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First 3 mm prints poorly, then fine after that
I have an Ender 3 that I have been pretty happy with so far, however it recently started an odd behavior and I can't figure out what's causing it.
What happens is that the first ~3 mm of the print comes out "sloppy". After that, everything clears up and it prints fine for the rest of the print. (Although it perhaps looks a little under extruded on the top layer)

It looks almost like it's over extruding. But if that's the case, why would it only be for the first 3 mm? Then the top layer looking under extruded makes that possibility even more unlikely.
This is consistently happening regardless of what I am printing, the brand of filament (I only print PLA), or the bed temp or hot end temp. I've tried tweaking with the bed leveling and giving a little more gap on the first layer, but that doesn't seem to change anything either. I also calibrated the extrusion multiplier and it's spot on now.
I use Ultimaker Cura 3.6 as my slicer. I tried resetting back to defaults to see if maybe I had inadvertently changed something but that didn't help either.
I have done a few upgrades - Marlin firmware, Capricorn tubing, glass bed, replaced the (broken) plastic extruder with one of the metal ones, new PTFE fittings. I didn't notice the problem until recently so I can't say if it started corresponding with any of those upgrades.
When I first got it, the prints came out beautifully from the first layer, so this is really frustrating me. I'd like to get it back the way it was.
Any suggestions on where to look?
Update: I did some slightly more controlled experimemts and I did get it looking a little better. It does seem related mostly to bed tempurature. The cooler I make the bed, the better it looks. However as it gets cooler, the prints are also starting to warp and break loose, so the print ends up failing completely. I had a hard time getting a successful print below about 45 degrees, and even at that temperature it still isn't completely clean. I'm using glue stick for adhesion and it just doesn't seem able to hold it without some heat. I traditionally have run around 50 degrees before this problem started though, so it seems odd I have to drop below that now.
Also, for more info, the cube dimensions are pretty close in the X and Y, but were about .5mm short in the Z. So the layers do seem to be settling.
I did check the bed temp with a non-contact thermometer and it was consistent with what the printer reported, so it doesnt seem to be a bad thermostat throwing things off.

what's your temperature settings?

I've tried several. Bed from 40-60. Nozzle from 195-220.

I've had similar prints with too small nozzle to bed distances, increase the distance by e.g. leveling with thicker paper or use an offset for Z.

After much trial and error, I think I finally figured out the solution.
Even though I could get better prints by tweaking with the temperatures, I could never totally eliminate the problem. The better I made it look by cooling down the bed, the more likely it would break free and the print would fail completely.
At one point though I happened to print something taller, and interestingly enough a similar band of ugly layers appeared higher up in the print as well.
So I started a closer inspection of the Z axis rollers. The Ender 3 has a funky setup where there are 3 rollers at each end of the X axis. Two are fixed and one can be adjusted to change the tension of the rollers against the Z rails. What I discovered was that a couple of the non-adjustable rollers weren't terribly tight and could be turned by fairly easily with my fingers. At the same time, the adjustable rollers are starting to wear a groove.
On a hunch, I decided to try re-adjusting the tension so that I could no longer turn any of them with my fingers. It definitely had an effect...now the bed was too high and it would no longer extrude the first layer because the nozzle was too close. This required going through the complete bed leveling process to get it back in spec.
Once I got it re-leveled, low and behold it's printing like new! The height is coming out spot-on too.

I suspect what was happening is that the rollers were too loose and at certain heights they we allowing movement in the Z axis. Perhaps there is a flat spot that was allowing the X rail to droop, then once it got past the flat spot it would print cleanly again.
I haven't printed anything tall enough yet to see if the bad layers still show up higher in the print, if they do, I think it is probably a sign that I need to replace some rollers. In the mean time, I'm thrilled to be getting decent prints again!
Update: This ended up NOT being the solution to my problem. However it does seem to be related. As I mentioned in the comments, the problem returned after a few days of the printer sitting unused. I have since been able to get it printing better by going the opposite route - loosening up the Z axis bearings. At the moment it is printing somewhat better, but still not perfect. I am also having under extrusion issues when may or may not be related. I have ordered some new rollers to see if that helps since some of them had a pretty good groove worn in them.
Another Update: I replaced several of the Z rollers that had become grooved with some that claimed to be a little harder material. So far this seems to have mostly cleared up the issue. I have now completed several large print jobs and the first layers have been coming out pretty good.
I also ended up taking out the Capricorn tubing on the extruder. The extruder skips were becoming quite bad and causing under extrusion issues throughout the print. The Capricorn has a little smaller inside diameter than the stock tubing and I wondered if it was too tight on some filaments. I went back to some plain white cheap PTFE and that problem mostly went away as well. I still hear the "click" once in a while, but it is fairly rare. I may try tweaking the motor current a little to see if I can get rid of that. All in all though, the printer seems to be printing about as good as it ever has.

Ugh! Left it alone for a few days, came back and printed another job last night and it's doing the same thing again! Back to the drawing board! :-(

did you ever get yours fixed permanently?

I just experienced a similar problem after taking things apart to fix an unrelated issue, and it turned out the Z lead screw clamp was not tight on the screw, allowing it to slip. Overtightened eccentric nuts were probably also involved.

Yes, I haven't had a noticeable problem in quite a while. The things that seemed to have the most effect were replacing the rollers with the harder ones and also installing an anti-backlash nut on the Z lead screw. Of course getting the tension just right with the eccentrics is important as well.

@SteveInCO Adjusting the eccentric inner wheels on the Z as per your post seems to have solved it for me.. for now - thanks for the detailed updates you did.

Actually, my problem ended up continually coming back, was a lot like OP's, and was frustrating to track down. Eventually, I re-aligned the Z rollers and (this is probably the most important part) loosened the screws holding the Z lead screw nut to the carriage, which I'd tightened after unnecessarily removing it. They should be backed off at least a quarter to half turn from fully tight.

Follow up a year later: the problem still has not returned after replacing the rollers and adding the anti-backlash nut. Really this little printer amazes me sometimes at how beautifully it prints for a $200 (+ a few mods) printer.

@SteveInCO what rollers did you end up replacing them original ones with? Do you have a link? Thank you!!!!!

I used these: https://www.amazon.com/gp/product/B07PRFPDRS. Still working great.

After much frustration with my printer, this post finally helped me find a solution to my problems.
My wheels were too tight (turning eccentric nut until I could turn wheels with a little bit of force). Also had some wear / grooves because of this. With new wheels and appropriate tension problems are now gone!
I went with "Iglidur" material based wheels as an upgrade as they claim to have much better properties compared to the original. So far, so good!

I had the exact same problem as you. And after trying all of your ideas (Thanks so much for the amound of information!!!), I discovered that in my case, the problem was actually the printer skipping a step every other layer (at the beginning), which lead to the exact same thing, the bottom layers being "compressed", leading to a lower height in general (and overextrusion at the bottom). In my case the solution was to tighten the screws that hold the Z-Motor in place (as well as printing a spacer for the motor, so that the axis-screw (no idea how that thing is called) wouldn't bend: https://www.thingiverse.com/thing:2925230) as the Z-Motor would push itself down and lift itself up every other step, resulting in a loss of a layer.

Has this problem come back or is your solution still working ?

I had this problem as well, the problem is not too much give on the Z axis, it's that there is not enough give, so loosen the Z-axis wheels on both sides till you can freely move one of the wheels with your hands.
This solved it for me.

I had trouble with the first few layers looking like over extruding (they were just compressed). Turns out the X axis was loose.  On zeroing for a new print the arm would be sloped like this |/| as the Z axis lifted it would slowly end up |\| over the duration of the print.

Same problem with my Ender 3, although not as severe as the OP, its about 0.5 mm over the first 1 mm that is lost.
After checking my motor as suggested, it was solid. However as with the OP, one of my adjustable wheels was loose on the Z axis, and could be turned by hand. Tightening the eccentric wheels on both sides to remove any slop has resolved the issue. Multiple test cubes have come out perfectly.

Good morning, and welcome to the 3D Printing SE site.  I see from your profile that although you are new to this site, you are familiar with the StackExchange structure.  On this site, your answer might be better presented as a comment on the question, since it does not, in itself, provide an answer.

While the original post didn't really answer the question, the subsequent edits appear to have added a resolution.

Hmmm, I think that your last edit has removed some interesting information wrt to the 0.1 and 0.2. I think it was fine at edit #4.You might want to do a roll-back?

It looks like you need to calibrate your Z0 by adjusting your endstop height. It's starting too low.
I think you are printing your first layer too low, and underextruding to compensate. Do the paper test with your Z at 0, confirm it's good. Do the 100 mm extrude test and confirm it's pulling in exactly 100 mm. Measure your filament diameter in several places and make sure the slicer value matches.

Can you elaborate? I don't see how the end stop height would affect anything as long as the bed is properly leveled. My skirts come out a nice even .2mm +/- .05mm all the way around so it seems to be set right.

I solved the problem by adding a second Z-axis leadscrew. The problem was that I could have either too tight Z-axis rollers or a sagging gantry. Both of this lead to the nozzle rubbing over the print. In case of sagging, rubbing on the right hand side of the print and a too large distance on the left. In case of too tight rollers, rubbing on the whole print or on whichever side had the tight rollers.
If you don't want to invest in a dual leadscrew setup, turn the excentric nuts that fix the rollers of the gantry to the Z-axis; making sure that they are tight enough but not overtight.

I had similar problem with my Tevo Tarantula. Tried all the options mentioned above as well. It seemed to be Z-axis height related. Changed my Z-axis flexible coupling to a solid coupling which solved it for me.

I too have a TEVO Tarantula Pro, two infact, the both did this out of the box (so to say).
I think I just solved it for me.
The comment above from Robet made me remember there was a small O-ring washer placed inside the flexi coupler when I built the printers.
The O-ring is the exact height of my first layer issues.
I removed it and made sure that the motor shaft and the lead screw made hard contact. (Yes, I know thats not how they are meant to be, but all my previous printers are like that and they are fine). Even stretching the flexi coupler a few mm before clamping it to the lead screw.
And now my issue is completely fixed!


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Under-extrusion after a certain amount of successful layers?
My CR-10 is starting prints, BUT then makes weird spiral pattern, layers go up vertically with large gaps. Hollow infill.

