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What techniques are needed to minimise layer separation after filament change?
I have been trying to make some small signs, and to highlight the text by changing between black and white filament at a layer just above where the text comes out of the back plate.
I've used Cura 4.12 and the "change filament" script to make the printer pause at the right layer.  The change and purge process works fine, no issue there.
However the second colour adheres poorly to the first.  Doesn't matter if I print Black then White, or White then Black.  Both filaments are the same brand.

Should I dab gluestick into the print at the same time as changing colour?  (read on)
Is there some way to re-preheat the object and get a better adhesion?

To save the print I've used superglue to stick the letters back on that have fallen off, but is definitely not ideal.

Here's an example:

The loose letters are held on well enough for printing, but only barely.  They can knock loose at a touch of a finger afterward.
I have tried changing filament on the first layer that is not the back board, and one or two layers up the letters.  One print I even changed filament a layer too low, and surprisingly that did not have adhesion problems.  Perhaps it is merely a function of surface contact area ?
Gluestick on the exposed surface while changing filament was useless - the whole thing simply didn't stick and the second colour never got any adhesion at all, merely wiping off.
As for timing, it seems to make little difference if I'm there waiting for the last layer to print, or if I let the printer sit for half an hour before noticing and changing colour.  The bed stays hot at 50 degrees, and the hot end is permitted to cool off.
There is a heating cycle, and then a purge/discharge-into-air that shows the transition between colours, so its not that the filament has lost a prime.
At the moment, a much more effective solution is to use a paint marker and colour-in the top layer with a contrasting colour.

This is very similar to an idea for a project I wanted to do. How long is the time from when the first color is finished to the time the next color starts printing? It sounds like the time in between is allowing the first color to cool down so as not to allow the second color to adhere.

@agarza: New extrusion should adhere just fine on already-fully-cooled previous layer. I think a more likely explanation is that there's initially underextrusion due to not priming the new material sufficiently, or oozing after it's primed but before resume.

Do not dab gluestick. This will create a water-soluble layer between the first color and the second that will ensure they don't adhere properly.

Can you show some pictures of the part that failed, that would give us some idea about the size, geometry, etc.?

One other thing to watch out for: if your pause-and-resume lifts the Z axis and lowers it back down, you might have Z reproducibility issues, due to undriven side of gantry poorly following the driven side, where the nozzle is too high after resume.

This is a material specific problem. If it was a slicing problem the layers of the same material wouldn’t adhere to each other. What two filaments are you using? Brand, type, your print temperature?

@ChinchillaWafers It was ESUN brand PLA+, one in black and one in white.  They were identical other than colour.

I'm having the exact problem. Did you finally find a solution? I tried everything and the only thing left is maybe the two filaments might have a different flow rate so the new layer came out too thin. I need to buy a more precise caliper before it can calibrate the flow rate of the two filaments.

@EdwardYen in the end, the single biggest help was making sure there were wider areas.  I was printing signs, and the text was just too fiddly.  Another sign with fewer letters printed much better, but each letter was thicker so it could stick better.   If a letter fell off, then a dab of superglue/CA glue worked fine to hold it on - nothing here was structural.   For one print where almost all the letters fell off, I just coloured in the raised letters with a paint marker, which worked out nicely.

It might be worth a try to manually kick the flow rate setting up 5-10 % and temperature about 5 °C for the first layer after the filament change, then returning to the original settings.  Consider too killing or reducing the cooling fan speed for the first layer only. The benefit of a skirt to get things flowing is not available when starting on the second color.
Another approach would be to make the letter-layer a negative image so it would be more of a flat, contiguous piece with letter shaped holes in it.  Printing time and filament usage would both be somewhat higher, however, unless the thickness of the letter-layer was reduced. It would only need to be a few layers thick.
Color order could be changed with this method too if black letters on a white field is the desired scheme.

I did some with white on black and some black on white.  The order seemed to make no difference. but the thickness of the letter did.

I meant swapping colors if you went to a full-size second color with letter shaped holes. That would preserve your original design of black letters on a white field.

I never had layer separation when changing filament to a different color. Even with three different colors within the same print. Or five layers of two different layers.
Both filaments should be made of the same material, for instance PLA. The filaments should be printable with the same settings. A test print should work well with both filaments.
Try a print with a pause and a simulated filament change. Printing with the same filament before and after the pause. You may try different durations of the pause. Is there layer separation even with a very short pause?

I'm actually having this problem -- one of the times I wasn't able to change filament due to using the wrong command and not being able to pull out the old stuff, so the filament didn't change. The behavior of the material was the same.

Most of your settings will not change with changing filament, if the new filament is the same material and OEM as the old.  The main settings to check after changing the filament are the initial z-height and planarization of the bed. If the z-height is too high the first few layers may not stick together well.
If you change filament materials or OEM, change the settings to match the new material.  The layers may have trouble sticking together if the extrusion temperature is too low.

After much fiddling about, the only positive conclusion I could come up with was to not make the letters too thin.  A chunky thick letter has more surface area to adhere, whereas a thin spidery letter is too fragile.
So print fewer words on each label, make the words more-bold, and if they still fall off after printing then CA glue/superglue is good enough to hold them together.


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Evenly spaced bulges and one spot of localized underextrusion
I am having two separate issues. One is specific to this particular model, the other is on all my prints, but more pronounced on 90° vertical walls.
The first issue is a localized area of under extrusion only in one area of the print. This issue is specific to this model. The second issue is evenly spaced horizontal bulges that appear approximately every 5mm during the first 30-35 mm of the print. This is a two-piece Christmas tree I designed for my wife and I have been printing both pieces together on the build plate.
I am printing on a mostly stock Voxelab Aquila with Voxelab Gold 1.75 mm PLA. I have changed the stock extruder to the aluminum extruder after the plastic one cracked, and am running a Satsana style shroud with stock fans. I am using CHEP's Cura 4.11 Ender 3 profile for .2 mm (good) - CHEP Cura Profiles, printing at 200 °C and 40 °C bed temp. I have lubed my Z screw with white lithium grease, checked that belts are tight and no screws or physical connection points are loose. I checked to make sure that the eccentric nuts are snug but not binding the gantry. I have calibrated my extruder E-steps and changed the value to 96.
Can someone offer me some guidance on where to go from here?

Looks like a z-seam.  See https://3dprinting.stackexchange.com/questions/15776/how-to-get-less-z-seam

It is not the vertical Z seam, I am referring to the horizontal banded bulges as seen on pictures 4 and 5 of my post. I have been trying to find a mechanical cause for them but have been unsuccessful thus far. I was able to fix the under extrusion by raising my printing temperature to 205 °C.

The horizontal bands may be instability in your Z axis.

What slicer and infill pattern and percentage are you using? While a Z axis issue is the most likely cause, things like this can also be a result of layer-dependent oozing in the infill area due to the way the infill pattern changes layer by layer, if travel in the infill area is done without retraction. Knowing the infill settings and slicer would allow computing the period one would expect for such an artifact.

The horizontal bands are 5mm apart, which is a common pitch for the screws often used for the Z axis.
I would look for something that binds, moves, slips, or touches once per screw revolution.  The movement repeats along the screw, so if it is a screw defect I would look for a scratch or bump that affects the screw along its axis.
If you don't see that, check for how the screw is constrained at both ends.  If they are loose constraints, does the screw wiggle while it is turning?
Move the nut to one extreme and rotate the screw.  Does it appear to have any bend?  Even a small degree of bending that doesn't bind the axis can add a small load to the drive.
The Z-azis error you are looking for is subtle.  It is probably 10% (or less) of the layer height.

5 mm common? For ball screws (1605), yes,  but not for trapezoid screws, that's usually 2, 4 or 8. This is an Ender clone using trapezoid screws.

@Oscar, I defer to your  knowledge of this machine.  I would still look first for some bending, binding, or damage in the Z drive system.  The photo clearly shows a 5mm period, not 4.  I will measure my Prusa I3 to see the lead.  It is a multi-start screw, so the movement is larger than the spacing between the trapezoids.

If you know the steps-per-mm you can just compute it from that.

Try setting the z-seam to random in your slicer.  In Slic3r it is Seam position under Advanced near the bottom of the Layer and perimeters page of the Print Settings.

source: Stack Exchange

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

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Filament not adhering to bed for the first 10 mm after every move

Update following advice from @R..GitHubSTOPHELPINGICE in the comments - I've increased the Z-offset from -2.97 to -3.10 and all now appears to be much better.

Printer: Ender 3 V2 with heated glass bed
Slicer: Cura 4.11
Temps: extruder 215 °C, bed 65 °C first layer, 60 °C remaining (works the best for the filament I'm using, lower for other filament).
Filament: 3DTomorrow UK PLA Filament - Anthracite Grey - 1.75 mm (But happens with all others too e.g. ERYONE, ZIRO)
Summary: On the first layer, every time the printer starts extruding to the bed after a move, the first approx. 10 mm doesn't stick, but the rest sticks perfectly.

The issue, as an example, I'm trying to print a case for a Raspberry Pi which has air vents on the bottom.  When the print starts, it does the line down the side which the first ~ 10 mm doesn't stick, but the rest does perfectly.  It prints the skirt, which again the first ~ 10 mm doesn't stick, but the rest does, then when it gets to doing the vent slots, the same again.
The photo hopefully shows what I'm trying to explain.

When printing a raft, again the first ~ 10 mm of the extrude doesn't stick, but the remaining does.

Once the raft is printed, the first layer sticks to it perfectly well

The bed is pretty level, I'm using a BLTouch to assist and has been cleaned with alcohol before the print.  Bed has been levelled and the Z-offset calibrated to -2.97.
I have Enable Retraction on, 5 mm, 45 mm/s speed. I've tried increasing and reducing these, increasing/decreasing print speed, manual Z-axis offset fine adjustments, etc.
I did think First 3 mm prints poorly, then fine after that was kind of the same issue, but there's no discussion of the issue being for every touch of the bed within the same print job.
Any advice would be appreciated.  I've loitered this community for quite a while and lots of Google searching hasn't come up with any suggestions (there's actually very little I could find on this kind of troubleshooting).

