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Is there anyone now permanently living in 3D-printed houses or buildings?
Are the following statements still true, or are they now out of date?

[3D printed architecture] The problem is this: No one has been able to successfully take the leap from printing a fancy art pavilion to printing a functional building, and it’s still not clear if the technology is going to save the world or be another decorative footnote of architectural history.

WinSun

For whatever reason, the only printed buildings that look remotely habitable have been built by Chinese companies. But just because they look habitable doesn’t mean that they are. No one lives in these houses, and when you get close enough, they don’t really look like the kind of place you’d want to live, unless you have a thing for creepy-cave chic.
(Both from https://architizer.com/blog/practice/details/3d-printed-buildings-future-or-gimmick/)

I'm not wanting to argue about the architectural concern for appearance.  As an engineer my concern is with structural integrity and reliability.  However, are people living in 3D houses?  That is the common concern.

I'd say I'd rather live in "creepy-cave chic" than not be able to afford a house at all...

There is no demonstration that these are any cheaper than using molds and pouring concrete.

@FourierFlux at that point the issue isn't material cost, but cost of equipment versus labor cost.  In the U.S. there is a labor shortage in construction.

Another issue with cost is there are multiple technologies and materials used for printing buildings.  Another issue is unless you hold labor wages now by essentially enslaving workers, the world will soon run out of cheap labor.  Automation is necessary for workers to produce more and get wages with a higher value.

Apparently the article in the question is out of date:
Here's a family in France living in a 3D-printed house (95 sq.m. 1022 sq.ft.) since 2018:
"The world's first family to live in a 3D-printed home"
By Michael Cowan
BBC's Victoria Derbyshire programme
Published6 July 2018
https://www.bbc.com/news/technology-44709534
They essentially 3D-printed the form to poor the concrete in the house in France.  The form was insulation and stayed in place.  This many be an easier way to meet building codes.
And it looks like the market is picking up right now.  A year ago in Austin, a 400 sq.ft (37 sq.m.) home is very small for a family and doesn't compete with the traditional housing market.  However, the house in Austin shown in the picture looks huge.

REAL ESTATE:
"3D-printed housing developments suddenly take off – here’s what they look like"
PUBLISHED FRI, MAR 12 2021 3:36 PM ESTUPDATED MON, MAR 22 202111:53 AM EDT
https://www.cnbc.com/2021/03/12/3d-printed-housing-developments-suddenly-take-off-heres-what-they-look-like.html
Here's another link of someone building 3D printed houses for public sales:
https://www.iconbuild.com/updates/icon-delivers-series-of-3d-printed-homes-for-homeless
A Rising Trend:
7 Biggest Companies Building 3D Printed Houses:
https://all3dp.com/2/2019-best-companies-building-3d-printed-houses/

So the short answer is no; but there such a house up for sale.

Actually a family in France lives in 3D Printed house since 2018.


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Why not use high rpm stepper motors with high microstepping with gear reduction in 3D printer?
3D printer use stepper motors for moving print head and extruding filament. They need to have good torque and resolution.
Microstepping improves resolution as much as 32 fold (I think) but reduces torque the higher you microstep.
So...

Why not rotate the motor with microstepping at high RPM (which also reduces torque) and increase the torque by heavy gear reduction using a worm gear?

Won't the movement of printhead  be even smoother and small errors in microstepping and unevenness of gears be averaged out using high RPM and gear reduction approach?

Does microstepping indeed provide accurate divisions of steps?

Can we get by with weaker motors because torque will be increased by gear reduction?

Can we get by with 48 step stepper motors instead of 200 step because gear reduction provides increased resolution?

There are extruders that use flex shaft to turn worm gear in direct extruder while motor is mounted on frame which turns flex shaft (zesty nimble comes to mind). Why don't they just use smallest possible stepper motor to rotate worm gear directly, instead?

Increasing motor RPM and using gear reduction should preserve the precision and torque, letting you use weaker, lighter motors, potentially reducing granularity of movement. I thought this was simpler approach and I wanted to understand what would I be losing as trade offs. I had considered more friction at worm gear and wear, higher heating of motor etc. But may be it's like "don't fix what ain't broken". 3D printers aren't that costly nowadays. I just wish they were even cheaper.

Engineering is the act of selecting trade-offs. While your idea would certainly work, it imposes it's own (rather large) set of tradeoffs. Among these: more complex, more wear, more potential harm from inadvertent axis moves, each moving interface either lowers precision or increases friction, fast printing with high RPMs would generate more heat, there's limits on how precise one can even work soggy plastic - no matter the precision of the machine, etc.

To answer each point:

Microstepping improves resolution as much as 32 fold (I think) but reduces torque the higher you micro-step.

Torque is not reduced by micro-stepping. Torque reduction only occurs when you are moving at high RPMs. The motor's phase resistance has to be conducive to the target RPM's (or step rate). Further, micro-stepping can go as has as 1/256, and I have personally used 1/128. Some will say that all higher micro-stepping does is improve smoothness not accuracy. I have personally tested 1/128 micro-stepping over a 17-inch long axis. I was able to achieve accuracy and repeatability to within 5 microns.

Why not rotate the motor with micro-stepping at high RPM (which also reduces torque) and increase the torque by heavy gear reduction using a worm gear?

Backlash! The whole point of stepper motors is that they produce backlash-free movement. Putting a transmission between the electromagnetic and the end effector will create backlash that has to be compensated for during the movement. Modern CNC systems account for this in their movement profiles and incorporate automatic backlash compensation (e.g. Mach3)

Won't the movement of printhead be even smoother and small errors in microstepping and unevenness of gears be averaged out using high RPM and gear reduction approach?

It is already smooth enough with 1/64th or greater micro-stepping. The extrusion nozzle only goes down to 2mm.

Does microstepping indeed provide accurate divisions of steps?

Yes. Yes, it does.

Can we get by with weaker motors because torque will be increased by gear reduction?

No, because it will just stall.

Can we get by with 48 step stepper motors instead of 200 step because gear reduction provides increased resolution?

Apart from the fact that no one makes 48 steps per revolution motors, using a gear reduction would be counterintuitive. Currently, there are 400 steps per revolution motors, which actually increase accuracy without any torque losses.

There are extruders that use flex shaft to turn worm gear in direct extruder while motor is mounted on frame which turns flex shaft (zesty nimble comes to mind). Why don't they just use smallest possible stepper motor to rotate worm gear directly, instead?

Torque! If they used a small motor to drive the extruder they would have to compensate for the torque loss with higher power (i.e. voltages). This would lead to cooling issues for that motor.
Bottom line is that if you size the motors and design the system correctly then a transmission is not needed. If you want more torque, get bigger motors. If the gantry needs to be light weight, then use a delta or corexy mechanism.

28BYJ-48 is common 48 steps motor in diy robotics. The info on microstepping is very confusing on internet. I've read that even half step microstepping doesn't ensure precisely half movement of a full step. You're saying microstepping offers all the precision and torque needed, in which case it seems I'm trying to solve a problem that doesn't exist. I don't understand however, why you're saying a weaker motor with gear reduction will stall. Doesn't gear reduction increase torque?

@MiteshPatel, A weaker motor with gear reduction still has to overcome the friction in the transmission system. Further, unless that "weaker" motor is sized correctly when it is spinning at a higher RPM it is more prone to stalling, due to Back EMF, causing a torque reduction.

There's an old rule that says "If the question starts with 'Why don't they,' the answer is most likely 'money.'"
In this case, the issue is the cost of worm gears.  Properly mating worm gears are much more expensive to make than common spur gears.  That probably accounts for most of it -- not to mention the 200 step motors we see on most FDM printers are a very common item, and the more you make of something the less each one costs.
Beyond that, you can't back-drive most worm gears (especially those with a high reduction ratio).  That wouldn't affect an extruder (or would it? I've seen a lot of Things for knobs to go on the extruder motor shaft), but if I couldn't back-drive my X or Y axes I'd be very annoyed (having to use the manual motion control in the firmware for everything like bed tramming) -- even the lead screw Z axis can be back-driven without undue effort.
So, bottom line, what we have now works well enough and making it (maybe a very little bit) better would cost more than what we gain would be worth.  IMO.

Thanks for your answer. You're of course right about prohibitive high costs of precise worm gears, but zesty nimble folks are already using plastic worm gears. Seems, with 1:40 reduction precision is non issue. Nema 17 motors used in most 3D printers are not very costly but using smaller, faster motors can be even cheaper. I'm thinking of same precision, but cheaper, not seeking more precision. Also, worm gears can be driven forward and backward by motor, but load can't back drive worm, which is advantage IMO.

I say again -- if I can't back-drive at least my X, Y, and Z axes, there will be some pretty sudden retrofitting going on.  "Back-drive" is the load end driving the motor, not direction of the motor driving the gear.   Most worm gears (even at only 40:1) can't be driven from the output shaft due to friction angles.

I don't understand why should load back drive motor. I think I'm missing something essential here. Is it so that if inertia of load is so much that if motor doesn't yield, something in the power train would break, most probably worm gear? I agree that load can't back drive a worm gear, but I was thinking that would make the mechanism stiffer and motor won't have to fight inertia of print head when changing direction. Worm gear would insulate motor from inertia of print head.

When I "level" my bed, I auto home, set my Z offset to the thickness of the feeler gage I use, and then disable steppers.  It would take several times as long if I had to go from X to Y "Move Axis" menus repeatedly to move the bed and hotend because I couldn't drive the (idle) stepper by pushing on the load.  Extruder is the one place a worm gear might not cause trouble -- but I don't see us needing that level of leverage there; existing geared extruders use 2:1 or 3:1 gearing and change the steps per millimeter in the firmware.

There are extruders that use flex shaft to turn worm gear in direct extruder while motor is mounted on frame which turns flex shaft (zesty nimble comes to mind). Why don't they just use smallest possible stepper motor to rotate worm gear directly, instead?