I don’t know if it’s:
 - My Slicing skills
- original files
- the printer itself
Long explanation. Questions at the end. I’ve had beautiful normal prints. Then I’ve had these abnormal spiral layer prints with infill issues and spaghetti monsters (the images don’t show but, where the prints pictured end, is not the full print, it did the weird spiral then just stopped layering altogether). I’m semi-new to printing and don’t have too much of a tech background apart from average use. Been researching a couple months, I’ve only been printing for about a week. I’ve had an amazing couple prints. Baby groot was flawless, barely noticeable layers. The test print (a rather thick disk with deep grid marks and a puppy on top) that came with the printer was the same smooth flawless, it wasn’t my first print though. So the behavior seems erratic. The two prints pictured had several successful print in between them.
I do know:
The elder wand file was in several tutorials and was printed successfully. Its in two parts. The first part, which is way shorter and thicker printed Amazingly. The second part pictured was double the height+ and 1/4 the thickness. I even printed it successfully once before going horizontally and flat against the bed. BUT I had to run the print three times because the filament would not stick to the glass. It was just being dragged along behind the nozzle. But I was observing so I ended the print before it went too far. All I did to change this was add a brim and supports. Which gave a “successful print” except the fact that one of the knobs has a flat spot and the support remnants were very noticeable. Resolution was terrible too. Hence why I decided to try printing it vertically.
The bigger print pictured is the base of a hufflepuff horecrux cup, the first time I printed it was with cura slicer, it came out beautifully but the stem snapped right under the base of the cup part st some point, and the left handle had some wierd stringing issues, like 7 pure strands of filament hanging out one corner, and the print failed s fee layers from top. However the file description only had one previous make listed and the thing with the top of the handle and print failed about the same with that persons print.
Sorry for the long post. I’d just really appreciate any help, and I wanted to give all the details.

It is a lot of text, but sorry, not really very useful. Instead of explaining that prints did to work you could describe the printer and post the type, the hotend (all-metal?), slicer settings, etc. and put these in the question by [edit].

This is partial answer and comment as it was too big to fit the comment section, it will be a proper answer once the question is updated by the OP.
What you call a weird spiral pattern is the result of under-extrusion. When there is under-extrusion, the resulting print is sparsely filled. The reason for this under-extrusion is most probably partial clogging of the nozzle, or an issue with the extruder itself. One explanation could be that you are suffering from heat creep, but the information you provide is not enough to explain this or any other solution further in detail. Clogging can e.g. be caused by retraction settings and/or temperature settings, without your settings it is a guess what this is actually causing this.

Looking at the print deteriorate the higher the Z becomes this is most probably a heat creep issue, so you print too hot with too large retraction settings.

This intermittent underextrusion can be caused by a broken part in the extruder on the CR-10 / Ender 3. Check if the plastic mount that holds the idler wheel in place is torn. Depending on the height and the resulting varying tension from the filament the idler wheel gets in and out of alignment.

While uncommon, this issue could be caused by having no minimum layer time set. This could lead to printing on a still very hot surface, which in turn ripples and moves, creating a little wave pattern. The wave pattern then can grow into this diagonal pattern.
You might manage to reduce the issue by setting a minimum layer time of 10 to 15 seconds.

Using a CR-10S which printed fine for about 6 months (PLA, 200/58°C), then similar problems started: Interestingly, the height of the "problem zone" appeared to be related to the melting point of the PLA used: lower melting point = problems appear at a lower height. Suspecting heat creep, I swapped both hot-end fans... but things got only marginally better.
As I could rule out extruder issues (metal extruder, new gear), the bowden tube (replaced, upgraded couplings), I looked at the hotend again. There was clearly not enough "melting power" (25mm/sec would print ok, but not 50mm/sec). I then checked the INSIDE temperature of the heater block (butting a thermocouple right behind the nozzle, with the bowden tube removed)... turns out that 200°C (set in Cura and shown on the display) are more like 180°C! In order to get near 200°C, I had to set 220°C in the slicer - and printing DID improve (underextrusions greatly reduced).
I'm still not happy with the situation, b/c deviations like this usually don't come out of the blue... it's not the first time that I read about CR10/CR10S hotend temperatures not being read correctly, so I suspect that this might be the reason for many "mysteriously" unter-extruding CR10s... (BTW: my temp values don't fluctuate and I have the correct capacitor on the mainboard).

Sounds like... somethign with your thermosensor or your heater cartridge is not correct. Did you alter your firmware or hardware? I suspect that you run the wrong temperature table.

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Ender 3 homing problem
I got myself a Creality Ender 3 and just finished assembling it and I noticed that the home position is at the right instead of the left. It also is about about 3 mm in front of the right corner.
Anyone could maybe help me to understand what is wrong?

Welcome to 3DPrinting.SE!

Homing is the process where the machine finds all the limits of the 3 axis (at the endstop switches), to have a common reference point for each axis. From the endstops, firmware defined values exist to give the printer head the offset to the home position, also known as origin (X=0, Y=0). If the origin position is in front of the plate, wrong offsets may be defined, but you can re-adjust the position.
If the stepper is driving the printer head away from the endstop on a particular axis on homing (in your case the X direction), there might be a few possible problems at hand:

The stepper cables are plugged in reversed
The wires in the stepper cable are switched
The stepper direction is reversed in firmware (this is not very probable for a kit or bought printer)
The stepper motor itself is build mirrored (not uncommon mistake for Y stepper motors on the Anet A8)

A quick fix would be to rotate the connector 180° of the cable going into the X stepper, if this works, you can disassemble the cable and properly arrange the stepper wires.

Did you make sure that the x,y,z and other cords / connectors, were connected to the right areas? TO clarify, the things that connect into the motors.

Hi!
Thanks for your comment!
Yeah, I just checked them. I believe they are all placed correctly...

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Adhesion problem when printing calibration test
Here is my first attempt at printing a "Bed Leveling Calibration test".

It obviously didn't come out as I would have hoped, but what can you say just looking at this picture?
Is it possible to tell from this calibration print which corners are not leveled? Or is this just a general lack of stickiness issue (e.g. i need glue)?
I leveled this thing with paper several times, but honestly, I'm terrible at leveling. I just got this new piece of glass and there's nothing on it. The glue residue is actually on the sheet beneath.
What are some tips for printing on glass? I hear some people say use glue, others say never use glue. Should I increase or lower the temp?
I'm printing Dikale PLA on Monoprice Select V2, extruder temp 200 °C and bed temp 70 °C. Initial layer speed is 30 mm/s (print speed is 60 mm/s but I don't think this print goes that far).

What can you say just looking at this picture?

->There are 2 obvious observations that can be drawn from your image.
First, the bed does not seem to be levelled correctly, the right side (especially the front right corner) is closer to the nozzle than the left and left-back side.

Is it possible to tell from this calibration print which corners are
  not leveled?

-> Yes, the front right corner is higher. The filament is much thinner there, it is more transparent than the rest of the lines.
Second, you have glass mounted onto an adhesion sheet similar to BuildTak. Note that such adhesion sheets are rough (to create more surface area for the filament to grip on), placing a sheet of glass on top of such a sheet will create small air pockets (less contact surface area to the glass plate as that is perfectly flat by its production process) and thus an unsatisfactory heat transfer process. Glass directly onto the Aluminium will have a higher temperature than with an insulator (BuildTak sheet) in between it, it is far more difficult to determine the bed temperature that way. For printing on glass, you could also raise the temperature compared to direct printing onto the metal bed.

Should I increase or lower the temp?

-> When using glass on top of the heated bed, you should raise the temperature a few degrees.
You should remove the BuildTak sheet and put the glass directly onto the Aluminium heat bed or remove the glass plate and print on the BuildTak sheet directly, level the bed better or consider installing an auto-level (touch) sensor if your printer electronics board supports that.

What are some tips for printing on glass?

Furthermore, use some PVA based spray (e.g. certain hairspray brands or specific print adhesion spray) or Polyvinylpyrrolidone based glues (certain glue sticks, white wood glue, etc.) to create a sticky surface for the filament to adhere to. I have great experience with PVA based sprays like 3DLAC, but there are great alternatives found in common household hairspray cans as well, as long as it contains PVA.

Or is this just a general lack of stickiness issue (e.g. i need glue)?

-> Yes, Polyvinylpyrrolidone/PVA based glue/spray will result in better adhesion.

A general remark is that you could listen at what others have tried, but you need to find out yourself what works best for you. In order to get the print to stick to the glass, you should use every trick there is to get good adhesion. If PVA based sprays or Polyvinylpyrrolidone based glues work for you, use it, if not, print on bare glass, use tape, BuilTak, elevate bed temperature, overextrude first layer, use brims/mouse ears, etc..

Can't stress enough how much of a difference a level bed and hair spray can help with adhesion. If your printer has it, or you can update the firmware, mesh bed leveling helps immensely (until you get an auto level sensor).

Nice tips! Never considered transfer of heat through the buildtak sheet. That is eye-opening

I've had fantastic results with the Anycubic Ultrabase as a build surface for materials from PLA to ABS to PETG to PEEK - all without any surface treatment.


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Temperature Tower came out too good
I've switched to a PLA of a different color and wanted to figure out what temperature my nozzle should be so I printed a temperature tower. However, the towers came out perfect and the only stringing was from the last bit of plastic oozing out when the print head moved to X-home.
I loaded the tower stl file in Ultimaker Cura and did the post processing script to change the temperature from 240 °C at layer 1 (changing from 200 for the skirt). And decreasing the temp by 10 degrees every segment after. Here is the resulting print vs the expected print:

I was expecting an over-extruded, blobby mess and stringing to make a spider feel at home towards the bottom, but this is one of my best prints yet.
I watched the print in its entirety and the printer was set to the respective temperatures and the nozzle reached them, as confirmed by OctoPrint:

And the G-Code does have post processing scripts generated by Ultimaker Cura:

Any ideas why my print looks so good? I'm printing PLA at various nozzle temps, 60 °C on bed with the Creality CR-10S sliced with Ulitmaker Cura 3.6.0.

Shouldn't there be bridges between the two columns at each level?

Not in this particular model. However uploaded images of the print show that globbing doesn't necessitate the bridges. I'll see if I find an image.

Added an image showing what I was expecting from the maker of the model.

Your material works well at a larger temperature range than expected. What was the problem?

I'm under the impression that 220 °C is extremely high for PLA let alone 240 °C.  Have a hit the lottery with this filament then?

