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Anet A6 assembly problem - remaining power cables don't match instructions
I've just built my son's A6 and have connected all cables apart from the last power cables. The mainboard says hotbed line and extruder line but the cable says heatbed.
The cables are two red which are crimped together and two black crimped together.
All of the videos online show a different mainboard and connections.
There are more connections than cables because the wires are crimped.
I can't get my head around which wires go where, any ideas?

Hi and welcome to SE.3DP. It sounds a bit confusing, but don't give up hope. Some photos might help us understand the issue better, and a schematic, possibly. Where do the two crimped cables go to? What component? If they both come from the hotbed/heatbed (it is the same thing), then plug them into the mainboard's hotbed pins. You also say that the extruder pins on the mainboard aren't connected. In that case, where do the wires from the extruder go to? What pins have you plugged the extruder into? Follow the wires carefully, and it should all make sense.

If, as you say, the mainboard and connections look different to the manual and the videos, then maybe you have bought a third party clone. Nevertheless, it shouldn't differ greatly. Please edit your question and add some close up photos of the board and connections - otherwise the question may get closed by the community for being unclear as to what you are asking..

The manual appears to be available here, Installation Instruction_Anet A6 3D Printer - Elektor
However, according to this comment from Hard copy of the build guide?, there is a mistake in the PDF of the manual, with respect to the heatbed, and as such, it is better to follow the videos:

I find it is better to use the 3 videos:

3D Printer Instruction--Anet 3D Printer A6 Assembly Video 1
3D Printer Instruction--Anet 3D Printer A6 Assembly Video 2
Printer Instruction- A6 - Hot Bed Level Adjustment and Print Test

Only errors in the videos and i believe the instuction the Hetbed
fixing plate i have build diffrently , rotated by 180 degrees
vertical, since it is better for the belt and somewhere in the video
during fixating of the end-switch and the blower he interchanged the
screws.

However, looking at the manual, if it is to be believed, then be aware that as well as one connection for the extruder motor, there are two connectors each for both the extruder and the hotbed heaters:

One for the separate heating elements, of the extruder and hotbed respectively, and;
One for the thermistor sensor (both the extruder and the hotbed have separate thermistors).

This makes five in total for the extruder and the hotbed combined.

However, the power connections for the Extruder motor has four pins (in white at the top), whereas the heating elements for the hotbed and the extruder have two pins and are of a different shape (in green on the left). The sensor connections for both the extruder and the sensor have three pins (in white at the bottom), but it should be easy not to confuse them, so long as you follow the wires to check to which component they go to.

Additional points to be aware of
From this comment in the same thread:

I just built an A6 three weeks ago and with the videos it is really a
breeze to assemble the unit.
Just pay attention to the heat bed mounting plate as it is installed
bottoms up in the video. The bar connecting the outer two plates where
the heat bed is finally mounted should be below the plates, not above
as in the video.
Also, if you still have time, order some decent toothed belt, Igus
Drylin RJ4JP-01, and toothwheels for the Y and X belts and replace the
original pulleys, bearings, and belts before you even assemble the
unit. I just changed mine last week and it does make a hell of a
difference - with this little upgrades (cost me less than 30$ for
everything - at Amazon) you upgrade from an okay printer to a really
decent machine.

The belt: https://www.amazon.com/Anycubic-Meters-Timing-Pulleys-Printer/dp/B0152ZNDLK
The pulleys: https://www.amazon.com/Aluminum-Bearing-Timing-3D-printers/dp/B0188HW4Z0
The bearings: https://www.amazon.com/Printer-Solid-Polymer-LM8UU-Bearing/dp/B06XPRCMJS
(actually, you need 8 pieces - not seven as in the images - 4 for the
Y-axis and 4 for the X-axis)

The above are not the actual articles I've bought because I am from
Europe where Amazon sells in different quantities.
If you want to go on the safe side, grab a second power supply and two
MOSFET boards to remove the high current from the mainboard:

PSU: https://www.amazon.com/eTopxizu-Universal-Regulated-Switching-Computer/dp/B00D7CWSCG
(just as an example)
MOSFET: https://www.amazon.com/Wangdd22-Printer-Expansion-Heatbed-Current/dp/B01MY50JL3
Power socket and switch: https://www.amazon.com/URBEST-Module-Switch-Certification-Socket/dp/B00ME5YAPK

Last recommendation: get some 3mm borosilicate glass to lay (clip)
over the heatbed. This will make the prints stick better and also
provide a perfectly flat surface for the builds (still, you'll need to
do the levelling)
Glass:
https://www.amazon.com/Signstek-Printer-Tempered-Borosilicate-2132003mm/dp/B00QQ5Q3BI
When assembling the heatbed mount, pay lots of attention to the 16
screws. Tighten them one by one diagonally and move the bed around. If
the bed feels stuck, loosen the last screws and shift the mounts
around a bit. The lighter this mount moves, the better your prints
will be.
One thing that you must be aware: This printer is a great little unit,
but it needs love, dedication and plenty upgrades. Out of the box it
works okay, but with the upgrades it becomes a really good unit.

Thanx for the help, got it running now.
The board in the pic is the older version, my problem was the wires for the extruder had been cut really short for some reason and not labled.

This sounds like a comment to Greenonline's answer.

Ok, good.Glad you got it sorted. Please mark this (your answer) as the accepted answer (using the tick button next to the answer), in order to remove your question from the unanswered question list, thanks As a beta site we need to keep our queues short. It would still be nice to see a photo of your (new version) board, and the short leads, in case anyone else has the same problems as you, at a later date. The more information you provide, the more useful your answer becomes to the community in general.


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How to change "home" settings on Ender 3
I have just got an Ender 3, I got a friend to build it for me, as my hands are not great. Which means I don't know what bit does what.
My problem is when I click on home setting, my nozzle is in front of my base plate and below it.
I have watched every video I can find about the set up, but they all assume that bit is ok. I have changed the axis setting to put it on it but it doesn't save the settings and as soon as I hit home its off the base plate again. I don't want to go any further re-printing, so at the moment it's just an ornament.
What am I doing wrong?

This isn't a matter of settings but physical adjustment (the endstop switches). Having the head home slightly off the bed in the X and/or Y direction is a good thing, because it means the Z homing can't crash into the bed if the bed height is misadjusted. On my Ender 3, the X axis homes slightly into the bed, but the Y homes such that the nozzle tip is in front of the bed. Note that normally you don't try to print at X=0 or Y=0 anyway.
As for the Z homing, you have to adjust the bed height ("bed leveling") via the 4 wheels under the corners of the bed to bring it to the right height. If you can't get it below the nozzle with the wheels all the way tightened, your Z endstop switch must be installed incorrectly. The Ender 3's Z endstop bracket is supposed to fit against the corner of the aluminum extrusion just below it so that it doesn't need adjustment, but it's possible to mount it incorrectly higher. This is a bad idea because if it loosens it can move. It might also be possible to incorrectly install it lower, in which case it would be misaligned because the machine screws couldn't be tightened down all the way. This is also a bad idea. Make sure it's in the right place.
As for actual bed height adjustment/leveling, there are lots of good guides to that and I won't try to reproduce/improve on them here. The "sheet of paper" method is very good.

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Under extrusion... sometimes
You can see small gaps in the print which looks like under extrusion (see image below).
What is the reason for that?
I've tried smaller retracting distances. Temperature looks stable.
Print settings:

PETG from Extruder
245 °C Printing temperature
50 mm/s print speed
25 mm/s wall speed
30 mm/s retracting speed
1 mm retraction distance -> stringing...
Print cooling fan is enabled

Setup:

E3D Titan Aero
Duet Wifi
1,5 A Motor current for feeder motor
250 mm/s2 feeder max acceleration

Slicer:

Ultimaker Cura 4.0

Welcome to 3dPrinting.SE! What is the filament size and layer thickness?

Try lowering the hotend temperature with 10 °C.

Here's your problem:

1 mm retraction distance -> stringing...

If you have stringing, that means that material that was supposed to end up as part of printed lines instead ended up somewhere else, leaving less material (underextrusion) where it was actually wanted. This particular test piece may not exhibit stringing, but it's likely that it occurred interior to the piece, in the infill region. Contrary to widespread(?) opinion, stringing here is not harmless. It's just not visibly ugly. But it still messes up the surface quality, and even more importantly the strength, of your print.
You don't say if your printer has a bowden extruder or direct drive. If a Bowden, the 1 mm of retraction is virtually useless; a typical Bowden system has more than 1 mm just of compression between the extruder gear and the hotend, meaning that retracting by 1 mm does not pull the filament back out of the hotend at all, and doesn't even relieve all the pressure that's pushing melted material out. I would recommend an absolute minimum of 5 mm for Bowden type extruders, unless your printer firmware has linear advance (Marlin 1.1.9+ or comparable features in other firmware) in which case you might be able to reduce it some. For direct drive, I don't have experience, but 1 mm is still probably too low; 2.5 mm is the believable recommendation I've heard.
In addition to retraction, you can further reduce material loss to stringing/oozing in the infill region by turning on Ultimaker Cura's "Zig-zaggify infill" option, which helps avoid in generating travel without retraction over unprinted area within the infill zone (see e.g. this issue). Turning slicer setting "combing" to "off" is an even more extreme option here. Of course make sure retraction is really on (not "retract at layer change", which is a separate, mostly useless option) and make sure "retraction minimum travel" is set low (something like 150 % of the nozzle width or less) to prevent retraction from getting skipped on short travel moves.
I also just noticed you wrote:

I've tried smaller retracting distances...

