, all Anet A8 with RAMPS 1.4 boards running identical firmware. One printer, however, has a Bowden extruder setup and RepRap 3 pin limit switches. Otherwise identical to the other 2 printers.
I'm mass-printing face shields, and I sliced the STL with 2 brackets at 180° angles and offset like so:

I'm trying to print this same G-code on all 3 printers. Same dimensions, same filament, etc. All 3 printers are on OctoPrint (separate Raspberry Pi devices)
However, on my 3rd printer, it's doing weird things. It will print the first layer of the frame facing the back. But when it goes to print the 2nd one (that's facing the front) it prints it right on top of the first one instead of offsetting it.
I noticed that the printer was starting off about 20 mm to the right. My initial thought was the X-axis was going past it's limit to the right, skipping the belt causing the 2nd piece to offset to the left. I corrected that by adjusting the #define X_MIN_POS to compensate (the only change in firmware between the 3 printers). Now it is printing centered as it should, but still trying to print both pieces on top of one another. I watched the printer until it hit this failure and can say for absolutely certain it's not going past its limit. It didn't even try to move over and print the 2nd piece properly.
I also tried printing another file and it would randomly offset toward the front on the Y-axis.
I have also checked to ensure my belts are snug and not skipping.
It sounds wrong to me, but it's almost like the machine is receiving the proper G-code but not processing it properly. Either that or something in OctoPrint is out of whack.
I've also attached the output from the terminal window in OctoPrint. I understand the commands, but darned if I can find where the error is occurring. I stopped the print right after it started to print the 2nd piece on top of the 1st.
Edit:
I forgot to include in my initial post the terminal output: pastebin.com/iEA8bNH9
Edit 2:
Adding image of behavior

The default X offset from home position for the Anet A8 is: #define X_MIN_POS -33. See also How to center my prints on the build platform? (Re-calibrate homing offset).

or look at an ender-3 specific one that has some more explanation... https://3dprinting.stackexchange.com/questions/6399

The print is now centered by adjusting the firmware. However, it is still overlapping both pieces.

Can you add an image of what is happening?

@0scar - Added picture. This time, it is randomly offsetting in both X and Y...

This looks a lot like layer shifting, could be a mechanical issue.


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Can any filament be used in with any 3D printer?
I recently heard that the 3D printing lab at my college can do fused-deposition with ABS and PLA, but I would like to use TPU, for greater flexibility.
Is it possible to feed a TPU filament into the same machine built for ABS/PLA? Or is there no difference? Assume the diameters of the filaments are the same.

Are you referring to fuse TPU to ABS?

@0scar No. I meant if the same machine can be loaded with any filament.

Is it possible to feed a TPU filament into the same machine built for ABS/PLA? Or is there no difference? Assume the diameters of the filaments are the same.

The question is not what the machine is built for but how it is built. Let's break stuff down some into why some filaments work better than others and the challenges with them.
Temperature range
The first obstacle is the temperature range of the printer. For example, if your printer's Extruder can't get over 220 °C, you can't print ABS. You need to make sure your printer can match your intended filament's temperature range.
TPU usually prints around between the same temperatures for PLA and ABS, so it should work from that range.
Heated Bed
Most Filaments work better with a heated bed, but some are almost impossible to be printed without. For TPU, a heated bed should be used but is not absolutely mandatory.
Heated Chamber
Some filaments can't be printed without a heated chamber, others like ABS highly benefit from it. TPU is ambivalent on this as far as I know.
Extruder Setup
There's basically 3 extruder setups. Pellet extruders are super rare, so we don't concern about them. The other two are Direct Drive and Bowden. In a Direct Drive, the extruder motor is right over the hotend, and pushes the filament directly into it. In a Bowden setup, the hotend and the extruder motor are connected via a Bowden tube. Both have benefits and drawbacks:
A Bowden makes for a lighter carriage, leading to faster printing speeds. A Direct Drive has much less trouble with elastic filaments and can do much better with retraction.
TPU is one of the filaments that works much better with Direct Drive.
Other considerations
Some Print services do print in machines set up for one filament type and that only, because it prevents cross-contamination of the nozzles, especially when a high-temperature print material remains in it when a low-temperature print comes next. Having for example a little bit of ABS left in a printer that runs PLA next can lead to very very extreme clogging.

While TPU prints best at ABS-like temperatures (lower viscosity), you definitely can print it at the higher and of PLA-like temperatures, and maybe even the mid to low end. I get decent extrusion even under 200°C but I haven't experimented with how good the adhesion is.

@R..GitHubSTOPHELPINGICE good point, I think it's best to say TPU is "between" PLA and ABS in temperatures then.

