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Glass bed for Ender 6
I have a warped glass bed on an Ender 6 that I recently bought. I want to replace this bed. However, the dimensions in which Ender 6 print bed comes (250x250x400 mm) are not available for purchase on sites like Amazon or Creality. Can anyone guide me about which bed I should buy?

You may be confusing the print size (the area you can print within) with the print bed (the physical size of the glass itself).

As @agarza has stated, you appear confused as to the size of the plate. The plate in the X-Y plane has only two dimensions, and then a thickness of only a few millimeters, in the Z direction. So, your quoted dimension of 250x250x400 makes little sense and would appear to be the build volume, rather than the build area (i.e. the dimensions of the plate). Correct your search terms and you'll probably find the right size glass plate that you are looking for. Also, please [edit] and update your question with the correct size.

You say that you recently purchased the printer. DId the printer already come out of the box with a warped glass plate or did it become warped through being used, i.e. warped by the heat bed (assuming that it has a heat bed)? If the latter, then the glass provided probably wasn't heat-proof borosilicate glass - which could be grounds for complaint, if the printer was advertised as being supplied with borosilicate. Either way, something seems wrong with your purchase...

If you just want to replace the glass, then you could go to any local glazing/window store and ask for a sheet of glass to be cut to the appropriate size.
It will probably be a lot cheaper than a glass sheet marketed as specific for 3D printers.
There are just one or two caveats:

Whilst the type of glass is (probably) unimportant (if you aren't using a heated bed) ensure that the sheet of glass that you get your bed cut from is flat. Ask the merchant for glass sheeting that is specifically made as flat as possible, and isn't already warped or with defects.
If you have a heated bed then you will (most likely) require heat proof glass1, i.e. borosilicate glass, one example of which is Pyrex. This may be not as easy to source as "normal" glass for windows, but it's still worth asking at your local store.

Note that if the printer was recently purchased then it should still be under warranty and you could ask the supplier to send a new glass sheet.

Footnote
1 You might (in all likelyhood) get away with just using normal glass plate, in junction with a heated bed, some glass is quite resiliant - it depends upon the quality and/or thickness (re. heat dissipation). Also, when taking into account the lower cost of normal glass, you might  not worry about any potential cracking and/or warping. However, if you prefer to err upon the side of caution, then use borosilicate glass.

Why special glass with a heated bed? Glass can take a lot more heat then any filament I know of

Good point, yet I thought that it would be prudent to err on the side of safe advice... I could replace will (most likely) with might and expand upon the answer...

The temperature of heated beds can increase quite quickly. Normal glass usually isn't made for big temperature differences between two of its ends (e.g. put one end in ice and the other above a fire) - therefor there are glasses specifically made to endure temperature differences (like laboratory glass). I doubt that on a heatbed, the temperature difference might be big enough to cause cracks, but in theory it is possible and might be a point to think about.


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Why layer shifting prints on Ender 3 Pro?
Prints on an Ender 3 Pro using a standard printing profile results in layer shifting or over extrusion.  I can’t figure out what the problem is.  I tried reducing the flow as well as print speed but nothing really changes. Any thoughts on the  XYZ cube test print below?

Have you checked belt tension?

Thanks.  I checked my belts and x axis was very loose.

Does your prints over adhere or ooze with all filaments? I've found different filaments needing quite different heats

This isn't what folks usually refer to as "layer shifts" - those are generally permanent (for the rest of the print) and don't correct unless you get an equal opposite-direction shift, and are caused by things like a stepper motor skipping a step, a belt skipping a tooth, or the print surface shifting on the bed.
Your problem looks more like excess play in the positioning, particularly on the X axis, likely due to a very loose belt. If so, it will manifest differently in different layers due to the geometry and the last direction of motion.
It's also possible that it's Z wobble, where the toolhead experiences a Z-coordinate-dependent displacement in the X and Y directions due to irregularities in the Z motion system. This could be a bent or nicked lead screw or nut, flat spots or other damage to the V roller wheels, or debris on the aluminum V slot extrusions that the V wheels are rolling on.
The fact that the top layer came out very clean and consistent makes me actually suspect it's the latter - some sort of Z wobble.

Appreciate the detailed comment.  Tightening the Z axis belt removed most of the print issues however there seems to be another issue where the print is over-adhered to the stock flexible print bed.  This also results in the first layers oozing out.  Kind of apparent in the provided picture but not as much as other prints.

Marking this as correct answer because it was detailed and in the answer format. Didn’t take care of 100% but about 90% of issues.

source: Stack Exchange

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

sort: votes


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Is there an extensive XYZ Cube diagnosis resource?
I love the idea of the XYZ test cube to help diagnose my bad prints.   I’m able to find online very common print issues however am looking for a resource that is more extensive. Often I run into a situation where my issue is not covered.
Would be great if there was a resource that had pictures of numerous bad or less than ideal XYZ prints with cause and fix for each. I’m thinking of more than 50 examples.
Does anyone know of such a resource?

An XYZ cube is a calibration test for dimensional accuracy testing, it is not meant for extensive trouble shooting. Therefor, there are no specific resources for cube irregularities, the regular resources can be used for trouble shooting.
One of the better resources for troubleshooting print problems is found at Simplify3D or one at All3DP.

Do note that the dimensions in X and Y and Z are based on mechanical ratio's of the steppers with their pulleys or threaded rods, you can calculate the amount of steps required for the dimensional accuracy. It is only necessary to adjust this if e.g. the pulley is of a different diameter than the specification (as in poor quality dimensional pulley accuracy). In the basis you should not adjust the steps per mm based on small sized calibration cubes.

What type of test would you recommend for extensive testing ?

@wallwalker What kind of printer is this? E.g. did you check the belt tension, it appears you have positioning problems. The initial distance also might be a bit too large, but it is difficult to see. On Thingiverse there are many calibration tests to be found.