The Flex3Drive, from which the Zesty was purportedly cloned, does admit using a very small NEMA-8 motor directly coupled to the worm gear in place of a flex shaft. This still adds a considerable (from the standpoint of machines aiming for 40 m/s² acceleration and such) amount of mass to the toolhead, and I'm not clear what E-axis speed/acceleration is attainable with 40:1 reduction and a low-power motor like that.
While the larger steppers typically used in 3D printers are perfectly capable of any plausible E-axis speed or acceleration you could want without gearing or with small reduction (e.g. 2:1 or 3:1), once you get up to worm gear level ratios, it's a question of the properties of your specific motor whether you can get enough speed for acceptable retraction performance or even normal print moves at very high speeds. For example, I have a Flex3Drive G5 and the orignal NEMA-17 E-stepper from my Ender 3 does not work well with it without further gearing on the motor side of the shaft. However, a "high RPM stepper" like you suggest should manage just fine with worm gear reduction.
Now, is there any reason to do this? If you're transmitting the force in a manner that can't deal with high torque, like a flex shaft, yes. Otherwise, no. As others have said, modern microstepping is ridiculously accurate.

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Filament getting stuck/nozzle is clogged
For some reason on my Raise 3D N2 plus with a Bondtech-Extruder I am sometimes seeing filament jams and sometimes it prints without any issues. I am using PLA at 215 °C.
When the filament is jammed I have to pull it out, remove the tip, and then I can load again and everything works perfectly fine again. I have attached a picture of what I pull out of the extruder each time. It looks like the bottom part is some kind of skin of the filament.
It's hard to see but the tip of the filament is a little thicker, so it's possible that this can't be pushed into the extruder, but why would it build up there? I am using 3 mm retract, could that be the issue? Or is my extruder not hot enough?

Heat creep can cause the filament to jam.  The thicker end on a Bowden tube extruder matches heat creep.  However, since lowering the extrusion temperature didn't help, it does not look like heat creep.

Retracting too far can cause the filament to jam trying to go forward again.  Have you tried less retraction?

PETG can jam if you print too fast.  I'm unaware of this problem with PLA.  However, this problem gets worse with lower extrusion temperature.

What is missing in the images for a direct drive extruder is any sign of the drive gear engaging the filament.  There are no teeth marks where the gear pushes the filament and no notch in the filament where the gear turns but doesn't move the filament.  Is your filament drive gear too loose against the filament to keep pushing it through the nozzle?

I tried less retracting, (1mm now) aswell as a lower temperature and while the part that caused jamming before printed successfully and now on the next part I started having issues on the second layer, the behavior is exactly the same as before and the pulled out filament looks exactly the same as before (also same length). It seems to be stuck right unter the heatsink in the metal throat tube (that's this one https://www.raise3d.com/products/throat-tube-v2-n-series-printer-only/), that's where the thin, non-theaded area is. The 1mm retraction shouldn't cause a jam there, right?

1 mm retraction shouldn't be a problem. The problem is when you retract the filament past a seam, then it catches on the seam going forward.  Does the filament buckle anywhere?

Not entirely sure if I understand what you mean with your question. I can't see the filament after the extruder motor, so no idea what happens there. When I pull it out I can see that at the tip the filament is thicker. Obviously that is the problem (or at least part of the problem), but I can't figure out what causes it. Even at low temperatures it doesn't work any better. Is 80mm/s print speed maybe too fast?

It appears you aren't seeing bent filament when you remove it, such as the pictures at https://3dprinting.stackexchange.com/questions/15629/what-are-ways-to-avoid-heat-creep

PLA should work at 80mm/s.  That would be too fast for PESTG, which likes 50mm/s or less.

My filament does not look like that, it's perfectly straight and even that thicker tip is straight, it's just too think to go through that throat tube. I think the throat tube might be damaged, I'll remove it tomorrow and check as on the tube that I have on my desk it can be pushed through. Maybe it is bent or something is stuck in there or whatever.....

This wouldn't let me rest ;) So i disassembled the throat tube and checked it: All fine, no damages and nothing is stuck. I also added more detailed pictures of the thicker tips, and as you can see it's basically always the same that's happening.

Another possibility is defective filament.  Does the filament have thick spots on it?

I looked at the filament, took about 10m from the spool, put it on the floor and then carefully looked at it and used a caliper and pulled the filament through it. I didn't see anything unusual and the caliper didn't get stuck. Then I double-checked with one of the pieces that I pulled out of the extruder, tried to pull it through the caliper and it got stuck. So now I know, that the next 10m of Filament are not too thick. My print only needs 2m of Filament, so this should mean at least 5 trouble-free prints if the filament is to blame.

Also what surprises me: When I pull out the filament, apparently I only pull out the upper part and the lower part stays in there. I think retraction might be to blame here (I inspected the G-Code and it printed fine the first layers without retract), let me try a print with retraction completely disabled. When that succeeds I might have to ask questions about oozing, but I'll think about that when I get that far ;)

It looks so much like heat creep in a Bowden tube.  Is there any chance the hotend is staying too long at extrusion temperature without moving?

No, the hotend is constantly moving and extruding during the print. Also my extruder is direct drive and not a bowden extruder. Since I discovered the retracts in this G-Code I am pretty sure it's retract related. That would also explain why it seems to happen pretty consistently at the same point on the same model but slicing it with different options has different effects. So far the new print runs nicely, I'll check in the morning to see how it came out (printing at 205 °C now, retractions disabled).

See 4. added to answer

There are marks on the filament and where the gear is grinding the filament is where I break it off to load the new filament in. This no-retract print succeed, but with some oozing/strings that shouldn't be there. I'm not really sure what to do now, either retract and risk messing up the print, or don't retract and have strings all over the print. I think setting the retraction distance below 1mm doesn't really make sense?

Lowering the extrusion temperature reduces the oozing.  However, lowering it too low  reduces layer adhesion.

If you need a higher extrusion temperature to stick to the bed, you can use a different temperature for the first layer.

Just had a jam again on a part that I printed 2 times successfully before that. I didn't even re-slice it. Maybe heat-creep is indeed the issue and the printer had enough time to cool down? I'm surprised there aren't more reports about this then, and there are fans cooling the heatsink, the temperature there should be sufficiently cool

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Help printing in ABS
My first attempt to print in ABS has been an unmitigated disaster, and I could do with some advice before I try again.
I've been trying to print a Bean Hopper Extension for Melitta Barista TS Smart coffee machine, but every time the layers separate, usually at or near a corner.

My first attempt had it lifting from the bed before a few layers had completed. When I tried it with a thin brim on the outside, it stuck down for a while, but eventually started lifting away from the bed. When I tried it with a raft, it got further, but then the print detached itself from the raft at one corner. My final attempt used a wider brim on both inside and outside, and it managed to get even further through the print. None of the brim had detached from the bed, but then I noticed layers higher up pulling apart, and when I eventually cancelled the print, I saw it had started separating earlier and managed to recover in later layers.
At this point I gave up and printed it in PLA, first time, but I would like to understand what I can do to improve my chances of printing this next time.
Also, I plan to redesign this with the outer wall extending straight up to the level of the bottom of the notch, with a flat top in which I intend to add a channel for a rubber seal. Will widening of part of the model cause more problems for an ABS print, or will it help strengthen it and prevent it separating as before?
I'm using an Ender 3 V2 with a heated bed, using Prit-stik as my bed glue.

ABS needs an enclosure, ABS shrinks a lot when cooling down. Have you tried that?

Nice question, and the detailed description doesn't really need one, but (just for academic purposes), would you happen to have a photo (or two) of the moody ABS layers (or the lifting from the bed) to hand?

See my answer, but really... ABS? get ABS+ or ASA, they warp much less.

... or use PETG (or any other modern co-polymer)

First of all, the bed should be at 100-110 °C and fan 0 %.
I had incredibly good results by using a (sacrificial) "draft shield" as shown below together with a large brim (10 mm). It creates a warmer micro-climate which keeps the print a bit warmer, with much less warping. My printer bed back then was 130x130 mm, therefore drafts were strong. You will get even better results, you have about 200x200 mm.

If you were able to add something like this, it would be even better:

You can get it by designing in Fusion 360 or anything else a "U" shaped part, which you will add twice to each print and scale accordingly.
The reason is that the normal draft shield will deform a lot and detach from the print bed at least in part, resulting in an opening at the bottom and a chimney effect which reduces the effectiveness of the shield. With the two U parts, it won't happen as easy.
The draft shield is the first thing to try.
You can also add a "shield" out of cardboard around the printer. You don't need to close the top, it will work quite good.
You can also get 2-4 20-40 W halogen lamps (from a car, for example, they run already at 12 V, but don't connect them to the same power supply as the printer!) and point them at the part. If you have two, mount them at the two sides of the horizontal gantry: they don't need to move horizontally, only vertically. They will keep the part quite warm without the need of an enclosure (but it would help).
If you have 4 mount them maybe at the corners of the bed, hoping the shaking won't kill them too quickly.
The solutions I listed so far result in better prints, but also in stronger prints because they reduce the causes for warping. The halogen lamps, in particular, keep the printed part quite hot and do wonders.
Another solution which is the easiest and which works extremely well but which weakens the print because it only hides the warping is to use Dimafix on the bed. The print will stick like there is no tomorrow (bed temperature above 90 °C) but the stresses are still there and the print may split in the middle between layers, if it's tall.

You make no mention of a heated enclosure, so I assume you aren't using one.  ABS undergoes significant contraction as it cools down.  If you're not using an enclosure, the temperature differences between the heated bed, the cool middle of the print, and the heat of the freshly-printed plastic will cause severe warping.

Not necessarily. You can avoid warping with some tricks

@FarO A draft shield is also creating a heated enclosure! ;-)

If you are printing very thin walls, corners can be difficult.  Rounding the corners helps.  Also, if you can leave the outside square, but round the inside (making the corner slightly thicker), this can help.


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CoreXY limit switch locations
I am trying to set up RepRap firmware for a CoreXY shown below.  There are 4 limit switches in the top plane and one for the Z-axis.
I believe that LS1 & 2 are considered for the X-axis and LS3 & 4 are for the Y-axis.  My question is do I need all of these switches?  Is it even possible to program this many in the firmware?

Looks like they've got one for each axis at min and max. Not necessary. My CoreXY homes to Xmax / Ymin.

I strongly recommend adding a second limit switch for Z, one per axis, so that you can level it via software. Also, it may be better to place the limit switch for Z at the bottom (Zmax), so that you never risk crashing the bed against the head

This is something I am trying to understand @FarO For CoreXY the head never moves downward like on a typical Cartesian.  It is the print bed that moves.  Right now I have a limit switch on the bottom of the Z axis and a BL touch at the top.  I think it is not possible to put a limit switch at the top with this setup.