This was probably based on erroneous advice. Reducing or eliminating retraction does not mitigate these sorts of problems; it creates them. The only reasons to reduce retraction distance are to fight problems with the extruder gear grinding down the filament after repeated retraction, and problems with jamming the path into the hotend due to pulling molten material back into the cool part where it then solidifies and jams. If you're not having such problems you should not reduce retraction. If you are having such problems, you should try to fix them in other ways that still let you keep the necessary amount of retraction not to have catastrophic print quality problems from material coming out in the wrong places.

I increased the retracting distance to 1.5mm. Speed was set to 30mm/s
Printing temperature is still 245°C
The screw which is pressing the filament to the drive gear was too tight.
So the stepper lost steps.
-> No stringing and no under extrusion anymore. prints are looking good now.

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Problems with under extrusion and clogs on CR-10
I've asked a question before on the extruder gear clicking on my CR-10, but I'm certain its because of the nozzle getting clogged for some reason. I'm using a standard 0.4 mm nozzle with white PLA and randomly during the print the extruder gear starts clicking on the fast parts and then under extrudes the rest of the print, eventually the hobbed gear digs away at the filament and doesn't grip anymore. Why would the nozzle keep getting clogged? Could it be because the filament isn't high enough quality and is leaving particles in the nozzle?

Additionally, when I performed a cold pull after breaking up the blockage on the inside, the filament came out like a thin film even though it was purging fine before I cooled it down. Why?

190 °C nozzle temperature (tried printing at 210 °C and the filament burned)
50 °C bed temperature
60 mm/s speed, outline 50 % - first layer being 30 mm/s
0.2 mm layer height

This starting happening after I returned to printing after a 6 month break, with the filament being stored in a cool and dry cupboard for around a year (the filament was on the cheaper side, but still highly recommended by SUNLU)

Why did you edit it? It was perfectly understandable before. I figured out the problem anyway, I printed with a higher quality sample filament I had and it worked perfectly.

Hi and welcome to 3D Printing.SE. At SE sites we need clear and well formatted questions, please take the [tour] and acquaint yourself using [help]. Great you put in a solution as an answer!

we strive to use the scientific notation, including the mandatory fixed-space between number and unit.

Turns out the filament was the problem, I tried printing a model with a high quality sample PLA filament I had and it printed perfectly; one of the cleanest prints I've had. Never skimp on filament.

That looks like a fine print, glad you solved it with new filament!

White PLA is usually some of the worst stuff to print with, generally avoid it. I would say. I myself are having a lot of problems with it as well.

I've printed a lot in white PLA which does not have the problems like you mention. To say that that is usually a general problem is a bold statement.

@0scar The colorant that is typically used for making the filament white has a negative impact on print quality, clogging the extrusion and so on. But with the right settings, you can sometimes fix it. Typically raising the temperature can levitate it. Share your brand of white pla, would like to try it.

If the pigment is the problem, then it would be a problem with other filaments as well (PETG, ABS, ...), or would that be mitigated by the temperature? Can you share a source for this, I'm curious to read about it. It also should be added to the answer to prevent discussion in the comments. My filament brand is ColorFabb.


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Printing with White pla, problems while printing a benchy boat
So I am having trouble with this white pla, I am currently printing with a tempature of 225 degrees and going lower worsen the printing, but what I find strange is that it is always the same area that screws up.
I am using a Prusa MK3S, and printing with this fillament: https://shop.prusa3d.com/en/filament/39-white-pla-filament-1kg.html

EDIT:
NEW INFORMATION, this only happens with my white pla. I have a Silver one, and it prints it perfectly.
Secound white print, see that silver pla is totally fine.

probably a problem with the Gcode. Try with a different file.

Do other models have problems at this same height? Have you re-sliced and tried the new gcode?

the underextrusion is at the end of the bow height...

@Davo Only my white pla fails, I can print it fine with the Silver filament I have.

@AvishkaKavinduB.Dambawinna It works fine, when I print the same fillament with another color. In this example Silver Pla.

Has this only failed once, or does it fail in the same place repeatedly - but only with white PLA?

@Davo Around the same place, only with with pla. I will put up a new image.

Even from the same manufacturer different colors of filament have (slightly) different properties requiring different settings of your slicer.
But here it seems you have some underextrusion at this hight. Have you tried again the same file with the same filament and the same settings? It could be a fault in the white filament at that spot that (temporarily) clogged your nozzle.

Have made 3 prints of the same boat, sadly fails at the same area but only with the white pla.


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Uneven layers- Ender 3
I got my ender 3 about a month ago, it was working fine. Tried a new brand, overture, this is when I started experiencing problems. First, I was clogging nozzles left and right, then I went back to hatchbox, and my layers are messed up...

Welcome to 3dPrinting.SE! How tight are the belts for your x-axis and y-axis? Is your bed tight to the slide? It looks to me you've got a lot of small layer shifts going on, which would indicate you've got slop in your assembly.

This looks like under-extrusion, have you cleaned the nozzle in between brands? Does the spool have friction so that it does not unspool freely?

Every time you use a new filament you should perform a new calibration: extrusion steps, filament diameter, temperature calibration tower, extrusion multiplier (if needed). Have you done it?

I have cleaned my nozzle (replaced it) cleaned my heatingblock. I have not performed a new calibration yet though. How would i do that?

What print settings are used? What temperature? It looks like underextrusion from a clogged nottle.

@Cherndon That is under extrusion due lack of force to feed the filament, also could be a problem of temperature which needs 10 to 15° C more. :D I had a lot of those "curly" layers, even my first hand made 3dprinter has some of those parts yet, that I will change on future.

I wonder if this problem is unrelated to your material or printer, and purely a matter of slicer breakage. Have you tried printing gcode files you created before the problem appeared? If you use Cura and upgraded it, you might have hit one of the bugs where it assumes by default you have 2.85 mm filament, even though your printer actually uses 1.75 mm. That will create underextrusion that has the whole printed object coming apart like an unravelling mummy. When I've seen it happen, it looks very similar to your picture.

Seems like in Movement without displaycement in x and y it seems to fit (neck-area).
I also would check your belts. There may be a bit too much friction.
Otherwise have you made some Testprints (calibration cube, boat)?
Especially the base looks bad. But it is not a cylinder or?
If you want, you may show us your 3dModell (rendered)

The print looks as if it has a lot of under-extruded sections, but indeed the base look odd.

Have you replaced your extruder stepper assembly with a metal one? I had a similar issue after a month of printing on my ender 3 because the plastic part had worn through and was causing drag on the filament.


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Can mold release agent be used in 3D printing?
Do we need mold release agent in 3D printing mold? If it is not used, what effect will it have on the product?

Could you [edit] your question to add more detail? Are you printing a mould that you will then use to mould something? What moulding technique, and what material? What stage of the process do you think you might need mould release agent?

It seems I misread your question.
3D Printed Mold
You were asking about (or the question now states) use of a mold release compound to prevent a molded part from sticking to a 3d print mold.
Yes.  It is always beneficial for the molded part to not stick to the mold.  Easy separation and part removal is important for the life of the mold and for the surface finish of the part.
There are two molding situations that seem important.
Flexible Mold or Object
In the first, either the part of the mold is elastic, so the actual sliding of one surface on the other isn't important.  Here, a mold release agent would help by preventing the cast object from binding to the mold material.
Stiff Mold and Object
The second case is where both the mold and the object are stiff, and the object must slide out of the mold.  Here the layer lines should be considered, since there may, locally, be reverse draft angles where the larger part can not slip past an obstructing filament line.  Using a process that doesn't leave filament lines, or using the thinnest possible filament layers, or smoothing the mold internal surfaces, or possibly filling the spaces between the ridges with another material may eliminate the problem.  A "mold release agent" would still be used to reduce the attachment of the object to the mold, although one may be able to use ample release agent both to fill the groves in the mold and prevent adhesion.

Welcome to the 3D Printing Stack Exchange site.
Used in Casting
A mold release agent is commonly used when a part is cast.  The release agent is placed on the inside of the mold before the liquid object is added.  As the object becomes solid, the release agent prevents the object from adhering to the mold.  As a result, the objects are easier to pop out of the mold, and in some processes, the mold can be reused.
3D Printing is Different
A mold release agent is used to allow the desired part to be separated from the mold.  In FDM (thin plastic extrusions bonding together into objects) 3D printing, the object is surrounded by air, except for the bottom where the object contacts the print bed.
Bed Adhesion
For most materials, getting the bottom of the object to stick firmly enough is the problem faced, rather than making it easy to remove.  In many cases, a compound is placed on the top of the bed to help the plastic stick to the bed.  It is a "mode adhesion agent" rather than a release agent.
For some combinations of materials, the bed material and the plastic have a particularly strong adhesion, such that it can be difficult to remove the object without damaging the bed surface.  Notably, this occurs with a PEI bed and PETG plastic.  In this and similar cases, the mold adhesion agents can be used on the bed.  This slightly separates the plastic from the bed material, and we can avoid bed damage.
Internal Adhesion
With multimaterial printers becoming more common, there are cases where two parts which might touch and stich during printing should be isolated during the printing process.  A second (or third) material can be used to isolate the parts.  If the isolation material is sufficiently different from the desired objects, it can be removed by a solvent.
This approach is limited to cases where the objects should be separated by at least one printer thickness of the soluble material.