One of the sites that I have gone to for identifying problems is All3DP.com's page "3D Printing Troubleshooting All Common Problems". Here are the FDM and SLA issues they cover:
FDM 3D Printing Problems
Nothing is Printing

Out of Filament
Nozzle Too Close to Print Bed
Blocked Nozzle
Print Head Misses the Bed
Snapped Filament
Stripped Filament

My Print Failed

Extrusion Stopped Mid-Print
Print Doesn't Stick to Print Bed
Supports Fell Apart

My Print Looks Bad

First Layer is Messy
Print Bows Out at Bottom (Elephant's Foot)
Print Edges are Bending (Warping)
Infill Looks Messy and Incomplete
Gaps Between Infill and Outer Wall
Infill is Visible from the Outside
Cracks Have Appeared in Tall Objects
Layers Don't Line Up Well
Some Layers are Missing
Print Leans When it Shouldn't
Overhangs are Messy
Surface Areas Beneath Supports are Rough
Print is Unusually Weak/Looks Wrong (Non-Manifold Edges)
Fine Detail Not Printing Correctly
Ripples and "Echoes" in Print (Ringing)
Diagonal Scars on Print
Print Looks Stringy and Droopy (Over-Extrusion)
Print Layers Look Uniformly Thin/Weak (Under-Extrusion)
Print Looks Melted and Deformed
Pits and Hollows in Top Layer (Pillowing)
Web-like Strings Cover the Print (Stringing)
Print Has Lost Dimensional Accuracy
Print Offset in Some Places
Bridges are Messy

Something Else

Print is Stuck to Print Bed

SLA 3D Printing Problems
Nothing is Printing

Resin too Cold
Printing too Fast
Underpowered Laser

My Print Failed

Prints Not Adhering to Print Plate
A Section of the Print/Supports Detached or Moved

My Print Looks Bad

Layers Have Separated (Delamination)
Small Fins and Disks Attached to Print (Ragging)

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


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Is there somewhere a procedure to manually calibrate the PID?
I own a Balco rebranding of the Duplicator i3+ and after having replaced the plastic driving gearbox with a metallic one, it appears that for some reason the extrusion temperature became unstable and I suppose I should to re-calibrate the parameters of the PID.
However, I have been using this machine stand alone and I do not have a computer nearby nor the space to put one. And since it has a tactile screen, it won't show me the result of the gcode execution.
Does anyone know of a manual procedure to calibrate a PID in order to at least stop the temperature swings ?

It is unlikely that the driving gearbox influences PID values, since PID calibration is performed without the filament moving. Maybe some wires got loose or damaged. Maybe you touched the thermistor, most likely explanation. I would not worry with PID until everything else has been checked. You would likely waste time

Well, I found it unlikely too, but I tried to put the original plastic gearbox back to make sure, and the temperature got stable again with the default PID parameters. The only explanation I suspect, would be that it touches the cool block's dissipator and changes it's thermal properties.


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Setting Heat Bed Height Manually Mid-Print?
So, I've gotten the G-code to work regarding the waiting 10 seconds as I wanted it to. However, does anyone know if there is any G-code that exists that will allow me to manually set the height of the heatbed? I'm trying to find out after each layer if I give it 10 seconds to fully 'cure' or 'cool' to see if the results will be better. But I need to move the bed down away from the extruder.

The way to do this is something like:
G91     ; Relative coordinates mode
G0 Z5   ; Move +5 on Z axis
G4 S10  ; Dwell for 10 seconds
G0 Z-5  ; Move -5 on Z axis
G90     ; (Return to) absolute coordinates mode

You can of course insert this manually in the gcode between layers, but most slicers have functionality (built-in or as plugins) to let you do that automatically, or of course you could use a text-processing utility like sed, awk, or perl to do the insertions automatically if you're familiar with something like that and it's more to your liking.
In a since-deleted answer, Trish raised some reasons you might not want to do this, including significantly increasing the time your print takes and possible difficulties getting the next layer to adhere to a fully cooled layer. I'm not convinced the latter is a real problem, but these concerns are worth considering. Some other reasons not to do what you're asking about include:

Even with perfectly dialed-in retraction, a hot nozzle dwelling for 10 seconds will almost certainly start to ooze, giving underextrusion and poor surface quality right after restarting.

Most cooling occurs via the part cooling fan. If you move it away from the part, it won't do much. So you might find even after wasting 10 seconds per layer, your layers still aren't cool.

If you want to cool the entire layer effectively before the next layer goes down, I would recommend "side fan" setups that produce a thin layer of airflow (ideally laminar) at the current Z height. You can find examples of this in lots of the #speedboatrace speed Benchy entries on YouTube, especially on Vorons and other CoreXY machines since it's the easiest to setup on a printer where the bed moves down (like yours) rather than the nozzle moving up, being that you can just mount the fans and ducts at fixed height.
If you want to experiment with this without actually making fancy fan ducts and mounts, just get a desk fan or box fan and point it at your printer. This works surprisingly well.


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Remove irrelevant menu from Marlin 2.0
I'm using a Velleman K8400 with a Velleman LED strips. The strips aren't able to adjust luminosity only color, so the Custom Lights menu item is irrelevant to my printer. How do I remove the menu item? I can see how to easily add menus and items, but not much reference as to how to remove them.

Based on your hardware configuration and the firmware setup of your Configuration.h, the LED menu will be made available through the menu_led.cpp sources. Apparently, this work for you already considering you see too many entries.
To disable entries, you need to disable these in the afore mentioned code file.
To find where this menu is added to the configuration of the LCD menu structure you could search (the GitHub.com website provides a powerful search tool to search within the sources of projects) for the "Custom Lights" menu caption in the Marlin sources to find this caption is used by constant MSG_CUSTOM_LEDS, see the language translation file language_en.h
LSTR MSG_CUSTOM_LEDS                    = _UxGT("Custom Lights");

Now searching for the MSG_CUSTOM_LEDS constant will lead you to the file menu_led.cpp; more specific, this line:
SUBMENU(MSG_CUSTOM_LEDS, menu_led_custom);

If you disable this line, recompile the firmware and upload it to your controller board you would see that the submenu has disappeared.


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What is the optimum infill style for printing a roughly spherical object on an Ender 5?
I'm going to print several fruit and vegetable on an Ender 5, with a maximum size of 6 inches. They are all roughly spherical in shape. Melons, squash, etc.
What is the optimum in fill type to use to balance printing speed and surface quality, rather than strength.
I'm using Creality Slicer

Infill should not affect the surface quality. It mainly affects:

rigidity of the part (resistance to squishing in components where the outside surface geometry doesn't already make it rigid. Some infill structures are more rigid (or rigid in different directions) than others. For example, concentric and cross patterns intentionally provide very little rigidity and mainly serve to support what's above them, and 2D patterns like grid and triangles are maximally rigid in the Z direction while ones like cubic and gyroid provide more uniform rigidity.

strength of layer adhesion. This is usually not an issue when printing with thick walls, but with thinner walls or large interiors, the bonding of the infill layers can play a fairly big role. 2D patterns (ones where each layer of infill lines up exactly with the layer below it) are much stronger than 3D ones (where the infill shifts as you go up, so all the infill lines are "overhanging").

integrity of top surfaces above infill. If the infill density is too low, the first few layers of top surface will have very little (in some regions, nothing) to rest on and will simply cave in or even extrude as spaghetti. Usually this self-corrects after a few layers but it means you need many more (maybe 6+) top layers to get a reliable top surface

integrity of details protruding above infill. This is similar to top layers, but even worse if there's not enough infill for the protrusion's walls to be supported by. Rather than self-correcting, you'll get very weak or no bonding, and possibly even a completely failed print.