From the pictures it looks like the distance between your bed and nozzle is too great. Note that "automatic bed leveling" fundamentally cannot help you get this right because it depends on a quantity it can't measure, the Z offset between the bed leveling probe and the nozzle tip. At best it can help you get the distance consistent[ly wrong].

This is also consistent with raft fixing the problem, since the raft has extra wide extrusions in the first layer whose width will just vary if the leveling is wrong, and after that, all print heights are just relative to the top of the raft.

Thanks for the comments.  before the photos, I had calibrated the distance from the nozzle to the bed - initially with a piece of paper, then by live calibrating.  The Z-offset was -2.97 IIRC.  I'll double check it, and confirm once it's finished in a few minutes.

@R..GitHubSTOPHELPINGICE - Thank you.  I did have it at -2.97 from manually levelling as it was printing, but have since gone down further to -3.10 and it's doing much better.  I honestly thought it looked too close at -2.97, but how wrong I was!  If you want to post that as a solution, I'll happily mark it as an answer.  Could have saved myself and you lot time and effort if I'd have just pushed it that little bit more!

From the pictures it looks like the distance between your bed and nozzle is too great. The way I see this is that the extrusion lines that should be pressed against each other have small gaps between them, and look rounded rather than flat. The only other way this could happen is with severe underextrusion/wrong esteps-per-mm, but that seems unlikely.
Note that "automatic bed leveling" fundamentally cannot help you get this right because it depends on a quantity it can't measure, the Z offset between the bed leveling probe and the nozzle tip. At best it can help you get the distance consistent[ly wrong].
This is also consistent with raft fixing the problem, since the raft has extra wide extrusions in the first layer whose width will just vary if the leveling is wrong, and after that, all print heights are just relative to the top of the raft.

Your assumption about under extrusion / e-stepping is correct, I had already calibrated that to +/- 0.1 mm over 100 mm.  Thank you for the guidance here, you were spot on.

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Is shell scripting possible with OpenSCAD?
I literally just started OpenSCAD today, so please take it easy on me, but is shell scripting possible with OpenSCAD? as in, to write a script in the OpenSCAD syntax, and have it output images, or animations? with or without having to render the image.
I've been reading the man pages, and I'm not sure if that can be done.

How is this being applied to 3D printing? I only ask to avoid your question being closed for not being on-topic.

can it simply be in relation to 3d modeling? or is that too far removed? I mean animation can show me how a model works, so maybe I don't have to waste time modeling mechanisms that wont work if they're printed.

No. OpenSCAD is not a scripting language. You cannot use it to generate any kind of executable code. All that it does is to create static geometrical objects that can be exported as STL files (and other formats). If you want to do scripting, use a scripting language such as Python. Note that Python has some wrappers for OpenSCAD that may allow you to do what you want. For example, see  OpenPySCAD.

Whilst OpenSCAD is not technically a scripting language, it has a command line interface which can be given parameters to produce variable models and easily driven from a more traditional scripting languages such as BASH or PowerShell. Or many other programming languages that suit your experience.

You can invoke OpenSCAD from the command line, and have it output image renderings or STL files. The -D command line option lets you pass variable definitions/overrides (or arbitrary scad code fragments) in, which can be used to animate or otherwise. And, like any command line too, you can invoke it from a shell script, although using a makefile tends to be a better option.


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3D from 2D picture options
If I want to make 3D printable objects out of my old drawings, what are my options? Do I need to redraw the entire thing in 3D or is there a better way?
This is an example of the sort of pictures I have, I long ago lost the original Macromedia files so I just have them like this.

I presume that what you are saying is that you only have a rasterized image file. For example a .PNG file, and that you don't have any kind of source file containing vectors.
Since you're already a skilled artist from the looks of it, you're largely limited by the software that you have access to, or how much you're willing to spend on new software.
Probably the simplest and cheapest way would be to use a free program such as Inkscape to redraw your image as lineart only (You can import the image into the software and then trace over it). Draw it completely flat and 2 dimensional with no shading or colors. Only lines to represent edges. Save it as a Structured Vector Image (The default file for Inkskape). Then import it into a free 3D package such as blender.
This will import your image as a series of 2D lines in a 3D space. You can then use traditional 3D art skills (Which you may or may not have yet) to give it 3 dimensions.
A complex shape like that might require a resin printer to print due to the high level of detail. Making it wouldn't be a task for the faint of heart.
A more expensive option would be to commission a professional to do it for you.

Yeah I've spent hours trying to find a shortcut, but I think you're right... start again from scratch

As an aside, consider if your objective is to extrude in a single direction, Blender is going to be far more complex than needed. Even Tinkercad will allow extrusion of SVG files. I'd also expect 3DBuilder (win10) to have that feature but I'm currently unable to verify.

Any 3D modelling package that can deal with an SVG file from an art package would do. They could even skip the SVG import and trace their image directly in the 3D software using curves. But that might be a little unintuitive when it comes to complicated details.

@fred_dot_u The issue isn't extruding an svg, I can do that a number of ways. It's the easiest way of getting an svg. I drew these 16 years ago when I had plenty of time and quiet (before I had 6 kids). On the bright side 3dbuilder will allow me to get an silhouette, messes up all the internal stuff but better than nothing

@Kilisi, I and a friend are teaching ourselves to learn Rhino3D using online resources. It's similar to blender, but perhaps not as complex, but also not a free program. Both of those programs would allow you to manually manipulate the elevation of the appropriate areas. If this was a real world carving, for example, you'd be able to perform photogrammetry to get a mesh, but a bunch of ifs do not create a solution.


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Creality Ender 3 Max won't print after homing
After successfully printing for a while with my Ender 3 Max I've encountered a problem I can't solve. The printer executes the heating and homing portion of the G-code after which it just sits in the middle (I have BLTouch installed, so homing ends in the middle). The print percentages go up (much quicker than they should) and the print "finishes". No filament is extruded and the head doesn't move at all.
What I've tried:

Different SD cards,
Checked the new G-code to make sure it doesn't only have the beginning and end,
Old G-code that worked the previous day,
Made sure that all axes, filament change, and purge work fine from the prepare menu,
Releveled the bed from the BLTouch leveling section from the control menu.

Everything but printing seems fine and now I'm stumped.


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What protection does a face mask offer when using a resin printer?
Printer manufacturers such as Elegoo ship their printers with masks and advice users to wear them when handling resin or unwashed prints.
In what way does the mask protect you?
For example, do the masks provide protection from inhaling toxic fumes, or are they primarily to prevent resin entering the mouth or nose?

It depends entirely on what mask filter you use.
The classic FFP range only filter particulates, athough there are filters that will protect against gases too. You would have to find out what sort of fumes are released from the resin (if any) and specify a filter accordingly.
The image below shows the filter type and what it can filter.

image link: https://www.bugoutbagbuilder.com/blog/best-gas-mask-filters-2019

Please [edit] your answer and add the source of the image, otherwise it could be considered plagiarism.

I'm exclusively referring to the ones that come in the box with the printers. They look like the ones that a dentist wears

@AaarghZombies If the mask is similar to a thin bit of fabric/material that just covers the nose and mouth then it almost certainly will not protect against fumes. It it probably just to stop the chemical entering the nose and mouth physically.


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What is the practical difference between using linear speed vs flow rate to determine print speed?
Most people, articles, videos, etc. refer to printing speed by linear speed (mm/s), but a lot of YouTubers prefer to talk about volumetric flow (mm3/s) (mm cubed per second).  I suspect that at some point in the past year or three, some of the more engineer-y types switched to this new measurement standard, but I'm not entirely sure what happened.  What is the practical difference between using linear speed vs flow rate to determine print speed?
For a follow-up, how can you go about changing your print speed as a flow rate in a slicer?  It's easy to find the linear speed, but I have not found the flow rate speed.  I use Cura and will start using Prusa Slic3r soon.

flow rate will need to account for layer "thickness."  flow rate is easier to relate to the material needs while linear speed is easier to relate to motor capabilities/limitations.

Linear print speed is widely written in marketing material and in filament manufacturers' official print setting recommendations, and is the value talked about by naive users, including a number of popular YouTube personalities. However, in most contexts it's at best the wrong number, and more often, meaingless.
For example, you will see printer manufacturers bragging that they can print at "250 mm/s", and it turns out what they mean is that, when you set the print speed in the slicer to "250 mm/s", it works. However, their profile has the acceleration set to 500 mm/s², and you need a straight line all the way across the bed to accelerate up to that speed momentarily before starting to slow down again, and overall average prints come out 5% faster than when you set it to "90 mm/s".
If you set this kind of lying (or incompetence, if you accept Hanlon's Razor) aside, and only talk about the actual velocity achieved under an acceleration profile, linear speed becomes meaningful, but probably not the right number, because it's missing any information about the actual limiting factors. Provided the speed isn't beyond the max RPM of your stepper motors (around 650 RPM for typical motors on 24V printers), any printer can print at that speed as long as your layer height is thin enough or your lines are narrow enough. In fact if you go look at a few of the top "1000 mm/s" YouTube videos, they're using 0.1 mm layer height or thinner - which is easy to do, but not interesting to most people. It's not helping you print faster because now you have twice as many (or more) layers to print.
Volumetric flow rate takes all of that into account. If you print at 20 mm³/s and I print at 10 mm³/s (and if these are actual average flow over the whole print, not just a speed limit that's rarely achieved due to acceleration profile limits), your print will finish in half the time of mine. That is a meaningful speed - one that can't be used to lie/mislead by printing thin layers or whatever. Moreover, it's the limit you need to know, for your particular hotend, extruder, and filament type, in order to be able to decide what speed to print at (whether you control this via volumetric flow limits or computing the corresponding linear speed limits yourself). If you're reading the filament manufacturer's recommendations, they didn't say it but they probably wrote those for 0.4 mm line width and 0.2 mm layer height, so you should multiply by 0.08 mm² to get the volumetric rate they intended.
This gets more important with slicers, particularly the upcoming Cura 5, which use varying line width (and thus varying relationship between the linear speed and volumetric speed) to extrude your layers. Now a single linear speed doesn't suffice to give you max performance while also staying within the physical limits of what you can extrude. Cura 5 has "Flow Equalization" to speed up or slow down to keep the volumetric rate matching what it would be at the nominal line width and speed.
Now, linear speed in mm/s is meaningful sometimes - particularly, if you're showcasing the printer's motion system. High voltage steppers, larger pulleys, servo motors, etc. all can achieve some very high linear speeds (over 1000 mm/s) that ordinary 24V steppers (much less 12V ones on older printers) with normal size pulleys simply cannot do. Even if these speeds are not usable for print moves (because the volumetric flow rate becomes the limiting factor for what you can do), they're always usable for travel moves, which can easily be 25% or more of the time spent in complex prints.