What you have is what I was recommending: in corexy Zmax is at the bottom

LS1 & 2 are considered for the X-axis

Yes, these correspond to X-max and X-min, respectfully.

LS3 & 4 are for the Y-axis

Yes, these correspond to Y-min and Y-max, respectfully.

do I need all of these switches?

Technically, no, you need one switch for each axis (if homing is used), but it can be saving your printer when somehow a layer shift has occurred which forces the head to move outside the bed dimensions.
Note that you even can use zero switches, but then you would need to position the print head yourself before each print and condition the G-code with a starting position, this is seen in some CNC  machines.
It is a good idea to use min and max switches, but not necessary. (My CoreXY printer doesn't have the Y-max endstop as there was a little too less space to place it, restricting Y bed size...)

Is it even possible to program this many in the firmware?

Yes, firmwares allow for min and max switches, sometimes even multiple min or max switches for a single axis. The problem is whether your controller board has enough pins exposed and connectors added on the circuit board. But, min and max switches for X, Y and Z axis are not uncommon anymore, look at the specs of the controller board.


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Ender 3 power problems, under-extrusion missing steps
My Ender 3 has started having problems printing.  It does not seem to be getting enough power.  I have cleaned the hot end, checked the PTFE tube seat, replaced nozzles.
It is missing steps on the extruder motor.  I increased vref for the E-axis first to 0.9, then 1.0, then 1.2. The extruder works properly, but now it is missing steps on the X-axis.

How have you diagnosed that it is a "power problem"?

What makes you think increasing e-steps will improve step skipping?  What filament are you using, what hot end temp?  Is this first layer only, later layers only, or all of them?

This is a common issue, there are a number of problems that could cause an extruder motor on the Ender 3 to skip steps besides the stepper needing an increase in current. If the extruder motor is missing steps--which usually results in a periodic clicking noise--this is likely due to one of the following common problems.

Nozzle is too close to bed
Print temperature is too low for a particular filament
Nozzle clog
Filament "clog" in the hot-end gap between Bowden tubing and nozzle
Extruder stepper motor is undercurrent

To quickly and effectively diagnose each of the problems above:
[1, 2]. Move the nozzle away from the bed ~(+20 mm Z) so that the nozzle is a good distance away and extrude 25 mm of filament. If the clicking stops and the extruder stepper is working properly, you know that the nozzle is too close to the bed and you should re-level the bed.
If the clicking/missing steps persist, you should increase the temperature of the hotend to the upper bound of the recommended temperature for the filament (ie. for Hatchbox PLA temp. range on label is: 180 °C - 210 °C). Extrude 25 mm of filament again and observe extruder motor as above.
[3, 4]. If the extruder motor is still missing steps, you are going to need to inspect the nozzle and hotend assembly in greater depth. You should remove the nozzle like this. See if you can clean it out or replace it if it is clogged (might be best to replace it if you have extra nozzles either way). Check to see if this fixes the extruder motor problem by extruding filament with the hotend sufficiently far away from the bed as in steps (1), (2) above.
If this still doesn't solve the issue, the most likely problem is (4) a gap of space in the hotend between the nozzle and Bowden tube getting filled with molten plastic. To fix this, remove the nozzle and disconnect the PTFE tubing. Slide the end of the PTFE tubing through the hot end and wipe off the end of the PTFE tubing with a paper towel to clear out all of the gunk before you pull it back through the hotend. Check the last few mm of the tubing for any gunk and if necessary cut the last few mm of the tubing (ideally using tube cutters) or replace the tube with Capricorn PTFE tubing. Tighten the nozzle to "finger-tight" ie. the tightest you can before you must use the wrench and spanner, then loosen the nozzle ONE FULL REVOLUTION. Now push the Bowden tubing down very hard so that is flush up against the nozzle. Now, properly re-tighten the nozzle all the way. This ensures there is a tight fit between the nozzle and the end of the tubing that prevents this gap from arising. If this is the issue, you may also want to look into replacing the Bowden tube coupler at the top of the hot-end assembly (the stock ones that come with the Ender 3 are cheap and often the root of issues). This entire problem and fix is extensively covered here
[5] The issue the OP suggested is not the definite cause of this issue and as such, it should be checked last as it is a "catch-all" solution which is less likely than 1-4. I would only increase the extruder stepper current as a last resort (assuming your Ender 3 has already been properly calibrated and functioning in the past). As the OP suggested, you would increase the current for the extruder stepper by using the vref potentiometer on the main control board like this.
The list above contains common/likely potential issues and best practices to troubleshoot them, not an exhaustive manual of possible reasons why the extruder motor is skipping steps or under-extrusion is occurring.

Nice first answer, John!  Please be sure to take the [tour] and read over the [FAQ] -- it's good for a little rep even if it's (seemingly) stuff you already know.


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Need accurate 90º angle with respect to the table
I have a Tevo Flash. Normally, I don't care about perpendicularity with respect to the table. But now I have a 5" disc on a ball bearing, held by a 3D printed tube with a flat bottom. If the tube's axis is not 100 % perpendicular to the bottom, the disc, when spun, wobbles at the edge: ~1/8".

As a test, I printed a vertical sample tube. I took close-up pics, on the printer's table, next to a carpenter's square. Down the table's Y axis, there's a vert. deviation of ~1 mm over 45 mm of height, between the sample tube and the square. Down the X-axis, the deviation is small.

How do I deal with it? Can a slicer (I have Simplify3D) compensate for it? I could gently "skew" the geo in 3D modeling software, but it seems inelegant.
Note: this has nothing to do with bed leveling. The bed is level, the printer has a BLTouch. The first layers look great. The problem is above the bed. The right angles of the aluminum-extrusion frame aren't 100 % exact. Measured with the carpenter's square, the vertical columns of the frame (Z) deviate 1-2 mm over 100 mm from perpendicular, with respect to the bottom frame (X-Y). Trying to fix the whole frame would be hard.
EDIT: I used a 0.127 mm shim (from a sacrificial steel gauge blade), it fixed most of it. With the printer laid horizontally (so I could work with the screws underneath) and the shim in, the vertical posts were 100% true (see pic). When I put the printer back into its vertical, working position, the posts tilted back a bit. I'll try a 0.15 mm shim.

Ah, yes a question about tramming.

Without sounding too harsh, please post your edit as an answer, it really deserves to be an answer! It shows effort to solve the issue and deserves an upvote! Technically, it doesn't belong in the question, you can update that answer if you progress in fixing the issue!

In answer to (doesn't have to the issue of the OP, but as a reaction for other readers):

Note: this has nothing to do with bed leveling. The bed is level, the printer has a BLTouch.

Having a BLTouch doesn't imply the bed is level! The bed is level when the nozzle moves in the same plane parallel to the bed, the bed shape is compensated for by the BLTouch, it can be very skew and still it will print.

The right angles of the aluminum-extrusion frame aren't 100 % exact.

That is a problem, the frame needs to be square. I don't think that it is a major operation to modify that, you can use some support struts, I've done that for a 2040 aluminum extrusion i3 clone.
Note, this is a portal style printer driven by a single Z lead screw (and a roller mount on the other Z post) as far as can be seen from the manufacturer photographs. (Update, the OP has a dual screw Z portal, so this possibly is not applicable to that specific version) Single Z screw portal printer types are also prone to unlevel over height, be sure the rollers of the nozzle carrier and the opposite Z post rollers are correctly functioning.
Although fixing the hardware is the preferred option, there is an alternative, you can solve this in firmware like e.g. Marlin.
You need to make some test prints and fill out the correct values to correct for the skewness, but this may be limited to overall Z skewness, not individual skew Z posts.
E.g. in Marlin, the configuration file can be used to compensate the skewness problem:
/**
 * Bed Skew Compensation
 *
 * This feature corrects for misalignment in the XYZ axes.
 *
 * Take the following steps to get the bed skew in the XY plane:
 *  1. Print a test square (e.g., https://www.thingiverse.com/thing:2563185)
 *  2. For XY_DIAG_AC measure the diagonal A to C
 *  3. For XY_DIAG_BD measure the diagonal B to D
 *  4. For XY_SIDE_AD measure the edge A to D
 *
 * Marlin automatically computes skew factors from these measurements.
 * Skew factors may also be computed and set manually:
 *
 *  - Compute AB     : SQRT(2*AC*AC+2*BD*BD-4*AD*AD)/2
 *  - XY_SKEW_FACTOR : TAN(PI/2-ACOS((AC*AC-AB*AB-AD*AD)/(2*AB*AD)))
 *
 * If desired, follow the same procedure for XZ and YZ.
 * Use these diagrams for reference:
 *
 *    Y                     Z                     Z
 *    ^     B-------C       ^     B-------C       ^     B-------C
 *    |    /       /        |    /       /        |    /       /
 *    |   /       /         |   /       /         |   /       /
 *    |  A-------D          |  A-------D          |  A-------D
 *    +-------------->X     +-------------->X     +-------------->Y
 *     XY_SKEW_FACTOR        XZ_SKEW_FACTOR        YZ_SKEW_FACTOR
 */
//#define SKEW_CORRECTION

But, this requires a new firmware installation, the reader should investigate whether this is within the capabilities of the reader.

Thanks for tracking this down in Marlin. Yes, XZ_SKEW & YZ_SKEW would compensate for the slight frame tilt. I don't have the time now to reinstall Marlin, much less to re-mount the whole frame. Since I need extreme square accuracy just for this one-off thing, I'll just "skew" the geo to compensate for what I've measured. Thanks.

PS. Thanks for clarifying it's for others :) I didn't say the bed is level because of the BL Touch, I just listed separate facts: the bed is level, the printer has a BL Touch, the issue is not related to either (but to a slight frame tilt). My version actually has two Z lead screws, but it's unrelated to the slight frame tilt.

@MrSparkly I've updated the answer a bit so that it contains more information for others with similar problems but different printers. Thanks for your understanding!