Temperature is not the only thing that affects stringing, so perhaps your mix of slicer setting (retraction, wipe, not traversing over outlines, etc) are perfect.

Try changing the fan speed and do another one: maybe you can improve the quality at high temperature. Below 220 you won't get optimal layer strength.


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How to log more than 300 lines of the OctoPrint terminal?
Is there a way to view more than the last 300 lines in the terminal tab on OctoPrint? Or is there a txt file of a log? Or even a setting/plugin that does either?
I keep finding my prints pausing as if I said to change the filament even though that wasn't set in the slicer, but I catch it long after the 300th line in the terminal so I can't see what OctoPrint is trying to do.

Serial logging has to be enabled. Warning: This will impact the performance of OctoPrint. Enabling this feature can be done under Settings -> Serial Connection -> Serial Logging and checking the box for "Log communication to serial.log.

One can download the log under Settings -> Logging and finding serial.log in the list of log files.
The file can also be found in the following directories (according to this FAQ)

All log files that OctoPrint writes can be found in the logs sub folder in its configuration directory:

on Linux: ~/.octoprint/logs
on Windows: %APPDATA%\OctoPrint\logs
on MacOSX: ~/Library/Application Support/OctoPrint/logs

While I was editing the answer to include the serial logging to later see that you also found the answer yourself, very good that you also posted an answer, we need multiple answers if possible! Hope this helps you out debugging your problem, good luck! +1

@0scar your answer sparked something and I was finally able to google the right phrase. I have it enabled now so time will tell...

Yes, you can show more than 300 lines in the terminal; just disable auto scrolling (reference).

Disabling Autoscroll now completely disables cutting off the lines (so
  you can have way more than 300 lines while that's disabled), filtering
  has been improved too and doesn't cause scrolling anymore.

Note that with disabled autoscrolling, you will be able to see more lines up to the point that the buffer is full. If you need even more lines to monitor, just enable the logging the data to file serial.log. If you open the options page (OctoPrint Settings), just tick the box for "Log communication to serial.log" under "Serial logging" of the "Serial connection" options.
This serial logging file is typically used for debug purposes, but as can be read from the options, it comes with a warning:

While this can negatively impact performance, a serial.log can be
  incredibly useful for debugging any issues observed in the
  communication between OctoPrint and your printer.

You can either access the log file through the OctoPrint options/setting through the "Logging" options tab, or direct download/copy from the logging directory:

on Linux: ~/.octoprint/logs
on Windows: %APPDATA%\OctoPrint\logs
on MacOSX: ~/Library/Application Support/OctoPrint/logs

So I would have to disable the auto scrolling at the start of the print and never leave the terminal tab because doing so enables auto scrolling. I also hit the buffer limit at 1500 lines so I don't think this option will be super helpful.

@LuxClaridge Updated if you even need more lines to monitor.

yep, serial.log is your friend more than the terminal.


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Print parts fail mid-print
I am trying to understand what could cause a misprint after several layers. It acts as if the extruder head bump to the PLA after a while. Thus moving the parts and then, it fails because it is not printing at the right location anymore.

The expected result, for one "pyramid" is the following:

The whole model is the cube gear:

I checked the extruder multiplier coefficient parameter. The width of the filament is ok: 1.75 mm. The Y axis seems to be properly calibrated, and if it was the problem, I would expect it to fail before anyway. But I don't have any idea of what could cause that aside from that. And the problem seems to general and "quite" repeatable based on this print and some others (I do not guarantee the same height of failure, but...).
I got a better result by printing layers by 0.3 mm with a 0.4 mm nozzle. But this failed print was with a 0.2 mm layer.
My configuration: I have a prusa i3, with a bowden extruder. It has a slight multiplication of the extruder size, because during my calibration, I noticed that not enough material was pushed. I also calibrated my Z axis as carefully as I could. So what could cause the problem?
During my prints, I also have a problem of small strings everywhere, that I didn't manage to solve completely with the hotend temperature, nor the withdrawal parameter set to 2 mm. And I don't have a fan blowing at the end object (I plan to add one eventually). And the bridge speed is supposed to go at 60 mm/s and non print move at 100 mm/s, thus fast enough I think to avoid strings.

The image you have added is not very clear, could you add an image from another perspective and show what the print needs to look like (i.e. the model)? What you describe is a problem called "layer shifting", but the image does not show that effect clearly.

Did you check whether the print shifted on the bed? Adding a brim or a raft (and adjusting the Z-axis zero) can help if that's the case.

@0scar : I added the asked information. I also tried another print with a 0.3 mm layer height instead of 0.2 mm. And it worked. Thus the layer height plays a big role. I added the information in the paragraph.

@CarlWitthoft Yes, the print did move. It seems that over layer stacking, the nozzle started hitting the print. Thus moving everything.
Whenever I have a difficult print such as this one, I tried printing a bigger "fundation" layer. And indeed, it helps for stability. But it doesn't solve the core problem. I try to understand how to solve that part. But as a workaround, it is something.

Your printer basically has 2 problems;

stringing, and
layer shifting

The second problem is most probably the result of the first issue. Excessive stringing leads to a lot of material outside the print object, when this clutters, the nozzle could get caught up and cause hindering of movement of a certain axis to result in a shifted layer print as the printer is not aware of this shift, it will continue the print from the shifted reference point.
From your second experiment you see that a larger layer height does not show excessive stringing and the print has therefore not been hindered by caught-up material to finish the product without layer shifting.
It is key to solve the stringing issue; stringing is the result of filament being extruded by pressure build-up in the nozzle that "leaks" out of the nozzle on travel movement of the print head. You will probably not see this happening when you print a single product; it is typically seen when printing multiple objects on the build plate. This usually implies that the printer need to be properly tuned. It is up to you to find the correct settings; test print objects, like calibration prints, help you find these correct settings.
Important print parameters to fight stringing are:

retraction, (do you retract enough prior to movement?)
coasting, (do you stop in time with extruding to make use of the overpressure in the nozzle?)
travel speed, (do you move fast enough to minimize the amount of filament leaking out?)
print temperature, (do you print at a temperature where the filament doesn't get too fluid?)
print part cooling, (do you have sufficient cooling?)

Once you optimized this, the stringing should be gone and the change of layer shifting should have reduced.

I will complete with details later today. But about the coasting: I didn't see any parameters for it in slic3r. Is it? For the print temperature, I am quite sure that is the right one. I already solicited your help about it in the past. But for the print part cooling, I certainly lack of it. I miss a fan that I plan to add.

However, I had some strings too one the "succeeded" part. The only thing: I removed them the day before taking the picture... But I indeed had less of them.

Alright, I managed to fry the power supply. I just replaced it. The travel speed for non print movement is 100 mm/s. The print speed for perimeters is 40 mm/s. I increased the retraction from 2 to 5 mm and its speed to 80 mm/s. It did improve the result. But I tested it back with 0.3 mm layer. I will still try to lower the layer height, which was the core of the question, to see if I have some improvement.

Ahh, and so far, I tried to add a cooling fan, but I doesn't run. I will investigate this problem as I believe it can really improve the quality of my prints.


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Unable to hit hot end temperature with part cooler on
I'm unable to use the parts cooler I printed. Every time I turn it on, the hot end temp drops too low, and for some reason the PID can't seem to get it back up:

This is a test to simulate the issue. The first drop is the fan kicking on, then the last bump is me turning the fan off. It's almost as if the set point drops when the fan kicks in. Any ideas? The PID is tuned (I ran the autotune) and works well without the fan on. This is a RepRap Guru Prusa clone.

This effect you describe is a commonly known problem that occurs when the print part cooling fan is not correctly positioned, i.e. if it blows air directly onto the nozzle or heater block and is best solved by printing an alternative part cooling fan duct. Alternatively you could insulate the heater block with some insulation cotton or silicone socks that fit over the heater block.


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Filament choice for coasters
Which filament is good for a coaster for a hot cup?
I don't expect PLA to be good because it can easily melt under a hot cup.
Note, I can't use ABS because I don't have an enclosed printer.

Do you mean as a coaster or trivet, so the table isn't damaged by the heat?

Yes, I mean trivet

As the answer suggests, there's a huge gap between any drinkable potion (your mouth won't put up with anything over about 85 C) and the melting point of PLA.

Even if you pour in boiling water in a cup, the outside of the cup will have a lower temperature. When resting on a coaster, usually a small part of the cup actually touches the coaster. Also, the design of the coaster could influence the heat transfer, a more open structure of the coaster may be beneficial. Some people print coasters in PLA although the glass temperature (temperature at which the plastic becomes soft, this is usually the temperature of your bed when you print the material) may be lower than than the temperature of the cup, the filament will weaken (for PLA at about 50 °C), but not melt , melting of PLA happens at a higher temperature (for PLA above 150 °C) than your mug can get (unless you pour liquid metal in it). It should therefore be doable in PLA, I have printed a PLA coaster that has very small ridges (about 1 mm) of an embossed image and placed a cup with boiling water on it, to find that the coaster is able to withstand the temperature of the cup without deforming (the ridges do not fail or deform).
To elaborate on the filament materials other than PLA; there are many filament types that have higher glass temperatures, but are still very printable. Various types of co-polyesters exist, like PETG, that have a higher glass temperature (> 85 °C), are a substitute for ABS and still very well printable. Nylon is also a material that can be used, there are brands that have low warp nylon.
Note that there are a few options to print ABS while you have a non-enclosed printer, you could

fabricate some cardboard pieces for a temporary enclosure,
place the printer in an non-draft room or
print the skirt height at the height of the print part.

Note that coasters have a relative low profile height, it should not be that big of a problem to print ABS coasters on an open printer.

FWIW I have printed a bunch of PLA coasters;  not even a hint of warping or melting from hot drink mugs.