Flow rate adds a dimension to the regularly used printing speed. Note that maximum volumetric flow is determined by the hotend (unless your extruder is under dimensioned or highly geared) as it cannot supply more molten filament than it can melt in a certain time.
So, instead of specifying the print speed, you should include the amount of material it can process. Volumetric flow includes nozzle diameter, layer thickness and hotend type.
E.g. a 60 mm/s of a 0.4 mm nozzle at a 0.2 mm  layer height has a very different volumetric flow (4.8 mm³/s) from a 60 mm/s 0.8 mm nozzle at a 0.4 mm  layer height (19.2 mm³/s). The latter may require a different hotend to get that flow, but usually it is advised to print slower with a larger nozzle.
Most practical is to use the linear printing speed. This is the value you find in the slicers. But, for a given hotend design it is good to keep the maximum volumetric flow into account to determine whether you are within the specifications of the hotend when you change certain printing/slicing parameters.


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What is the difference between PET/PETE and PETG?
I've heard that PETG, what we print with, is slightly different than PET or PETE, which is commercially available.  Yet, PET bottles seem easy enough to recycle into prints according to these videos:
#1 Multicolor printing-Details of free filament production from recycled bottle (PET)for 3D printer

Precious Plastic channel
https://www.youtube.com/channel/UCqA-SppbeUi5ou0isB27mgg
What properties change between PET and PETG?  Obviously, the additives will change, but what are the properties and parameters that change that make PETG more suited to 3D printing?  Especially given the fact that PETG is fairly hygroscopic, which I believe took a while for the community to uncover.
While more science is better as far as an answer, please keep it relevant to practical 3D printing as well.

I use PETG when I want the object to be somewhat rigid, but flexible enough not to break, especially object having thin parts.  PETG is strong enough to print two layer 0.5 mm thick and be very flexible in the z direction, such as printing straps.
Basically PETG is amorphous while PET/PETE is crystalline.  Amorphous gives a slightly lower melting point and less out-gassing, characteristics better for 3D printing.  PETs crystal structure makes it more rigid than PETG, but leaves PETG more impact resistant and easier to print.  The more rigid PET translates to more dimensional accuracy as with PLA.
From https://www.oberk.com/packaging-crash-course/differences-in-pet

PETE (or PET)

PETE is the most common variation of the thermoplastic polymer resin. The clarity of PET is considered to be the best of all plastics with very good chemical resistance. PETE is formed into containers via 1-Step or 2-Step Injection Blow Molding.

PETG

Polyethylene Terephthalate Glycol (PETG) is an amorphous variation of PET. PETG cannot be oriented and therefore you will not find pre-forms of this type of resin. Extrusion, Injection Blow Moulding and 1-Step Injection Stretch Blow Moulding are all possible for PETG, it is also used frequently for 3D printing. Clarity and chemical resistance are considered good when compared to the previous three variations, however PETG has poor impact resistance.

Why is PETG used for 3D printing?
Quote from https://www.3dnatives.com/en/petg-3d-printing-guide-181220194/#!

The characteristics of PETG

PETG is therefore a copolymer, combining the properties of PET and glycol. The addition of the latter reduces the overheating issues of PET and therefore its brittle appearance. Among the main characteristics of PETG are its hardness, impact and chemical resistance, transparency and ductility. It is an easily extruded material with good thermal stability. It is particularly appreciated for its food compatibility. On the downside, note that it requires a heating plate to avoid the warping effects found in ABS 3D printing – even if the warping rate is low, it is better to use a BuildTak sheet to make sure the material grips. It is also more prone to scratches than PLA. Finally, it can quickly take moisture and will keep better in a cool and dry environment.

To add to Perry's answer, which is already very informative:
PETG is subject to creep (permanent deformation under continuous mechanical load), especially at temperatures above room temperature. As a result, many 3D printer designs utilizing printed parts caution against using PETG. PET is generally regarded as not subject to creep below around 80°C.
Unlike PETG, which is amorphous and does not crystallize, PET can be annealed (made to crystallize intentionally after printing is complete) at temperatures between 80 and 100 °C, after which it can handle loads at higher temperatures, reportedly up to 100 °C. However, annealing produces some dimensional changes, which may make it difficult to utilize this property.
PETG has considerably lower glass transition temperature, melting point, and heat deflection temperature than PET.
While this varies by PETG formulation, generally PET can (and often must, due to crystallization concerns when printing slow) be printed at much higher speeds than PETG.
PETG gunks up and sticks badly to most nozzle materials when printing. Certain coated nozzles, and tungsten carbide nozzles, can significantly reduce but not eliminate this effect. PET does not gunk up or stick to the nozzle.
PET is less sensitive to buildplate temperature, and can even be printed on an unheated bed, although this may lead to corners lifting without sufficient adhesion. PETG is very hard to print well without high bed temperature; layer delamination and failure of first or second layer to adhere are common issues with insufficient heat.
PET has extreme layer bonding, giving near or fully isotropic part strength. PETG generally has issues with delamination/separation at layer lines. In my experience, it is far worse than PLA in this regard.


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Is resin 3D printing considered "additive"?
Subtractive manufacturing has been the way of the world for a while, but additive manufacturing, which is synonymous with 3D printing, has disrupted all of that.
If extrusion-based printing is considered additive, then can we call resin printing additive?
Resin printers start with a resin bath and then essentially "subtract" the material it needs (via UV light). This is just a matter of terminology, no big deal.

your bath is the equivalent of a spool of material.  you "subtract" the material you need from a spool.  sadly one cannot add matter to existence easily thanks to laws of conservation; something added is always subtracted from elsewhere.  if with a conventional mill, your goal were to add chips to the floor...

Resin printing (aka stereo lithography) was actually invented before (FFF/FDM) filament extrusion printing.  The term 3D printing was more or less created as a generic way to name and describe both along with a handful of other methods.
It is additive because you add layers to other layers to build the part rather than carving up an original solid block.
Resin printing is no more subtractive than removing the tip of the filament in FFF is subtractive.

Very nice punch line! Resin printing is no more subtractive than removing the tip of the filament in FFF is subtractive. :-)

It really took me a little while to understand why you thought that it was subtractive, but I can now see your point. Which is, that seeing as the resin model is created within the tank/bath, you are saying that the bath is analogous to a block of aluminium which is whittled away, using CNC, to make a 3D model. The resulting aluminium model was once within the block of aluminium, as was the resin 3D model - therefore, you posit, resin 3D printing is subtractive.
The more I thought about it, the more it seemed as if you were, actually, correct.
However, then I realised that we were neglecting the hardening process. It is the hardening of the resin that is done in an additive manner, in order to slowly build up the model, therefore the process is additive.
You aren't removing/subtracting non-hardened resin from the model (which would result in a non-hardened wobbly model), but instead, as user10489's answer states, you are adding hardened resin layers.


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Massive blobs/under extrusion/"pearl necklace" only after first few layers (Ender 3 V2)
I am struggling with a problem. In short: I have managed to set up my Ender 3 V2 in such a way that the first few layers print (almost) perfectly, but after the first few layers (do not know exactly, but maybe after 2-4 layers) I am having massive issues with (maybe) under extrusion, with the filament coming out in a "pearl necklace" shape. Here are a few images for illustration:
First layer of bed level test (this source). The filament is nicely flat on the print bed, also it still sticks when I rub it with my fingers.

Third/fourth layer of bed level test. The upper layers are of this "pearl necklace" shape (maybe there is an established name for that?), i.e. something like ---o---o---o---

Similarly with the Benchy. I printed the first few layers. The first layer is quite clean and you can make out the font nicely (this turned upside down, i.e. you're looking at it from the bottom).

After the first few layers, the shape of the filament is again this problematic pearl necklace shape (you can already see that at the boundary of the previous image, where you can see those layers).

I'm totally at loss at how to resolve this issue. How can the print quality degrade so much after the first few layers? I don't even have any good hypotheses (temperature dropping after some time? Z-offset needs to be adjusted for every layer? Hot end starts clogging during the print?).

What has changed recently? It looks like massive under extrusion.

I am a new user (I have obtained the printer second hand and I had no prior experience). So I haven't had a successful print before.

So I finally managed to solve the issue. It was indeed (massive) under extrusion (during the whole print).
Let me first explain why this does not show up in the first layers (according to what I read somewhere else online):
The under-extrusion issue is already present in the first layers, but it does not become visible due to the print bed giving enough "counterpressure". This means that the material is squished between the bed and the nozzle, making up for the under-extrusion. After a few layers, this does not happen anymore, and the lack of flow begins to show.
How I solved the issue:
I made an extrusion calibration according to this Snapmaker forum article. Basically, I measured off 100 mm from my extruder input, marked the 100 mm mark with a black sharpie and told the printer to extrude (what he believes to be) 100 mm of filament. This turned out the be not 100 mm but rather approximately 25 mm (which means that the printer is extruding about 25 % of what it is supposed to do). Then I went and changed the printer's flow rate to four times the current rate, which solved the issue.
Why was the extruder so bad?
I don't know exactly, but I had to hot-glue two parts in my extruder together because they were freely moving against each other and the motor's torque was not transferred to the extruder's axle. Could be I introduced some friction this way, but I saw the same under-extrusion issues before I noticed this issue, so I don't really know.