If you've measured the frame and it's not square, that's almost surely your problem and you need to fix it. But having a BLtouch does not mean your bed is level. The effect you're seeing is exactly what you get from using a BLtouch and mesh leveling to compensate for a non-level bed, and it's a very bad thing and why these fake leveling systems are band-aids to make it easier to get started printing something minimally viable, not something that gives you a working, precise printer. The bed needs to be physically square with the Z axis.

The vertical axis of your print is determined by the machine's Z axis, not by the "bed level" compensation of a BL Touch or similar bed error compensation system.
When you print after BL Touch measures the bed height, the firmware moves the Z axis up and down to compensate for errors in the bed (including non-planar bed surface, which is its main utility) -- but as you print and the hotend moves up layer by layer, the movement is determined by the Z axis -- with a common gantry type printer, this is set by the vertical frame.  If that frame isn't perpendicular to the X and Y axes, the verticals of the print won't be, either.
To correct your Y axis tilt, you need to correct your vertical frame tilt.  The simplest way to do this is likely to be installing an adjustable frame brace system (you can print all the parts except for a couple threaded rods).  That will let you make a precise adjustment, print another test like the one in the question, and verify that it's accurate, before printing your "disk on a donut" actual part.


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E3D Clone heatbreak / nozzle leak issue
I've built a custom machine based on the AM8 (Anet A8 upgrade). I've got an E3D V6 clone hotend in, seems like a decent clone. I've replaced the heat break, heat block, and nozzle several times but after a given period it seems like filament leaks up the heat break. The heat break and nozzle are "all-metal" titanium versions.
How I set it up: I insert the nozzle all the way into heat block, I unscrew it about 3/4 of a turn. I insert the heat break until it makes contact. I then tighten using pliers and spanner. I assemble onto the printer. I heat until 285 °C, give it a few minutes, tighten as much as I think I can before something would break. I let it cool down. I heat again to 285 °C, tighten again as much as I can. Cool down. Then ready for printing (mainly using PETG at 240 °C).
What am I doing wrong? What should I be doing differently?

Maybe it is a not-so-decent clone?

Possibly... but I fail to see how the extruder would cause the leak. Any info would be helpful.

Not a solution, but I don’t like that the bottom fin of the heat break doesn’t get air blown on it the same as the rest, the blue air guide misses it. That’s the most important area to keep cool, lest heat creep up and the filament gets soft too high in the tube and jams.

Your blue plastic fan shroud is upside down.

Do you know that tightening should not be "as much as you can" but "just a bit more than hand-tight"? check one of these so you don't make mistakes again: https://www.thingiverse.com/thing:2613057

How does this happen?
For melted filament to leak around the heat break threads, it has to first get through the metal-to-metal machined surface joint where the heat break contacts the nozzle.  Given this keeps happening, the problem must be a systematic error of some kind.
Thermal Cycling
Based on your description of your installation procedure (heat to 285 °C, tighten, cool, reheat to 285 °C, retighten, cool, print at 240 °C) I see a potential issue: titanium is subject to brittle fracture.  Your titanium hot end and nozzle, together, are being overstressed with the combination of heating well beyond print temperature, overtightening, and cooling (the aluminum heat block has a much high expansion coefficient than titanium).
Suggestion
What I'd recommend is to change to a brass nozzle or, if you need to print with abrasive filament, hardened steel, and a 304 or 316 stainless heat break.  The steel or brass nozzles will cost less than titanium and do at least as good a job (brass is best for thermal transfer to the filament, though it has limited wear life), while stainless steel for the heat break will have similar or lower thermal conductivity and is less brittle.  As a bonus, with your tightening routine, the brass nozzle material will deform when it is compressed against the stainless heat break and act as a gasket, rather than fracturing after a few heat/cool cycles.
An Additional Concern
While answering comments, I was reminded of another possible issue: the same reason aluminum wiring is no longer used for in-wall home electrical installations.  Aluminum tends to deform permanently after heat expansion under constraint, rather than recovering its original shape (as copper and brass will do), and expands several times as much per degree as titanium does.  Even if the heat block is an alloy rather than conductor grade pure aluminum, this will occur (though most alloys are significantly harder/stronger than pure metal) with the heat, tighten, cool process.  Also, 280 °C may be hot enough for aluminum to undergo heat creep (a slow, permanent deformation under stress normally well below the yield point).  The rule I recall from material science courses in college, almost forty years ago, is that creep becomes an issue when the absolute temperature is more than about half the melting point, for most metals, and pure aluminum melts at about 933 °K while you're printing at 553 °K (by comparison, 70/30 brass, as used for firearm cartridges, has a solidus -- the lower melting point of a two-component alloy -- of about 1183 °K.
This permanent deformation of the aluminum heat block at the threads may result in the threads becoming loose, thus allowing extrusion pressure to force molten filament between the heat block and heat break.  That layer of filament material then acts as an insulator, increasing the temperature differential between the heat block and heat break -- and with the heat break now running cooler, the gap opens further.
A Suggested Solution
One solution to this would be to switch to a brass or copper heat block.  Not only do these metals have a higher melting point than most aluminum alloys, making them less prone to creep at printing temperatures, but they have much more tendency to return to original dimension after a heat/cool cycle when constrained (which is why copper house wires don't become loose over time the way aluminum ones do).  The change in mass and conductivity might make it desirable to recalibrate the temperature control PID, if present, but this is a one-time operation, compared to having to disassemble and clean the heat block and heat break periodically due to leaks.

I had similar issues initially when heating and tightening at a lower temperature, around 250°C, I read some forums where E3D recommended 285°C. I have cleaned and inspected old heat breaks and nozzles and could not find any defects with the naked eye. Titanium all metal heat breaks are readily available but I will see if I can source an all steel one (the micro swiss seems very expensive) and revert back if this resolves the issue

I see stainless ones all over AliExpress, but if you're in a hurry I'd start by checking Amazon or the E3D home site.

Titanium may be subject to stress cracks but... 280 °C for titanium is nothing, we are not talking about tin! Second, those cracks are not expected before hundreds (at least) of cycles unless he got a defective part to begin with.

@FarO Brittle failure of titanium isn't the same as fatigue -- and the relevant material for the heat cycling is the aluminum heat block, which expands several times as much with temperature as the titanium heat break and nozzle.

Verification: When you tighten the nozzle against the heat break, the nozzle is not tightened completely against the heater block.  If the nozzle tightens completely against the heater block, it will not finish tightening against the heat break.

Note: the heat break is thin between the heater block and heat sink to minimize conduction of heat.  Over-tightening the heat break into the heat sink with break the heat break.

Verification: your heat break is all metal (no Teflon tube in the filament path).  If it's not all metal, 285 °C may be damaging the Teflon tube.  If not all metal, tighten the nozzle to the heat break at 250 °C, which is the limiting temperature for an extuder that isn't all metal.

The titanium heat break has higher thermal resistance, which helps to isolate the heat break from the heater block.  However, higher thermal resistance is a disadvantage for the nozzle, where you want the heat. For non-abrasive filaments, such as PETG, a brass nozzle is easier to get a good seal as well was better heat conduction.  PETG is particularly sensitive to jamming from not adequately heating up when printing too fast.  While the nozzle heats the filament, the filament cools the tip.  Thus, you will need to print slower with a titanium nozzle.

From the information so far, it appears to be difficulty get a seal between to titanium pieces.  It seams like they could use a different titanium alloy.  Titanium glasses frames are flexible, not brittle.  However, brittle alloys are usually harder, but the heat break doesn't need to be hard like the nozzle.  Of course, brass is easier to get a seal because it actually deforms to fit shape of heat break.

"When you tighten the nozzle against the heat break, the nozzle is not tightened completely against the heater block."  In the process of forcing the nozzle against the heat break, it does so by engaging the threads of the heater block. The same applies to the heat break. All three components are tightened against each other, but the key factor is that the nozzle upper surface is flush and properly engaged with the flush heat break surface.

Do you see any sign of cracking as Zeiss mentioned?

The nozzle is initially inserted all the way into the heat block, then about 3/4 turn outwards before inserting the heat break. This gives enough space for nozzle to be tightened at temperature. Heat break is  all metal.

@PerryWebb no cracks I can see with the naked eye

I'm wondering if the aluminum heater block is strong enough to crack the titanium.  The aluminum alloy of the heater blocks tends to give, especially at elevated temperatures.


text:
Lowest temperature PLA pulley print will withstand
I am looking to print an HTD Timing Belt pulley to be used in a laboratory setting that can get very cold for extended periods of time. By "very cold" I mean adjacent metal chambers get cooled with liquid nitrogen to lower than -200 °C. For the purposes of having a threshold temperature tolerance, assume that the metal chambers coming directly in contact with the pulley may get as cold as mK close to absolute zero.
While it was my intention to print this pulley out of PLA, I am unsure whether or not it will be able to withstand negative temperatures of this magnitude or if it will become brittle--or something else will happen to the structure of the print when it experiences these temperatures. I am open to printing any other material if there are some materials that will hold up better than PLA for low temperatures. It is preferable for me to print this part instead of machine it for the sake of a deadline. I was also wondering if there is some infill pattern, infill density, or other structural print parameters that would help reinforce a printed part against becoming brittle when imposed to such low temperatures.

What plastics do you already know can take the cold soaks you describe?  Perhaps thermosets rather than thermoplastics (which would suggest an SLA rather than FDM print)?

Do you know a thermoset that would be good to experiment with for testing out these low temperature constraints?

Not offhand, just exploring options.  I don't work in cryogenics, I repair power tools.  I thought it might be possible to just look up the properties of various plastics, like we used to do with the "Rubber Bible" -- CRC manual -- when I was in college ~40 years ago.

Of course, steel works better than plastics when very cold.

@PerryWebb Actually, most steels become very brittle when chilled, even well above liquid nitrogen temperature.  There are recorded cases of cold-induced brittleness causing failures in building structures (under construction) at fairly ordinary outdoor winter temperatures.

True, but even brittle steal is much stronger than plastic, as long as you aren't hammering on it or bending it.  If both the steel and plastic become brittle, the plastic will break first.  Put a steel ball from a bearing and a rubber or plastic ball in liquid N2, then throw them on the floor to see which will break first.

Another example: a steel trashcan will usually hold LN2 OK, but a plastic trashcan will usually crack if filled with LN2.  Teflon tends to hold up well at LN2 temperature.  It would make good bearings but too slick for pulleys  and a difficult melting point for printing.