The asker asked for a 3D printed mold specifically

This question lead to an idea of using some "release agent" as anti-stick remedy between support and the printing part.
Basically the main purpose of mold release agent is to prevent sticking.
So if the 3d printer will have extra nozzle to dispense agent on top of printed support and before next layers then yes this will be perfect for 3d printing.
Support will do role of supporting but not stick to the printed part and as result could be easily removed.
But I am sure almost any oil will do the trick.
My experience with molds in 3d printing:
I used 3d printed PLA molds with "oven backing clay" which I believe is mostly vinyl mixed with some organic compounds. With some thinning liquid from the same manufacturer I was able to make clay flow and be injected into mold.
I used oil to make clay release from molds easily. After been released parts baked in oven for 30 minutes under 110C. Then they left for some time to cool down and polymerize. The final parts look like plastic but much stronger and obviously heat resistant.
This technique could be used to design and test molds that finally will be metal and to be used in real injection molding process. This is what was my original target.

Isn't that pretty much what PVA-layers in the contact areas would be from 2-material prints?

Yes, PVA is good material for supports. And actually supports should not be slippery so likely oil will not always work.  So yes, PVA is a go. Just it's price contradicts with knowing it will be thrown away.

That's why you only print the interference layers in PVA and the actual carrying structure from a cheaper material.


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Ender 3 Pro Filament extrusion problems
I run quite a few Ender 3 Pro's using the same slicer settings (Simplify3D), and just recently I have noticed a very odd extrusion problem.
I find that at about the same height on several printers the printer under extrudes by quite a margin. After that, it either continues to under extrude for the rest of the print or it will go back to extruding proper amounts of filament with no problem. This destroys the print and makes it both structurally weak and defective. I am wasting quite a bit of PLA trying to fix this problem so any help would be appreciated.
Here is what I have done so far:

I first made sure that the hobbed gear is clean.
I tried extruding the filament with a very hot temp (240C) there were no problems here and the filament extruded fine albeit, it was not on the bed, just extruding into the air to see if the problem was heat.
I tried the same thing as above but with a low temp (180) this also proved just fine again extruding in the air.
I calibrated my E steps per mm, those are fine and accurate.
I tried increasing my flow rate to 118%
I tried switching to a different nozzle
I tried switching to a different hobbed gear
I tried switching the mechanism that pushes the filament up against the hobbed gear

That's about it. Not sure where to go from here so if anyone out there can think of anything I missed, I would love to hear it!
EDIT 1:
As per @fred_dot_u asked, the elapsed time at the layer of failure is roughly four hours in. I have also attached a picture of one example of this kind of failure below. I would also like to mention that this is happening on several of these printers as I have 18 printers running in one room. Our current theory is that the power draw is simply too high and so the printers are not getting the heat they need, however, the thermistors still register a solid 195C on my printers that are currently running.

EDIT 2:
Here is another picture of a different model with the same layer failure problem but at a lower layer height. This model was printed along with 11 other identical models on the same bed, all of which failed at the same height.

Hi and welcome to SE.3DP!

Can you assign a particular elapsed time to the problem you are experiencing? This question is founded on an overheat possibility of your extruder but that is not a certainty, merely one other aspect to check.

@fred_dot_u I'm not entirely sure what you mean, but I edited my question to answer what I think you are asking. Please feel free to let me know if that is not what you were looking for.

Is the Z position of the failure consistent? What are your print speed settings? Layer height? It may be that due to acceleration limits and geometry of the sliced layers, you don't achieve the top speed until this layer, and that the top speed you've set is faster than the printer can extrude. Also what are your retraction settings? It could be lost material due to travel without retraction.

@R.. The Z position failure is not consistently the same height, but is generally pretty close (within a few millimeters between prints and between printers). I have these models printing at 3600mm/min with a layer height of .2mm with a .4mm nozzle. I have my retraction speed at 3400mm/min with a retraction of 8mm, no restart distance, and no vertical lift distance. I have the nozzle coast for 1 mm and wipe for 3mm.

Have you tried disabling coasting? It fundamentally underextrudes, and the effects will be cumulative and dependent on the particulars of how the slicer orders the lines to be extruded. You should not need coasting unless you've disabled retraction for some reason; it's a hack that's a poor substitute for what linear advance does on printers that support it.

Also, 3600 mm/min (60mm/s) might be too high a sustained extrusion rate. At your layer height and nozzle size, it comes out to 4.8mm³/s, which might be faster than the printer can keep melting material. This would be consistent with my theory that the problems start when you get to layers that happen to have enough straight linear motion that the printer has time to accelerate up to the full speed before turning a corner.

@R.. Alright, I will adjust settings in the next print and let you know the results tomorrow. I will adjust down to 2400mm/min and disable coasting. However, even if I do change these settings, they are still working on some of my other printers. Not sure why though.

Good luck. Let us know how it turns out. If these ideas turn out to be helpful I'll write up an answer explaining why.

As it concerns similar heights for various printers, have you checked the spool to extruder feeding? Could be that the filament kinks at the same height over and over.

@0scar I have not checked that, but I will monitor that closely on the next few prints.

@R.. So the print has worked beautifully! I think the speed was critical in this matter which is unfortunate time wise but a solution nonetheless.

@DanielBozarth: Great to hear! You might actually be able to decrease the overall print time, while keeping the max speed lowered, by relaxing (increasing) the acceleration/jerk limits. Most of the time printing an object with fine details/sharp corners is spent moving a lot slower than the max speed, which is why you weren't hitting a problem with extrusion rate keeping up until you got to layers where it did reach speed.

@R.. Alright sounds great, I think I will ask another question about good acceleration and Jerk settings but for now, what you said earlier is the answer.

@DanielBozarth:I already put some in my answer. :-) But indeed it's not complete and advises you to experiment, so a question about the max accel/jerk the Ender 3 can handle, or about how to conduct experiments to determine this for a printer, would be nice.

There's a known issue across Creality printers with the PTFE tube (bowden) slipping in the coupler on the hotend side, allowing molten material to push back around/up inside it rather than making it out the nozzle. I haven't experienced any such problem myself, even after applying some fairly serious abuse to that part of my Ender 3, but this video from CHEP claims it was the source of his problems and explains the issue well.
I believe my Ender 3 came with an extra replacement for this coupler; if yours did, and this seems to be the problem, you can see if the second one they supplied is better. Otherwise it's an easy component to source third-party replacements for.

Based on the image and your report that the problem consistently appears at the same part of the print, this is clearly an (either absolute or net) underextrusion problem, but (mostly) localized to particular layers. I say absolute or net because it might be extruding too little total material, or extruding the right amount of material but losing some of it to unwanted extrusion (oozing/stringing) in the wrong places. Either of these could be related to geometry of the layers involved.
One factor here is probably coasting, which you mentioned in a comment you have enabled. The small amount of coasting probably means it's not a big factor, but coasting always underextrudes. That's fundamentally how it works. You should not need coasting unless you've disabled retraction for some reason; it's a hack that's a poor substitute for part of what linear advance does on printers that support it.
You also mentioned a 60 mm/s print speed setting. At 0.2 mm layer height and 0.4 mm nozzle diameter, that's 4.8 mm³/s volumetric extrusion rate, which is roughly the limit of what you can expect to achieve with your printer's hotend. If you try to print faster than the hotend can keep up with, the material won't melt sufficiently fast to pass through the nozzle orifice. This will naturally slow it down allowing further melting to take place, but in the mean time the extruder gear will either grind into the filament or (much less likely, I think) the motor will skip steps.
Note that print speed settings control maximum speed, which is why you won't necessarily hit problems from having them too high right away, but only at particular layers. In prints with small details, especially with sharp corners, the majority of the printer's time is spent accelerating and decelerating between speeds far lower than the nominal/max print speed, and if you only reach an excessive max speed momentarily now and then, it might not continue for long enough for the material to cool down, in which case everything just works out.
Part of why I mention this is that, if you're trying to keep print time under control, setting a higher max speed might not even help you. Usually acceleration/jerk is the limiting factor to how fast you can print. Max print speed should be set according to the extrusion rate the hotend/extruder can keep up with, and print acceleration/jerk should be set according to the dynamical properties of the printer's axes. If you increase them too much you might get rough surfaces, ringing, or even skipped steps/layer shifts, but you can go pretty high. 3000 mm²/s is probably the absolute max I'd try on an Ender 3. I did this and had some success, but some failures; I don't recall what jerk was and it might have been a factor too. The Y axis in particular can't handle acceleration as well as the X axis can, due to having to move the whole bed, not just the hotend assembly. Somewhere between 500 and 2000 is probably reasonable, but I'd experiment a good deal before trying it on a long-running print.
One additional method to increase speed might be reducing line widths to less than the nozzle width. This proportionally decreases the volumetric extrusion rate the hotend has to keep up with. But I'm not sure how well line widths less than nozzle width work for outer walls. This may adversely affect part strength too, which might not be a problem for your particular usage case.