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Printrbot Metal Plus wireless printing with ESP3D
Several years ago, I purchased a Printrbot Metal Plus with a dual extruder option and the LCD attachment/accessory. Printrbot has now gone out of business, and the USB connection isn't working very well for reasons I'm not quite sure of (It has native USB that emulates a UART connection to a computer, but it hasn't connected to Cura since a few months after I bought it, not that I really noticed at the time).
I have been printing via the LCD control accessory for all print jobs since, both due to it being more convenient and due to the USB not working.
Since it would be more convenient (and also because the remaining single point of failure concerns me when dealing with equipment this expensive), I would like to connect an ESP8266 with the ESP3D firmware to my printer. This would allow wireless printing and control of the printer from a web or network interface. I even have several ESP8266 modules lying around waiting to be programmed from an unrelated project.
https://github.com/luc-github/ESP3D
My problem is that, due to the extra controller board for the second print head and due to the LCD being installed, I am not sure if the hardware UART (there's supposed to be one somewhere, but it wasn't well broken-out since the controller uses USB instead) is being used or is available right now.
I'm also not even sure where on the motherboard it is (assuming it even has one), since, with the folding of the company, most of the documentation seems to have evaporated.
https://reprap.org/wiki/Printrboard#Schematic
The above URL is the only resource I was able to find with details on that. I read it some time ago, but wasn't really able to map the pins to the board layout or the descriptions on the chip. On my check just now, I wasn't even able to find a UART.
Does anyone know enough about these printers to say where to look for a UART or to tell whether it's used by one of the attachments I have?
Notes:
I would also be happy with a method to convert a UART to USB and back, assuming that it's my computer that's having issues connecting and not the printer.
I have also tried Octoprint, but that has its own issues, namely that I have to use a Raspberry Pi and that some of the configuration needs to be done on the Pi itself, as well as the corruption possibility and I suspect a different use case. One advantage of using the ESP8266 is that it is mostly safe from corruption and its main software is read-only.
I am not certain what board revision is used in my printer, since it arrived pre-assembled and I'd rather not open up the case (it's really nasty to try to get to, since you have to flip the entire thing over).
I would thus appreciate any help you can give in finding any documentation that might say which it is or that directly applies to a board so that I can modify the instructions to suit my case should that part differ.
Similarly, I never was able to figure out what exactly the dual-head daughterboard is despite some effort, and that was back when the site existed still. The documentation was never the best; it was fine up until you need to replace the firmware or figure out what exactly is actually in there, since most of this seemingly wasn't actually written down. IIRC, they even said some time later that they no longer shipped with it, so I have no idea.

Welcome to 3dPrinting.SE!

Did you get to find out an answer? I am in a similar quest. I'd like to enable the Marlin firmware to use RX1 and TX1 (there are pins 5 and 7 of EXT1). I did what I thought are the correct firmware changes with no success.

BTW: this is my situation: https://3dprinting.stackexchange.com/questions/8320/printrboard-rev-d-rx1-and-tx1-second-serial-port-marlin

I have not heard anything. Your answer does seem to make mine less likely. Unless I can rebuild the firmware and enable that port, with the changes Printrbot probably made and which may now be lost since they folded, it may not even be possible to use that port if it DOES exist?!


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Flexible filament how to print a hollow "sleeve"
I need to print a flexible, hollow "sleeve" or "cover" for an elongated part, kind of like a soft "skin" for a "finger" (see pic). I'm not sure how to approach the hollow space problem, i.e. how to print a flexible surface that is above an enclosed, hollow space. I could print supports inside, but they'd be hard to remove from inside the space, because I can't quite access all corners with a tool from outside. I could print this in 2 parts ("bottom" / "walls" + "ceiling" separately), but I'd prefer not to glue if I don't have to. Any ideas how to approach this?

Welcome to 3dPrinting.SE!

Print orientation is usually the key to print with a minimum of supports. If you print this part with the sharp point down, you will get some support structures on the outside for overhang support to prevent it from tipping over, but no support on the inside.

I wonder whether it's possible to print flexible items with this much complexity without some internal support.  My guess is that the allowable overhang angle is much less than for rigid materials.

I think it's dependent on the softness of the filament. I saw a video where the guy printed a glove (with TPU I think) and it seemed to print alright without supports. I doubt something like ninjaflex would be as simple.

@CarlWitthoft Fortunately, the overhang angle for support generation is a parameter in the slicer settings.


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Periodical under extrusion with Slic3r
I got myself an Ender 3 printer, put it together and tried the test g-code, worked fine. But i sometimes have problems with under extrusion, as shown in the picture below.

As you can see, the part to the left is almost not printed, but the part to the right is fine. These "holes" are a lot of places, and i dont understand what is causing a temporary clog or whatever the problem may be.
Anyone know something about this problem?

Have you run this gcode multiple times, and do you get the same underextrusion in the same location every time? If not, it could be just a temporary filament advancement issue.

I can confirm it does not happen in the same places every time the same g-code is run. But it is happening every time I print something, so where would I start trying to diagnose it?

Also, extrusion seems uneven, starting pretty good and getting bad pretty quick

Does your spool unroll freely? You specifically mention Slic3r, so does this imply that it does not happen with Ultimaker Cura for instance?

I tried lubricating the spool holder, but it didn't help, so I believe it moves as it should. I tried cura as the first slicer, but for some reason it just fucks up completely on my ender 3, probably don't have it set up correctly. I have gotten a few decent prints from Slic3r, but the issue remains.

What you experience is temporary under-extrusion. This could be a typical result of friction in the supply of filament to the extruder. I've run into this also a week ago when the shaft of the spool holder caught a plastic bag next to it which wrapped around the shaft creating a lot of friction. Friction can also be caused by filament that gets entangled on the spool, this is usually a problem if the spool unrolls too freely on the holder (too less friction);it unrolls a few windings, and then tightens those entangling the filament. Also, if you use 2.85 mm filament on small diameter spools, the last stretch of filament has the smallest curvature and as such requires the most force to pull it to the extruder (this can go in steps).
Furthermore, slipping of the extruder gear is also a (rare) possibility (when using a stepper directly to drive the extruder gear, a flat spot on the stepper shaft should prevent this).
Be sure to inspect the filament release from spool to extruder and try to see (and listen!) what happens when you print a part when you experience the under-extrusion.


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Slic3r top layer issues, small gaps, weird extruder paths
When slicing with Slic3r Prusa edition the top layer of most models turns out pretty bad. There are usually small gaps or weird patterns. This does not happen with Ultimaker Cura, it will have a nice smooth top layer. Is there anything settings wise that I can do in Slic3r to get the same quality of top layer as Ultimaker Cura?

Slow your top layer print speed waaaay down. Top layer ironing would help if it was available.

I don't think that's the issue. Adjusting the top layer speed did not change the slicer output.
Messing around with other slic3r settings I've noticed if I completely disable retraction it will fix some of the weird pathing but not all of it.

Instead of showing us sliced print parts, please post an image of the actual product you printed. Also, share some of the slicer settings that you use e.g. extrusion width of certain lines.

This issue also seems like Coasting behavior. You should check into that direction.

To have a very smooth finish on top layer, I usually act on these settings :
in Print Settings :
Layers & Perimeters :
  Horizontal shells : 3 / 3

Infill:
  Infill, Top/bottom fill patterns : Archimedean Chords ;

Speed:
  .for print moves :
   Top solid infill : 20  (mm/s)

Advanced:
  Extrusion width, Top solid infill : 0.2 (mm)

= This gives very slow movement in a circular way, the small extrusion creates an ironing effect, thus very nice finish.
Considering your slicer behavior, have you tried changing number of top shelves & Infill type ?

makes me wonder , it would be nice to have the setups grouped by layer type instead of being all over the place. I'm frequently frustated just trying to remember where THAT setting is lol

Maybe slic3r just has a more realistic rendering, and that is already the complete answer.
If you print out the parts, the cura sliced part is not really that smooth.
I was curious about this myself, and printed the same part without optimzing, using curas and slic3r defaults. Indeed the artefacts shown in slic3r show up in both prints.
The part in the first image was sliced with slic3r (1.42 alpha).
The part in the second image was sliced with cura (3.1 as shipped with ubuntu). Additionally to the same diagonal top-left bottom-right effects, which the cura print shows, there are also some strings going from the center to the bottom-left and top-right corners.
I did not optimize anything about the top layer.

This does not provide an answer to the question. Once you have sufficient reputation you will be able to comment on any post; instead, provide answers that don't require clarification from the asker. - From Review

Assuming the comparison of my prints is valid, both slicers have results of similar quality (contrary to what the rendered images suggest). But if the quality is similar, what remains from the question is "How to achieve better top layer quality with slic3r?"... which is a bit broad .


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Resources on getting horus/ciclop scanners to work?
I have a Ciclop (HE3D version) scanner ready to try to use, but it seems the Horus software is hopelessly bitrotted. It has breakage from API-level changes at least in the Python bindings for OpenGL, OpenCV, matplotlib, and wxPython, and possibly also incompatibility with the V4L2 camera drivers for Linux versions later than whatever the authors were using at the time. After attempting to fix those as best I can, I'm still getting no output from the camera. (Note: The camera works fine with other apps and OpenCV test program, so it's not a camera problem.)
Is anyone using the Horus software successfully? Are there forks or alternate software that are usable, or exact details on what historical operating system and Python ecosystem version is needed to make it work?

How is a tool for 3D scanning not also a tool for 3D printing?

I don't know if this will work but BQ commercializes a Ciclops scanner and have some downloads in their webpage (https://www.bq.com/en/support/ciclop/support-sheet).
There are different Horus and driver versions, maybe some will work for you(?).
Hope it helps!

Thanks, but it doesn't appear to. The release versions of Horus there (0.1.x) are older than the version I have from git, and even that is bitrotted with respect to modern versions of all the python modules it uses. Making this work is probably going to require actively fixing it or containerizing it (or just running on a dedicated box) with horribly outdated OS/packages... :(


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PETG nozzle clearance and extrusion multiplier
I've started printing PETG recently and I'm happy with results so far, awesome strength and good looking (except for stringing). But I've noticed that PETG prints better with more distance nozzle-plate than usual, and under-extrusion make parts looking better than both normal/over-extrusion.

What distance nozzle-plate is optimal for PETG? (i.e. the distance between nozzle and build plate during calibration)
What extrusion percentage is optimal for PETG?

Your second question seems a bit strange, any value lower than 100 % will cause under-extrusion, so what is optimal? Any value different than 100 % means that you have not calibrated the nozzle well.

Is it solely the clearance on the first layer that's a problem here? If so, adjust the Z-axis stop. If the nozzle appears to be running into every layer, then as @Oscar suggests, your "underextrusion" value is really a proper calibration for the nozzle in use.   BTW: what is "dirty" ? If you mean burnt bits, just drop the temperature.