Glad you sorted it out, but, not the preferred way to do this. It could be that the extruder is just too broken to reuse. Also make sure you slice for the correct filament diameter and that the steps per mm are correct for the extruder. You can get the current value from the menu/display, once this is correct you would never have to use large flow modifiers, this is not what that modifier is supposed to be used for.


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Axes no longer moving Ender 5 Plus
The printer was working fine until the nozzle jammed, so I cleaned it out but accidentally unplugged the BLTouch. I plugged it straight back in again but now none of the axes will move at all, not even manually. The BLTouch lights up still, I’ve checked the connector on it and it all looks fine.
Completely stumped. Any ideas please let me know! Cheers

Have you checked the BLTouch connections from one end to the other? I had a slightly different problem with my BLTouch and turns out the connector in between was loose. After I rechecked all my wiring everything worked out fine.

No cigar, all connected up fine. Found a video on YouTube of the same issue but there was no solve posted. Someone said about re-flashing firmware but I’ve never done that.

https://youtu.be/5drDnH5y1Yc


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How many bottom layers for a DLP printer?
I just got an Anycubic Photon 4k DLP printer, and am experimenting with the print parameters in Photon Workshop.
I noticed that the number of bottom layers (40 second exposure time) was defaulted to 6.
Experimenting to get better quality near the build plate, I reduced the bottom layer to 1. This resulted in the first layer adhering just as well as before, but the part de-laminated from the first layer. The default exposure time on the other layers is 2 seconds and that has been working well.
Physically I do not see why the part would de-laminate from a well-adhered layer 1, but not de-laminate at a layer 6? maybe 6 bottom layers is hard coded in the slicing software and it just skipped exposing them? Curious if anyone else has run into this or understands the epoxy exposure dynamics a bit better.


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How hot is too hot for magnetic beds?
How hot is too hot for any given magnetic layer holding a steel bed surface?  Are certain types or grades of magnets more or less suited for this purpose?  How can I ascertain which kind I have if the manufacturer doesn't tell me?
I've heard that some magnetic beds should not be used for certain materials because those materials require a very hot bed for adhesion.  But in the modern age where resellers and even manufacturers don't usually know what they are selling, what are the rules of thumb, and where are the limits?

Depends on the magnets used
Magnets demagnetize under heat and are fully demagnetized once their Curie temperature is reached. This Curie temperature depends heavily on the type of magnet, and it is not the point where they already suffer demagnetization but where they have none left. This means, that the useable temperature band is much lower - and in some cases, low temperature can negatively impact a magnet's holding force.

Typical Magnet tapes and foils as one uses them for example kitchen magnets can start to fail as early as 65 °C and have Curie temperatures around 80-85 °C - making them unsuitable for printing high-temperature printing.
The Chromium-Oxide magnetic tapes on cassettes are totally demagnetized at 113 °C.
Neodymium-iron-boron magnets stuffer permanent damage over 100 °C and totally lose their magnetization at the Curie temperature of 320 °C
Samarium–cobalt magnets only suffer damage over 250 to 550 °C and have a Curie Temperature of 700 to 850 °C,


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Marlin NOZZLE_CLEAN_STROKES half a pattern?
I have Marlin 2.0.9.2 configured to wipe the nozzle on a brass brush mounted to the side of the bed of my printer. It does 3 zigzag movements. It cleans up the ooze nicely from the nozzle BUT... the pattern ends where it began, so it cleans the ooze and then right at the end of the pattern it picks it back up off the brush. Is there a way to do 2.5 or 3.5 patterns, and avoid this? All the cleaning options (straight, circle, zigzag) seem to be cyclic...


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How to tell if I have TMC2208 or A4988 Drivers on Creality Silent V4.2.3 Board?
I have a new Creality Ender 2 Pro with a Creality 4.2.3 mainboard. I'm attempting to compile Marlin to fix a bug. How can I tell what driver chips I have on this board?
I've narrowed it down to likely A4988 or TMC2208_STANDALONE or possibly the TMC2225. Strangely Creality only has documentation for the 4.2.2 and the 4.2.7 boards (not 4.2.3)
4.2.2 => TMC2208
4.2.3 => ?
4.2.7 => TMC2225
Some say you can tell the driver just by listening to the noise it makes. Here is a video of the printer running. The motors are nearly silent to my ear.

Resources

https://github.com/Creality3DPrinting/Ender-3/issues/58#issuecomment-842935869
4.2.2 schematic
Marlin Config pull request

How could A4988 be an option for a "silent" board?

According to 'The-EG' comment in this GitHub issue, Add Creality Ender 2 Pro config #633, you can often determine the stepper drivers by one of a few ways:

Listen to the sound. The 'TMC22**' will sound much quieter

Look for a marking in Sharpie on the SD Card reader
C = HR4998
E = A4988
A = TMC2208
B = TMC2209
H = TMC2225

Remove the heat sync
https://github.com/MarlinFirmware/Configurations/pull/633#issuecomment-995480295
After removing the heat sync, it appears that the Chip is actually a MS35775

Indeed! And, as far as Marlin is concerned the TMC2225 and TMC2208 are the same, so it's hopefully a matter of 2208/25 vs 2209. Unless Creality did something completely off the wall...

Of which known driver is this a clone?

MS35775 appears to be TMC208 compatible.  You can find the data sheet on relmon.com here is the overview:

2-Phase stepping motor peak current of 2A
Step / dir interface 2, 4, 8, 16, or 32 microstep
Internal 256 micro steps
Quiet mode
Fast mode
HS Rdson 0.29 Ω ,LS Rdson 0.28 Ω
Voltage range 4.75 ~ 36V
When the motor is still, it will enter into the power saving mode automatically
Internal resistor mode is optional (no need for external sense resistor)
Single wire UART bus and OTP control
QFN28 package


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Why do concrete 3D printers zigzag?
Why do concrete 3D printers lay the concrete in a zigzag shape? I know pouring it in a straight line makes it unstable, but the zigzag shape reduces the contact of the top layer to the layer below. What is the advantage?

If the layers use the same zig zag, why would it reduce contact?  This seems like a normal infill method to me, but I know almost nothing about the physics of wet concrete.  The point of infill patterns is to reduce material use while connecting all the edges.

@Aryaz just imagine the top layer as concrete block but instead using an square is a triangle due zigzag. Then the architect can continue with more and different 3D printing infill or traditional construction. The purpose of infill is to strengthen the walls.

Presumably to decrease material costs, speed up printing time and reduce curing time.  The thicker the concrete, the more time it takes to cure.  You need it strong enough for the next layer by the time the print-head comes around again.
When the concrete is poured in a zigzag it has a thicker/wider base, meaning it can be built higher and walls can be wider before they need a corner for strength.
Additionally, small sealed voids in the wall improve the thermal insulation properties of the wall.
Last - if the wall has vertical voids with a zigzag infill between vertical walls, then those spaces can be used to run wires for power/phone/network or water pipes, to hide and protect them instead of surface mounting them inside,

not quite last.  there are also benefits to even curing from void passages.

The zigzag is more rigid.  You can push a square into a trapezoid without putting any of the sides in compression or tension.  However, if you make a trapezoid with two triangles, the diagonal dividing the trapezoid. into squares resists an external force changing the shape of the trapezoid. Thus, the zigzag takes less material for adequate support than making squares as does cinder blocks.
Look at steel joist design.

Steel can cope well with both tension and compression loads.  Plain concrete cannot survive tension loads, that's the job of internal pre-tensioning, aka pre-stressed concrete.

@Criggie True, but zigzag beats cinder blocks. The spaces serve the same purpose as cinder block spaces.


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MESH_INSET vs PROBING_MARGIN
I've been tinkering with my 3DTouch (basically a BLTouch clone) on my CoreXY and have been trying to set up UBL in Marlin. There are a few configurations I haven't been able to find any useful resources about, as I'm having a hard time understanding and tackling some of them.
I do not understand MESH_INSET and PROBING_MARGIN and/or their difference.
Also couldn't find anything useful about SEGMENT_LEVELED_MOVES and LEVELED_SEGMENT_LENGTH.

You can find an answer on PROBING_MARGIN and MESH_INSET here.


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Anycubic i3 Mega layers don't stick together/are too thin
My Anycubic i3 Mega suddenly stopped printing properly. As you can see on the images attached, the printed filament seems to be too thin which causes the layers to not stick together.
I already:

cleaned the extruder
replaced the hotend (the old one was quite dirty)
leveled the bed
increased the printing temperature (bed from 55 °C to 60 °C, nozzle from 200 °C to 215 °C and later 230 °C)

Is the ring supposed to be solid from inner diameter to outer? Conversely, should the gaps between the rings be there?

It is difficult to see if it is under extrusion or if the initial gap is too large. Do you have a better image?

I get this characteristic in the first few layers if the initial z-height is too high. Is the nozzle flattening out the extrusion or is it still round as extruded?

I have increased the extruder speed to 130%, now its working. Still no idea why...
And @fred_dot_u the gaps shouldn't be there


text:
Switching computers for 3D printer
Does anyone know how to move a project I'm working on in VSCode on my Mac onto a different Windows computer? It's a Marlin firmware file using Auto Build Marlin and I want to move it from my main Mac computer to the old Windows computer I'm designating for the 3D printer.

Seems like this is more of a coding question than a 3d printing question ?

You could use version control to keep the project on GitHub, then you can clone the project to anywhere you like:

How to add a new project to Github using VS Code
Using Version Control in VS Code

There's quite a lot of reading there, but you will end up with a more robust result than simply copying files across.