@DanielBozarth: Check whether it might be this: https://m.youtube.com/watch?v=x35aWmnZ_A0 I just ran across.

Alright, I will take a close look at this issue and write back with results.

After inspecting one of my printers that was displaying this problem, I found molten plastic on the inside of the coupler so it seems that the issue was that the stock coupler was slipping and not holding firm. I have some replacements on hand and I am running a test print on that printer as we speak.

@DanielBozarth: OK, I added a second answer.


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When should I replace the nozzle on my printer?
I have what I assume to be a brass nozzle, and I only print in PLA. I am starting to have some issues with first layers and stringing. I'm wondering if I should replace the nozzle. What signs should I look for to know when to replace the nozzle?

Replacing the nozzle depends on many things,

the nozzle material (copper/brass, steel, hardened steel, Olsson Ruby Nozzle),
the type of filament you print,
how frequently you use the 3D printer.

To replace a nozzle, there are probably a few reasons for doing so. A nozzle can wear out (see: How to identify nozzle wear; not only from the friction  of standard filament, but especially when used with abrasive filament like glow-in-the-dark PLA, and glass or carbon fibre filled filament) causing the outer shape and the inner nozzle diameter to change size. This can result in lower quality prints or difficulty in getting the print to stick to the bed. Having a metal wire or drill bit of the diameter of the nozzle will tell you if the hole itself has worn out. Sometimes, a visual inspection may sometimes be enough for you to tell that it has worn out:

(source: filament2print.com)
Please note that an interesting video is posted by Stefan from CNC Kitchen on nozzle wear:

Nozzles can collect burned particles inside, partly clogging the nozzle, causing the extrusion to be non-ideal. A sign for this is when the filament is not leaving the nozzle straight when freely extruded at height, but curls up.
Furthermore, when used frequently, nozzles can get coated with filament which is sometimes hard to remove. This sometimes causes freshly extruded filament to stick to the nozzle, certainly if it curls up like mentioned before.
Note that nozzles are very cheap with respect to the complete assembly and replacing them is a matter of 2 minutes work. So if you're unsure about how to improve the quality of printing after having tried fixing flow rate and nozzle to bed height, you could replace the nozzle, see e.g.:

(source: The 3D Print General)
Depending on the quality of the nozzle and the filament, a nozzle replacement for one brand might be necessary much sooner than for another printer. E.g. my Ultimaker 3E has literally printed kilometers of PETG without the need to replace the nozzle (or "core" as it is called for this printer), while the brass nozzle of my first cheap, now dust collecting, Anet A8 printer has been replaced a few times.

This is a good answer, but please introduce https://www.youtube.com/watch?v=uvlMeTnjriQ because it completes it perfectly.

@FarO Thanks for the suggestion, I will incorporate it into the answer!


text:
How to calculate the extruder gear ratio given a desired max printing speed filament diameter and nozzle diameter?
I have a Printrbot LC with the following extruder gears:

Stepper on the right, filament toothed gear inside, same size of the small stepper gear.
I don't have much more information besides the model of the motor (42BYGH4807), but the reduction ratio (NEMA stepper -> toothed gear on the filament) is about 2:1, the filament is pushed at half the circumference speed of the stepper motor gear (small on the photo).
I am using 3 mm filament with a 0.4 mm nozzle and I can print at 80 mm/s without particular issues.
I would like to switch to 1.75 mm filament and sometimes use 0.8 mm nozzle, meaning that I need the filament to be pushed faster:

3 mm vs 1.75 mm means 3x faster
0.8 mm vs 0.4 mm nozzle it's another 4x speed
using Klipper firmware I may likely set a higher linear print speed, so there could be another 1.2x speed factor for the filament.

However, I'm not sure how far I am right now from my current maximum extrusion speed. Maybe I'm already at near the max, maybe I still have a 2-3x safety margin.
Since I will likely need to change the extruder gears to push the filament 15x faster I wonder how to calculate the optimal gear ratio given an expected maximum linear printing speed, filament diameter and nozzle diameter.
Since stepper motors get less and less torque at increasing stepping rate, maybe the answer depends also on filament viscosity and microstepping settings?

Have you tried to print at increasing speeds until you find a speed past which the extruder cannot keep up, and then calculating back from there?

I prefer a theoretical answer, try and fail is time consuming and inaccurate.

Is this theoretical enough, and what you are after: What are the appropriate ranges of gear ratios for 1.75 mm and 3 mm filament extruders?

Do you have a hotend capable of keeping up with the speeds you want?

@R.. good point, actually that's THE answer, without going into complicated calculations as in the linked answer. The stepper must be fast enough to push enough filament to saturate the flow rate of the extruder. I'm not sure how high the flow rate with the Ubis 13S is, but I think about 15 mm^3/s. With 1.7 mm filament diameter, that means a bit more than 6 mm/s, which is easy to achieve.

That won't be a problem, many steppers drive 1.75 mm filament directly, the stepper you use is pretty common, so why need a gear ratio?

Well I expected it to be adapted, since it is tuned for 3 mm and this will change

Yes, change it to "no gear reduction" (2 similar gears that is) if you want it to run 1.75 mm filament. Note that belt driven extruders create much less noise and have reduced play with respect to gear driven ones.

@0scar nice tip

@0scar maybe with a planetary gear no modifications to the firmware are required...

A related answer was provided in Is E-axis steps/mm resolution limiting factor in print quality?
The gear ratio has two main constraints:

it should allow you to reach the printing speed you want, so it cannot reduce too much otherwise the motor cannot spin that fast and it cannot output enough torque,
it should allow the stepper motor to control extrusion accurately, that means outputting several microsteps for each millimeter of print when printing at the thinnest layer height with the thinnest nozzle.

The steps to define a gear ratio are:

pick the number of microsteps per millimeter, or in other words how long would be a line equivalent to one single microstep, for a given layer thickness and line width (which depends on the nozzle). For example, 0.2 mm (the extruder will not be able to extrude less than what you need for a line 0.1 mm long, which is reasonable).
based on the radius of the hobbed bolt or hobbed gear (the one gripping on the filament) and therefore the amount of filament pushed with one rotation, the number of steps per revolution of the motor, the desired length per microstep, the filament diameter, calculate the reduction ratio
based on that reduction ratio and on the motor you have, with its torque curve based on supply voltage, check at which speed it can output its maximum torque.
check which maximum extrusion speed you can achieve with that motor and that reduction ratio.
if the maximum speed is too low, either reduce the gear ratio and compromise on the accuracy for small moves, or look for a motor which can rotate faster
if the maximum printing speed is way higher than realistically needed, increase the gear reduction to get more pushing power. Ideally, you want the motor to spin almost as fast as possible at the fastest printing speed (which, realistically, is usually in the 30-60 mm^3/s assuming a Mosquito magnum or Dragon HF hotend).

For example, I took some sample data and I did the calculations for various extruders and reduction factors. See image with results. The maximum RPM was VERY conservative, in general it can be also 500 rpm.

You can see that the Orbiter (last line) was designed with about 80-90 mm^3/s, which is a bit more than realistically possible, so that it can achieve better pushing force.
See also this graph from here which compares different extruders. You can see that between the Sherpa mini 8t and 10t (10 has a lower reduction ratio, so it needs to rotate slower for the same printing speed) the former has more torque. Since the maximum desired extrusion rate is still achievable, it made sense to increase the reduction ratio with a 8t motor.


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Creating a heated chamber from a very large heated bed
In this instructable, a user creates a heated bed from a wooden plank, some nails, insulated copper wire, and a DC switch. He does place an aluminum bed on top of it, but for our heated chamber, we won't use any aluminum on top of these wires. We aren't trying to heat an aluminum bed, but an entire chamber.

Assume I place a wire loom like this underneath my 3D printer.  (I might place some aluminum foil between the wood and the copper wire, to reflect heat upwards more? Is that safe?)
Then assume I have a cardboard box that has aluminum foil lining the walls on its inside. Assume the total size of my printer is 500mm x 500mm x 500mm. When I place the cardboard box over my printer, do you think it would take less than 1 hour for the top of the cardboard box to reach 60 degrees Celsius?
Do you think there are any other hazards here I am not considering?
Could I, theoretically, do this entirely with cardboard, and no wood?
Could I, theoretically, line the inside of my cardboard box like this? Or might the cardboard ignite?
I'd like to use cardboard because it is both lightweight and insulative. I can remove it easier to check all areas of my printer, unlike an enclosure.

To be honest this sounds like a fire waiting to happen. Even with the aluminum foil you will be conducting heat down into the structure of the heater. Using a cardboard box as the enclosure is commonly done but also not recommended and requires supervision. The difference being it has no direct (hopefully) contact with the heating element.