For the type of object you're printing, I suspect infill is of very low importance. You would probably do best to use 3 walls (at least 1.2 mm total thickness) and something like 5-10% gyroid infill. Before you print, just look at the sliced preview and make sure anything printed above the infill
seems to have infill supporting it from below.

Could you please specify why you recommend gyroid infill?

@AaarghZombies: Gyroid infill is generally the fastest to print for a given density, except for a few dubious options that don't provide much rigidity, so it makes a really good "default choice" if you're not particularly looking for special properties from the infill.

neglected factors: Infill also adds weight and can act as compartmentalizing, almost like a ship does it.


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I was updating my firmware for my 400XL kit for Ender 3 Pro and got an original firmware from the Creality website, but VSCode couldn't read it
Basically,

I got the XL
I installed the kit
I downloaded the firmware from the Marlin GitHub page (Version 1.1.9 for Ender 3 Pro v2)
I put it in VSCode but it says that it is not binary or uses unsupported text so VSCode can't even show me what is going on.

Question:

How can I make it into a supported text or read it?
Did I do it right using this method?
If not, what is my next option?

What exact firmware did you download? One of the ".bin" files? Those are already compiled and can not be edited, you'll need to download one in .zip format, where the whole Marlin "configuration.h" etc. structure is present.
Except for the very last option on their download page ("Ender-3 Pro_1.1.6.2V_Source Code.zip"), all files (illegaly) only contain the .bin or .hex files.
1.1.9 is ancient and obsolete.
It's probably a good idea to download a fresh copy of up-to-date Marlin (https://github.com/MarlinFirmware/Marlin) and copy over the correct configuration files from https://github.com/MarlinFirmware/Configurations/tree/import-2.0.x/config/examples/Creality/Ender-3%20Pro to get you started.


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Which 3D printing material is best for floating designs?
I am trying to print a shape (e.g. square container) using clear resin. However, I am facing the problem of the design sinking when I put it water. I am right now trying to make it hollow from the inside in some spots to reduce its density, but not sure how far can that take me. It is necessary for me that the print floats!

Do you guys have any tips? like a different print mater? or a change in shape that will help the design float?

My understanding of resin is that it's less suitable for this than FDM because it doesn't admit leaving air gaps in the interior. You probably need to make it hollow with a hole for a plug.

@github Resin printing is generally better for water and gas-tight fittings than fdm, which must be painstakingly calibrated and sliced to not have little pinhole gaps that leak. Suggestion of leaving a drain and making/finding a plug is good.

It appears your design has holes in the side near the bottom. It might be that these holes are letting water in and that's causing it to float. Simply tape over the holes to see if it will float, and if so, reprint without the holes. After all, boats float. At least, until they get holes in the hull...

@ChinchillaWafers: That was traditionally an issue but is becoming less and less so because of better hardware and software. Particularly, the advent of geared extruders with serious grip on the filament, rather than the ungeared flat hob stuff like a stock Ender 3, has made it practical to actually push out very close to the exact amount of material requested. And firmware advances (linear advance/pressure advance) as well as slicer advances (not leaving stupid gaps) have made it possible to actually get that material put in the right places.

The material doesn't matter*
Floating designs are exactly that: designs. If the design is made to float, and your printer can create a watertight shell (which is a different problem than the material), then you can use any material. Well, almost any, because:
Only one caveat remains
The only type of material that isn't suitable is any material that will dissolve in the fluid it will swim in. Like PVA in water.
Otherwise, the material only matters for other properties, but not for "it can float".
How to design a floating item?
When does a design float? Well, the rule described by Archimedes is often described as "An item floats if when the volume of water it displaces is lighter than the item." In other words: if its density is lower than water.
However, it's not that simple after the first look: What is the volume and weight of the boat? After all, we can make steel, which weighs upwards of 3 tons per cubic meter float while water is only 1 ton a cubic meter. What is the mystery part? It is simple: the underwater ship does not allow ingress.
Draft depth
So, we want a solid wall from the lowest part to the line the item will sink into when it reaches equilibrium. That's the draft depth. For ships, there is a formula to quickly calculate the draft depth based on knowing how much water will be displaced:

Seal all the holes and gaps in the boat. Now measure the volume the item displaces when it is put onto the water. Call it $V$.
Take the surface area of the boat. Call it $A$.
The Draft $d$ is now $d=\frac V A$

In the alternative:

Make a volume item by removing the holes into the contained volume and filling those voids to the upper rim. Have your CAD tell you the contained Volume. This is $V_w$.
Weigh your printed item. This is $M_p$. We turn that into Displaced Volume $V_d$ by using water density: $V_d=M_p*1000\frac {\text {mm}^3}{\text g}$
Make a plane cut of our volume item, so that the lower part of the item has the same volume as the displaced volume. That is how much of the boat will be underwater.

The second method also works for tilted or very asymmetric shapes (like a bot listing), while the first is roughly over the thumb.
Now, how does that help with the design? Remember, we had sealed the slots earlier. If the slots are in any way below our draft depth, then water ingress happens through that slot - and the slot will have to be moved above the draft depth.
Dasign adjustments
There are several adjustments to get the item to have a lower draft, but all of them boil down to reducing the density.
In the case of your design, the hanging floor of the basin can have a lot of it cut away and turned into a grid of sorts, which would reduce the impact this part of the print has to the total density.
You could also move the slots up enough so that it will be above the waterline, even if filled to an expected degree.
If you really need to include voids, you will need to alter your printing code in between layers, because resin printers don't typically raise the print fuly out of the resin vat and have such hollows filled with resin as a result. And please try to avoid Cupping


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Marlin + BLTouch layer compression
I have an Ender 3 Pro which I recently added an SKR Mini E3 v2.0 with Marlin and BLTouch.  I have run into an odd issue where roughly the first 10 mm of the print are compressed into ~7 mm of Z height.  I don't think its mechanical based on the following process.

Power on the printer, Auto Home.
Move the print head to the middle of the bed ~1 mm off the print surface (move the nozzle down until it touches, then back of 1 mm)
Measure the nozzle height relative to the print bed, command a 10 mm Z move, measure the Z nozzle height it's 10 mm higher.
Level the bed with the BLTouch (The Z offset is correct and 0 mm is basically at the print surface)
Repeat the process above, start with the nozzle 1 mm off the bed, command a 10 mm move.  The measured height of the nozzle is now only 7.5 mm higher than it was.
Anything I try after this (rehoming, running bed leveling again) still results in a 7.5 mm move when a 10 mm is commanded.  It's only the 10 mm closest to the bed, a second 10 mm postive move results in 10 mm delta to the nozzle height.