@CarlWitthoft Your comment about the temperature makes perfect sense in light of of the OP's mentioning of stringing also!

Clearance is machine, not material dependant. You also speak about initial layer thickness, not clearance, which is space between parts

By dirty I mean that the nozzle seems to gather all strings (or whatever) and gets dirtier and dirtier during the print. The print itself remains good, I mean that there are no trace of nozzle dragging over the surface.

@FredoCorleone I have assumed that  with "clearance" you meant the paper distance when bed levelling, also known as Z offset, maybe it is better you make that more clear. Both questions are now unclear. Please update by [edit], thanks!

I've tried to make my question clearer. If not I'm more than willing to edit again.

@FredoCorleone So you mean the calibration distance between nozzle and bed or first layer height, it is still not clear what you mean.

Calibration distance...

How long of a print it is and does ot show "buggers" from material collecting on the nozzle? I mean PETG does stick to nozzle somewhat no matter what you do. That's why it's recommended to clean the ouside of the nozzle before each print.

Here is the mental framework that I use to reason about PETG: In a nutshell you want to avoid nozzle contact.
Unlike most other plastics, PETG sticks to hot brass really well and every time the nozzle moves through material it will pick up some of it. Material around the the nozzle then sticks to a random place creating a blob. It can also cook, turn transparent brown and drop into the print. Investing in a plated nozzle or silicone socks helps but doesn't eliminate the problem completely.
Now to the questions.
1) Nozzle Distance
Distance to the plate has to be such that the plastic is laid down precisely without the nozzle dragging through the material (remember, avoid nozzle contact). Precise lines require the build plate to be level and the flow perfectly calibrated. If nozzle is too low and/or the layer is over-extruded then PETG will stick to the nozzle and rip the lines off the plate again. Inspecting the first layer is required for best results. I like to print a layer test pattern after the flow has been calibrated and tweak Z offset in 0.02mm increments until it's perfect.
With many other plastics it's ok to have a large amount of "squish" in the first layer as it helps to work around minor leveling issues. This is where the cookie-cutter recommendation to raise the nozzle when printing with PETG is coming from.
2) Extrusion percentage
Flow has to be near perfect. Down to one percent perfect. Even a slightest over extrusion and some of the excess material will end up on the nozzle when it makes the next pass. Under extrusion isn't great either as this can lead to holes and affect overhangs where thinner strands of a previous pass may not be enough for the next line to stick to.
There are two critical parameters: diameter of the filament and extrusion multiplier. This is how to determine the settings:

Measure filament diameter. I use an average of ten measurements over about a meter (yard) of filament taken in multiple orientations.
Calibrate the extrusion multiplier using a method described in Prusa
manual:
I print a 40x40x40 cube in vase mode with extrusion multiplier set
to 1 and fixed extrusion width (e.g. 0.45mm), measure the wall
thickness in three spots on every side, average the results and
compute the correction factor.

I perform flow calibration for every new roll of filament.

To calibrate flow percentage I make a mark on the filament itself, about 10cm then I extrude 10cm within the move axis panel and then divide 10cm for whatever it has extruded. Is it good?

@Fredo Corleone - this is a different process called E-steps calibration. It is a prerequisite for a good setup. However it's done once when you assemble the printer. The process described here is fine tuning for every individual roll of filament.

@fredo-corleone The reason additional calibration is needed is that e-steps calibration handles the length of filament going into the machine. However the volume that is extruded also depends on the shape (how oval it is) and diameter of the filament (measured first to get close).

Also where did you enter that number? This should go to printer firmware and not into slicer.

I've just finished calibrating the extruder stepper, now it extrudes exactly the right amount! And I'm currently calibrating the flow. It seems that my printer over-extrude a bit (printed wall is around 0.45mm while line width is 0.4mm).

@FredoCorleone If you get 0.45 instead of 0.4 then it's ~12% over-extrusion. Not unheard of but doesn't smell right. Assuming 0.4mm nozzle, the default extrusion width should be more than 0.4mm. Are you sure 0.4mm is correct? If you're using slic3r then set everything under Print Settings -> Advanced -> Extrusion Width to 0.45 and print that cube again. This will make sure that there is no automagic involved in calculating extrusion width.

@FredoCorleone I don't know what you meant by line width here. However if it's the line width of the model (STL) then it may not match the actual extrusion width the printer can achieve. Extrusion width is determined by slicer settings and in the simplest case slicer will use a default extrusion width (generally larger than the nozzle diameter) and attempt to fill the walls with the number of lines that best approximate the desired thickness. E.g. a 0.4mm wall will come out ~0.45mm thick if this is what the extrusion width in the slicer was set to.

By line width I meant extrusion width, it's called that way in Cura. Anyway I've successfully calibrated my printer. Thanks

Measuring the wall width is a very bad way to tune extrusion multiplier. Your caliper may be accurate down to 0.05 mm, the wall width is 0.45 mm. Your uncertainty (optimistic) is 11%. Extrusion multiplier should be accurate down to 1-2%, therefore you cannot get there with a measuring technique accurate to 11%.

Yes calipers are not accurate enough.  I don't see calipers mentioned anywhere in the answer nor the linked pages. Prusa docs linked above call for using a micrometer.

I have printed literally kilometers of 2.85 mm PETG filament on various 3D printers, and frankly, I do not share your opinion on an increased calibration distance/offset (like using thicker paper when levelling you build plate or increasing the Z offset by G-code M851). I even lower the default first layer height in Ultimaker Cura (0.2 mm prints fine). I am aware that on the web there are folks that do increase the calibration offset, or increase the first layer height, but that should not be necessary on a well tuned printer with sufficient first layer adhesion (e.g. printing on glass with 3DLAC).
Furthermore, the best extrusion multiplier for printing PETG is 100 % on a well tuned extruder for a constant diameter quality filament brand.

On my Ender 3 Pro's I have found the following works well (also remember settings can be effected by different brand/quality of filament):

Bed to nozzle 0.2-0.3 mm,
Multiplier 100 %,
Nozzle ~230 °C/bed 70 °C,
Speed 50 mm/s.
Cooling off first few layers but from there cooling and retraction is part specific.

If you use retraction, it may help to slow it down to 25 mm/s and adjust retract distance if your using Bowden tube or direct drive. Last, a must have, a can of hair spray, works great and less expensive than the glues.


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Correct nozzle replacement
I have a Monoprice Maker Ultimate 3D Printer and have tried to replace the nozzle.
The nozzles I bought turned out to be too small.

What are the important specifications of a nozzle?

Thread size
Thread length
That plastic tube thing?

Monoprice is very bad at publishing the specs, can I work it out with a caliper?

This is a so-called MK10 nozzle, it is larger than the normal nozzles you find (as you found out).
There are quite a few questions on this nozzle, with e.g. this answer or this answer.
This nozzle uses M7 (metric threads of 7 mm) to have more room to fit the PTFE tube (white tube) in the nozzle itself. This tube forms the barrier between the heating source and the filament feed so that it does not melt too soon. You can find these nozzles on those typical auction websites by searching for "MK10 and M7".
When you have ordered the correct nozzle you could reuse the existing PTFE liner if it has not degraded or damaged, or buy replacement PTFE tube of 4 mm outer diameter and 1.9 or 2 mm inner diameter and cut a similar sized replacement liner.

Thanks.  Would this be what I probably need then:. SIENOC 0.2/0.3/0.4/0.5/0.6/0.8mm Nozzle 3D Printer Extruder Print Head for M7 MK10 Makerbot 1.75mm (6pk) https://www.amazon.co.uk/dp/B07FYC2QWC/ref=cm_sw_r_cp_apa_i_5cmtCbXE6BASB

I would just replace the PTFE tube since often when you pull it out you slightly damage it. This can greatly increase you chances of getting faulty extrusion. Just buy a 50cm length of PTFE tube and you'll be set for a long time :)

Maker Select, Select V2, and Plus are Mk10. I thought Ultimate was Mk11?

What part fits?
A replacement nozzle needs to fit 3 parameters:

Thread diameter and pitch need to match up, to allow mounting
Thread length should be close to the original to allow secure fastening
The style needs to fit: there are quite some styles of nozzle - most are not lined, yours is PTFE lined to the nozzle (see also Can the filament tube be outside of the nozzle?)

Monoprice nozzles are not compatible with what is known as Ultimaker Mk8 or E3D style (which you bought). They are Ultimaker Mk10 style.
What's a good nozzle?
Now, what separates a good replacement nozzle from a bad one?

good machining to leave no burs and a smooth interior.
a good inner geometry that allows easy flow
outlet hole is to size

Finding premade replacement parts
As a first measure to not get the wrong replacement parts, make sure to add the manufacturer of your printer to the search and then check the thread diameter if given. In your case, you might have to add Monoprice or Toymaker, as those use this style of nozzle.
Reverse engineering a Nozzle
Now, which measurements do you need to reverse engineer it?

nozzle front pitch angle
hex head flat-to-flat & hight
recess diameter & hight
screw shaft relief diameter & hight
thread outer diameter & length
inner bore diameter at entry (and in case of a lined one: after the step) & corresponding depth of drilling
amount of chamfering

With these, it's possible to do do a CNC model or a sketch of the outside and produce pretty much blanks or shells on a lathe that just need their last little bit of drilling... and here comes the tricky part: till now, all could be accessed from the outside. We are missing one profile though: the last piece of the inner bore geometry.
This one can't easily be measured, but if one can push some plastic in, let it cool and then pull it out, one might get a molding of it, which might allow to reverse engineer a fitting drill for the last piece.

authors: ชวัลลักษณ์ จันทร์ทองโชติ


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Lower Layers are messy
This picture pretty much shows the problem:

I print on a CR-10 and this thing is pretty much just a problem factory. Anyways, the latest problem that was never there before is that for some reason the first 2-4mm of the print are totally messed up like in the picture. That isnt that much of a problem for bigger parts (as in the right one) but smaller things such as the pi-coin (left) are absolutely useless now.
Things ive already checked that haven't fixed the problem:

Different PLA filament types (geetech, Janbex)
Different nozzles (0.3mm, 0.4mm)
Variations of smaller line withs (up to .05mm smaller)
Nozzle temperatures between 180°C and 215°C
Bed temperatures between room temp. and 80°C
Flowrates 85% of actual flowrate up to 105%
Printing speeds of 30mm/s to 80mm/s
Different location on the buildplate in case that parts of the rail are worn out
Cooling fan active all the time, off all the time, off for the first layers
Checked bed leveling
Checked extrusion
-Variations of all of these things

It is noticable that the first few lines are layed down perfectly but when filling out the circles (in the case of these models) the layer becomes very rough. After that every new layer just suffers from the quality of the previous one. There is also a scratching sound when the nozzle moves over the object. I slice with Cura (latest version) and Z-hop is active.
I also checked the Z-rod and it at least looks fine to me.
I am really running out of ideas. I even checked every screw on the printer (and found out that the x-Rail wasn't perfectly straight but that didnt fix it either).
This problem occured after I replaced the entire print head with a new one since the old one kept clogging.