Ok. I will try this with an Infrared Heat Lamp instead of the extra large heated bed. This is a bad question so I may delete it soon.

Using the heated bed to heat up the chamber is not a bad idea, in fact it is the easiest way to do so. What is dangerous about your idea is making a DIY heater out of cardboard and wire.

Most certainly mount it in an enclosed box of nonflammable material.  Compare, e.g., with the slicone heating mats used in reptile cages.   The risks you're taking with DIY wiring is that the wire itself can overheat and burn unless you have really good knowledge of thermistors, control circuitry, etc.

I was thinking recently that using a hair dryer or two might be a better way to get the air temperature in the chamber up to whatever level you need.

Yea, hair dryers use a lot of amps though. They use around 15A at 120V! My fuse is rated at less than 15A...

Cardboard is fundamentally paper. Paper ignites - just as Ray Bradbury claims - at around 233 °C or 451 °F.
A thin heater wire usually glows red hot under operation. Not dark red, not blood cherry, not dark cherry, it's usually medium cherry to dark orange in operation, as one can easily tell by looking into a trusty toaster oven, which also shows us how powerful of a heating element this is.
In a typical toaster, heater wires are mounted in a metal frame and backed by some non-flammable material that looks like paper but is not. In a 2004 patent for such a method, they use a sheet of mica. But how hot is our wire? Well, under mains power, the wire of a toaster reaches 700-900 °C within seconds, heating the inner chamber of the toaster despite the slots to about 200-250 °C so quick that the bread roasts deliciously... until the heat controlling bimetal strip releases it up.
We operate these wires for at best a few minutes. In an electric forge, pretty much the same wires with a little more thickness to them are run at lemon glow for hours... and they are embedded in firebrick material to prevent them from igniting stuff touching them by accident!
How we know the temperature? Incandescence charts of course:
Conclusion
Paper or cardboard backing on heater wires is a bad idea. Mounting the heater wire to a metal frame that is as nonconductive as possible and without a chance that something accidentally touches it is needed. Fiberglass or rock material would serve as a good carrier, an aluminium block with radiators would give a good heating-to-surface mix, especially is precautions are taken to make the wire surface nonconductive.
Even using wood close to such a heater is a gamble I would not want to take. It's also best to mount the heating element into an enclosure that can't touch the wooden outer chamber and that stays put if the enclosure is opened or removed.

I never knew about Incandescence charts. This is a great answer, thanks


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What is the MKS Base AUX header connector type?
I'm looking to crimp wires to the AUX-1 and EXP pins of my MKS base. For sanity reasons, i cant directly use Dupont jumpers, they keep coming out.

BIQU MKS-Base V1.6 Plate Controller Board for 3D Printer Ramps 1.4
In the above product image, the type of housing is the "black" colored headers on the board, around the top left corner of the board. Each header has ~10 male pins inside of it
Most of the other pins are of JST-XH type, for anyone else wondering.

You need a 2.54 mm pitch (similar pitch to Dupont) female IDC (insulation displacement connectors on a ribbon cable) connector of 2x5P (pins) for the header connectors that have a notch. (for comparison, note that e.g. RAMPS 1.4 has 2x5p dupont headers on the shield for the AUX headers, not the notch type headers)

These connectors are usually crimped onto flat ribbon cables and used to connect the display to the board. These connectors have a rectangular notch to fit the gap in the housing to correctly position the cable (which the 2x5P Dupont don't have).

For reference/difference, an image of the Dupont 2x4P and 2x5P is shown below, highlighting both sides ("up" on the left, "down" on the right):

authors: عبدالله الخالدي


text:
Can you recommend professional 3D metal printing books?
I am a fresh graduate student in 3D metal printing. My undergraduate major is mechanical engineering. Later research will focus on the process of metal 3D printing. I hope that you can recommend some excellent 3D metal printing books for learning.

Could be a duplicate of 3d printing references for beginner, but that isn't specifically metal

Don't requests for resources go to Meta?

Google throws up three: 3D Printing with Metals for Design Engineers, Explained, Additive Manufacturing of Metals: The Technology, Materials, Design and Production, Additive Manufacturing of Metals: From Fundamental Technology to Rocket Nozzles, Medical Implants, and Custom Jewelry (Springer Series in Materials Science)

This is free 3D Printing of metals

@Davo - Not sure, where did you read that? Is there an SE.Meta link?

@Greenonline I'm probably remembering this from this Meta.ELU Q&A, and that I believed it to be a site-wide policy. My apologies.

This is a free ebook that I have perused briefly which it looks interesting, and it is free (did I say that already?)

3D Printing of metals

Manoj Gupta
ISBN 978-3-03842-591-5 (Pbk);
ISBN 978-3-03842-592-2 (PDF)

Three other books that might be of interest are:

3D Printing with Metals for Design Engineers, Explained

Ann R. Thryft
Downloadable free ebook, but some sort of sign up is required

Additive Manufacturing of Metals: The Technology, Materials, Design and Production,

Yang, L., Hsu, K., Baughman, B., Godfrey, D., Medina, F., Menon, M., Wiener, S.
ISBN 978-3-319-55128-9

Additive Manufacturing of Metals: From Fundamental Technology to Rocket Nozzles, Medical Implants, and Custom Jewelry (Springer Series in Materials Science)

Although, as the title contains a (rather obvious) mis-spelling, it does not bode well for the rest of the book.
John O. Milewski
ISBN-13: 978-3319582047
ISBN-10: 3319582046

Just wanted to add that ultimately you get a lot more quick practical knowledge from your machine's manufacturer or DMLS service provider so don't forget to look at publications from the industry leaders.  They have incentive to make sure you succeed when using their products.  Just beware the salesmanship.
For example Stratasys:
https://www.stratasysdirect.com/resources/design-guidelines/direct-metal-laser-sintering
I believe there's also a very similar guide from Xometry and others.  Gpi also had some good insights on some of the more exotic materials.


text:
Smooth finish on large parts
I would like to print a vase that has a width/length/height footprint of 100x100x200 mm, and the surface finish is of particular interest to me. Ideally, I would like to do a minimum of sanding/XTC-3D coating after printing, if any.
What would be the best material to work with?

what material do you want to print  in? what resolution do you have thought about?"

I'm not set on the material.The vase will only be used for display. The resolution is not too much of an issue, I'm mostly looking for a smooth surface "out of the printer", or with minimal post-processing.

The resolution is linked to the surface quality. A lower layer height will produce a much more smooth finish than a coarse layer height, but the adhesion for larger layer heights is better than for very fine layers.

So the resulting resolution would be independent of the material selected, just the speed at which the object is printed?

Yes. The surface smoothness depends on how thick the layers are, not what they're made of. Compare the walls of a cabin made from huge logs to those of one made from saplings. More smaller layers give a smoother average surface than fewer thicker layers.

@Davo though the choice of the right material or printer type can make smoothing trivial or open other options to smooth.

From the printer...
Non-post-processed surface smoothness of a print is mainly a function of the Layer height during print: it is smoother if one reduces the height of the steps taken between the layers. A very good FDM machine can achieve down to 0.05 mm layer height, but 0.1 mm is what most hobbyist machines can achieve if well dialed in. SLA printers cure resin in layers down to 25 micron reliably and some can get down to 12.5 micron - a quarter of the best achievable FDM.
Reducing the layer height in FDM comes at the cost of mainly three factors:

Print time increases roughly antiproportional to the layer height. 0.1 mm is about double the print time of 0.2 mm and so on.
The prints tensile strength gets reduced by increasing the number of layers increases, creating additional possible weakpoints.
The thinner the layer, the more susceptible the print is to errors like clogged nozzles or variations of the filament thickness.

SLA printers are not affected by the print strength loss and the errors from clogged nozzles and can print entirely clear material without air inclusions. They are affected by the print time increase though. Usually, SLA prints come out of the vat covered in residual resin and curing them in the proper post-processing method results in this resin smoothing over the surface perfectly.
Simple Postprocessing...
Many prints can easily be post-processed.
Sanding
PLA and ABS can be easily sanded down to somewhat smooth, but you'll need to spend time and muscle grease or go electric. A sander with 300+ grit can help a lot. If you have a rotational body, you could sand the vase on a lathe.
Putty
A plastic putty could be smeared over the stepped surface to smooth it and then sanded smooth. I personally like Valejo plastic putty, as it doesn't shrink, but Tamya putty also is a good alternative, bonding strong.
Primer-Filler
Independent of the base material, using a spray coating can easily fill in the notches and crannies left behind during printing. Printing in 0.15 mm and giving it a short spray coat of primer-filler twice, sanding over rough spots between did a good job of smoothing prints for me.
Vapor Smoothing
If you chose ABS, you could use Acetone vapor to smooth over the surface of a print in almost an instant. This can achieve Super smooth results with tall layer heights, as you practically melt the plastic over, but it comes at the loss of small surface details.
Exposure time is the limiting factor here: the longer the exposure to the acetone vapor, the more the surface is smoothed and the less details remain. Think of exposure time like running the smooth filter in blender once or twice each second.