Yes, it would be ideal to machine the part of steel, however it is much easier to print it for the purposes of prototyping.

I found this article which seems to suggest PTFE is a good choice of plastic for a cryogenic environment.  I've read that there are PTFE filaments available for FDM printers, though there are some caveats.  First, you will need an all-metal hot end; enough heat to melt a PTFE filament will melt the PTFE filament guide if it is in contact with the nozzle.  Second, you will likely need to edit your printer's firmware to permit printing at the high temperatures required.  Third, it may require some testing to determine whether FDM printed PTFE will meet your mechanical needs (shear strength, layer adhesion, etc.) and fourth, you might need an unusual build surface, since the polymers used for many existing surfaces can't take the temperatures needed for bed adhesion.
Finally, as with a PTFE guide tube in contact with the nozzle, at the temperatures required you need to be aware of and take precautions against outgassing by the melting PTFE.

The need for higher extrusion temperature is what I would expect.  However, that's assuming the same function between the brittle cold temperature and the almost liquid phase.

You could try PETG. PETG labware works down to -70, and there is a video clip where a PET bottle filled with liquid nitrogen that withstands appreciable pressure.
But for whichever material is used, thermal cycling may be a problem.

Welcome to 3D Printing SE and thank you for your contribution. When you get a chance, please take the [tour] to understand how the site works and how it is different than others.

Thank you for the suggestion--I will try it. Unfortunately for my purposes, -70C compliance is essentially meaningless to me (of course assuming you did not mean 70K). The temperatures I am referring to are an order of magnitude lower ~ -459.67C.  I am sure thermal cycling is a potential issue that could induce material fatigue characteristics.


text:
BLTouch always shows high on right side of the plate
My BLTouch was working great. Until one day, it just started showing the right side as being high on every read.
I've tried leveling many times manually and with the BLTouch. But every time I use the bed visualizer, it shows high on the right. I've even rotated the glass build plate with the same result.
Any ideas what could be causing this? The bed leveling image below was done immediately after manually leveling the bed.

I think I found the problem. I think there was some crosstalk between the BLTouch wires and the other wires it was tied together leading to the hotend. When I moved the BLTouch wires away from the others the problem went away.
I will be added a sheild to the cable in the future like in this youtube video

The OP already found the problem and answered the question hinting to shielding of the cable. If this is the actual problem, of fiddling with the cables might have caused this, an alternative solution is presented as I've experienced similar behavior.
If one side of the bed is higher than the rest, even when rotating the glass bed, you might experience that the nozzle carriage is tilting on that side. E.g. when using a Bowden extruder assembly, a too short Bowden tube (or cables in a non-Bowden setup) the tube (or cables) pull at the carriage causing it to lift at the furthest points from the extruder; this tilting can cause the nozzle to go up a few tenths of a millimeter.


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Ender 3 Pro not reading new G-code files on original SD Card
I´ve been using my Ender 3 Pro for almost 1 year now. Always using the provided SD card. For a couple of days, the printed does not read any new file that I load to the SD card, but it does with the older files (and it then prints correctly as well).
I tried deleting some old files that I don't need, I tried turning it on with the SD card, I tried inserting the card after turning the printer on. It's always the same.
I am using another SD card and it works properly.
Any idea?

Welcome to 3D Printing Stack Exchange!  Please take the [tour] and read over the [FAQ] to get a better idea of how Stack Exchange works.

The original card I got with my ender3 also wore out recently.

I'd try to putting the SD card in your computer and formatting it (pulling off the files you want to save before doing so). If it still doesn't work, throw it in the trash.

SD and MicroSD cards use a type of memory (Flash RAM) that is subject to wearing out -- the actual memory cells deteriorate very slightly each time data is written to them, and SD, MicroSD, and thumb drives typically don't use the very best flash RAM (as would hopefully be the case for internal Solid State Drives that house the operating system and user storage in your computer).
Further, the constant plugging and unplugging of these cards also puts wear on the connectors.
Either of these factors can result in one or more devices losing the ability to read the card, and this can result in only old files being accessible (though it's much more common for the card to become read-only, or even become unreadable).
If you can still read the original card in your computer, please make a complete copy of the contents immediately, and then write those contents to a new card (as well as keeping a copy on your computer's storage) -- and throw the old card away, so you don't accidentally use it for anything.

Something in the Ender 3 stock firmware (and even custom Marlin builds) is prone to corrupting SD cards, especially if you've removed and re-inserted them without using the unmount command on the menu first. I never tracked down exactly what it was before switching away from Marlin, but whenever it happened, making a new directory, moving all the files to it, and deleting the old directory seemed to work (assuming you don't keep files in top-level directory) to get it to read them again. When that didn't work, moving them off to the host computer, reformatting the SD card, and moving the files back always worked.


text:
Friction between nozzle material and abrasive filaments
Usually the hardness of the material is considered primary for nozzles used with abrasive filaments.  Has friction between between nozzle material and abrasive filaments been considered? It seems that friction as well as hardness would play a roll in how long the nozzle lasts.  Perhaps, this is considered with ruby tipped nozzles.

How is friction not just wear in progress?

@Zeiss So you are saying friction is accounted for by measuring the wear of the abrasive filament on the nozzle rather than measuring the friction properties between the nozzle material and the filament material at extrusion temperature.  If so, you could put that in an answer.

No, I'm saying they're effectively the same process -- friction measures the force and energy it takes to wear away the nozzle material.

Yes, Friction between nozzles and the material plays a part in the printing process. Eventually, the nozzle diameter will widen if the printer is using an abrasive filament that is using things like carbon fibre or iron. The ruby nozzle is essentially a catch-all that won't wear out no matter the filament you buy. However, the steel nozzle is good enough when it comes to most abrasive filaments; and it has the added bonus of insulating the molten filament from the outside air much better than the much more thermally conductive brass nozzles.

But insulating isn't what we generally want the nozzle to do -- rather, we'd usually want to see it conducting heat from the heat block to the filament to ensure proper melting at useful feed rates.

@ZeissIkon, actually no. By the time the filament gets to the nozzle, it should already be molten.  There are hot end socks that cover the heat block as well as the nozzle:
https://fabbaloo.com/wp-content/uploads/2020/05/image-asset_img_5eb0b9ad4941a.jpg

Ruby is chromium doped sapphire.  I assume ruby is desired because of visibility, the reason it is desired for mechanical watches.

@user77232 Generally, there are only a few millimeters of heat break in which the filament ought to come into contact with hot metal before reaching the nozzle -- and that only if you have an all metal hotend.  Otherwise, if the filament is melting significantly in the PTFE tube, isn't that "heat creep" that can lead to clogs, retraction failures, etc.?

Remember the ruby tips are on brass nozzles, which have better heat conduction than steel, except for the ruby.  However, some people who have used both say the steel works fine and the ruby isn't worth it.

Friction is known to differ and it has been considered at least in some products: here Micro-Swiss sells a plated nozzle with reduced friction and increased hardness.
It is not clear from any known measurement whether the friction plays any role in the print performances, since so far lower friction coatings (Nickel) are also harder, therefore you never know whether the increased lifespan is due to the reduced friction or the harder coating.
Also, I am not aware of any test where a lower friction nozzle results in higher flow rate and print speed. I am only aware of a diamond-filled PLA which claims higher printing speed, confirmed by CNC kitchen (last graph).


text:
Re-doing manual bed leveling
I have a Ender 5 Pro with a BLTouch auto bed leveler, running  TH3D's version of Marlin: TH3D UFW 2.14. During my initial setup several months ago, I naively assumed that the BLTouch didn't need a manually leveled bed so I cranked the manual bed adjustment screws to be as compressed as possible. This has worked pretty well, until recent large prints have shown I need to adjust the back right of the bed as it's too low.
I adjusted all four of the the manual screws to be about halfway so I have room to play but when I run the Level Corners command, the first corner (front-left) is now way too high and the nozzle attempts to move several millimeters past where it should go (the plate moves up until it collides with the nozzle and then continues a few millimeters more...). I have tried poking every setting I can find but I cannot get the printer to reset what it thinks its z-offset should be.
Not sure what my next steps are as resetting bed leveling is not a common task from what I can tell.

It occurred to me that one could level the bed by physically moving the gantry and bed with the printer off. So I did that and a test print seems to be adhering to the bed much better than it ever has in the past. But before I answer my own question, I'd like to know if there's a better, don't-move-parts-yourself, way to do this adjustment.

Can you explain the "This has worked pretty well, until recent large prints have shown I need to adjust the back right of the bed as it's too low."? what's the difference between large prints and smaller prints? or do you mean that you were reaching the maximum printing volume and with the springs compressed you couldn't anymore (not sure why that would be)

@FarO Correct, I hadn't printed anything large enough that ran into the back right corner. Most of what I've been printing sits within a few centimeters of the center of the plate, so the problem wasn't as obvious until now (the print being 12cm square).

A BLTouch doesn't level the bed, it compensates for the geometry and adjusts print head movement, it is always required to tram (level) the bed with respect to the nozzle X-Y plane (of which the Z is perpendicular to this plane). If the build plate is skew, the bottom of the print will be skew, the top will be square with the head movement plane (the default compensation of the BLTouch is smeared out over the first 10 mm of the print, note this can be disabled or height changed).
To properly tram the bed, you need some room for the screws to go up and down. Home the X, home the Y and finally home Z. Then you jog the nozzle down (using a printer interfacing application over USB or the LCD from the printer itself, optionally you can use a console, the latter is very handy for sending G-code commands for the Z-offset determination later) to the bed to fit a sheet of A4 or Us Letter paper (alternatively, use feeler gauges) between the nozzle and the heated bed (pulling the paper should give you a little resistance), de-power the steppers and manually move the print head and bed to reach all corners and adjust the screws to have the nozzle at a paper distance of the bed. Note that if the nozzle will not reach to the bed, Z=0, you need to disable the Z endstop with M211 S0, don't forget to enable them after the Z-offset determination M211 S1. Do home the printer after each manual movement and screw adjustment as moving it manually may introduce some extra clearance of induced torque on the head. Doing this manually will prevent damaging the bed opposed to moving the head over the build surface using the LCD movement commands (scratching the surface). Manually, you will be able to stop when the nozzle hits the surface, if so adjust corner screw of the corner you are moving to. Repeat this sequence for each corner multiple times until the bed is parallel to the X-Y print head plane. Now you are ready to set Z-offset, which is found in this answer.


text:
Way to add identity to an all metal hot end
Is there any convention on how to mark an all metal hotend to distinguish it from a hotend with a PTFE tube in the heatbreak? Once assembled for a German Riprap 3D printer, they look exactly the same on the outside.   I'm trying to decide on a way of marking them to indicate the difference.
Hotend with heatsink

Exposed part of heatbreak between heater block and heatsink

Easy to see PTFE tube on nozzle side of heatbreak (all metal hotend has an all metal heatbreak with no PTFE)

Even after removing heatsink, PTFE tube is difficult to see in heatbreak (all metal hotend has an all metal heatbreak with no PTFE)

Nozzle end of all metal heatbreak

Heatsink end of all metal heatbreak

Heatbreak neck isn't visible when everything's in place?