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Missing outer wall on some layers?
It seems there are some missing lines on the outer wall on the Z-axis with my prints. I'm not able to pinpoint the problem. Does anyone have ideas about what might be wrong with my setup/settings?
Example:

Here are some settings that I think are relevant:
Printer: Ender 3 v1
Filament: Das Filament
Slicer: Cura

Hotend temp: 215 °C
Layer height: 0.2 mm
Wall speed: 30 mm/s
Travel speed: 200 mm/s
Retraction distance: 6.5 mm
Combing mode: not in skin (Max comb: 30)

Cheers

In case others are interested in the solution, after playing with various settings, increasing the nozzle temperature fixed the issue. Using 217-218 I'm able to get a decent surface now.

I had to raise temperatures and turn off enclosure fans during Winter because the room temperature around the 3D printer is colder.

If this solved the problem, your extruder is just marginally able to push a sufficient amount of material through the hotend at the speed and temperature you're at. Normally I would expect an Ender 3 to do somewhat better than that, so you may have other underlying problems I'll try to address in an answer.

The OP solved the problem by increasing temperature from 210 to "217-218". While it's good to have it working now, this likely suggests other problems with the printer thaat should be investigated.
If the change in temperature made the difference to get this print working, your extruder is just marginally able to push a sufficient amount of material through the hotend at the speed and temperature you're at. Normally I would expect an Ender 3 to do somewhat better, even with the stock extruder and hotend. Here are a few things you might want to check:

Is the filament properly dried? If it's absorbed moisture, the vapor phase transition will absorb at lot of heat from the hotend, making the effective extrusion temperature significantly lower than the block temperature. In my experience, it behaves like it's 20-25 ˚C lower than what you have it set to. You can kinda compensate for this by increasing the temperature (keeping an eye not to go over the safe temperature for the PTFE lining, max of about 250 ˚C) but the right solution if this is your problem is to dry your filament.

Is anything mechanically wrong with the extruder? A crack in the tension arm or weak spring can leave it very underpowered.

Are the extruder hob gear teeth clogged with plastic shavings? This will also leave it underpowered.

Thank you for the reply. I'm rather new to 3d printing (2+ year) though I think there are definitely two factors that contributed to this problem: 1. The filament, I don't need to increase the temp that much with my Creality filaments, so there is something wrong with Das Filament brand (it's new our of box). 2. The weather is getting much colder now so the room temperature is much lower


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What filament would be best for Creality's Ender 3 v2?
What would the best filament for an Ender 3 V2 be? I don't mind about the look but I would like for you to be able to bridge with it and for it to be reasonably cheap. If possible could you give several different options at different prices, different qualities and could you describe which website/company you can get it from.

Shopping questions like this are out of scope for the site. If you could be more specific about what properties you want, you could reformulate this question into one about what materials have the desired properties and make it in-scope.

Really, there are only a few materials that print well on a stock Ender 3 (PLA, PVB, and to a lesser extent PETG, ASA, ABS, and TPU) and they each have specific reasons you might choose them. Exotic materials beyond that list mostly require high-temperature capabilities and/or heated chamber.

Sorry - no one here can tell you to buy brand X from website Y.
However there are an enormous number of options and eliminating some broad categories can help.

Presuming your printer is stock, it has a brass nozzle, and therefore anything "reinforced" or abrasive is not feasible.  That excludes carbon fibre or nylon-reinforced filaments.

ABS is probably unprintable, unless you've added a heated enclosure

TPU might work, but it has properties that suit certain kinds of jobs, like flexible phone cases.  If you're not printing those things, TPU is wasted.

PETG is also a maybe - I have no experience with it.

PLA is the best for printing on an entry-level printer like an ender3.

You can eliminate all 2.85mm and 3mm filament, because your stock nozzle is a 1.75mm
I've personally not tried TPU or PETG on my ender3v2, mostly because committing to a whole roll is an expense I can't justify.
If I were you I'd ask anyone locally who prints, "where do you get good filament?" and use that as a starting point.  Ask your local library if they have a 3d printing service (this is astonishingly common) and where they source filament.
Some people only use the cheapest filament available, others have preferred brands, and others use only premium supplies.  Figure out what your personality is.
Going cheap is reasonable if you're only toying about.  If this printer is doing real work for people, consider stepping up to something better - cost of failed prints will outweigh the cost of better filament as your skills improve.
I would suggest exploring different styles of PLA, like the metallic-look or Silk mixes.  You can also get great effects from Rainbow PLA, which mean you have to have fewer colours in stock.  Lastly PLA+ mixtures exist, which are improvements on plain PLA.

Notes on printing PETG  https://3dprinting.stackexchange.com/questions/10288/how-to-work-with-petg-settings-caveats-etc


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First / bottom layers not printing?
New to the group so please let me know if I am not asking / formatting correctly.
So I have just started 3D resin printing with my new Elegoo Saturn. I have printed a couple of free STL files with no problem. I drew up a part for my modeling project with SketchUp maker. Exported the STL file into Chitubox and made a test print after slicing the file. The bottom layer(s) do not seem to print ... the bottom plate should be 4 mm but always prints at 2-3 mm. This makes my clearance groves almost disappear. What should be thru holes have a small layer closing the hole. The bottom layer seems to be "smashed out ... not a clean edge.
I have read, watched, studied lots of "help" on the web, make several slow changes to bottom layer print times, adjustments to lift / rest / etc, and lots more test prints which all have failed.

Have another go with adding the photos - they're always helpful.  I can't get anything but an error from your links.

I fixed the images, they should be visible now. Thanks.

we experience exactly the same problems on a saturn s and saturn 2 - might be a software issue with chitubox...
Did you solve that problem?


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Creality CR-10S Pro V2 Auto Bed Leveling probe sticks
My CR-10 is only a couple of months old. It came factory fitted with auto bed leveling.
Recently, the bed leveling probe has stuck in the withdrawn position whilst it is measuring prior to a print. Whilst stuck in this position the red light flashes. I am able to temporarily resolve the problem by gently pulling the probe down, but then have to start the measuring process all over again.
This problem is occurring more often and if I don't sit through the lengthy measuring process and restart if necessary, the printer will carry on printing in 'mid-air'.

Have you found a permanent solution to this? If so, please post the solution.

Having moved the probe up and down gently to ensure it wasn't catching, I restarted the machine and have not been troubled since.


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Can't make Ender 3 V1 Level
I have an Ender 3 V1 with a glass Creality plate. I was having difficulty using manual levelling and my prints were struggling, so I ordered a 3DTouch. I have installed the 3DTouch and used Creality's BLTouch firmware. But my bed is still not level.
So my build is an Ender 3 V1 with:

Extruder upgraded to all-metal extruder
Glass bed upgrade
3DTouch Upgrade
Capricorn Tubing
Yellow bed springs

I manually levelled my bed using my 3DTouch. I used the G30 command in Pronterface to probe each corner of the plate. At each corner, I would adjust the knob until the 3DTouch read 0.0. I did this iteratively multiple times until I thought it was reasonably level. The four corner values were something like 0.1, 0.0, -0.2, and 0.3 mm.
I have also put a straight edge with an Angle Finder Phone App. The bed is quite level. It reads 0, 1, or 2°
depending on how I place the level. X-axis gantry has a 1° tilt.
Here is my current bed levelling mesh:

After doing this, I added G29 after G28 in my starting G-Code in Cura. I sliced a model from Thingiverse that had 5 squares and some lines. Here are the results:

I am using:

Filament : PLA
Bed Temp : 60 °C
Nozzle Temp : 200 °C

Some miscellaneous notes:

The bed was cleaned thoroughly prior to use
I rotated the bed 90° and the print looked the exact same way
I ensured that the bed soaked in some heat for some time prior to printing
I have set my Z offset to -1.800 mm
The frame and components seem to be square and tightened down. Nothing is shaking around and seems to be in order.

I would really appreciate help on this. I'm really not sure what to do next. I've been really excited about 3D printing and I hope I can find a solution to this.
Leveling using CHEP's video
So I have rebuilt my 3D printer using CHEP's video. I noticed that one or two things were off compared to how it was supposed to be. I will be doing some test prints to see if that actually fixed things. I am hopeful.
I did a mesh before any other changes, and the slant is very clear now. See below. I believe one of the plates on the gantry wasn't completely straight.

Leveling after rebuilding printer
Here is my latest mesh, after rebuilding the printer and then re-levelling its bed manually.

These are the results of the print. I had to change my Z offset to -1.60 mm. The broken line is my fault. It was caused by my finger. The focus is the corners. As I mentioned, this is after rebuilding my printer.

Edit
I would like to have more probing points than Creality's 3x3 grid. To my understanding, Creality's source code is not available, and so I will be rolling my own with Marlin 2.0. I downloaded the latest Marlin from https://github.com/MarlinFirmware/Marlin/releases, and copied the 4.2.2 Creality configuration from the default Configurations. I then changed the following:

I ensured #define PDITEMP is not commented so that I can do PID tuning of the nozzle.
Similar to 1., I ensured that #define PIDTEMPBED is not commented so that I can do PID tuning of the bed.
I commented #define Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN since I will be using the 5-pin BLTouch port that is on my 4.2.2. board.
I uncommented #define USE_PROBE_FOR_Z_HOMING since I removed my z-axis endstop and want to use my 3DTouch as the z endstop.
Uncommented #define BLTOUCH since the 3DTouch is a BLTouch clone.
Changed my x and y offsets in the setting #define NOZZLE_TO_PROBE_OFFSET { -42, -8, 0 }. I left the z-offset 0, since I will be using the tuning tool to adjust that and observe the squish. For the x and y, I measured the distance between my probe and the nozzle using a digital caliper.
I adjusted the probe margin from 10 to 15, since I have clips that previously would interfere with the 3DTouch. 15 should give more distance. #define PROBING_MARGIN 15
I enabled and set MULTIPLE_PROBING to 3. I'm paranoid about the current accuracy, and am willing to see if that improves anything at the expense of a few additional minutes. #define MULTIPLE_PROBING 3. I think 2 should be fine for general use.
Uncommented #define Z_MIN_PROBE_REPEATABILITY_TEST. I want to test my 3DTouch and uncommenting allows the use of M48 to test it.
Uncommented #define PROBING_FANS_OFF, #define PROBING_ESTEPPERS_OFF, #define PROBING_STEPPERS_OFF, #define DELAY_BEFORE_PROBING 200. The documentation this may improve probing results. I'm all in.
Uncommented #define NO_MOTION_BEFORE_HOMING and #define HOME_AFTER_DEACTIVATE.
Uncommented #define AUTO_BED_LEVELING_BILINEAR
Uncommented #define RESTORE_LEVELING_AFTER_G28. This is to ensure the mesh is applied even after G28, which disables the mesh otherwise.
Ensures that this setting was 10. #define DEFAULT_LEVELING_FADE_HEIGHT 10.0
I set the following : #define GRID_MAX_POINTS_X 7. Ensures a 7x7 mesh grid is created. This could be more or less. 49 points is an improvement over Creality's 9, although a bit much. Worthwhile in my case.
Uncommented #define EXTRAPOLATE_BEYOND_GRID. I was actually wondering if this was causing some of the inconsistent prints near the edge.
Uncommented #define LCD_BED_LEVELING. This is to unlock more options for ABL in the menu.
Uncommented #define LEVEL_BED_CORNERS. This should make moving between corners for manual levelling easier.
Uncommented #define LEVEL_CORNERS_USE_PROBE. This is to achieve exactly what I was doing with G30 in Pronterface. I changed to tolerance with #define LEVEL_CORNERS_PROBE_TOLERANCE 0.03
Uncommented #define Z_SAFE_HOMING, which is important for the BLTouch.
Changed my PLA profile according to what I have determined to be best with #define PREHEAT_1_TEMP_HOTEND 200 and #define PREHEAT_1_TEMP_BED 60

I had to comment #define BLTOUCH_SET_5V_MODE for things to compile. I also had to modify #define LEVEL_CORNERS_INSET_LFRB { 30, 30, 45, 45 }, due to the margin I set as well as the offset of my touch. Otherwise, the above configuration was fine, in terms of compilation.
I'll post back with the results.
Here are the results for the M48 3DTouch test. Are these values good?

Measurement
Value

Mean
0.063667

Min
0.061

Max
0.068

Range
0.007

STD
0.002478

I reduced the speed of the probing in half in order to make the probing more accurate. This was done by changing from #define Z_PROBE_FEEDRATE_FAST (4*60) to #define Z_PROBE_FEEDRATE_FAST (2*60). I also made the mesh grid 8x8 because might as well.
These are my M48 repeatability results. Interesting to compare to the above table which probed at double the speed.

Measurement
Value

Mean
0.005500

Min
0.002

Max
0.010

Range
0.008

STD
0.001908

I also changed the filament (brand new). Just as another variable to modify.
The following prints are the result.
The mesh before this print is as follows:

Levelling the X-Axis Gantry
As Oscar in the comments has mentioned, I have read some other forum posts that described the cause of uneven lines and similar inconsistencies as what I am noticing, as being due to the X-axis Gantry that moves up and down as not being level.
I used a digital caliper and measured the x axis gantry relative to the frame of the 3D printer. So for example, I put my caliper against the base metal extrusion and then against the x-axis gantry. I did this on both sides.
The side without the Z-Axis lead screw (right side) was above the side with the Z-Axis lead screw (left side) by about 1.7mm. I'm surprised that CHEP and some other build videos never mentioned to check this, but it does seem logical to consider. Making the brackets flush is NOT adequate. When I do make it flush, then one side is higher than the other. The build videos say to make it flush. This will make things OFF.
To adjust this, I took off the gantry, slightly loosened the bolts on both side plates, so that it was stiff enough that it wouldn't move easily, but could make subtle adjustments by twisting it hard enough. I then put the gantry back on the printer, did some measurements and corresponding adjustments. I then carefully threaded the gantry off and tightened the plates.
Currently, my left and right side have a difference of .17mm. I figured I won't get anything better by hand. I'll do another test print tonight. 1.7mm vs .17mm is a reasonable difference.

No problem, it is our job to gently teach newcomers the rules,. Note, you are encouraged to give as much information as possible if relevant to the question, your own research is much appreciated! Also, posting your own answers when you find them later is perfectly valid! You can even accept your own answer after 48 hours of posting! Remember SE works a little different, but in the end we want good questions with solid answers where the community votes on the questions and answers spreading their gratitude through reputation. Get the Q and A's coming! :-)

One red flag:

I have also put a straight edge with an Angle Finder Phone App. The bed is quite level. It reads 0, 1, or 2° depending on how I place the level. X-axis gantry has a 1° tilt.

"Level" in the sense of bed leveling does not have anything to do with being level relative to the earth's gravity. If your X axis is tilted but your bed isn't, there's your problem. They have to be square to each other, not level with respect to any external reference (you can operate your printer on its side or upside down for all it cares).
If you find that, no matter how much you try to tune the bed leveling, it keeps coming out different by the time you print, you probably don't have a problem with your bed but with the X axis gantry and Z motion system it's attached to. If the frame the Z carriages run up and down is not entirely square, or if the wheel tension is not right, the undriven side might not follow correctly with the driven side. This means sometimes positioning at the right (viewed from front) side of the printer will come out too high, and other times too low, depending on a lot of factors, the most obvious one being last direction of Z travel.

Thank you. I really appreciate your response.
I wanted to mention that I understand that level measurements are not significant. But I thought it was interesting enough to post about. My bed levelling was done on the basis of distance from the nozzle, and the level was just an observation and did not influence levelling.
Thanks. I will try to further investigate the x-axis gantry that is moving up and down. The tilt on that was 1 degree, downwards towards the side with no z-axis. However, I found the bed to also have a tile of 1 degree to that side.

You need to check the X gantry, the Ender design is flawed by using a single Z screw on one side. Please check the rollers and check the belt tension. All the leveling graphs show that the bed is lower on the right side (or the gantry higher), it could be that the rollers on the right post (when facing the printer) are causing the right side to be lower.

Question for you. Do you think there is a problem with using G30 to level a bed? I noticed that even when I use my G30 approach, I seem to still end up with a slanted bed. Is there some flaw to the G30 approach? I tried searching for it online, but I pretty much found nothing about using G30 to manually adjust the knobs. But I thought it would be far more scientific and precise than the paper method.

Even with a 3DTouch, bed leveling needs to be done manually, I never use G30 or have used the past 6 years, instead I do a G28, lower the head to paper thickness between nozzle and bed, than de-power the steppers and manually tram the bed everywhere (corners and middle of the bed) so that it is as level as possible (note to use G28, move to a corner, move down and de-power multiple times). This ensures that the bed is in the same plane as the nozzle, unless the bed is really skew/bent this should work. When done you only have to set the correct Z offset and add G29 to the start G-code.

@geekgeek4 The problem you are facing is not the G30 or manual leveling procedure, but most logically a mechanical issue. I'm not here to speak evil of the Ender design because it can work well when properly set up and tuned, but the design can lead to frustrations for new users when it does not perform up to par. P.S. note that comments are not here to last forever, you might see them disappear after a while when comments are addressed in the Q and A's. :-)


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TronXY X1 Configure bed offsets
I have this printer with the 1.1.6 Marlin. The issue with it is when the printer starts printing the position of the hotend is offset
I am using Cura as the slicer. There, I tried this G-code to configure offset
G28 ;Home
G1 Z15.0 F6000 ;Move the platform down 15mm
;Prime the extruder
G92 E0
G1 F200 E3
G92 X5 Y-10
M206 X10
M206 X1 Y1
G92 E0

But they are not applied.
What could be the issue?

First, you need to make sure the slicer does slice the print object correctly, so beware of the option called "Origin at center" in Ultimaker Cura; this should not be checked for most printers (Delta printers have the center in the middle).
Second, please look into How to center my prints on the build platform? (Re-calibrate homing offset) to center your print to the build plate.


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Nozzle getting clogged all the time
Recently, my Ender 3D Pro has been unable to print any large models successfully with PLA as the filament starts to expand inside the Teflon tube, causing a clog after about an hour of printing. I am starting to suspect that the problem is heat creep.

This occurs with the two brands of PLA filament that I use (3D Fila and Voolt 3D).
The hotend that I am using is the one that comes with the printer, I don't know what it is made out of.

I have tried many things to patch this problem:

Try to unclog it with the needle
Replace nozzle (three times)
Check if the Teflon tube is touching the nozzle
Increase temperature from 200 to 220 °C
Increase temperature from 200 to 215 °C

If the problem is indeed heat creep, I have plans to control the heat sink temperature with a Peltier and an extra thermometer. Any other ideas are appreciated.

Is it B-grade rolls or good quality filament? I had bad filament appear to clog but it was hung in the extruder with a bulge.

PLA does not clog unless dirty. Something about your printer is seriously FUBAR. I would bet the problem is the extruder being worn out, dirty or incorrectly tightened and therefore not gripping the filament. Heat creep is certainly not the problem unless your fan is broken.

Since you mentioned "Check if the Teflon tube is touching the nozzle", it sounds like you've disassembled the tube from the couplings and put it back together. This is error-prone and in my experience the main/only likely cause of clogging in Creality hotends. Heat creep is unlikely unless you're operating in a very high ambient temperature or have a failing/failed fan.
The tube can't just be "touching" the nozzle. It needs to be compressed against it. There are various ways to do this, but what usually worked best for me (before I moved to a different setup) was to back the coupler out of the heat sink by at least 1-2 full turns, press the tube all the way in against the nozzle, then tighten the coupler back down to compress the end of the tube against the nozzle mating surface.
The end of the tube also needs to be clean cut, straight, and undamaged. If it's charred, bent, gnarled, whatever, cut it straight with a razor blade while holding it in a jig to make sure the cut is perpendicular. You can find several such jigs (PTFE tube cutting tools) on Thingiverse or make your own or buy one. I like to also take the razor blade and chamfer the outside of the tube end ever so slightly before inserting it. I do this by hand, but I've seen videos of it being done with a jig that looks something like a pencil sharpener, which would probably be the best way.