Similarly, ethylacetate or propylene carbonate could be used for PLA prints, though timing might differ from the well established "a couple of seconds" for acetone vapor. Note that these two chemicals are much more expensive.
Costs
Checking prices, I was quoted about 90 €/l for (chemical grade) Ethyl Acetate and 130 €/l for (chemical grade) Propylene Carbonate via a laboratory supply. Useable Acetone (not chemical grade) comes about 3.70 €/l in home depot. For comparison: chemical-grade Acetone comes with a price tag of about 50 €/l.
Considering that ABS filaments and PLA filaments typically price similarily,  ABS+Acetone Vapor is the least costly chemical Vapor smoothing.

ABS + acetone is probably what the OP wants to do here.


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Is it possible extrude faces along normals individually in OpenSCAD?
For the geometry I am making, I want to extrude each face individually along its normal.
This is a standard procedure in 3D modeling software like Blender; see Example 3 here.
Is this possible in OpenSCAD?

Extruding faces is only possible on 2D polygons. From a 3D object you cannot capture the face and extrude it. To extrude "faces" you would need to define the shape of the face and extend it in the third dimension of your choice. This way a 3D shape is created that could be concatenated (joined using e.g. union) to the original shape. For the extrusion, the function linear_extrude is available:
linear_extrude(height = fanwidth, center = true, convexity = 10, twist = -fanrot, slices = 20, scale = 1.0, $fn = 16) {...}

As long as you can know the plane a face is in, you can projection it to a 2D shape then extrude that. You can also capture a thin slice around a face manually via intersection and then hull it with a translate of itself. (Depending on the object the latter may or may not give exact results.)

@R.. Very good examples to extrude "faces"! Please add that as a separate answer, or include it into your current answer.

I've added this as a separate answer since it's unrelated to my existing one.

@R.. Very nice, and certainly good that you separated the answers!

For extruding a single face, as long as you can know the plane the face is in, you can projection it to a 2D shape then linear_extrude that. In general you need the cut=true variant of projection, and you need to translate/rotate the object to be projected such that the face is in the XY plane (this is the "as long as you can know") part. Unfortunately this is subject to numerical instability, so you probably have to translate it by an extra 0.001 or so to cross the XY plane, in which case you'll end up with an approximation of the face rather than an exact version of it.
(Strictly speaking OpenSCAD doesn't have exact things anyway, except in the case of faces sharing points in a polyhedron, so this limitation probably doesn't make the situation any worse than it already is in OpenSCAD).
Once you have the projection, you can linear_extrude it in any direction you want, manipulate the result (e.g. skew with a transformation matrix), and rotate and translate it back onto the face. It should be possible to wrap up this whole operation into a module that operates on its child[ren].
Another approach would be capturing a thin slice around the face manually via intersection, then performing a hull with a translate of itself, but this will only work if it's convex (otherwise hull will fill in the convex hull of the 2D face shape too).

Built-in to the language and its CSG model, no - processing the CSG tree is a completely separate phase following execution of the functional language, and there is no way to "read back" anything from the conversion of the model into faces in order to operate on the faces.
However, you can do this if you're willing to do some heavy lifting yourself, or look for library code from someone else who's already done it. What it would involve is working out a description form of your own in terms of nested lists representing the model, with a module for converting the list to an OpenSCAD CSG tree. You can then write functions to manipulate this description in arbitrary ways, essentially reinventing the CSG phase of OpenSCAD within its own language. Some lesser versions of this have definitely been done in the past for things like implementing "loft" type functionality in OpenSCAD.


text:
Reasons for a PLA print not sticking to bed all the sudden?

Plastic: Same Matterhacker PLA (filament I use every day)
Printer: Anycubic i3 Mega (the one I use every day)
Slicer: Ultimaker Cura 4.2.1

I don't know what's causing it, I haven't changed any slicer settings to my knowledge, I haven't changed anything on the printers end, and I'm using the same filament I've always used. But for some reason, the first layer is simply not sticking. At first I noticed when doing a print the nozzle seemed a little higher than normal for the first layer, but then it started having problems where 0 % of the filament would stick to the bed and it would all just come off and turn into a mess. I've checked and checked, but I see no reason the printer would just start doing this now all the sudden when it's worked perfectly for a year now.

EDIT: Something I've noticed since posting this is that older sliced models seem to print just fine, which means there's something about the newser slicer settings that's causing it. I don't know what I would have changed though and/or how to restore to my original settings.

Did you re-level your bed?

Sure sounds like the nozzle height has been increased a little, or the bed has lowered a little.

@Pᴀᴜʟsᴛᴇʀ2 I did not, however after trying to do so I found lowering it made things worse, and lifting it up had no effect until it got high enough to where the extruder just knocked the filament off the bed.

@CrossRoads I didn't change anything, I don't know how that would have happened, but after trying to re-align the bed to a better position it did not help (See my response to Pᴀᴜʟsᴛᴇʀ2 for more information on that). I don't know how my nozzle height would have changed, but if it did how do I re-calibrate that?

Please add an image and optionally a link to a video recording for us to see what is actually happening. Is this a nozzle to bed distance problem, or an adhesion problem. Do you use an adhesive agent between bed and filament?

I added a WhamBam system to my printer. Magnet goes on the aluminum (or glass in your case?) bed. Flex steel plate plops down on that, PEX material get stuck to the flex plate.
PLA sticks to it great, but releases with just a simple flex of the plate. Leaves nice smooth bottom surface on prints. Glass & hairspray & gluesticks, fuhgetabout it!
I've posted some videos of it in use in this forum before.

@0scar I can look into it, but it's not something I can highly well film

@TomasBy I've looked at other acetone type chemicals before and they seem to have no effect on the filament, any suggestions on what type of acetone and/or how to apply it?

@CrossRoads It's been fine up till now though, what could have happened since then that would have gone from nice sturdy prints to non of it sticking to the bed whatsoever?

Now that you have added more information that older sliced models do print correctly, you should look into your slicer. Have you upgraded the software (considering the version number you did) since last sliced models, have you accidentally changed a parameter, can you revert all changes, reslice and compare to older sliced models? Best start is to download a calibration cube and slice and print it. Post the settings as text or an image for people to help you solve this problem! Hope it can be fixed soon!

@0scar I've just tried resetting all settings on the slicer, even installed an older version in a VM for good measure, no change, yet the older models still work. I don't everything that's been stated so far defies logic, but do you have any idea what's happening?

I'm really sorry, I'm out of ideas. I think you researched the problem systematically, only thing you could try is re-slice an older model and compare G-code or use a different slicer, e.g. Slic3r. Note I use different slicers for different machines too. :)

Please don't edit the question to include "EDIT:" this is unnecessary, the question is good as it was, we'll revert the question for you. Note that the text under the line already explains that this is added later "...I've noticed since posting..." Your question is perfectly fine! Hope you get it solved soon! My best bet would be to try a different slicer and compare G-codes. Or G-code comparison of files that print well and newly sliced of the same model.

I have this strange behaviour too. Since Cura 3.2.1 I cannot print any good models any more. Looks like there is not enough filament coming out of the extruder. Going back to 3.2.1 solves the problem. My printer is a Wanhao Duplicator i3 plus. Hope that this helps a bit.

There are 3 general factors about print adhesion you always have to keep in mind:

Have a sufficient surface for the print to stick. A pyramid printed on the tip can't print properly.
Check the leveling of your bed occasionally and relevel the bed. By removing prints, one can easily unlevel it over time without noticing it.
Clean your print bed from fingerprints and grease every so often. Fats are good separators between the print and the bed. Getting them off with Isopropyl alcohol or other solvents can restore print surfaces in an instant.

In this specific case, there are some hints that make the general things less of an issue though: Old sliced items print fine, newer not. This hints that you changed something in the print settings. Among the settings that are good for adhesion, check your old G-code for the following three:

Bed temperature. I use 60 °C bed temperature for PLA and have good results on bed adhesion. Others print with 50 °C. However, going too low can make the plastic not stick well anymore.
Extrusion temperature. When the plastic extrudes, it has to be molten enough to push out enough and cold enough to solidify within moments and stick to the surface of the bed. If it is too hot, it would be dragged along, if it's too cold it doesn't get to stick either. I use 190-200 °C for PLA.
The first layer height might be different. I usually use 0.2 mm for this setting, no matter what the actual layer height is, and get good adhesion and not too much trouble with tiny unevenness.
The reason might be a mechanical issue, in that the Z-endstops (in an Anycubic i3, there are two, hidden in the frame sides) might have bent, moved or misaligned over time. Check its positioning. If the mount is broken, there are replacement part designs.

This is nothing new, I follow that all the time and I guarantee that's not the problem.

I've tried that already as noted in my original post

Ok, I can try that, I don't think it would happen so suddenly and everywhere on the bed at once though.

These are good general tips, and I will be looking into them more to see the cause but I'm 99% sure that's not the problem due to it being so sudden, what other reasons do you know of?

@UltraGamer With painters tape, it can be a problem that the tape is slick.The last addition makes me thinkng though...