All prints consistently have the same compression of the first layers.
Two other pieces of information that seem like they are relevant, the Z zero when homed is about 2.5 mm lower than when I run bed leveling.  ENABLE_LEVELING_FADE_HEIGHT is set to 10.0 mm.  Those two numbers combined seem really suspicious to me, but its not clear to me what to change if that is the problem.
This calibration block should be 50 mm high, it's 47 mm high and the 3 mm are lost in the first 25mm step:

Does the Z screw move at all during the printing of the first 3 mm?

Yes, its a proportional reduction.  I ran some test last night (sorry I haven't updated the question yet), and it appears to be caused by the offset between the z homing switch and the bed height.  If they are aligned, the problem goes away.  So its definitely related to the levelling fade height option.  I'm just not sure why the fad accounts for offset as well as the bed being skewed.


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What is this 4 pin header on the Creality 4.2.3 board?
What might these 4 pins be on the Creality 4.2.3 board be?
The silkscreen says
G
SC
SD
V

It is next to the pin header for the LCD, so I suspect it is either a UART or TFT port.
Googling I suspect SD might be short for SDA and SC might be short for SCL. Which are common I2C pin descriptions.
https://github.com/MarlinFirmware/Marlin/pull/23307#issuecomment-996371949

I found the unofficial schematics for the very similar 4.2.2 Creality board.
It contains a 4 pin header titled ICSP port.
Note that these appear to be 3.3 V pins


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How can cyanoacrylate haze be removed from PLA?
Using cyanoacrylate to glue PLA parts sometimes leaves a white residue or haze near the glue locations.  Is there an easy way to remove it?
I've tried water and alcohol swabs but after drying the haze remains.

Chemistry excursus: the white haze is not the PLA but the CA curing in a rough surface fashion and turning white.

Is this question a duplicate of the earlier question How to get superglue off PLA filament?..? I don't want to flag is as a duplicate myself, as I'll end up unilaterally closing this question and I may not be correct in my assumption...

@Greenonline I'd even say: merge the two.

Doing a Google search turned up the article "How To Prevent/Remove White Superglue Residue" on MyCustomHotwheels.com.
According to the article, the haze is caused "by trace amounts of moisture on the substrate surfaces". Of course, the author does talk about how to prevent this haze beforehand by using quality Superglue.
Towards the bottom of the article, there are two solutions to removing the haze: a heat gun and petroleum jelly. Two YouTube videos provide live demonstrations of the removal of the haze (provided below).
The heat gun method uses 100 ° air. The narrator of the video does not specify Celsius or Fahrenheit but he does have an accent so I would guess that he's not American and therefore the temperature is probably Celsius.
The petroleum jelly is used in the second video. The narrator doesn't have great success at first until he cleans the plastic a second time.

100 °F would be the heat of a hand, not needing a heatgun at all. I use a heatgun to debubble Epoxy at times, while it is still wet.

I tried a heat gun with a digital temperature control, set at 100° C. It didn't touch the haze; no effect at all.  I was reluctant to dial the heat any higher so gave up on that.  I then went to Vaseline and was immediately successful.  The white haze disappears instantly with no rubbing required. After wiping off all the Vaseline the surface remained perfectly clean.  It couldn't have been easier. I'm marking this answer accepted.  Thanks for the help.

Incidentally, this whitish "haze" is exactly what I've found happens when objects printed with certain "PLA" filaments (likely containing additives other than PLA, since PLA isn't supposed to be affected by it) are exposed to acetone. CA glue is soluble in acetone and likely contains acetone or similar solvents, and it seems a plausible explanation is that the solvent is leeching whatever part of the material is soluble out of the part, then depositing it back on the surface after it dries. The pigments are likely not soluble and remain below.
I've had some success just rubbing the "haze" material off with a cloth while it's not entirely dry, but that's without the CA adhesive which would make rubbing it while wet... inadvisible.
If the part is amenable to sanding, sanding lightly once it's fully dry may be a good option.
For what it's worth, I don't get this effect using CA glue on PLA, but I always use the extremely low-viscosity, fast-drying type (Loctite 420 and other brand equivalents), so using one of these might be a solution for the future (although not for any part already affected).

Acetone or alcohol hasn't worked at all for me, if anything it made it worse by stripping the PLA of the sheen its supposed to have. I have tried various types of Acetone as well, all with similar results.
I know this will sound crazy, but I have been doing this for about 6 months. I use Sesame Oil, applied generously with a Q-tip, and then I "rub it in/dry it off" with a paper towel. This has worked on various sheens of PLA and PLA+ and completely removes any evidence of super glue. I haven't seen the oil dry out yet either. At first I thought the oil would wear off or dry out, but it has not yet and its been 6 months since I've been doing this.


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PETG layers are super rough
I own a spool of PETG and I have been having major print quality issues: layer offsets, chunks of 3D print strewn across the buildplate and other things. I traced these effects to a single culprit: rough layers. I don't know how to fix this. I haven't had this issue at all with any of my other PETG filament colors. And the buildplate height is just where it needs to be, so why is this happening?
Print settings

Layer height: 0.23 mm
Extruder: 235 °C
Bed: 80 °C
Retraction length: 6 mm
Retraction extra restart length: 0.3 mm
Z-Hop height: 0.25 mm
Base print speed: 45 mm/s
Extrusion ratio: 106 %

What slicer are you using? Do you have "combing" enabled?

I am using Flash print. I dont know where to find "combing in my print settings" @R..GitHubSTOPHELPINGICE

Go a little warmer. Maybe 242. Also, that retraction number looks okay if you have a bowden setup, but it's way too high if you don't (1.5 is a better starting number)

Do you have a picture you could add?

You are probably over extruding, this causes an excess amount of filament causing the mentioned problems. PETG is softer than PLA, so the extruder teeth grip deeper into the filament. This smaller diameter causes too much filament flow. Try to decrease the flow modifier for this spool of PETG.
Furthermore, your spool may have picked up some moisture, please dry the spool prior to use.

Go a little warmer. Maybe 242.
Also, that 6 mm retraction number looks okay if you have a Bowden setup, but it's way too high if you don't (1.5 is a better starting number).
Finally, there are those who disagree on this point, but I only change my extrusion from the default 100% when I notice issues on specific prints. Ultimately, the extra 6% extruded material has to go somewhere, and it's likely contributing to the roughness.