Apparently, that was the problem. To solve it, I followed a hack from this video: link. Basically, the idea is to put a small piece of Teflon tube inside the hotend before attaching the other one.

This sounds like heat creep may be the problem. For preventing heat creep to occur you should do the opposite, print at lower temperature, tweak retraction length and increase cooling of the cold end.
A Peltier element is not very effective cooler, use a bigger fan, or a fan with a higher flow rate. Note that the Peltier element required a large cooling body and a fan as well, so this adds a lot of weight to and limits space of the hotend. You should not go there, it has been tried before.


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BLTouch not working on Creality Ender 3 Pro
When starting the printer, the bed leveling sensor does its little startup thing and then lights up static red. When pressing "Level Bed" or "Auto Home" it homes X and Y and after that sends the Z-axis crashing into the bed.
Is there anything I can change in the firmware to debug or fix this? I have checked the wiring and it's correct.
The BLTouch is not a genuine Creality since at the time it for some reason was not available in my country. The BLTouch is connected like any other BLTouch; 2 wires to the Z endstop connector, and 3 of them to "+5V", "GNF" and "IN". The firmware I got of Marlins GitHub and modified the Ender 3 Pro firmware I got of Marlins configuration GitHub (Marlin BugFix 2.0).
The stuff I modified I put here:
Configuration.h
#define USE_PROBE_FOR_Z_HOMING
#define BLTOUCH
#define NOZZLE_TO_PROBE_OFFSET { -42, -5, 0 }
#define AUTO_BED_LEVELING_BILINEAR
#define PREHEAT_BEFORE_LEVELING
#define LEVELING_BED_TEMP 65
#define GRID_MAX_POINTS_X 5
#define LCD_BED_LEVELING
#define Z_SAFE_HOMING

Configuration_adv.h
#define BABYSTEP_ZPROBE_OFFSET

I compiled this firmware with PlatformIO in VSCode with env: STM32F103RET6_creality.
The board I used is version 4.2.2 32-bit.
The video I used can be seen here:

Have you flashed a bootloader first? The original Ender3 came without a bootloader. See point 2: https://3dprinting.stackexchange.com/questions/12153/updating-marlin-firmware-step-by-step-guide

@Trish No, if you have a 32 bit board you just need to put the new firmware on an sd card and it installs it. I have verified that it got the firmware so thats not a problem.

That didn't work for the original, which had no bootloader and a 16 bit board

The later Ender 3 Pros Shipped with V4 boards wich are 32 bit and comes with a bootloader that can firmware update from an sd card

I know this is an old post, but I think I figured out the answer.
I had the EXACT SAME PROBLEM TODAY while trying to compile custom Marlin firmware (version 2.1.2.1) for the same exact setup as you have. My BLtouch probe is plugged into the dedicated probe header on the mainboard, and the Z endstop switch is also still plugged in. The bed probe wouldn't trigger while homing or bed leveling, and the nozzle would plow straight down.
The issue is in the firmware. The line #define Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN was not commented out in my Configuration.h. The printer was expecting an interrupt from the Z endstop switch. It wasn't looking for an interrupt from the bed probe, so the probe triggering wouldn't do anything, and it continued to move. Eventually, the nozzle would hit the bed. If you have this issue still, recompile your firmware with this line commented out in your Configuration.h, at around line 1280.
Please let me know if this works for you.

This is sadly as you said an old post, i have not attempted to use my BLTouch since then. I was a begginer then and i still consider myself a beginner. BUT everything you said aligns pretty good with my issues. I believe this might actually work. I will not guarantee i will try it. But after this post i might dig up my old BLTouch and give it another go. Just logged into my account after a long time and saw this :-). Thank you so much.


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3D Printing with malicious intent
I have a bit of an odd request. I am studying the vulnerability of 3D printers and would like to know if there is a way to disable the limit switches on, for example, an Ender 3 in the G-code.
Ideally, the exploit would be used by plugging in the malicious code via SD card into the 3D printer. I have found ways to change the nozzle temp and things like that, however, nothing on the limit switches.
If I were the manufacturer, I wouldn't implement the function, so if it's not possible it will not be a surprise. If that's the case, what would be some other options for tearing this thing up?

Have you done basic research, like examining the list of gcodes recognized by the ender3?

I don’t think we should be using 3D Printing Stack Exchange to develop a public blueprint for hackers to destroy people’s 3D printers

I think it is important to be aware that a gcode can set your temperature to something that can damage the printer.  But by the same token, I don't think you should be printing gcode from someone else that hasn't run through your own slicer with your own fine tuning for your printer.

@ChinchillaWafers the information on how to do it is already public as every Gcode and their functions are available from the Firmware vendor's website: https://marlinfw.org/meta/gcode/
The threat vector is from unsecured web interfaces primarily. But physical access to the printer will not prevent blatant misuse and abuse. If a hacker has physical access to your printer - you have bigger problems than someone trying to run malicious gcode. Additionally, schools might like to know "how" a student can destroy a printer and what to look for. (Hard rule of no outside Gcode fixes this threat.)

Just my thoughts... I'm tempted to upvote this question, purely for its audacity, as well as its usefulness in making people aware that you could totally shaft a printer if care is not taken with the (G-)code used. Also, it has resulted in a very useful answer (and hopefully others to come). The other negative votes, if given due to a distaste for the topic, I think may be a little unfair - if this were on Meta then yes distaste may be demonstrated by down voting, but on the main site downvotes should be for lack of research, etc. and it seems like the OP has at least done a bit of research.

The question actually poses a good thought start for "how to mitigate risks and design a threat model to protect your print farm" - though framed as 'can one make this to damage the printer?'

Ethics and justification:
If you have physical access to the device you could just... physically damage the device. Running arbitrary G-code is just more complicated
Most printer farms have a strict no outside G-code policy for good reason. Because direct physical access to the printer does not provide any security.
This is also a problem for CNC Mills and other equipment. The firmware is not there to protect you. If you ask the system to put the spindle into XYZ_POS, the device's job is to deliver your 300 dollar end mill into the part as expediently and directly as you have told it. It does not hold your hand.
As a result, it's probably best that no one run pre-compiled G-code. You should use an STL and generate your own G-code. Not only does it allow you to properly tune the print for your specific printer, but it prevents nasties from breaking your printer.
Do not test this on a system you do not own. You will face civil and criminal liability for any damages as a result of performing this on printers that are not your own. Additionally, I would question the value of your research provided that physical access to a device automatically makes it vulnerable; let alone running arbitrary code from an untrusted source.
To help your research: Most "secure" facilities prevent even touching a machine with external code. All code has to be generated on trusted and isolated machines by trusted persons. There is no guarantee that the "trusted" person can't manufacture a job that will crash their 300,000 dollar CNC mill and cause damage - but there are serious repercussions for doing so.
It's extremely difficult to "tear up" a printer by turning off the endstops.
You can disable physical endstops with a simple command M121.
However, this only does so much.
With M121, the printer is only really vulnerable before it has been homed. Most printers will auto home when starting a print, or refuse to print until they are homed. If issuing M121 then arbitrarily trying to ram it past an endstop, it will continue until it counts steps to the software endstop value [XYZ]_MIN_POS to [XYZ]_MAX_POS.
Older printers didn't have software endstops and would keep going until they were stopped or turned off. But this wouldn't explicitly cause damage as physical limitations would prevent it. Outside of old designs that do not physically limit the Z position - and crashing the nozzle into the printer.
Nowadays - the printer would crash into the axis limit and then stop because it would hit the software endstop (and funnily enough, be homed as a result - I have done this as an experiment on my own printers)
This would not damage the printer - just be annoying for a short time until it hits the software endstop.
You can however make it work like an older printer provided it does not have stall or crash sensing (like Prusas have by default) by issuing M211 S0.
This turns off the software endstops. And should allow it to continually try to reach the value programmed in the G-code. It should continue to count until it gets to XYZ_POS then finally stop.
Will this cause damage? Maybe. If the Z-axis is high and it can physically push its way into the printbed hard enough it can cause damage to the hotend. However, generally, most printers are designed (these days) that the Z-axis cannot go too far into the print bed and cause (too much) damage. Modified printers can be vulnerable if they modify the bed but do not physically limit the Z-axis from going down too far. Additionally, when the printer autohomes on print it usually will set zero to the endstop before the payload can be run, giving a home and only allowing excursion to the axis positives. When this happens, no damage can really occur outside of overheating the steppers/drivers and possibly damaging belts.
There are also some firmware protections to help protect the end-user (e.g. Prusa Crash Detection) - depending on the printer these may need to be circumvented as well.
How you can really tear up a printer? If you have physical access to it - you have total control over it. Simply being physically near it is enough for you to just throw it out a window. It's arbitrary to try to run any code. But if you're trying to research how a threat actor can mess up someone's printer?
Thomas Sandladerer made an excellent video on these vulnerabilities (specific to 3D printers) here:

In his video, he's speaking directly on the threat of running pre-formed G-code from public sources. (Something that you should not do - something that no one should do)
Conclusion:
In security, physical access to a system by an untrusted person or running untrusted code on a machine is not allowed.
For this vulnerability to be exploited, it requires a person to do things that they should not be doing - running generated G-code from an untrusted source. This includes from "friends" or even family.
I won't tell you how to "really tear up" a 3D printer as there are a plethora of horror stories out on the internet of printers catching fire let alone the threat of running some random code on your printer. How to do it is publicly available. You just have to figure it out yourself.
The lesson here is simple: Just don't run pre-compiled G-code.

Thanks for not providing a manual to tear up a printer! I can think of a couple of ways, but refrained to answer to have a dedicated landing page for people that want to destroy other peoples' machines. Very elegantly answered by dodging/bending/interpreting the question to not running pre-compiled G-code which is very good advice!. Welcome to 3DPrinting.SE!

If you want to tear up a printer, I suggest a hammer.

Disabling endstops usually just causes the printer to lose track of the origin when the printer tries to go past the end stop.

The most sure way to cause significant damage is probably to print a solid block of plastic then slowly lower the hotend into it while continuing to extrude. This does not rely on bypassing endstops because the object you're hitting isn't part of the printer but something dynamically created.