I'm not using painters tape though, because the bed is glass, usually, there are no problems with it sticking to the bed at all. You did add another 3 reasons though, I've checked the first 2 and they are fine, I don't think I changed any slicer settings but I am going to try to reset it to see if that improves it. What is Z-endstop though and how can I re-position it?

@UltraGamer the z endstop is the physical limit switch that triggers "here is Z=0"

Where is that located on the printer?

@UltraGamer the left gantry carries a little trigger switch around - That's it.

I don't see it, could you link a picture to where it would be on a standard printer?

@UltraGamer it's hidden in the frame, and there are two.

This seems like a long-shot, but I've noticed at this time of year many 3D prints fail.  We noticed 4 printers all went dead and had massive non-stick issues last year about this time.  Turns out it was mostly around changes in temperature and humidity - the outside temperature changed inside AC settings/wind-flow, etc.
So, you might think through some of the meta-causes of where the printer is, and if temp/air/humidity might be just enough chaos to not make the material stick.  Right in September, I start putting a light layer of glue down on the glass bed under each print or increasing the use of rafts...

Ok, That could be it considering it is in the garage, Do you have any idea why most of the older sliced models work though?

I’ve found that when it’s colder outside I slow down my print speed, especially on the first few layers. Maybe those older slicers had lower speeds?

After looking at the gcode, nothing appears to have changed on the speed side, anything else?


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Power supply not working
Yesterday during a print, the printer just stopped working and all motors and fans stopped. My printer is a Graber i3.
Just before that I saw a flare coming from somewhere in the extruder or from the power supply, I couldn’t actually see.
Checked the voltage coming into the RAMPS and it was 0 V, checked voltage coming from the power supply, also 0 V. Checked the voltage coming into the power supply and it was 217 V... that’s okay, the power supply is switched to 220 V.
Today I tried further troubleshooting, by connecting the power supply to 127 V and having it switched to that voltage, before that I disconnected the RAMPS cable in case it was shorted. The result was the power supply did not work, the voltage coming from it was 0 V.
Got in contact with the manufacturer since the printer is brand new and he is sending me a new power supply, but I do want to try to find the root cause of the problem, so I started looking for shorts in the RAMPS, hotbed is okay, no continuity. Neither of the other connections have shorts, until I got to the hot end heating cartridge, in this convection I found 5 Ω resistance between phases. This was at first no surprise because it makes sense since it’s a heating element, but wanted to make sure, is it okay to have this resistance in the cartridge?
Do you guys have any other suggestion for troubleshooting or possible root causes for this issue?
UPDATE 02/OCT/2019:
I decided to open the power supply, so maybe I could fix it and have it as a back up. First thing I see once opened, the fuse was blown! So I replaced it, since it is soldered and it is a 8A 250V 3x10mm, which happens to be hard to find... took quite a while. Once the repair was done, plugged it in and boom, another firework happened, this time blowing a resistor and not the fuse.
Conclusion: it wasn’t the fuse, another thing caused the first and second shortening.

Have you checked the fuse for the power supply?

Haven’t found an access to the fuse without having to disassemble it. Since it’s under warranty I decided not to open it.

Hmmmm ... seems to be the fuse would be user accessible. That's the idea: user blows a fuse; user replaces fuse.

What kind of printer you have? To check for errors in the board, supply it with 5 V via USB. Note that a Heater Cartridge should have an expected Resistance depending on its wattage. 5 Ohm is about what a 12V 30W heater cartridge should have according to e3D

@Pᴀᴜʟsᴛᴇʀ2 In many cases, that is definitely not the idea. The fuse is designed to blow if there is a malfunction in the power supply. If you replaced the fuse, the fuse would blow again soon after since the power supply is malfunctioning. Since the power supply is not user servicable (i.e., the user cannot resolve the malfunction themselves) having the fuse be replacable is pointless.

I would expect the root cause to simply be the power supply itself.
5 Ω is a reasonable resistance for a 12 V / 30 W heater. It seems strange that you are not seeing continuity in the heated bed as this should also have a low resistance (since it's a heater as well). This might be worth investigating further, but I think it's more likely the power supply itself is the cause (and you simply made a measurement error).

the most common fault in a power supply is that one of the capacitors has a short.

Hi, checking further found the resistance of the hot bed to be around 10 ohm.


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How to calculate the proper layer height multiples?
We all know, that the best layer hight is, when you have multiples of full steps. If it is not, sometimes steps get skipped and end up bad layer-to-layer adhesion when one height step missed a tiny bit and then the next catches up, creating an extra-thick layer. For example, this was printed somewhat deliberately, and here, the extra spaced layers are perfect for delaminating the print with just a fingernail:

The Ender 3 I have uses the following Z-Rod:

Diameter 8 mm
4 flutes
ca 13 Threads per inch

That is according to the table, a 2 mm pitch for one thread.
As a result, it's an 8 mm pitch for each of the 4 threads.

The firmware (Marlin) I use claims in configuration.h that the NEMA17 motor would be using 400 Steps per mm in Z. configuration_adv.h tells that the microsteps on the Z-axis motor are 16.
In the printer's menu, Babystepping is in increments of 0.049 mm (though some rounding error seems to be there: 5 Babysteps are 0.250 mm).

Note that this is only an issue on printers without high-quality microstepping drivers for the motors.

Is the image in your question actually something you're having a problem with? It looks unrelated to layer height being a multiple of whole step, so aside from your question being valid and meaningful as stated, there may also be an XY problem here.

@Mark: Indeed, I switched to using multiples of 0.04 on my Ender 3, but I don't think it actually helped anything. As tested here, the A4988 stepper drivers which are stock on Ender 3 don't seem to have a serious problem with microstepping accuracy, and I think that's especially true if you're moving by more than 1-2 microsteps (typical layer move is between 35 and 100 microsteps) at a time. If there's interest I might do some test prints and post an answer (or a new Q & A) with the results.

@R.. the picture was created by purposefully setting the layer hight to accumulate an error that ticks over.

@Trish: You mean something like 0.2-0.04/16? I'd like to try to reproduce it. Do you perhaps have a really early Ender 3 that had bad stepper drivers or had them in the wrong mode? I seem to recall that being an issue they fixed early on. The test print looks like it has more problems going on than just inconsistent layer height.

@R.. 0.2125 layer height (+1/4 microstep) and doing all the movements in absolute movements instead of relative forced the result, as the target heights were as a result at 0.2125 mm (for the stepper that's effectively a 0.2 mm), 0.425 (0.4), 0.675 (for the stepper that's, depending on rounding or truncting, 0.6 or 0.7), 0.9 (here they are both 0.9) and so on.

that the NEMA17 motor would be using 400 Steps per mm in Z. configuration_adv.h tells that the microsteps on the Z-axis motor are 16.

Easy. There are 400 microsteps in a millimeter, and 16 microsteps in a full step. So, there are 400/16=25 full steps in a millimeter. So a full step is 1/25th of a millimeter, or 0.04 mm. Your layer height should be a multiple of this.
As your leadscrew has a lead of 8 mm (i.e., a full rotation will move the Z-axis by 8 mm), a full step is either 8/200=0.04 mm (for a 1.8 degree stepper) or 8/400=0.02 mm (for a 0.9 degree stepper). So, apparently, you have a 1.8 degree stepper (and this is the most common type of stepper).

This video explains it well, too: Better Quality 3D Prints Using MAGIC NUMBERS on ENDER 3, CR-10, A10

I see you've already accepted an answer, but based on your comments I think you have some misunderstandings of the topic which are worth clarifying as part of answering this question.

0.2125 layer height (+1/4 microstep) and doing all the movements in absolute movements instead of relative forced the result, as the target heights were as a result at 0.2125 mm (for the stepper that's effectively a 0.2 mm), 0.425 (0.4), 0.675 (for the stepper that's, depending on rounding or truncting, 0.6 or 0.7), 0.9 (here they are both 0.9) and so on.