Welcome to 3DPrinting.SE!

Have you looked at this question? It appears to be a similar defect. Your question is very complete!

Referring to the scratching, this could indicate that the nozzle is a little too close to the bed. This can be caused by a non-uniform bed, but that is unlikely in your case as you have tried printing on different areas of the build plate, this implies that the bed is correctly levelled. Still, the nozzle may be too close while having a perfect level bed (easily checked by using a metal ruler on its side over the bed). You could print an adjustable Z endstop trigger mechanism, there can be a few found on Thingiverse, e.g. this one or this one, it should enable you to fine-tune the nozzle to bed distance by turning the adjustment screw; the following image shows an example:

Note that a recent question has a solution that describes that the rollers had too much play on the profile.

My 10S came out of the factory with loose rollers so that linked question is definitely something to check.


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Printrbot Simple + OctoPrint on PC not working
I am running the newest version of OctoPrint server on my Windows 10 PC, and accessing it with Mozilla Firefox on the same PC.
I also installed Cura 15.04 and selected the Printrbot Simple profile, and pointed to the Cura install path in the OctoPrint client so that it can use it for slicing.
I plugged in my printer and it was recognized by OctoPrint. The nozzle temperature is correctly shown, and I can turn the fans on/off in the control tab.
However, I cannot do anything else in the control tab, including moving the axes. I have not imported any sort of printer profile into OctoPrint, since I cannot figure out how to or where to find my printer's information.
There has not been any kind of calibration process I can find either.
Can anybody help me find a print profile/calibrate my printer, and just get it working so I can move the axes/print something out?

Welcome to 3dPrinting.SE!

What does octoprint.log say in terms of errors?

octoprint.log has 0 errors in it. When I look in the Gcode console, all of the G28 (homing axis) all have "ok" as a response. No errors can be found anywhere. The printer just doesn't move aaaa

Before any axis can move the printer must be homed correctly (G28 command, or an equivalent home button, there are 2: an X/Y and a Z button). A correct printer profile must also be defined; this profile contains some bed geometry and speed data, these are some basic values that are easy to add through the wrench button and "printer profiles" menu item.
Note that Cura 15.04 is very old, more recent version with far more options and better stability can be downloaded, but won't work integrated in OctoPrint, instead you download the most recent version of Ultimaker Cura directly from Ultimaker.com slice your product and store the G-code file to later import this into OctoPrint.
Please take care in choosing an optimal power plan in Windows 10, if your computer goes to sleep during a print (or updates or crashes) your print is lost; using a Raspberry Pi is far more safe.

Thank you for the reply! I have not defined a profile yet, I will have to figure that out. The homing buttons do nothing for me currently, so that is hopefully due to not having a profile set up yet.

I have defined a profile.
Using both the G28 command and the homing button, nothing happens. No error in terminal (I recieve an "ok") and nothing out of the ordinary in octoprint.log. Fans can turn on and off thats it

authors: ยืนงง ในยานอวกาศ ที่มีไฟ


text:
Converting .nii file to .stl file
I'm trying to convert a .nii file to a .stl file using this tutorial.
Since my computer runs Windows, I'm running FreeSurfer (Linux) on VirtualBox. I was unable to allow Guest Additions, so I downloaded my .nii file by email. I ran this command to extract the data from the file using FreeSurfer: recon-all -s mybrain -all -i /home/fsuser/Desktop/brainscan.nii
Unfortunately, it did not work, and I received this error message:

"WARNING: tcsh v6.17.06 has an exit code bug! Please update tcsh!

ERROR: Flag -i/home/fsuser/Desktop/anat_stripped.nii unrecognized. -s mybrain -all -i/home/fsuser/Desktop/anat_stripped.nii Linux xubuntu-VirtualBox 3.2.0-23-generic #36-Ubuntu SMP Tue Apr 10 20:41:14 UTC 2012 i686 i686 i386 GNU/Linux

recon-all -s mybrain exited with ERRORS at Fri Jan 25 20:08:01 EST 2019

For more details, see the log file To report a problem, see http://surfer.nmr.mgh.harvard.edu/fswiki/BugReporting"

I think the problem is that I don't have an application in VirtualBox that can open a .nii file. I tried to download Mango, but when I unzipped the file, there was no executable. What should I do so my .nii file can be converted to a .stl file?

Did you download Mango for windows or linux?

Did you install the third tool listed in the tutorial -- "Convert DICOM to NIFTI" ?

Looks like you didn't include a space between the -i flag and the file, though you did include the space in this question. Try running the command but include spaces between your flags and file directories:
recon-all -s mybrain -all -i /home/fsuser/Desktop/brainscan.nii


text:
Prusa i3 improvement - cooling fan
I wanted to add a cooling fan to my Prusa i3. The board used by this printer is an MKS GEN L v1.0, such as this one:

The cooling fan plug seems to be the white one on the top left corner, just below the step motor drivers. I plug a working 5 V DC fan, but it is not rotating. What could be the cause? The cooling fan has been enabled permanently using Slic3r to generate the G-code I am printing.
The board is powered by a 12 V power supply.
Are there some modifications to do on the embedded software side?

Please update the question by [edit] and add printer "make and model", which firmware you use, if you uploaded/configured the firmware yourself. Thanks!

The MKS GEN L v1.0 is a board that according to the information found on the web operates to run on a voltage between 12 - 24 V, this means that all peripherals on the board should match this voltage. A 5 V fan should therefore not be connected.
First, you need to establish that you are using the correct fan port on the board.
Which port to use?
If you take a closer look at the board layout you will find that the top fan connector cannot be controlled, it is a fixed voltage power supply of 12 - 24 V (so basically depending on the power that is supplied to the board).
This can be seen from the board layout:

Or zoomed in on the top left corner:

Note that no pin number is given, this means that it is a constant power supply fan header. A 5 V fan attaching to this port does not seem to be a good solution, it can easily burn out the fan electronics. This fan should match the voltage of the power supply you use, so when powered by a 12 V power supply, attach a 12 V fan or a 24 V fan when the board is powered by 24 V.
As said, this fan port is not controlled by PWM and can therefore not be scheduled from within your slicer, however, it makes an excellent fan for cooling the cold end of the nozzle assembly.
To schedule a fan for print part cooling through the slicer you need to attach the fan to the other fan header below the X stepper driver on the left, if you look closely to the schematics, you see that that is a fan that can be scheduled using the digital pin D9.

Note that this fan also operates at the voltage specified by your power supply; a 5 V fan should not be connected to this port either!
The solution to your problem is to buy a fan of the correct voltage and connect it to the correct fan header.
As you have tried connecting a fan to the lower fan port, and conclude that the fan has never rotated but still rotates when supplied with a correct voltage, you need to ask yourself if this port is:

configured correctly in the firmware, or
not broken.

Now that you know where to connect the fan for print part cooling, connect a fan that matches the power supply voltage.
Why is the fan not working?
The microprocessor of the board schedules and reads various ports or pins based on the firmware it runs. This implies that the setup of the firmware is very important in the use of certain ports. It is therefore important to research if this port:

was meant to be used by the printer manufacturer (so enabled in the firmware)
or board is controlled by which firmware

Once you establish that it is enabled (e.g. the manufacturer describes that the printer has a print part cooling fan), you should try printing a part where you enable the print fan in the slicer software. If not, you need to change the firmware configuration to enable the fan. If this does not work, you should address your attention to why it is not working. A multimeter can be used to read the voltage of the fan MOSFET output or the D9 output. If either one of those doesn't record a voltage, your board or MOSFET are probably broken. To fix this, you could solder an unused pin to the fan MOSFET or a new MOSFET and change the firmware. Another option is to buy a new board and flash a new configuration of a printer firmware onto it.

Sorry, my explanations were probably not very clear. I was indeed using the D9 pin. And before plugging in the fan, I checked whether or not I could get a voltage, which I didn't... I thought that maybe, there were a load verification on the startup phase.
The 5V fan still function properly, which means I most probably never got any voltage on the D9 pin...

As the D9 is connected to the MOSFET, it schedules the voltage of the power supply unit (12 - 24 V), if the fan still works, it did not receive a voltage over 5 V (or it has some protection for overvolting, but I don't know if that is done on such fans, most probably not).

I also guess that it didn't receive the voltage. And it would be consistent to my multi-meter prior measures. But how could that be?

@EmileD. Have you correctly configured the firmware configuration? Maybe you could add your configuration.h (as a link).

That was the thing then... I didn't update the firmware and I don't know how to do it. Is there some kind of tutorial I could follow for that? I guess it some kind of Arduino flashing I should use? And since I don't think I received any configuration.h with my printer, how to start without soft-braking anything?