@Zeiss The neck is visible but looks the same.. I'm trying to decide on a way of marking them to indicate the difference.

No PTFE at all on all metal hotend heatbreak; see images added.

Yes, I see.  Now it's clear.  Not obvious how to distinguish them when installed, though.  Hmmm...

Given your heatbreaks are the same material and external dimensions, it seems that the most practical way to distinguish one from the other would be to mount the all metal heatbreaks in a heat sink that's anodized to some other color than natural aluminum -- red or blue, for instance.
If you can't buy them that way, or already have plenty on hand, anodizing is fairly easy to do at home -- you need battery acid, a car battery (or heavy duty charger for one), and some strongly colored dye to apply after the anodize has established the oxide layer on the aluminum part.  There are many online references on how to proceed and how to stay safe while handling the acid.
If you have machining capability, another option would be to make, say, a copper heat sink for the all metal heatbreak, while keeping the aluminum for the conventional one.

Usually, the neck of an all-metal heat break would be thinner (as it does not need to contain the PTFE tube, and making it overly thick would conduct heat unneccesarily). This may be observable when one loses track of what is where.
If one needs to see at a glance, I do not think there is a convention.

Questioner's photos of his conventional and all metal heat breaks show no such neck difference.

I do not see the necks to compare, just the ends. But suggestions sounds a bit too "easy", I agree.


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How should I finish a food safe print?
I'd like to print a mouse shell from food safe PLA.
I need it to be food safe, because sweat can dissolve any harmful chemical from it just like foods. I am not sure about how to finish it after sanding the result. I read that people use food safe epoxy to seal it before painting to get a smooth surface. I read that others seal it after painting to cover the paint, which is possibly not food safe.
So I am not sure if I should seal it before or after painting or maybe both? I read that some people use shellac or even nail polish instead of epoxy to get something that they think is food safe. So the entire topic is starting to get somewhat chaotic for me. What materials should I use for sealing and painting and in which order?

If you're using food safe PLA, there are no "harmful chemicals" soluble in sweat. The food safety issues that remain are surface imperfections where bacteria or mold may grow. These are almost certainly not an issue unless you're actually eating from the object or otherwise putting it in your mouth/body. People touch similar objects and have them in contact with sweaty hands all the time - athletic equipment, bicycle handlebar grips, steering wheels, etc.
For a user with serious medical issues affecting their immune system, this still may be an issue and you need to follow whatever instructions medical professionals have given about contact with objects that may be contaminated. But otherwise there is no need for any coating for a mouse shell except for aesthetics. You can use whatever you like, but be aware that, unlike PLA, most coatings do involve moderate to high levels of VOC (which are ideally down to non-harmful levels after it's finished setting/curing).


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PLA Jamming- is the heat break too hot or too cold?
I’m getting nothing but jams with a new BCN3D Sigma R19 printer, printing PLA at 195 °C, two brands (BCN’s own brand and Monoprice orange). 6.5 mm retraction, as used in BCN’s PLA profile. Using their fork of Cura. Full enclosure, but it gets maybe to 32 °C inside, just warm. It prints fine for a few layers, then it jams, usually partially-I caught it in the act and the extruder (the Bondtech dual gear Bowden extruder they switched to on this model) would make knocking sounds as it skipped steps, and the plastic under extrudes in spider webs. It would valiantly try to keep going, and just chew up the filament a little, then extrude, then skip, etc.
After thinking the problem was the extruder, taking it apart, cleaning, trying a few different tensions on the hobbed gears, my attention shifted to the hotend. I did some cold pulls with nylon, and each time the nylon would come out with this frayed ring of plastic about 15 mm above the cone from the nozzle tip. It’s like it was a separate piece of plastic from the filament, but it seems like it constricts the path. This ring is about the depth where the heat break screws into the heat block. I supposed it could have started higher in the cool end and gotten pushed down? I suspect the grooves pressed into the filament by the Bondtech might be prone to hang up on this plastic gunk ring.
Their hotend design is all metal, similar to the V6 (and apparently manufactured custom for them by E3D). Different, taller nozzle. It has a 30 mm fan blowing on the fins. There is no shroud on the fan, like the blue thing on the V6. The heat block is halfway up into the enclosed part with the cool end and fan. The fan blows on the heat break and the block.
One of my cold pulls shows a little bulge, right about where I think the brass nozzle butts into the heat break steel piece. I’m wondering if there is a gap there that plastic melts into? They do an inconvenient thing where they sell the hotend as a whole piece for $125, and apparently you can’t unscrew the nozzle like a V6, people report the threads get ripped out of the heat block. All to say, it isn’t advised to completely disassemble the hotend.
I thought the little fan might not be moving enough air across the cooling fins, so I tried to replace it with a new fan that moves more CFM, but it just screeches, it seems the fan isn’t really driven by 12 V, but maybe a PWM thing at 24 V. It was fine on 12 V DC when I bench tested it.
I disassembled the cold end from the heat break, and verified it had thermal paste on the threads.
My question is if anyone has experience with the gunk ring? Is my heat break getting cooled down into the heat block, or is heat creep getting up into the cool end? Or is the little gap or chamfer where the heat break meets the nozzle causing clogs?
I can work on more cooling (faster fan), or design a shroud for the existing fan so it doesn’t cool the heat break+heater block), to  just not sure which.

EDIT: The filament partially jams (the extruder skips steps an knocks) even without printing, while just loading and purging over empty space, no retractions.

Printing PLA in an enclosure is generally a bad idea without active cooling of the enclosure. At 32°C you almost surely have heat creep in addition to little hope of getting extruded material to cool quickly enough not to deform before the next layer is added on it.

My first thought is heat creep.  I've never seen a heatsink on the hot-end that couldn't use more air and a lower temperature.  IF not heat creep, then perahps under-temperature.
But, since you've worked on this issue without success, and the extruder skipping happens even wit a steady flow and no backpressure against the bed or part, perhaps we should look elsewhere.
First thing to check would be the friction of the filament through the Bowden tube, and the attachment points.  First, I would back off the extruder pressure, remove the nozzle, and see if you can easily and without jerks or hangups slide fresh filament past the extruder gears all the way through the hot end and out where the nozzle would be.  You'll be doing this cold with the printer off.  That should feel slick and easy.  If you need to push with any significant force, find where the friction is happening and fix it.
If it flow smoothly, try checking the extruder motor, the extruder gear, and if it is a dual gear system, check both of them.  Try running the extruder (you'll need to hear the hot end) with no filament.  Does everything turn easily?  Try inserting filament in the extruder, pulling back on the filament, and extruding forward.  Is the motion smooth?  If not, check the gearing to see if a piece of filament or anything else if interfering with the motion.
If you can check the motor current, see if it is running to spec on both coils, in all directions.  You could have a problem with one half of one H-bridge.
If you have two extruders, does the problem happen with both, or only one?
I would still mostly suspect that heat creep, or under-temperature.  195 °C may be a little cool.  My Prusa prints PLA at 215 °C.  I have had heat creep problems with the Prusa, which I addressed by directing more air through the heat sink fins -- too much was passing around the sides of the heat sink without actually cooling it.

Thank you for the in depth look at my problem. Since posting it I found the feeder tube for the extruder was twisted some, and adding resistance to the feed path. Also the monoprice orange PLA left long strings in the Bowden tube when I unloaded the spool, I think this wispy stuff was getting re melted when the filament got moving through the tube next print. And the tension on the extruder was pressing notches into the filament so it wasn’t smooth, more prone to getting caught. I modded the heat break fan to be higher speed (24v fan hooked to the +24v supply). So far success w small prints

Is this what your hotends look like?

They look like Bowden tube extruders.  Your images are consistent with heat creek for Bowden tub extruders.  Can you print with the enclosure open to see if the problem is at least less?
Here is a full discussion on heat creep.
What are ways to avoid heat creep?

With the plexi hood off, the extruder still knocks/skips steps when I’m just testing the extruder, purging the filament. This is after it’s been heated a couple minutes. Of note is the wall between the cool end and the part cooling fan has several holes in it. The part cooling fan moves extra air on the cool end fins. The default PLA  profile runs the fan 100%, I had some warping (even with the enclosure) so I turned it down to 50%. I’ll try it blasting full again. If so maybe that would prove the hotend fan alone isn’t moving enough air?

I doubt the problem is heat creep if it acts the same with the enclose off.  Even if it didn't fix the behavior, it should reduce it.


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Hotends where heatbreak is not load-bearing?
Having started with an Ender 3, it just seemed natural to me that the heatbreak should not be load-bearing; Creality's stock hotend has 2 bolts holding the heat block to the heat sink, which of course waste some heating power and increase the cooling needed to avoid heat creep, but serve the important purpose of keeping the nozzle position rigid relative to the carriage and making it so you don't bend or snap the heatbreak when changing nozzles.
Looking at hotends (especially all-metal ones) for a possible future printer build, I'm surprised to see that many (most?) don't have this property, and have the heatbreak playing a load-bearing role. This seems really undesirable. Only the Mosquito makes a point of doing this right, and supposedly has a patent on this or related design decisions. Is that really the case? Are there basic all-metal hotends that are designed to avoid making the heatbreak load-bearing that don't cost $150?