It sounds like your understanding is that the stepper driver is "rounding"/"truncating" to Z positions that are multiples of 0.1 mm. Perhaps that's based on the LCD status display of the Ender 3's firmware, which is based on Marlin 1.0 or something around that version, and shows current coordinates rounded or truncated (I forget which) to one decimal place. This does not have anything to do with the positioning limitations of the actual machine; it's just bad user interface design.
The actual firmware position is translated from the floating point value in the gcode to the nearest step/microstep that the stepper driver can represent. With full steps being 0.04 mm, microsteps are 0.0025 mm (1/16 of a step). All of these positions are "exact" in a logical sense, but of course subject to physical limits of the mechanical parts and accuracy of microstepping. On the topic of microstepping accuracy, you should read How Accurate Is Microstepping Really? Most if not all models of the Ender 3 have A4988 stepper drivers, one of the chips reviewed in that article. But the important part is that there's no rounding/truncation to whole steps taking place. Rather, the stepper driver is trying to position the motor in between whole steps by balancing the magnetic fields pulling it in each direction, with the goal of producing a linear interpolation between the two adjacent full steps. How well it does this is a matter of the quality of the stepper drivers and the load on the motor.
Back to your test, your layer height of 0.2125 mm is not one step plus 1/4 microstep. It's 5 steps (5 * 0.04 mm) plus 0.0125 mm which is 5 microsteps. This is probably a decent test - 5 is 1 mod 16, so you'll end up with a period-16 cycle of microstep positions, at 5, 10, 15, 4, 9, 14, 3, 8, 13, 2, 7, 12, 1, 6, and 11 microsteps mod the whole step. This is pretty close to a period of 3, so you might expect to see some irregularity from poor microstepping accuracy that looks periodic every 3 layers, or you might see it repeating only every 16 layers (every 3.4 mm). But regardless I would not expect delamination problems from this. I think there's another serious extrusion problem behind the photo in your question, and you should probably open a new question about what it might be.

well, after some tweaking with the printer, the effect I was aiming for was probably helped by the extruder lever being broken. As said, the print was deliberately made to fail. But oyu mention some very good points how I failed to properly fail (the iteration of the error-layer was btw quite consistently every 1.2 mm, about every 10 layers)


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Does matching whole Z-motor steps for layer height actually matter on Ender 3?
This question asks about computing the fundamental layer height unit for full Z-motor steps, on the basis of a theory that layer thickness can be inconsistent if the height is at different micro-stepping positions on different layers. The specific printer mentioned in the question is an Ender 3, which I also have, and while I've wondered in the past based on this video whether using whole-step layer heights helps, I haven't seen conclusive evidence that it really does.
According to the research in How Accurate Is Microstepping Really?, the A4988 stepper drivers (which this printer uses) have near-linear microstepping response, at least under the test conditions, which suggests there's little or no benefit to using whole-step layer heights.
Has anyone done experiments to determine/demonstrate whether use of layer heights that aren't whole steps actually leads to extrusion/layer adhesion problems or other structural or cosmetic issues?
I did a quick test with a 20 mm cube and 0.2 mm layers (5 full steps, left) and 0.1975 mm layers (1 microstep short of 5 full steps, right) and there is no readily apparent difference:

And repeated with single walls:

Could you report the printed height of both (using a caliper)? Just out of interest and for information as the 0.1975 mm layer cube requires "101.2" (effectively 101) layers to reach 20 mm, while the 0.2 mm needs 100 layers. E.g. it could be that it is doing 0.2 mm layer heights for many layers.

@0scar: My caliper only measures to 0.1 mm so it probably won't be very helpful. I don't see how it could be doing 0.2 mm for all layers though - the Z moves are in absolute coordinates, and clearly right in the gcode.

You are right, not for all layers, but it must be some, e.g. those close to the full step.

I'm also not sure where the idea comes from with the "full steps as layer height".
You will rarely end up at exactly a full step at Z=0, so even "even" layer heights like 0.2 mm would have to stepper driver move to stepper to locations which are off by a few microsteps. Now, this might mean the stepper reliably falls back to the last full step, and all subsequent layers are identical again (except for the 1st), but that would just mean you've got far too low Z axis currents / too much weight to begin with.

@0scar: Both measure 20.0 mm on one side, 19.8 mm on the other side; seems to be from damage to bed surface making bottom not entirely level.

@towe: It's not a matter of falling back to full steps. It's about non-linearity of microstep positioning. See this article: https://hackaday.com/2016/08/29/how-accurate-is-microstepping-really/

Aside: clear/natural PLA with flash photography is really nice for looking at this kind of detail.

@0scar: Actually that 0.2 mm difference from one side to the other is probably from the scraper knife removing the print from that side while the bed is still warm.


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Hotend drops to 175 ºC once extrusion starts (MINTEMP error reported)

Hotend drops from 205 °C to 175 °C, and then the printer errors MINTEMP. How can I fix this? Fan is not starting yet.
#define  DEFAULT_Kp 28.65
#define  DEFAULT_Ki 2.80
#define  DEFAULT_Kd 73.33

#define HEATER_0_MINTEMP 5

MINTEMP is 5 °C? It's impossible it's getting that cold.

Is your fan coming on? Do you have an M106 in your gcode?

Your hotend thermistor is reporting -27 ºC considering the bed of 27 ºC (so your ambient is about 27 ºC) there must be something seriously wrong, possibly the thermistor.

@0scar the dropping spikes tell the story of disconnecting the sensor...

@Trish Excatly, something seriously wrong. You see the ambient temperature being (very shortly) reported correctly at about -10 minutes in the graph, so this must be a connection issue or faulty sensor.

Yes this is a connection issue, some wire can be loose or internally broken. If the sensed temp is negative the thermistor is damaged or a broken end terminal. This error is normal when your wires are not well routed and protected or too tight.

Sudden drops in temperature curves like in your picture are usually missing readings on the thermosensor:
Disconnecting the sensor from the board registers as min-temp of the sensor while shorting out as max-temp, so it triggers the mintemp/maxtemp security protocol: shutdown.
One could disable mintemp/maxtemp protection, but that wouldn't solve the issue. The issue is usually the wiring of the sensor. To find the fault, put temperature on the sensor but keep the motors disabled. Watch the read temperature. Move the printhead manually and slowly. If it suddenly drops and throws the error, you might have a faulty lead close to the printhead. If not, you need to open the electronics box to check if the connection to the board is ok. In the worst case, you might need to exchange the whole temperature sensor.


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E3D V6 Original vs Clone
What is the difference between an original E3D V6 rather than a clone?
I know an original would have its own advantages, since there is a huge price difference between the two. Will there be a huge difference in the output? By considering the following:

Print quality
Printing Speed
Maintenance
Life Span

If anyone has used both, please share your experience.

This is a question of opinion, and the answer depends entirely on the phrase "worth it".  Generally, we try to avoid this kind of opinion question, since there is no correct answer possible.

Possibly a duplicate of Can cheap hotend parts sourced from China actually produce good prints?

Maintenance, lifespan and printspeed are more functions of the printer as a whole, not the hotend. The quality is more often than not a function of speed, material and nozzle than the question of the hotend design. There are often objective differences - the heatbreak on a genuine e3d v6 is necked, not lined all the way, many clones are not necked and lined

Is the same but cheaper. may differ a little but works.Quality depends on your experience also life span and maintenance.

While most components (cooling body, heatblock, heater cartridges, thermistors) of knockoff e3d-v6 hotends can be similar enough to not notice in a large part, or at least functionally the same. Note that I don't say the parts are necessarily interchangeable - a lot what is sold under the name is not what it claims to be. The main distinguishing difference is the heatbreak: a proper e3d v6 hotend is hard to manufacture, so let's compare the designs of the real and the knockoffs.
Original
e3D v6 heatbreaks are necked considerably and have a socket with an airgap to the cooling body in top to take the lining and prevent heat flow to the PTFE pipe. This makes it an "all-metal" hotend, because the liner stops in the cold zone, where the cooling block is screwed on, and thus gets the least heat to the bowden, allowing to print hotter than with a lined hotend. The cooling block and the heather block threads are also not the same: M6 and M7. They are flat at the front to securely butt the nozzle thread against.
Their internal and external geometry looks like this:

Knockoffs
Knockoffs vary a lot how their heatbreak is constructed. Some are lined all the way through. Others are pass-through - and neither is an all-metal hotend. Some knockoffs are necked but use the same thread on both sides.
gallery of knockoffs

Conclusion
If you print a lot of high-temperature materials, the need for a proper all-metal hotend is there. Many knockoffs don't do this necking properly or invalidate its effect by lining the hotend all the way through.
Note that the machining quality can be quite different.
Due to sizing, not all knockoffs allow to mount a genuine heatbreak with knockoff cooler and heater block.


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Very messy prints with lots of fuzz on edges
Recently my prints come out very messy. I tightened everything up and checked the extrusion multiplier.
I have an Ender 3 Pro which I use together with Cura 4.2.1 (and Octoprint). I print in PLA at 190°C. The print bed is set to 70°C. The Bed temperature is lower though, since I use a glas bed on top of the heated bed. I use a print cooling fan at 100%. The layer height is set to 0.2 mm, the line width 0.4mm from the 0.4mm nozzle. My retraction is 5mm at 45mm/s.
Does anyone have any idea what the reason could be?

Hello Chry007. Your question is very terse and hard to answer without knowing a couple of things about your printer setup. Please [edit] and fill in the [placeholders] in the template I added and then remove the leading < afterward. This will turn it visible and help us help you find the actual problem.

Are the walls very sparse/porous/brittle? It looks to me like you might have severe underextrusion from filament diameter being set to 2.85 or 3 rather than 1.75 (a common problem with Cura).

Hi R., not at all. I can' break the model with my hands. I just doublechecked the settings in Cura and it's set to 1.75mm

@Chry007 speed retraction is too low, the amount of retraction is too high...

I figured out the problem. I reduced printing speed and printing temperature and the print came out decent. Still some issues but worlds better then before. I will try a few more settings to determine exactly what was the actual Issue. I will also try what @Fernando Baltazar recommended and update here what exactly changed the printing quality.

"Retraction amount is too high" is not a thing unless you have increased it to some extreme amount or have a specialized hotend. Lower than 5 mm is definitely bad.

I can confirm. I tried with 3.5mm and the only result was more stringing.

what speed and temp did you end up going with?