@EmileD. I'll update the answer to include this option so that you can accept. Note that questions in comments cannot be answered, but how to install a firmware is already covered by questions.


text:
ANet A8 running Marlin v1.1.9 Auto Bedlevel with ROKO SN04-N
I'm trying to get the ROKO (SN04-N) sensor to work with my Anet A8. First of all, while trying to screw it to the extruder, I tightened it too much and sort of broke the acrylic plate... sort of. I had to use a very thin steel plate with two holes to enforce the acrylic plate. It still works.
Now, I followed instructions in this video. (Please note that the video is not in English.) After the first "Auto Home" operation, the guy draws on the bed and then measures. My measurements are slightly different.
At the 19-minute mark, the guy is hard-coding the values but I don’t understand how he calculated them? My measured offsets are: X_PROBE_OFFSET_FROM_EXTRUDER 16 and Y_PROBE_OFFSET_FROM_EXTRUDER 58. In his video, his calculations were 18 mm for the X offset and 57 mm for the Y offset. Either way, I’m not able to compile the code as a sanity check fails:

`static_assert(FRONT_PROBE_BED_POSITION >= MIN_PROBE_Y, "FRONT_PROBE_BED_POSITION is outside the probe region.");`

Here are the sensor limitation values from the configuration file:
// Set the boundaries for probing (where the probe can reach).
#define LEFT_PROBE_BED_POSITION 20 //MIN_PROBE_EDGE
#define RIGHT_PROBE_BED_POSITION 200 //(X_BED_SIZE - MIN_PROBE_EDGE)
#define FRONT_PROBE_BED_POSITION 47 //MIN_PROBE_EDGE
#define BACK_PROBE_BED_POSITION 200 //(Y_BED_SIZE - MIN_PROBE_EDGE)

What am I doing wrong?
Note that I'm using Marlin Firmware v1.1.9

Too bad you broke the acrylic plate (nice temporary fix though), but you can easily print a replacement part once your machine is up and running.
Probe positioning is defined in the Marlin configuration as:

 *      +-- BACK ---+
 *      |           |
 *    L |    (+) P  | R -- probe (20,20)
 *    E |           | I
 *    F | (-) N (+) | G -- nozzle (10,10)
 *    T |           | H
 *      |    (-)    | T
 *      |           |
 *      O-- FRONT --+
 *    (0,0)

This implies that your sensor is located on the back-right when facing the machine and need to have the following constants set:

#define X_PROBE_OFFSET_FROM_EXTRUDER 16   // X offset: -left  +right  [of the nozzle]
#define Y_PROBE_OFFSET_FROM_EXTRUDER 58   // Y offset: -front +behind [the nozzle]
#define Z_PROBE_OFFSET_FROM_EXTRUDER 0    // Z offset: -below +above  [the nozzle]

In order to calculate the correct limits of travel for the sensor, you need to subtract the offset values from the bed size at the max limits.
An additional offset may be required for some sensors, so please add an additional offset in the configuration by defining:
#define MIN_PROBE_EDGE 10

As the sensor is off-center with respect to your nozzle, one can only assume that you have no extra space to move the whole printhead and therefore need to confine the head within the limits of the max/min bed size (there should be some extra space, this can be seen from the offsets for the origin as in values for X_MIN_POS and Y_MIN_POS, but for the sake of simplicity these will not be taken into account).
Basically, your positive Y and positive X offset result in the following schematic.

Or, if you include the #define MIN_PROBE_EDGE [value]

Bed limits for the sensor then will need to be calculated based on the values of your offset of the sensor. E.g. when your nozzle is at (X=0, Y-0), or (0, 0), your sensor is at (16, 58). If you don't want to move the head further left and forward (to respect to origin as limit!), this is the minimum position of the sensor. When the sensor is at the back-right position of (220, 220), the actual head is at (220-16=204, 220-58=162).
This means that the limits for the sensor without a minimum offset are (16, 58) and (220, 220):

#define LEFT_PROBE_BED_POSITION (X_PROBE_OFFSET_FROM_EXTRUDER + MIN_PROBE_EDGE)
#define RIGHT_PROBE_BED_POSITION (X_BED_SIZE - MIN_PROBE_EDGE)
#define FRONT_PROBE_BED_POSITION (Y_PROBE_OFFSET_FROM_EXTRUDER + MIN_PROBE_EDGE)
#define BACK_PROBE_BED_POSITION (Y_BED_SIZE - MIN_PROBE_EDGE)

would translate with a MIN_PROBE_EDGE = 0 to:

#define LEFT_PROBE_BED_POSITION 16
#define RIGHT_PROBE_BED_POSITION 220
#define FRONT_PROBE_BED_POSITION 58
#define BACK_PROBE_BED_POSITION 220

and would translate with a MIN_PROBE_EDGE = 10 to:

#define LEFT_PROBE_BED_POSITION 26
#define RIGHT_PROBE_BED_POSITION 210
#define FRONT_PROBE_BED_POSITION 68
#define BACK_PROBE_BED_POSITION 210

The assertion in code: FRONT_PROBE_BED_POSITION >= MIN_PROBE_Y would now translate to (58 >= 58) (or 68 >= 58), in your case it was (47 >= 58) which clearly is not true.

Please look into this answer, this answer or this answer for more information.


text:
Which is the right filiament type to print breakable children's toy parts such as small gears
Probably the question sounds a little strange; however, I am looking for a filament which is breakable and not so steady and reliable as PLA. I want to print parts similar to the following gears for instance (They are from Lego, a children's toy).
They should break after some time or in any way become unusable after an accidental period (1 minute to several days) of use. Yes, you read right: I want to print parts that are frangible and probably will break! I plan to use Ultimaker 3 as 3D printer. So I'm looking for a suitable filament. Maybe I can merge two types of filament?
Could Ultimaker's TPU filament (https://ultimaker.com/en/products/materials/tpu-95a) be useful for my purpose? Or can anybody recommend me another filament that can be useful for my intended use? The primary purpose is that the printed part is not stable enough to serve its original purpose for longer than a foreseeable time (1 minute to several days). I appreciate your advice and ideas.

Note: I don't want to sell them; I want to use them for my private project. So please no legal issues. They are not helpful for my question. I don't ask for legal advice.

Turn your extrusion multiplier down so you are deliberately under extruding.

I think I need to make something clear here. I do not intend to make copies of legally protected materials. My reason is not that I want to make these cheaper than the manufacturer sells them. I want to make them myself so that they have breakages (and they don't have to be precisely the Lego gears, just like that). I am interested in ideas and proposals on how to do this.

is there a good reason to print new parts with built-in (but unquantifiable or unrepeatable) fragility as opposed to buying stock parts and cutting controllable failure/fracture lines?   Let's get to RootCauseAnalysis:  why do you want things to fail, and do you want the failures to be repeatable?

When children are involved, wouldn't it be better to try to make it unbreakable? For the sake of their well being. :) If you have a 1.75 mm filament machine, set the slicer at 2.85 mm, you get a sparsely filled print. Happens once in a while when you upgrade the Ultimaker Cura version when if defaults back to 2.85 mm.

deliberate/planned obsolescence is the term you look for
If you design parts that break after some time, you plan their obsolescence. That you do by a deliberate choice of material and working conditions. Designing a part that will break after a certain time can be done by choosing the correct stresses that will make your chosen material break.
In a gear that is meant to break at certain stress, one can weaken the teeth or the sprues, so that normal operation stresses will very likely break the safety margin and destroy the gear.
is it a material choice?
Any material is suitable to make a planned break, as long as the design is suitable. Performing a stress analysis of your part will tell you where to weaken it to enforce it will break - if the part was solid. As printed parts in FDM aren't solid, take the result with salt - it will tell where but not when it fails. Do the experiment for actual numbers.
is it a print setting thing?
Besides deliberately under-engineering some part of the gear, a usually perfectly fine gear would lose a lot of strength by deliberately reducing how massive it is: the stability of a print is affected by the form and amount of the infill just as much as the number of shells. Some random setting examples:

1-shelled, 1-bottom/top-layer, 5% infill piece is very likely so fragile you might not get it off the build plate
these parameters at 2-5-10% results in a somewhat durable piece.
2-5-20% is more than twice as strong as 2-5-10%.

To find the exact breaking point of a setup, one might need to toy with the parameters and experiment. It might be interesting to use no top- or bottom-layers and thus turn to create all the spokes of the gear in the shape of infill and outer shell. Also, some infills are better at withstanding forces than others - for example, Gyroid or Hex infill is rather stable on pressure while spaghetti is quite weak.
Other parameters also can change the infill stability: speeding up the print of the infill compared to the shell and using a thinner line considerably weakens the infill, thus reducing the needed load to break it. This is a somewhat easy parameter to tweak if you want to go for breaking the spokes (see below).
planned obsolescence and how to under-engineer safely
Sometimes, planned destruction is good for safety: a safety valve is supposed to break under overpressure to release the pressure in a safe way.
But planned obsolescence can also be a safety risk: If a toy breaks under normal use, it is a safety hazard for the broken off parts can be swallowed by children. Another factor to look at is where broken off parts end up in the machinery - they might jam other pieces that are not meant to self-destruct and destroy them.

Design the pieces to break in a safe way - the larger the chunks, the better you prevent them from going into places they should not.
Design the teeth to deform or melt rather than shearing off
Design the axles to sheer free by losing their keying
Design the spokes of the gears to break, separating gear rim from axle & hub, either of which goes nowhere due to the other gears and the mounting
Encase the self-destruct gears in some sort of gearbox to prevent the pieces from going flying

Industrial machinery design usually goes the melting way: Let's take a hand mixer. It contains a gearset that has one drive gear connected to a second gear, so that both mixers spin opposite. Under normal use, these spin pretty fast, creating heat from the friction. In a good design, these two gears are made from metal or a high heat tolerant polymer. But if one plans for having them break, these gears are made from a material that will heat under the friction in such a way, that after a set time (around 5 minutes), the teeth will be sufficiently weakened to deform and grind away, destroying them in the process.
Preferred Material
I would actually deliberately under-design the gears for the expected loads and then go for a solid material printed in SLA or SLS from either a resin (which will break with pieces and bits going flying, so a gearbox is mandatory!) or a polyamide (nylon).  These parts would match the stress analysis fully.
If FDM is the only option, the material choice depends on the failure mode you opted for:

In case you opt for destruction from heat on the teeth or axle, a low melting material like PLA is perfectly fine, but make sure to engineer the chance of breaking teeth low. ABS can perform a little better but needs more heat (and thus more RPM) to self destruct.
In case of designing for a breaking failure of spokes or keying, PLA is an excellent choice, as it is sufficiently brittle.
PETG is a good compromise between ABS deformability and PLA's printing ease.

Footnotes
Gear DesignWhen designing your gears, keep in mind that gears are rather complicated. I actually advise to take a look on the gross oversimplification of This Old Tony because it allows you to see where you can make teeth break very easily by design!
planned obsolescence and consumer rightsWhile planned obsolescence can be an important safety factor, planning obsolescence in consumer products for sale to break them after a calculated time is unethical and can be a consumer rights violation. Remember, that legally demanded warranty and a right to repair exist in a lot of countries.
LEGO is Copyrighted, Patented and TrademarkedCopying Lego designs would be a Trademark Violation, Patent infringement and a copyright violation by using their designs. They protect them.