The drop-in replacement all metal hotends for the Ender 3 that I've looked at seem to have the two screws -- though I've read/heard opinions that these are intended to be removed after assembly, these are common Mk. 8 type hot ends, but with 2 mm bore through the entire heat break instead of 4 mm.  That seems to be the only modification (other than not anodizing the aluminum heat sink).
While the brand name units of this type run approximately 65 USD at retail, they're available from Chinese vendors for under 10 USD plus a few dollars shipping, if you don't mind waiting a few weeks instead of a couple days to receive your part -- and if they aren't from the same production but sold without extensive vendor support, they're very close physical copies, according to review videos I've seen.
It's also possible to replace just the heat break for similar cost, either in stainless or titanium, with a 2 mm bore unit; this would obviously preserve whatever additional mounting hardware exists on/between your original heat block and heat sink.
BTW, if they aren't already, replacing the screws with stainless will significantly reduce heat loss through the screws -- stainless is a much poorer conductor of heat than common steels used with plated screws.

As mentioned in the question, I'm looking at this more from a standpont of a future build, not Ender 3; I just mentioned the Ender as the basis for what I'm used to. Maybe the right solution is what you're saying, just putting a suitable heat break in a mk8 type hotend. Are these readily available with proper mating surface to avoid clogging where they meet the nozzle?

@R..GitHubSTOPHELPINGICE I've seen them in both stainless and titanium on Amazon, never mind AliExpress.  I recommend stainless -- lower heat conductivity and a bit cheaper, plus not prone to brittle fracture.  I'd also suggest looking for a brass or copper heat block, it'll give less trouble at higher temps than aluminum.

I eventually ended up doing just what you suggested: replacing just the heat break with this: https://www.amazon.com/dp/B08TCD4M1S. Moreover, OEM-equivalent heater blocks and heat sinks are available dirt cheap (like 5 pieces for under $10) so this also seems like a very good way to go if you're not starting with a Creality printer but want a cost-effective and structurally-sound hotend.

You ask in general, not specifically for Ender, so since you mention the Mosquito, which has a characteristic shape and a size, the obvious alternative which doesn't cost that much is the Phaetus Dragon.
It copies the idea of the Mosquito, but it is repackaged in a shape and size fully equivalent to standard v6 hotends so it's a drop-in replacement for any v6 hotend. You don't have one, but in general...
Footnote: Slice Engineering got the patent in US, but not in Europe and China, yet. Also, in Europe their idea apparently was found as not original. Who knows...

Yes, I saw the Dragon (Phaetus = rebranding of Triangle Labs?) and it seems to be a near full clone (with better compatibility with other ecosystems) of the Mosquito and as such it's still rather expensive, and arguably also clones things for which Slice's patent is justified (unlike basic structural soundness with obvious prior art). I'll definitely consider it.

It's not clear who's cloning who. I heard that Phaetus is the original Chinese, and TL licenses it from them. This would make sense, since Phaetus still sells the product, while TL stopped due to pressure from Slice Eng. Concerning the features where the patent is justified, we can discuss it in the chat if you want, ping me in that case.

@R..GitHubSTOPHELPINGICE an advantage of the Dragon variants is that you can completely remove the circular v6 connector and screw the top of the heatsink directly to your carriage/toolhead (it is not warm anyway) which allows you to get a more compact carriage and a sturdier mount (it doesn't rotate when you change nozzle). By reducing its height this way I could fit a direct drive extruder too

Yes.. wait, the Mosquito can rotate on its mount? That's rather bad if it's not absolutely perfectly centered on the axis of rotation, since it will affect positioning accuracy... Dragon does indeed sound nice, but mk8 style has that property (screwing top of heatsink directly to effector plate) too and is a lot cheaper. Hmm, options...

@R..GitHubSTOPHELPINGICE no, but you mention a "future printer build" and I was thinking about v6 connectors, which are round and may rotate. Mosquito cannot rotate, it's screwed like the Dragon, just bulkier.

Ah, thanks for clarifying. Yeah, the E3D v6 mount design doesn't make sense to me.


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What is the best way to collect sanding dust?
I am pretty sure that sanding makes a lot of microplastics, so it would be nice to collect the dust, and melt it to got a blob of plastic again instead of millions of tiny particles. What is the best way for collecting it, do you use any dust extractor, or are there different techniques like sanding wet surfaces and filtering it from water?

What material? In my experience sanding PLA just doesn't work without water. You quickly hit the glass transition temperature then it just softens.

@R..GitHubSTOPHELPINGICE It is PLA, maybe later ABS. I figured meanwhile, that it would be the best to treat the water with chemicals to break down the microplastics.

Melting it has a significant energy impact. As suggested, vacuuming with bags or without bags and then dumping it in the garbage is the best, it will be collected, separated, burned.

@FarO If you throw it to the garbage it will show up in the food chain. Nobody will recognize microplastics, for them it is just a bag of dust. Burning won't happen either in most countries, they just throw it to a landfill. Better to handle it where you produce it.

I decided to collect the dust and treat both PLA and ABS with chemicals to completely break them down. That solves the issue and I won't rely on false hopes that somehow it does not end up in the environment.

What chemical did you find that breaks down PLA?  From my reading, there are few solvents that will affect it...

@ZeissIkon PLA is a lot easier than ABS. Just google PLA hydrolysis. https://www.mdpi.com/1996-1944/13/9/2111/pdf Looks like a few weeks in 20% HCl is more than enough for PLA. I am not sure about ABS yet. I need to read a lot more about this, probably using google scholar for a few weeks.

ABS is used for drain pipes, so it's chemically pretty tough stuff.  Most folks who want do something to it use solvents (acetone is top of the list) but you don't want to put those into your own environment, never mind the world -- and they don't break it down anyway; when the solvent evaporates the ABS is left behind.

@ZeissIkon Yes, maybe I forget about ABS and print only PLA. Though I have an MSc in biochemical engineering, so maybe I'll figure it out later when I need it. Currently it is not a priority.

FWIW, properties wise, PETG does almost everything ABS does, but is somewhat easier to print (say people who've been at this much longer than I have).  Probably not any easier to break down, though, but easier to re- or up-cycle...

@ZeissIkon I am a beginner at printing, I really need to see what durability and properties PLA has first. If it is not enough, then I'll check PETG. Thanks for the tip!

Check YouTube for Maker's Muse channel, he had a video where he showed prints that had been outdoors in Australia for a year.  Overall, even PLA held up well.  Don't use it for anything that goes in your car, though; it'll sag above about 120F, which cars in summer easily exceed.

@ZeissIkon Currently I want to print something like this: https://support.logi.com/hc/en-us/articles/360025267154--Product-Gallery-G7-Laser-Mouse I don't like the shape of current mice, but the sensors and wireless tech are pretty bad in the case of 10+ years old mice like this one. So I decided to print a new shell for my G603. Not sure how long it will take to learn scanning, design, printing. It will be fun. :-)

For something that will live on your desk, there's no reason to look any further than PLA.

@ZeissIkon Yes, sweat is the only problem, but food grade PLA is ok I think. I might coat it with epoxy if it is not durable enough. I was thinking on transparent plastic or multiple layers too. It will be a fun project, maybe I print multiple different ones.

As an environmental thing, micro plastics are an urgent problem for ocean life, it’s getting into the entire food chain. With that in mind dumping it down the drain would be the worst, city filtration systems can’t get the tiny bits of plastic before it drains into the ocean. Sanding outside is kind of bad. I sand stuff over a lined waste basket outside, which maybe catches 75% of the dust. Inside (or outside) with a vacuum running would be good, I think best would be a vacuum with disposable bags. Yes it is still micro plastics, but it ends up at the dump, where the soil is already poisoned, and hopefully nowhere near the ocean/waterways, and likely will stay there while it breaks down. PLA takes ~80 years, but ABS takes 1000 years.
The idea of collecting the dust and fusing it sounds like it would be too much hassle to be feasible long term, it’s good, sustainable habits over years that add up.
As a side note, card scraping is a nice way to smooth 3D prints, that doesn’t make fine dust.

PLA may actually degrade faster as a microplastic than it would as a solid blob.

And not all the garbage goes to the dump. It is often (and hopefully) burned.

while down the drain isn't a good idea, the sewage processing  will remove it before it is released.  It's plastic thrown on the ground and washed down the storm drains with the unprocessed rain water that causes the problem, unless you are in a country that doesn't process sewage.


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What's causing my PLA prints to lift like this?
I'm printing a Soma cube I found on Thingiverse -- it's a puzzle toy I remember from the early 1970s, and the kind of thing that ought to be really easy-peasy to print.  Each of the seven pieces is made of four cubes (or three for one piece) joined face to face in every possible combination, so that they can be assembled to make a single 3x3 cube (the claim in the day was, in literally tens of millions of ways -- though many of those were reflections or rotations of others).
Problem is, in order for the seven pieces to fit together correctly to make the 3x3 cube, they have to be flat and square on all faces, and dimensionally accurate.
I have an Ender 3 that's just a few weeks old (first print was May 8th to 9th of this year, also my own first 3D print).  I'm printing these parts in gray Amazon Basics PLA at 200 °C, with the Creality coated glass build surface at 55 °C.  I'm printing on a raft; the first layer goes down well, but over the course of the first forty or so layers, I get this:

I presume this is due to the upper layers shrinking, though the horizontal dimensions look fine at the level where I stopped the print.  I have Cura Slicer 4.9.1 set to print with no part cooling for initial layer, increasing to 100 % at layer 4.  When I removed this part (immediately after stopping the print, so the bed was still in the low 50s), it was still stuck fairly well -- except where it had lifted.
What's causing this warping/lifting?

You may want to clean very well the bed... maybe you left some grease from your fingers while removing previous prints. PLA shrinks, but it should not affect prints smaller than 10 cm. For info: you can reduce the infill further to save plastic and time, it's not a mechanical part :)

I'm already printing this at 10 % gyroid.  Must have some infill, or the top skin will sag.  I guess I could cut back to 5 %.  Also, I'm getting good adhesion with a brim only at 50 °C.

What's causing this warping/lifting?