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What are the limits of SLA 3D printing for optical lenses (e.g. glasses)
I'm interested in making optical lenses, but I do not want to spend too much on it. What are the limits and criteria which will help me decide which SLA printer will make it possible or not?
I suppose the first criterion will be the resolution which will require more or less polishing afterwards, but are there other things to check and some which would constitute an absolute no-go with low-range machines?

Seems to me the most important criteria is how transparent is the resin after it's cured. If it's not transparent enough, it doesn't matter how much (or little) you have to polish it, you won't get light through it.

You are right about that, but the fact that this technology IS used, means that resins which are OK for that DO exist. e.g.: https://formlabs.com/blog/creating-camera-lenses-with-stereolithography/


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Not printing the holes
I am new at this and maybe my model is not the best, I adapted it for another one actually. Can you tell me why I can't get the holes printed? I already checked the faces and they are all in the correct orientation (I think)
What happens is that I start printing with the holes facing down and they are not printed at all. I never let it keep going for long but it seems to be completely filled inside.
You can check the file here.

Please consider to edit your post with the original file you modified and also the program with which you created the modifications. If you are able, use the original program to address the specific areas of the model indicated by the red lines.

I see inverted faces.. your cylinder is it inside out

@Trish, I don't understand what you mean by inside out

@PatriciaMartins, STL files are a bunch of triangles, which have an inside and an outside. If a triangle represents a surface viewable from the outside, it is an outside triangle. If a triangle is misplaced, the inside will be visible. In Meshmixer, the result is a zebra-striped surface, none of which are visible in the image I created/attached to the answer.

Additionally, when I performed a plane cut in Meshmixer, perpendicular to the axis of rotation, the internal surfaces became visible, and were zebra-striped, which tells me that the insides are on the inside, where they belong.

@fred_dot_u the Purple-Blue marking in blender demarks areas that are either inverted triangles or other areas that lead to a non manifold area.

@Trish, perhaps the perspective of the screen capture is masking the internal confused normals. I see you've performed nearly the same sequence to clean up the model as I did, and provided clear images of the failed points.

@fred_dot_u indeed. I used blender, which actually got me to the result by just removing a couple of vertices

Do you have a plan/drawing with dimensions?  Might be easier and safer to recreate it from scratch in various tools, and see how they all compare.

@Trish, I suspected you were a Blender wizard. I suspected also this would have been created in Blender, although that has no foundation, just a guess.

The problem is internal geomoetry
The body you modeled consists of a non-manifold shell: There exists a fully enclosed shell on the inside of the item that tries to define an "outside" of the body. In the following picture, I have hidden part of the geometry to better show the problematic internal surfaces in orange:

Automatic processes such as Meshmixer or Windows 10 3D builder interpret such an internal, one-sided open cylinder as "This probably is missing a surface on both ends". This solution leads to two intersecting and manifold shells - a cylinder overlapping the drilled holes and the body with the drilled holes - which then promptly get treated with a boolean union... and voila! No more holes. Or even no more outer shell as the easiest solution is to just stitch that lower surface and discard the rest. This is what happens when Meshmixer does just that: you are left with the cone half and some inverted artifact areas.

So the best solution is to ensure the parts don't contain such volumes encased by a non-manifold surface in the first place. Due to the nature of the part, in this case, it is rather simple: Simply removing the circle of vertices that spans up both the plane, as well as the cylinder, marked orange results in all internal surfaces getting removed. Note that due to the orange parts sharing (at least partially) vertices with the wanted outside, this has to be done manually. Would both surfaces share no vertex, a simple "separate shells" operation could result in a very quick way to remove offending structures.

Without the internal geometry, the model gets interpreted correctly - the mere presence of such superfluous internal geometry makes the slicer believe that some surfaces are inverted or missing, and thus need to be inverted or stitched - and the solution to the slicing is... utter mess.

The overall appearance is that the normals are "normal," that you have no reversed facets, but there are discontinuities within the model that Meshmixer and Netfabb show as failure points. Windows 10 3DBuilder also attempts a repair which fills in the holes.

The Meshmixer capture image shows red lines and points at the flaws in the model. Both above programs fill the faces, which works fine on the cylinder, but fills in the plane where the holes reside, as well as removes the internal holes/cylinders, preventing a simple plane cut repair.
Additional examination of the original model shows an internal cylinder formed axially on the end face red warning markers in the image above.
I used Rhino3D v6 to slip inside, select the cylinder and remove it. Because the cylinder is "inside" the overall model, there's no inside face and outside face, causing the software to glitch.
On the red line along the circumference of the cylinder, there's an internal disk/disc with an internal diameter to match the previously removed internal cylinder. As it also resides within the overall model, the same trouble applies: no true inside/outside surface for the software to comprehend.
Once these were removed, a problematic set of errors appeared. I'm working on that. Work completed. Windows 10 3DBuilder has a pretty amazing repair facility, once the deep stuff is cleaned away. The end result passes the Meshmixer Inspector test and I suspect will work for you. The cylinder appears to be 37 mm in diameter (about an inch and a half) which is rather tiny, but with the flaws repaired, will scale up just fine.
It loaded into Simplify3D slicer with no errors and appears will print nicely, although with support required along the beveled portion of the cylinder.

Could you please post the last paragraph as a comment on the question? (And remove it from the answer)

Your repair too just removed the internal geometry. The twice "normals this way" in a row results in the slicer interpreting one side as "this MUST be inside out or is lacking a surface"


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My Ender 3 v2 has randomly turned off and no longer turns on. Any suggestions on how to fix this?
About a day ago my Ender 3 v2 just shut off while printing. It didn’t really bother me since this has happened many times before and switching the power supply off and then turning it on would fix the issue. This time though the printer is no longer turning on. I opened up the power supply and the indicator light is turning on, but when I check the outputs with a voltage meter it says 0. What could be the problem here?

Could be a fuse or some other part blown... are you certified to perform mains voltage work?

Is it under warranty still?  There's no reason to fiddle with something that should be replaced under warranty.

And there is even less reason to fiddle with mains voltage inside a running power supply unit - which might kill you if you mishandle it.

Check all the connections - I had something similar and fixed it by pushing a plug back into its socket.

Thanks for the suggestions guys. There was no fuses that were blown and all the wires were secured in their sockets. My printer was already out of warranty so I ended up just ordering a new one which will arrive today.

I don't know what the PSU of an Ender 3 v2 looks like, but lots of PSU have a last-resort fuse: a fuse that's internal, only works once and is not easily replaced. It's quite possibly that one blew out and that's why the indicator still works while the rest doesn't.