Also, if these are exact duplicates of Lego products, there's copyright infringement which could be possible. In the States, copyright law (if I'm reading it correctly) says Lego's copyright on their design is good through then end of 2047. It is far from expired. Lego goes after infringement as well.

Please do not let this thread degenerate into the clarification and discussion of patent issues. It would be a good idea to remove it from your answer. Everyone has something to say about this issue and knows something better than somebody else. What this question is really about is how you can reprint gears with a 3D printer so that they have fractures. The Lego gears were just an example that I found on Google. My target gears are a bit bigger (maybe 1cm more diameter). So please, give concrete suggestions/ideas. Thank you in advance

@user3352632 - As Trish stated, it's not the filament which you need to worry about, it's how you set the print up. Set it to single wall thickness and 5% infill. Should last you a good 5 minutes if you can get it off the bed without it self destructing.

@user3352632 ok, revised it a lot. The legal point is still a valid caveat in case someone other than you wants to use this knowledge to make a deliberate breaking part in an object for sale, so it stays in, but I pulled the emphasis from it by putting it to footnotes. The main point now is how to design it to break and where one can tweek to get that done - mainly under the aspects of how to achieve a safe breaking.7

For lego, their patent expired on most of the bricks long ago, though these gears might be more recent. They're copyright claim is dubious for these works, and trademark doesn't grant as many rights as we often think it does ( you can do anything you want with a trademark, as long as you keep it to yourself).

I won't even ask why you need this and I assume you've done your homework about the issues. 3D printed gears are notorious for failing even when designed well, so the idea in general should be pretty doable.
TPU would be a terrible choice for a number of reasons. It's flexible which would make it a bad gear to begin with, but it is also very very tough. So it may last quite a long time, but perform very poorly. You specifically mention not using PLA, but I doubt you'll find a material that suites what you are looking for, more likely the print settings should be changed.
Design Ideas
My personal recommendation would be to use a good material such as PETG, ABS or PLA and deliberately under-design it. This way when it is overloaded, the part will fail. Be sure to consider how you want the part to fail, this will decide which material you should. As for how to under-design it: This would take a bit of testing. 3D printers create an enormous range of material properties due to infill, layer height, etc. For a starting point, change the infill level down until you get the desired results.
Those parts look pretty thin to begin with, if the infill is not an option, try to reduce your wall thickness and thickness of top and bottom layers. One pass thick walls with no infill will be awfully weak and flexible. That flex should be enough to get you what you need. Eventually you can get it down to just a shell of a part with 0.2 or 0.1 mm thickness all around.
Material Choice
PLA will shatter, possibly resulting in further failure if caught in other gears. The small parts may cause an issue though when it fails.
ABS will deform and probably not shatter, but it is difficult to print with. I would not recommend this.
PETG is on of my favorite materials - it is relatively easy to print with, very strong and bends instead of shattering on failure. This may be a good material to use.

This metod will be difficult with gears but doable. Print cold and slightly under extruded. This will cause part to fail in layers. You may need to print the part on side to ensure a non functioning gear. Use PLA or PETG. Breaking TPU is next to impossible.


text:
LCD full graphic smart controller, no character display and screen blinking
After uncommenting the REPRAP_DISCOUNT_FULL_GRAPHIC_SMART_CONTROLLER, the display is blinking and no characters are shown on the screen, I have already switched the cables between EXP1 and EXP2, but it did not succeed.

This question could use some more information and pictures. It is a fact that some of the cheap displays have the EXP ports upside down, I have had that myself so I cut out some slots for the notches on the cable connector.

this problem can be solved by turning the slots on the display, as in the image below. Some Chinese displays are inverted from factory.

Yes, my experience was the same, I didn't know you could turn the plastic all the way around, good to know for next time! I just cut some extra slots...

I've just switched the slots and it worked like a charm, it made my day!


text:
Anet A8 with Marlin firmware: Auto Home is crashing into bed
I got things moving from the answer to a previous question. Now, since the base-video I'm following is non-English, I want the next phase fixed: Probing failed
Auto Homing showing failing Z-homing

After the final adjusted firmware upload, and bringing the sensor up, I see that the extruder pushes the bed down a bit when I auto home and then the LCD screen says probing failed.
If compare to the latest (v1.1.9) Configuration.h file from GitHub, here are the changes:
#define FIX_MOUNTED_PROBE // Line #0719, Uncommented

#define X_PROBE_OFFSET_FROM_EXTRUDER 16  // Line # 0779, Was 0
#define Y_PROBE_OFFSET_FROM_EXTRUDER 58  // Line # 0780, Was 0

#define Z_HOMING_HEIGHT 5 // Line # 0870, Was 4

// #define MIN_SOFTWARE_ENDSTOP_Z // Line # 0907 Commented

#define AUTO_BED_LEVELING_LINEAR // Line # 0977, Uncommented

#define LEFT_PROBE_BED_POSITION  (X_PROBE_OFFSET_FROM_EXTRUDER + MIN_PROBE_EDGE) // Line # 1027, Uncommented
#define RIGHT_PROBE_BED_POSITION (X_BED_SIZE                   - MIN_PROBE_EDGE) // Line # 1028, Uncommented
#define FRONT_PROBE_BED_POSITION (Y_PROBE_OFFSET_FROM_EXTRUDER + MIN_PROBE_EDGE) // Line # 1029, Uncommented
#define BACK_PROBE_BED_POSITION  (Y_BED_SIZE                   - MIN_PROBE_EDGE) // Line # 1030, Uncommented

#define Z_SAFE_HOMING // Line # 1144, Uncommented

From the above changeset, lines 1027-1030 are from the other SO question I mentioned above, the remaining are following the video.
After completing the steps up to the point where I push the firmware and have to lift the ROKO up I followed instructions in this video, my "Auto Home" operation is failing.
Update 1
I used Pronterface as recommended by @dgrat in comments below and got this result:
>>> M119
SENDING:M119
Reporting endstop status
x_min: open
y_min: open
z_min: TRIGGERED

I did not get the Probing failed message this time.
What's next?
Update 2
I also went ahead and tried out the second answer, where @0scar is recommending to uncomment #define MIN_SOFTWARE_ENDSTOP_Z.
The results are exactly the same: The head hits the hotbed and goes back and then comes down slowly hitting and compressing the spring a bit before stopping. I did not get the Probing failed message this time.

Does the endstop trigger?

@dgrat How do I detect that trigger?

There is a command for that. http://marlinfw.org/docs/gcode/M119.html. I use it now and then with http://www.pronterface.com/. You are not the first one with such problems. I suggest to always test the switches before using the machine to avoid damage.

@dgrat please check update to thread

I also tested that raising the z-axis by just 2 nm makes the A4 paper on the bed move with an acceptable resistance. Have I hardcoded the Z position somehow?

You should un-comment the following line to get rid of the Probing failed error message:
// #define MIN_SOFTWARE_ENDSTOP_Z // Line # 0907 Commented

to
#define MIN_SOFTWARE_ENDSTOP_Z

You have basically disabled the use of the minimum Z endstop, while in fact you are using one, the difference is that it is a sensor now, not a mechanical switch.
Please note the distance of the sensor to the bed, it looks as though it is pretty far away. Before sending an auto home command, it is better to test the endstop triggering beforehand; an external application (e.g. Pronterface, Repetier-Host, OctoPrint, etc.), USB cable and a laptop/computer can be used to send G-code commands through the terminal of the external application. Code M119 will output the endstop trigger status to the terminal.

I'll make this change and push firmware again. Will get back on this. I do not know why the guy in the video commented this out.

@HassanGulzar Have you fixed this, if not update your question so that other people may answer, or an update can be made.

Not yet. I have to redo the setup to verify if I've done anything wrong

I tried with the line uncommented but the result is the same. The head still pushed down on the hot plate such that the springs are a bit compressed.

@HassanGulzar As far as can be seen the configuration is fine, to be sure add a link to your configuration.h file. What you describe now is that it works correctly, but it is not tuned correctly.

authors: Яков Стрелков


text:
Reinforce screw holes
I made some 3D printed supports for tools, using screws to fix it to the wall, some of them broken because of the screw forces. Is there a way to reinforce only the screw holes where it will have more stress/compress? I am using PLA, Fusion 360 and Ultimaker Cura.

you might want to look at the slicing too

Welcome to 3dPrinting.SE! I'm not completely understanding what you are trying to reinforce? Are they just holes which the screw goes through? Or are they actual threads you are printing which you need to reinforce? Could you provide a picture of the area you are working with?

This question is not very clear, are you interested in local increase of the infill (see e.g. this question), dimensional hole accuracy or techniques to design support fixtures/lugs?

Thanks for your reply Oscar, the e.g. you shared here is exactly what I need. I think you understand the question very well. Cheers.

Looking at the answers, you are after local strengthening, this can be done by changing the infill percentage around holes and is described in this question; this could imply that this is a duplicate.

Are you using screws similar to drywall screws which have a flat head that tapers down to the screw or a pan head screw which usually has a rounded head and flat bottom?

You can test different print settings. Trying to visualize, but I believe you can increase the perimeter lines, since there is a hole, this will increase the resistance in that area. Or try to change the orientation with which the part will be printed

Hello thanks for your input, I am trying to find how to increase the perimeter line in Fusion360, where is it? :)

@Manolo These settings are made inside the CURA (shell settings)

You can use a washer between the screw head and the plastic material to distribute the load
In my designs I also put in a depression to fit the washer so that it sits flush with the resultant surface.

Thanks for your reply, this is a good idea, I will try to do that as well.

In order to add localised extra walls, I will sometimes cut a torus shape around the part that I want to strengthen. This can result in n*wall, infill, n*wall, void, n*wall.
See the images in this answer if the description is not clear.


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Print box bigger than the printer bed
I am trying to make a box that is 420 mm wide by 86 mm tall by 100 mm long, I wonder if there is a good technique to design, cut, print and fit all parts together to be safe and hard.

Are you making a simple box? Or does it have some kind of detail or structure? The photo below exemplifies a structure attached to connectors that have been created outside of Fusion, but you can also use it as an idea to create your own!

Link to OPENSCAD LIBRARY
If you are thinking of cutting into parts, you can also create a kind of male / female (puzzle) in the parts that fit. Something like that ...

Here is some interesting information to study How to design Snap-fit Joints for 3D Printing

Great this is what I needed... :)