@R..GitHubSTOPHELPINGICE Thomas's video that I submitted in my answer demonstrates this concept. :)

Physical Access is worse
If you really want to brick a printer, physical access allows to destroy any printer physically.
If you really want to mess it up only via a remote command later, you would not just run arbitrary G-code, you'd replace the firmware with one that looks and feels the same but contains neither Thermal Runaway Protection nor a Maxtemp. This way, the machine would just try to heat to arbitrary temperatures as commanded - making it possibly a fire hazard. In the worst case, installing bad Firmware is as simple as inserting a prepared SD and having the printer run a firmware update to your modified version!
You see, Physical Access means any malicious person can turn a printer into what accounts to a timebomb, but as 0scar points out, it takes no malicious intent to mess up a printer - just being bad at maintaining or using it.
Network Access suffices
Let's for the sake of argument assume all we have is remote terminal access to the printer. No necessarily video feedback, just terminal access, for example via Octoprint. This is sufficient to send arbitrary G-code, and some combinations can be outright devastating - which is why remote print servers are usually password secured and should never be public access!
With the right Terminal, Altering the EEPROM is easy
If you have remote access and can use a terminal that allows directly altering the EEPROM, changing fundamental values like the position of the endstops or the size of the printer quite easily. Repetier Host for example can do that, but usually uses a direct physical cable - which gets us back to Physical Access is worse.
You worry about the wrong command
Now, the worst command that with bad intent is very likely to destroy printers is the M500 command to save altered values into the EEPROM. This can result in problems if G-code before the command contains code that changes basic settings that are not firmware locked.
For example, M301 with nonsensical values can force very bad PID-setting that could result, depending on how they are set up, in massively overshooting the target temperature, regularly tripping Thermal Runaway Protection or just bad prints. With Particular bad settings and with disabled TRP, one might actually turn the printer into a fire-hazard.
Due to the problems M500 (and M301) can cause, Prusaprinters/printables does not allow to upload any g-code that contains this command, but the best protection against this command is to NEVER run G-code that you didn't compile yourself.
Besides the M500 and M301, even the totally normal group of M201 to -M203 can really mess up a printer in not necessarily a permanent fashion without M500... unless they are used to destroy the printer outright. Which can totally be done by setting ludicrous speeds and acceleration, then telling the printer that its printhead is at a height well above the bed (besides that it was just a few millimeters away) and slamming down with maximum force to pierce a hole into the bed. But as many of the feedrate commands (like M203) are used in normal prints, it's hard to spy such commands - and thus nigh impossible to spot beforehand.
Blocking Malicious G-code
Some companies, fearing accidental M500 or other setting-altering commands, have disabled EEPROM. This however makes maintenance much harder, but prevents altering critical settings at all - they are now fixed in the firmware and have to be altered by recompiling and uploading an altered firmware. If done properly and combined with proper physical access control to the ability to upload firmware (e.g. sealed maintenance panel) can pretty much prevent malicious G-code to have any effect.

Potential threat?
I can imagine that this is a potential threat for printers that are operated in an environment where there are lots of people using the printer where there is access to the SD card (e.g. schools, libraries or maker spaces). It would literally take a file on the SD card to be run the next time the printer boots to change settings through G-code. As you can imagine, it is quite easy to change the coordinates of the origin - this has been discussed in previous questions - but also speeds, endstop state and acceleration values for instance.
Would it destroy a printer?
Yes, it can. Lead screw motion is stronger than belts, the latter will just skip, but lead screws may do some serious damage depending on the printer construction (I've had my unintentional fair share of that). But, the most obvious problem is the time that is needed to fix the problem; re-calibrating and repairing.
Limited to malicious intent?
No, managing an Ultimaker 3 Extended for a staff association I can talk from experience that it doesn't take malicious code, or intent, to mess up a printer. Working from home due to COVID-19 measures (my work needs those who can work at home to stay at home, in order to allow those who operate machines and test equipment to go to work and comply with the x people per y square meter rules that the government laid out) I have been away from the UM3E to find it in a terrible state a year later. It appeared that there have been people, that had no experience in slicing, using the wrong type of materials for slicing with respect to that was loaded into the machine... (we operate non-Ultimaker materials, so the material is not recognized by the RFID reader). The printer is now under lock and key...

Poor printer! I hope you could rescue it.


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How to properly run a PID Tuning and update the firmware?
The Firmware Step-by-step guide remarks to only mess with PID-Tuning settings in the firmware when you know what you are doing. Apparently, defining those settings in the firmware is a somewhat involved process, so this begs the question:
How do you acquire the PID-tuning settings properly and update the boars of a printer so it retains these settings through power cycling?
Let's for simplicity assume there is a Marlin Firmware or a derivative using the same command codes is installed, so we can assume all the commands from the Marlin G-code repository work.

Step 0: Terminal connection
To do any work on the settings of the board, you'll need to run a Terminal - for setting that up, please see the relevant question here.
Step 1: What do we have?
The second step is dissecting the settings that are set already. To do so, send M503 to read the relevant settings from the SRAM of the board and display them in the Terminal of your choice.
Step 2: Try a PID Autotune
To run a PID Autotune, just start by sending this for your first hotend to enforce a 3-cycle PID tuning for the 200 °C region:
M303 C3 S200
For your second hotend, you'd send M303 C3 E1 S200 - the E-value is 0-indexed and defaults to 0 for the first hotend, so E1 is the second hotend.
For your heatbed (and PLA) you send M303 C3 E-1 S60 as -1 is the function dependant value for the heated bed.
Step 3: Setting the PID settings
After having obtained the PID settings from running the tuning cycle, we need to send those to the chips. To do so use M301 for a hotend and M304 for the heatbed, using the given values from step 2 as parameters.
Note again, that if you have more than one hotend, you absolutely need to have an E-value if you try to set the second hotend, as the default value is, again, E0 for the first hotend.
Step 4: Saving
To properly save the values into the EEPROM - provided it is enabled - is to just send one command to finalize:

M500

If your EEPROM is not enabled, you'd need to take the line you wrote for Step 3 and insert that into your pre-print G-code, thus overwriting the PID settings in the SRAM before each print.


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Temperature problems
For some reason whenever I turn on my printer, my nozzle says that it is at 120 °C even though it is not set at anything and my bed says that it is set at 180 °C even though it is not set to anything. I replaced my hotend and the problem is still there. Does anyone else know why this?

What printer do you have? What firmware are you running? Has anything other than the hotend been modified? Please [edit] in additional information so we can help you. The more information, the better.

There are several hundred printer types out there, and the number of variants goes into the 4 digit range. misreading a temperature could have numerous reasons, and in some printers it is more common than others.

This is a common problem that affects many printer types, and is caused by the fact that most controller boards do not have over-voltage protection on thermistor (temperature sensor) inputs. If the thermistor wires come into electrical contact with the heater wires (with the printer switched on and the heaters running), this can ruin the analogue to digital convertor (ADC) circuits on the printer's microcontroller. The only solution is to replace the controller board.
This problem typically occurs when users are performing essential maintenance on their printers. For example, when trying to remove filament that has accumulated around the hot end during a print failure. Never try to remove filament with the printer switched on (and never use a wire brush to do so). If you need to pre-heat the hot end to soften the filament, always switch the printer off before attempting to remove the filament, and try to ensure that the thermistor wires are not damaged in any way.
There are controller boards that have over-voltage protection on thermistor inputs, although this is still fairly uncommon. The BigTreeTech SKR 2 (not to be confused with the SKR 1.4 V2) has such protection.


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Calibration of Y-axis produces different results on single model with different length even after E-step calibration
TL;DR;
If I calibrate my Y-axis steps/mm based on the long side of the model shown below, the calibration cube part is printed too big. If I calibrate the steps/mm based on the calibration cube part, the long side of the model comes out too short. Any ideas/hints on what the problem is?
I have an Anycubic Chiron 3D printer without any technical modifications. For calibration purposes, I created a specific design that allows for measuring longer and shorter lengths as well as the diameter of holes. I mainly did this because an error in the settings of steps/mm will be more visible on a larger print and holes often came out too small for me in my prints. You can find pictures of my design below.
Now, I have three other printers (Artillery Sidewinder X1, Tronxy X5SA-400, Geeetech A30T) that print the model OK. Whenever there is a problem with the X- and Y-steps/mm setting it will be equally visible on the shorter "calibration cube" part of the model as well as on the longer parts. While for the latter 3 printers this expectation holds true, the Chiron produces different results.
If I calibrate the steps/mm for the Y-axis based on the long side correctly, the calibration cube part is off by about +0.2 mm. Of course, if I calibrate the steps/mm based on the calibration cube part, the long side is too short. This really confuses me as I would have expected that a potential error would be visible on both parts of the model.
The error can be observed consistently. The prints come out OK, just the measurements are off.
My first guess was that it might have something to do with the extruder, but I calibrated the extruder several times already without luck. My second guess would be that it might have something to do with the nozzle size not being accurate. Last not least, maybe some steps could be missed consistently by the motor on longer lines because the stepper voltage is not correctly set? I'm just speculating...
I already checked the belt, belt tension and the pulleys. It is also not important on which part of the bed I print. I also replaced the stepper drivers (A4988) by TMC2208 drivers as I had these available from another project. No luck, though, same result with the new drivers.
Any help/hint is appreciated.

I am unfamiliar with this printer.  Can you tweak X and Y values separately ?

Yes, there are separate motors for the X- and Y-axis. The steps/mm can also be set separately.

have you checked the condition/tension of your drive belts and the pulleys?  There might be some backlash/play.

Good point, but yes, I already checked the belt and the pulleys. I also would expect the print to be less consistent if these things would come into play. I‘ll add this info the the question. Thank you for trying to help me!

You should not tweak the steps per mm for the X and Y, these are given by the mechanical layout of the machine and the stepper and the driver. Furthermore, 0.2 mm is within the margins of 3D printing, nothing to worry about.