I'm not familiar with that particular power supply, but usually they have a fuse. In your case it's more likely to be a capacitator causing the problem though as fuses are not intermittent problems and they're usually situated before any board lights for obvious reasons. They normally either work or fail.
I'm assuming you checked for loose wires and connections.
This is a job for an electrician, capacitators cannot easily be tested without proper equipment and need some good soldering skills to replace properly. If they're liquid filled then you can sometimes see doming on the top of the capacitator where it looks a bit deformed. Or even a leak. If they're solid state then there is no easy way to see if they're failing.


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Anet A8 inaccurate printing
I'm trying to print this with an Anet A8

It's supposed to be completely cylindrical but it's printing it all wobbly and with edges.

I'm a complete noob with 3D printing, so any tips would be highly appreciated

Consider to print a calibration test cube to determine if you have an X axis problem or a Y axis problem. This will help narrow the focus of troubleshooting. Also provide speeds and temperatures and material specifications, i.e., PLA, 60 mm/sec, 60 °C bed, 200 °C nozzle. Probably unrelated, but often useful.

When your belts are not tight enough or there is friction, you get these problems with positioning, please look into the belt tension and comment back if so, I will then post an answer.

Definitely print a calibration cube first. If print one with a bit of a brim, you can often tell a lot by how the rounded corners of the brim look as well. Saves you from having to print a calibration cylinder :-)


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Weird top layers on Ender 3 Pro
This problem has been occurring for a while. On the top of round objects, you can see the individual layers. Maybe I just need a lower layer height.

Please [edit] in additional information such as printing temps, speeds, etc. to help offer a solution.

See this answer, it describes why the top layers of dome/round shapes are rough.

At the top of curves layers will always be more visible because the layers are increasing offset from each other. Layer height will help with this, but if you really want it smooth you will need to do some post-processing.
Usually if possible I avoid having a top surface like that of any significant size. But when I do I either leave it and post process or add some little design elements to break it up a bit. So it's still there but not really noticeable.

Kilisi is absolutely right that you necessarily (without advanced non-planar slicing techniques that aren't available in production slicers) have a "stairstep" effect whenever you have a shallow angle top surface like that. However, it looks from your picture like you also have some gaps that are accentuating the problem and making your top surface non-watertight. This can be fixed.
Slicers (at least Cura) are fairly bad about figuring out where they have to put material under the very top layer to ensure that you have a solid wall of the desired thickness. Where the outer wall face is pointing almost-upward, you would need either a lot more outer perimeters than the shell thickness you want, because they're significantly offset from each other (often by as much or more than the whole 2D wall width) at each successive layer. Using excessively many walls will solve this, but wastes a lot of print time and material. Using more top layers is the easiest fix I know. I find that 5 top layers at 0.2 layer height pretty much always gives solid curved tops, even with spherical top shape. The only way that might fail is if you have really low infill and they all "sink in" rather than bonding properly.
Of course these gaps could also be caused by underextrusion or misplaced extrusion. Check instructions for enabling and calibrating Linear Advance/Pressure Advance on your printer for one of the big ingredients in fixing top gaps and related extrusion inaccuracy problems.


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Creality Ender 3 V2 little yellow switch on power supply
I just bought and built a Creality Ender 3 V2.  The last step of the setup is to flip this little yellow switch on the power supply to be either 115 V or 230 V.  From my other research, I think that I have to flip the switch to 115 V because I live in the US. Since US standard outlets give 120 V of electricity and not 115 V, I am confused.  Why is 115 V "correct" if the voltage I will supply is actually 120 V?  Will this extra 5 volts burn out the printer?

It won't burn it out. The voltage is between 110 to 125. Power supplies are designed to work in that range. So sometimes you'll see appliances rated for 110 V, 115 V, 120 V... they actually are all the same.

Came to answer this, but you beat me to it! The only thing I would've added was this link that explains that the 115 V can suggest that it will operate despite the voltage drop in the cord between printer (or other appliance) and outlet.

so, just to make sure I understand, you are saying that American outlets actually output between 110V and 125V and appliances with ratings anywhere in that range are probably the same?

Not probably, it's standard for any appliances with the 230/120 V rating switch. So the 230 side would work in New Zealand or elsewhere that has a 240 V rating.

@brothman01, go visit [diy.se] for 10,000 questions (give or take...) about the varying voltages. This answer is 100% correct. The US has officially been 120/240v for about 40-50 years, but people still talk about 110v and 220v. Most devices will function just fine with about a 10% variation in voltage, and with international markets, most are actually auto-sensing and will switch internally between 120v & 240v. It's rather surprising that you have to manually flip the switch to specify.


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Does an uneven resin printer matter if the build plate is level with LCD?
I am using an Elegoo Saturn S and have leveled the build plate per manufacturer's instructions a handful of times. However, I have yet to get a successful print except for the rook model that came with the printer and a couple Validation Matrix prints, which are pretty thin. I've switched resins and am finding more luck with grey vs white. White always resulted in delamination at some point early in the print and supports not printing (even with thicker supports). Grey is printing alright for the most part but most of the raft falls off the build plate. There's just enough adhesion that the print does not outright fail (surprisingly) but a good 60%-70% of the raft is hanging loose. I had one print that could have finished and the current print is about half loose
I assume that this is a leveling issue, but as I said, I've leveled the bed numerous times. I bought a new build plate (to counteract another problem) and I've recently changed the FEP. It wasn't until this change and switching to grey resin that I've had any remote success. One thing I've noticed is that the resin pools more to the left side suggesting the work area is not level. Would this matter? I figured that if the build plate is level with the LCD, it shouldn't matter if everything is off. The angle seems to be about 2 or 3 degrees.
My current settings:

Bottom Layers: 5
Bottom Exposure: 30 s (white resin adheres too well almost for bottom)
Bottom Lift: 5 mm
Normal Exposure: 2.5 or 3 s (monochrome LCD)
Normal Lift: 4 mm
Retract Speed: 70 mm/m (for both bottom and normal)
Layer Thickness: 0.05 mm

Originally sliced with ChituBox, but that stopped working for some reason. Slicing with Lychee now.

You mean the printer is sitting not parallel to the ground?

@Trish Correct. I've tried shimming the feet so it's more level but it's still pretty uneven. As far as I can tell the build plate is level with the LCD. It's the whole printer unit that is leaning.

You have a 3D printer. Print some shims to level the printer. They don't have to be perfect, just functional.

Within reason, yes
If you can't put the printer down 100 % even, that's ok. The most crucial thing is, that during the whole operation the resin level in the printer does never get over the edge of the print basin and that at the lowest level, everything is covered still. It's still better to settle the printer as even as possible.