Regarding your particular question about TPU, any machine that can print PLA should be able to print TPU. Bed temperature is even less of an issue, and the needed nozzle temperature is roughly the same. The only potential difficulty is that, if the entire path from the extruder gear to the hotend isn't tightly confined, the soft filament can kink rather than advancing properly. However, this isn't a show-stopper - it can almost always be solved with printable upgrades to constrain the path.
If your printer has a bowden extruder, you have to go pretty slow with TPU because there's so much room for the filament to compress between the extruder gear and the nozzle, making the response to extruder advancement and retraction lagged. But this can largely be solved by upgrading the printer's firmware to one with "linear advance" or "pressure advance" feature that compensates. I can print TPU very well at 30 mm/s on my Ender 3 with firmware upgraded to Marlin 2.0, with a whopping 5.0 as the linear advance spring constant.

Most printers can print most filaments. However, some more exotic filaments are not suitable for all printers:

To print a flexible filament such as TPU, the filament path from the extruder needs to be well-constrained. A bowden extruder is generally less good at handling flexible filaments than a direct extruder. Some direct extruders without a well-constrained filament path may also be unsuitable.
A printer without a heated bed won't be able to print filaments that tend to warp such as ABS.
A printer without a (heated) enclosure won't be able to print filaments that tend to warp a lot such as polycarbonate
A printer with a PTFE-lined hotend won't be able to print filaments that require higher temperatures. PETG is at the upper end of what can be (safely) printed with a PTFE-lined hotend, while filaments such as polycarbonate require temperatures well outside the usable range.
A printer with a standard brass nozzle won't be able to print (not long, anyways) abrasive filaments such as glow-in-the-dark.

It is likely the printer at your lab will be able to handle TPU just fine. If it is a bowden printer then you might have some difficulty printing but it might still work depending on exactly how soft the filament is and how well-constrained the filament path.

Some bullets are shortcuts, from experience I know that  Bowden and 2.85 mm filament work just fine (although I acknowledge that 1.75 mm is more commonly used). PTFE lined heatbreaks can print ABS and PETG. Also not all direct 1.75 mm extruders can print TPU without tweaks/guides, the filament can buckle in the extruder, so a direct extruder isn't a given fact for successful printing of TPU.

Point 4 is just wrong. There is no reason to want an all-metal hotend for PETG. You only need that for exotic materials that require temperatures well over 250°C, which is the absolute hottest you'd reasonably want to go with PETG - it will be a dripping mess above that. Point 1 is kinda true, but it's just a matter of print speed. TPU is totally doable with a bowden and not even terribly hard.

@R..GitHubSTOPHELPINGICE E3D lists the maximum temperature of their lite6 hotend as 245C. PTFE actually starts releasing toxic fumes at temperatures (much) lower than that.. I would consider printing PETG with a PTFE-lined hotend less than ideal. I have updated accordingly.

@TomvanderZanden: Thanks for the link. This is the first I've seen of any citations on rigorous treatment of the subject at temperatures involved in 3D printing non-exotic materials. Some of the wording like "offgases particulate matter" is a bit dubious though and I suspect we'd need to read deeper into the sources to find out what it's really saying and whether there's any evidence of likely harm from the temperatures and amount of PTFE involved.


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Prints are Squished
My printer prints stuff okay but its all squished and much shorter than the model, My z Axis Esteps is fine I checked for loose wires and overheating but I can't figure it out. My Temp is 195, .15 Layer Height, PLA, Marlin Firmware

Hi and welcome to 3DPrinting.SE! We love to help, but without enough information that is very hard. Please at least add a photo that shows the problem. It sounds like the Z axis doesn't advance enough, this can be related to a driver issue (not enough current).

On an X1 straight out of the box it might also be an issue of the Z-axis binding (it should turn easily)

authors: غلامرضا رحیمزاده


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When to use an anti-backlash bolt for a Z drive gear?
I am building an HEVO printer with a 300x300 build plate and the project includes two T8 lead screws, lead 8 mm ("Tr8x8(p2)").
I read that such long lead may worsen backlash issues, so anti-backlash bolts are often used. They however increase the torque required to drive the build platform (quite important, since 8 mm lead involves using microstepping for fine adjustments) and they also reduce the usable vertical travel.
Since the build plate has already a significant weight (2020 frame, 2x 2 mm aluminium plates, 4 mm borosilicate bed, 8 linear bearings, heater), I wonder what is an approximate weight threshold to decide for using the anti-backlash or to skip it.

I have exactly the same machine (using Tr8x4(p2)), I installed POM backlash nuts, but I'm using the native steps for Z movement.

The weight of the bed already provides anti-backlash. I don't think using anti-backlash nuts would provide any further improvement.

@TomvanderZanden I thought so, but I wondered whether a general rule is available.

I'd just use a lower lead...