The warping and lifting is caused by insufficient adhesion. This can be caused by an incorrect first layer (it is difficult to see the raft, but generally, rafts have no solid bottom, so less adhesion as there is less material), e.g. not sufficiently squished to the plate. Note that a raft is absolutely unnecessary for PLA, you should use it for high temperature filaments that experience a lot of shrinkage, PLA does not.
What you should do is make sure the bed is completely clean and free from grease. Use isopropyl/isopropanol alcohol to clean the bed.
Temperature of the bed should be fine, but you could try to notch it up with 5 °C.
I've seen people use an adhesive between the bed and the print, even on coated beds. But, I can imagine you don't want to try that, it needs more cleaning.
Also, make sure that the printer isn't in front of a window or in the path of an air-conditioning airflow.

Printing on a raft, on a Creality polymer coated glass build surface (shouldn't need, and shouldn't use other adhesion agents).

@ZeissIkon So the answer is still valid, you should clean it properly, add more heat and optionally an adhesive, I've seen people use it like that. The answer is that you do not have enough adhesion. I accidentally typed brim where I meant  raft. Note that a raft is necessary for high temperature filaments, not PLA, you should print directly onto the sheet of glass.

My rafts were lifting with PETG on both the coated glass bed and the textured magnetic sheet at 75 C, as well, but I didn't get a picture of that.

@FarO You should edit that last into the answer -- everything else seems to say "if it doesn't stick, raise the temperature" despite there obviously being a limit to that.

"rafts have no solid bottom, so less adhesion as there is less material." This hadn't even occurred to me until you edited your answer.  Seems obvious when I think about it; I've used a raft to avoid elephant foot, but I think I've got that beat with other settings now (at least based on the last part I printed with a brim) -- and the prints direct on the plate are sticking.

You should not need more heat. I print PLA pretty much exclusively on an unheated bed.

@R..GitHubSTOPHELPINGICE yes but the small contraction which happens when cooling down after print on a 40-50 °C heated bed helps detachment. Indeed PLA works on cold surface too.

If you know that the bed surface is clean and that the filament and the bed material are compatible (as in this case), you may want to optimise the bed temperature.
It is known that the plastic shrinks a little, so the upper layers pull and the bottom layer has to hold everything flat. It happens also with PLA.
Too hot bed? sometime adhesion is increased, but the first layer is soft and all the flatness work is held by the adhesive. It will likely fail.
Too cold? the first layer will hold well its shape, but little adhesion will result in it failing.
If you can't reach a good adhesion, you have to optimise the bed temperature yourself. Print a wedge at different bed temperatures and pick the best result.
See here for the detailed instructions and here for an explanation.
For information, from personal experience sometimes I had better adhesion by lowering the temperature. For example, 75 °C for PETG seems definitely too much to me, because at that temperature PETG has almost no rigidity. The same with nylon: at 100-120 °C I couldn't get it to work. At 80 °C I could get some results. PETG at 60 °C is good, PLA at 50 °C max, ABS up to 110 °C but 100 °C may be already good (the issue is different with ABS)

You need to get a little closer in your first layer. I have this same machine (and several others). You shouldn't have that problem with PLA, it's a lot more common with ABS.
So if it's pulling away from the bed, it hasn't adhered all the way, to begin with. Try micro stepping closer with the firmware or just hand adjusting the wheels a slight amount closer and get a good first layer smoosh!
If you need more help with this printer, I have a whole playlist of videos specific to it at on YouTube
that should be of help to you!

I've been setting to effectively zero clearance -- Z step to 0.075 mm and set nozzle tight on a 0.08 mm feeler gage.  All first layer thickness is in the slicer.

yes its is programmed to a certain height in the slicer, and it calculates its extrusion rate based on that and speed and other things. you dont want it to actually come out at that height though, you need to compress the first layer. see the picture.

With effectively 5 micron plate clearance, and the slicer set with wider than 0.4 mm line width (and IIRC 0.3 mm first layer height), and 95% first layer extrusion (for elephant foot control).  My first layer on the print above went down well.  Aside from elephant foot, I think Cura's default settings for Ender 3 are just about right.

What has worked for me is to keep the bed temperature constant at 60 °C.  Use a higher extrusion temperature for the first layer to promote adhesion.  (Differences in PLA composition could cause these temperatures to vary.)

Sometimes it helps to have an bed temperature for the 1st layer as high as 75 °C to promote adhesion.  While depositing the first layer with this bed temperature promotes adhesion, leaving the bed temperature this high actually decreases it, besides risking the print sagging under its weight.

Additional adhesion layers such as glue sticks might help.

If not already using it, less stiff fill patterns (rectangular) can help, as well as a lower percentage fill.

Increase bed adhesion and/or decrease temperature gradient over the part. As the object builds, and it gets further away from the heated build plate, the plastic gets colder and shrinks. The bottom stays warm and does not shrink, this makes the part want to bow/warp. At the plastic’s glass temperature, where it transitions from liquid to solid (PLA is 60 °C), it has little shrink. That’s why heated beds stick to the plastic, but as it cools the object pops off-it shrinks and breaks the bond.
Other answers have good advice-clean oils off the bed, ensure the first layer is squished into the bed. Ensure the bed is level, so the first layer is squished down uniformly. I would disagree that an adhesive is not necessary. I use a glue stick and it works, where glass alone couldn’t keep my corners stuck down. It is common to run a 60 °C bed for the first PLA layer and cool it off 5 degrees, as a little cooler can still adhere but have less tendency for the part to “elephant foot” from the bottom layers being too warm and gradually deforming. Your 55 °C seems fine, you could still cool it off to 50 °C. I don’t think there is any benefit to running it extra hot (unless the glass surface runs cooler than the bed thermistor reports) as it will be more prone to elephant foot the part.
What I felt compelled to add to the other answers is that if the upper layers aren’t as cold, i.e. they are closer in temperature to the bed layers, less of a temperature gradient over the part, they won’t shrink as much and will have less strength to warp and peel up the corners. I’ve used a couple of 150 W heat lamps, shining at the bed, and have been able to print big flat objects without a brim. It especially helps in the winter. The cooling fans, while they help the print quality, increase the coldness/shrink of the upper layers. I think it would be worthwhile to try less cooling fan, so long as the object doesn’t deform/sag. Often the same corner will lift; if something makes it cooler on that corner, like the cooling fan blows on it longer, the heat break fan blows on it, or it’s draftier. If so, a different part orientation could possibly help.
One nuclear option you can try on large flat prints, if you just can’t keep the brim or raft stuck down with adhesive and whatnot, is to pause a few layers in, and tape the brim down with painter's tape.


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Prusa MK3S not extruding during printing but extruder working
I didn't have any printer-related problem for the past 6 months, but now all of a sudden my Prusa MK3S stopped extruding during printing.
This is very strange as I can easily load\unload filament and control the step motor via Settings\Move axis\Extruder. When I did so, the filament got extruded normally.
However, when I try to print something or do First Layer Calibration, nothing comes out of the nozzle. I tried changing the Live Z (maybe nozzle too low) and it didn't help. I once managed to extrude something by increasing the temperature and the flow (in the printer's menu) to a ridiculous value of 999. Obviously, this isn't the best way to solve the problem.
Is there an easy way to fix this? I only had this problem yesterday and with some midrange-priced PETG
Edit: I tried different filaments, default slicer profiles, reinstalling slicer (prusa slicer) and drivers. None of these methods really helped.

If you move the extruder and hot end to where your print would start (say, 1 mm above the build surface), can you still manually extrude filament?

@ZeissIkon I tried and had no issue. I also played around with print settings a bit and managed to get the first layer or two extruded. Still no clue as to why the rest failed

Tried fresh or freshly dried filament?  Could your filament be mislabeled nylon, and not melting at PETG temperature?

@ZeissIkon I used branded PETG and PLA so it couldn't have been moisture and I don't have any Nylon at the moment. I think the problem occurs regardless of the filament.  I will take the extruder apart and see what might be the cause.

The brand label on the filament doesn't keep it from absorbing moisture from the air -- or did you mean "brand new"?  PLA at least does absorb moisture, though not as badly as nylon; that said, however, I've got a couple spools of Amazon Basics PLA that I opened first when I got my printer (7 weeks ago now) and they still print well (kept in my air conditioned house).

The filament I used is relatively new (1.5 weeks for both PETG and PLA) so it shouldn't be damaged by moisture yet.  In the original comment I meant that my filament is rather high quality too. I suspect that something is wrong with the extruder/hotend

It doesn't seem to be heat creep. See What are ways to avoid heat creep?

Have you measured the actually temperature of the heater block?  You may have a failing sensor (thermistor) or sensor circuitry.  Optically is the best way to measure.  The least expensive way is with multimeters that come with a temperature sensor, such as a thermocouple (lowest cost about $20 U.S.).

I don't think the problem is heating-related (I can load filament and extrude it manually) but it's a good idea to double check the temperature as you suggested.

As it turned out, rebuilding the extruder actually helped. I took it apart to the point where both fans were loose as well as the extruder motor and the hotend. I didn't find anything wrong after a quick look so I put it all back together.
Then i ran the first layer calibration and for some reason it worked. I know it's neither the most satisfying solution, nor the most informative one, so sorry about that. Either way, thank you for the suggestions, I still have no idea what caused the problem.
That being said, I hypothesize that something was wrong with the hotend. That is because when I had this probem, molten filament wouldn't exit the heated nozzle on its own. Now when I heat up the hotend, the filament comes out (without the motor working)

Sounds like a possible clogged nozzle.

That is possible but I forgot to mention that I also took out the PTFE tube and put it back in. So that may add another factor.

I have the exact same issue.  I still haven't figured out what is going on, but my next step is to work backwards.
I brought my machine in for repairs at our local shop, and the end result was "heat creep" .  It worked for a few prints, then stopped.  It jammed on me and in the process of removing the jam, I broke the leads to the heat block.  When I decide to go back in, I will see if when I reassembled the extruder, I knocked off enough thermal paste to make a difference...  :(

While it is great to hear that you are working on the issue, this doesn't seem like a definitive answer, but more of a comment. Please take the [tour] to get a better understanding of how the Q&A mechanism of SE works - it isn't like a thread of messages that you see on other internet "forums". It might be better to either [edit] your answer to provide a definitive answer, if and when you can... or to (maybe) convert this answer to a comment under the question.