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Chitubox stopped slicing files correctly
I just bought an Elegoo Saturn S and used ChituBox for slicing. I had sliced a couple of models but for some reason the printer stopped recognizing the .ctb files the other day. I sliced a model and started the print, but it failed. Then when I tweaked the settings and sliced again, the printer said that the file was an unrecognized file type. The file shows up and I can see the name and .ctb, but the image is a folder instead of the actual model. I sliced directly to the USB as well as sliced to the PC and copied the file over to the jump drive.
I looked online and saw that I should to downgrade from ChituBox 1.9.0 down to 1.8.something. Since I was using 1.9.2, I assumed that the former advice was out of date and didn't want to deal with downgrading since there's a whole process with log files and directories or something.
Another commenter said that the firmware may be out of date so I ensured that my firmware is up to date.
Another recommendation was to try a new USB stick since the one with the printer is garbage, but the problem persisted. I formatted both drives a couple of times and nothing worked. I've switched to Lychee which sliced files that the printer actually recognized as files.
While the blaring answer is "Just use Lychee, duh!" I am curious if there is a fix/workaround for ChituBox in case this pops up again.
Update: Well, this seems to happen with Lychee now too. I slice a file and the printer still recognizes that the file exists including the .ctb filetype and it shows a folder instead of a preview of the model. When I go to print, the printer says "Unrecognized file extension." This happens with the jump drive that came with the printer. The second jump drive I use doesn't even get recognized by the printer. Everything is blank when I plug it in. From my limited research, allegedly the Saturn doesn't do well with USB 3.0 for some reason.
Resliced files and sliced new files using both Lychee and ChituBox on two brand new, USB 2.0 16 GB jump drives of differing brands. I was informed that perhaps the size of the jump drive may be a problem. Both jump drives are using FAT32, as recommended on an Elegoo forum. Problem persists.

After a week of consternation, I finally figured it out. I had to order a new build plate since the original got cured resin on it and is no longer a flat surface. Elegoo does not sell replacement Saturn S build plates (which are larger) but sells replacement Saturn plates.
To avoid trying to print on an absent portion of the build plate, I added the Saturn profile to my slicer software. Not a lot of models will need that extra 2 mm of build plate edges, but I'd rather have the slicer figure out the orientation of the model on a smaller plate than do it manually myself. I assumed that these profiles were just for entering optimized print settings (exposure times, build volume, etc.) and that the Saturn and Saturn S were close enough that I could cut this corner.
I have been slicing under the Saturn profile, which results in "unrecognized file format" errors. It dawned on me that perhaps I should not use that profile so I sliced with my previously working Saturn S profile. Printer recognized the format, model was previewed, and it is currently printing right now.
So, if you are slicing models and your printer stops recognizing the sliced files, perhaps you are on the wrong profile. I asked this question to see if anyone knows the particulars behind these profiles since it seems they are more than just the printer settings.


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When Z-axis is autohoming the print head moves too far to the right and starts grinding
Installing BLTouch on Ender 3 with SKR Mini E3 v2 motherboard, flash the firmware and do the first autohome, X and Y-axis autohome to the endstops just fine, but then the print head moves to the position it wants to be in to start the Z-axis homing, and it tries to move past the opposite end of the X-axis and starts grinding.
It grinds for a second or two then stops and begins the Z-axis homing with the BLTouch, but I haven't completed the Z-homing to see if that works yet as I quickly shut down the printer when grinding starts so that it won't damage anything.
I tried changing print bed size in firmware and print margins, but that didn't help, I also thought it might be due to the "z-safe-homing" option being enabled in the firmware but when I disabled that I got an error when I tried to compile it saying that it needs to be enabled when using the BLTouch.
I've been trying to sort this for a few weeks now and haven't had any luck so I thought I'd reach out.

Please post a link to your configuration.h file.

https://www.dropbox.com/s/z6hix30bpice9dz/Configuration.h?dl=0

Are you using the Z-endstop or the complete Z-probe header of the E3 Mini V2.0? Note that there are some differences with the default Ender 3 config profile.

complete z-probe header, bltouch is plugged into bltouch slot in motherboard, z-stop is removed (nothing plugged into z-stop slot)

Recently, ran into the same issue on Ender 3 V2 after flashing Klipper. Default Marlin had no issues but klipper was grinding the Y axis after every print when it goes to Y235... it could only go to Y230
After a lot of digging it turned out that Ender end-switch is 5mm off before the actual physical end.
End up fixing it with the following settings in printer.cfg
[stepper_y]
step_pin: PB8
dir_pin: PB7
enable_pin: !PC3
microsteps: 16
rotation_distance: 40
endstop_pin: ^PA6
position_endstop: 5 #End-stop is not at 0
position_max: 235 #If endstop is 0 235 will grind
position_min: 5 #Prevents moving to 0 and griding in this direction
homing_speed: 20

Don't know what the equivalent for Marlin is. Good luck.


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Practical overhang limits
What are the real overhang limits? I see a lot online about 45 %, then up to 60 %, but I'm routinely doing them at up to 90 % for "shortish" distances and 80%+ for several centimeters at a time. I haven't tried to see how far I can do it, since I don't have filament to waste on that sort of thing.
It's making me wonder how believable all the YouTube and website experts are. Same thing with stringing, they all talk about it on Ender 3's but this print has been going for 25 hours and has maybe two tiny strings.
This is the second time I've printed this same STL with no supports.

0.2 mm layer height
Ender 3 Pro
Generic PLA

"Real overhang limits" are hard to define. If you want accurate extrusion, such that precision parts fit together correctly or angled geometric surfaces that are supposed to be flat come out flat, each extrusion line must have at least some minimal portion of itself (probably including its center line) printed on top of and against existing material underneath that already has sufficient rigidity (both geometrically and in terms of cooling) not to deflect when printing against it. In this sense, the overhang angle is arctan(lw * (1-k) / lh) where lh is layer height, lw is line width (normally nozzle width), and k is the portion of overlap you demand. For example at 0.4 line width, 0.2 layer height, and 50% overlap, you get out exactly 45°.
If you just want the printed part to have basic structural integrity, things get a lot more fuzzy, and dependent on the geometry - particularly, the convexity/cocavity of any overhanging extrusions. Concave overhangs, like the inside of a spherical dome, will quickly fail as soon as you lose most or all of the overlap - expect them to hard-fail at arctan(lw/lh) (63° in 0.4/0.2 case) since the material will just be dragged inward around the curve with nothing to stick to. You might get a little bit more overhang if there's already a horizontally adjacent extrusion in the new layer for the material to stick to, but in my experience it will be unreliable.
Convex overhangs, on the other hand, can work out even when they're extreme. This is because the curvature of the toolhead path pulls the new material towards/against a region where it has existing material to bond to.
Keep in mind that layer height is a free parameter you can tune, that greatly increases the overhang available to you. Some slicers also have "adaptive layer height" settings to use thinner layers precisely in the layers that have severe overhangs. Line width is also a parameter you can tune, and increasing it works in your favor up to a point. But once you get to a point where the "wider than nozzle" line is attempted over thin air, it will fail badly, sagging down rather than expanding to the desired width, and not bonding to adjacent lines. So if you use wider lines to get better overhangs, you need to be very attentive not to go over angles that would place their centers off of the previous layer.