First of all, let's look at the geometry: We have a static XY and changing Z on our build plate. This mitigates several problems we might have faced in a different setup, mainly that our lead screw has loads changing from one face to the other: all loads always go into $-Z$, so the lower surface of the Trapezoidal threads in the brass nut of the bed carrier and the upper surface of the screw will always rub against each other.
However, let's talk about your lead. Tr8x8(p2) is not a Metric ISO-Trapezoidal pattern that is commonly recognized - the only 8 mm diameter one in that standard is Tr8x1.5, very flat and very well suited for putting high loads onto it because there are several engagement surfaces in the nut and a low pitch angle - the thread only has about a 5° (+-1°)to the horizontal. Assuming a 15 mm nut, that's 10 times the projected engagement surface for a total area of about 214 mm².
A Tr8x8 is a very common oddball as in, it's not in the metric tables but available everywhere. It is considerably steeper, and with a 16 mm nut (for easier calculation) would result in 2 times the projected surfaceof a single engagement per thread. But that's only a projected area of 42.8 mm² per thread - about 1/5th of the Tr8x1.5, which correlates directly into that much less friction, because the friction is linear with the surface, which is linear to the length of the nut.
Taking an "intermediary" TR8x4 gets us about 1/2.5th of the Tr8.1.5's holding power per thread at the cost of half of the speed. From a physical standpoint, I'd  take this one, also increasing the precision of the Z-movement by a factor of 2 in comparison to the Tr8x8.
Tradeoffs
Generally speaking, we have a tradeoff here:

Pitch is proportional to the movement speed

double the pitch and you move twice as fast

Pitch is anti-proportional to holding power/torque and Z-position accuracy

half the pitch gives twice the torque and the Z-position error is in average reduced by half

holding power is proportional to the diameter of the rod and the number of threads engaging with the nut
Z-position accuracy is anti-proportional to the effective step-size of the motor

Z-position accuracy can be increased by using a reduction gearset: a 2:1 reduction gear halves the step-size and doubles the torque at the price of halving the movement speed. However, it can and will introduce slop and backlash.

Due to the geometry, the slop in the nut should not be an issue, as the relevant engagement surfaces never change. Further, the heavier the bed, the fewer problems you'll have with fast movements, as gravity will prevent the bed from going "airborne" at the end of travel towards the printhead. Travel away from the printhead, as it will do during printing, should never experience such.

Well with bed mesh leveling movement is in both directions, but never fast. But if the only issue is going "airborne", then I can reduce the weight of the bed using a pulley and a counterweight to quite low values, before backlash becomes an issue? This would reduce the torque required to move the bed in position, and also allow higher microstepping (which is an issue if you need a lot of torque, which I would avoid).

@FarO actually reducing the weight increases the chance of going airborne, so keep it high, then the weight force will ensure contact. Only if you go really fast you even get the chance to go airborne. But yes, reducing the weight does reduce the torque needed.

Do you know how to calculate, roughly, the torque required to lift a defined weight with different lead screws? of course assuming reasonable lubrication. This way, the weight could be kept lower than what the motor can hold, but also high enough to avoid loss of contact.

But does the weight even matter to calculate loss of contact ("going airborne")? shouldn't it depend only on the downward vertical acceleration of the bed? which can be easily controlled using the print/machine settings.

The airborne state is extremely unlikely to appear in normal operation unless you regularly hit your printer from below, that's why I said it is unelectable. For the other... we had that somewhere...

@FarO https://3dprinting.stackexchange.com/questions/6949/ball-screw-maintaining-z-axis-position-when-motor-is-off/6954#6954 and https://3dprinting.stackexchange.com/questions/7695/z-axis-stepper-motor-and-lead-screw-torque-calculation/9827#9827


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Ender 3 X-axis layer shifting
I've been having a problem lately with some minor layer shifting with my Ender 3. It just started recently and I've made no changes to the printer since it was working fine. The layer shifting is always on the X-axis and it's not a large amount. Just enough to render my prints useless. The shift can happen in either direction on the X-axis. See attached photo.
Things I've tried:

Retensioning the belts

Printing at slower speeds

Checking all bed connections to make sure the bed is solid

Reducing the jerk setting

Activating Z-hop

Reducing acceleration

Increased retraction.

The problem occurs on multiple STL files that used to work fine.
Any help would be appreciated

Did you reslize the model?

In the case of the model I show in the photo, I resized the top to stretch it a little taller. In other models that are showing the same layer shifting, I did not resize,

not resize, RE-sliced. As in, did you print old G-code or freshly sliced one?

I've run prints with gcode files that predate this problem and the same shifting occurs. I even went so far as to uninstall Cura 4.5 and reinstall 4.1 and still get the layer shifts

I know this is old, but from the picture these are very clearly not "layer shifts". There is no accumulation of error, just layer-dependent (direction-dependent?) minor displacement, which is always just lack of rigidity in some part of the motion/positioning system.

OK I found the answer. I removed the extruder cover and found that the 2 screws attaching the extruder assembly were loose. A very simple fix to a very irritating problem.