Thats a pretty good explanation, what would you call 'extreme'?

@Kilisi: I don't have a figure in mind, but I know I've printed some solid parts, including cosmetic surface quality, with convex overhangs over 70°. If you slice to print walls from the innermost going outward, I can imagine that a convex overhang (with continuous curvature, not long straight segments) might work well even when only the innermost wall of the new layer sits on existing material from the previous layer, which could be up to something like 80° with 3 walls (and 0.4/0.2).

Makes sense. I don't really do complex parts. Good to know other people have done steeper overhangs. Why does everyone talk about parts, I can't see a market for them, anything I print would be cheaper and faster to buy.

@Kilisi: "Part" is kinda just the generic term a lot of folks use for "printed object", but there's so much you can print that is a "part" in the sense of filling some mechanical/structural role that would be prohibitively difficult to obtain in any other way short of just buying a complete replacement for whatever needs it. This includes things like door closer brackets (one I did recently), gears, specialized tubing couplers/adapters, electronics enclosures, and of course components for more 3D printers, CNC machines, or other tools/machinery used for making things.

I get that some parts are hard to obtain, but I'm an engineer I could fabricate a structural part out of wood, metal, plastic or something else faster and stronger than anything I could 3d print.

"why would anyone buy 3d printed parts" sounds like a good question to ask separately.

@user10489: The question suggested in the comments here didn't seem to be about buying 3d printed parts, just questioning the very concept of making them. If you'd like to take a stab at asking this question in a form that's within the scope of the site, not too opinion-based, etc. I'd be happy to take a stab at answering it.

@R..GitHubSTOPHELPINGICE great, I asked it in a separate question, interested in your take on the matter, you seem to have a good logical grasp of things.

@user10489 the question was asked, feel free to give your thoughts on the matter

It is very difficult to determine a definitive number/value for the overhang angle, this is very dependent on the temperature, speed, material, nr. of walls amount of cooling fan percentage and the effectivity of the fan duct and your object geometry. Probably more settings are applicable.
You could find out what the specific values for you printer and your settings are by printing an overhang test, e.g. like this one:

Such a test will give you definitive answers on the overhang angle for your specific slicer settings and machine capabilities.

From my limited experience there is very little in the way of overhangs that won't print for a short distance. Depending what you're printing and what it's end use will be.
In this case it needs to be robust enough for daily use holding napkins and toothpicks and cutlery at a restaurant.
The model in the question printed for about 3 centimeters well over the threshold as shown in the picture and will print a bit more before joining the rest of the arm.
The overhang tests available online are in my opinion a waste of time. It would be very bad design to print something like them because if it's not joining anything it would be too fragile to be any use. Dropping it off a table accidently or breathing too hard near it might result in it snapping.
So if the distance is short anything up to about 80 - 85 % is possible. What happens is that the leading edge bends upwards a little bit after it prints. Then the next layer heats it soft and pushes it down and deposits on top of it (which then warps upwards) until it eventually reaches the join where the final warp is pushed down and joins nicely.
You can do all the fancy tests you want, but this is how it actually works in practice.
I find that post processing afterwards is minimal, less than if I'd used supports.


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Does VHB tape stick better on 3D prints if the surface is completely flat or roughed up?
I made a hook recently that I put up with VHB tape. It fell off around 2 weeks later (the hook come loose from the tape). It's just a hook for an empty backpack, so let's say it is under medium load.
Every time I design something like this I wonder if it helps to roughen up the surface before applying the tape. I'd imagine that the tape grabs onto grooves made with a knife or sandpaper but I am not sure tbh. I've seen some videos where someone preheats the tape before applying it but without explaining why.
Does anyone know how that works best?

If you ook into the VHB design document, the section "How to Prepare Specific Surfaces" describes how to treat the surface:

For higher adhesion, a primer should be used according to the document.
This reference describes that roughing up plastic parts can be beneficial for the adhesion of some tapes:

Abrade the Surface:  Roughing up the surface (i.e. sanding) will loosen up any accumulated dirt, rust, or chipped paint.  It will aid in the adhesion to painted surfaces or plastic items.  A finely- abraded surface with shallow scratches created by a circular motion (rather than straight lines) has the best potential for a strong and persistent bond.  This method can create up to a 40 % increase in surface area and can result in greater immediate and long-term bonding potential.  Scrub pads, fine steel wool, or sandpaper can achieve the right level of abrasion.  A palm sander could be helpful for larger jobs.  Avoid using coarse abrasive materials because a too-rough substrate may inhibit the adhesive flow onto the surface.   Always clean with the IPA/Water solution, or other solvents, and make sure all loose particles are removed.  While it is not typical, some high-bond tapes adhere best to smooth, glassy surfaces, so double check with the manufacturer before you abrade the surface and compromise the bond strength.

Both references describe the use of a cleaning solution based on 50 % water and 50 % IPA.

A higher temperature is beneficial for obtaining the bond strength faster, the VHB design document shows that increasing temperature shortens the time when the full bond strength is reached:


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Hotend melting mount
I have an old custom 3D printer that I bought a new hotend for since the old one broke, and apparently, I made a mistake.
The old hotend had insulation on it that prevented it from melting the mounting point on the printer itself, but the new one is all metal.
When I heated up the new head for the first time it melted the mounting point and fell out.
When is the best solution for my case?
Is there some insulation I can put on the new head? I can't find another insulated head anywhere.

Adding photos of the old and new hotend could be beneficial for answering the question.

As stated, photos would help us understand better... couldn't use reuse the insulation from the old hotend, i.e. cannibalise it?

I assume that the mounting plate is plastic (hopefully metal isn't melting), but this may be good information to include. Does your hot end have a cooling fan? Usually the heat break has a fan. Perhaps this could help (though I doubt it).

Hotends need insulation. Not just to prevent melting the mounting bracket, but:

To prevent heat loss to the air, especially with part cooling fans active, that could reduce the ability to heat or even trigger thermal runaway protection from complete inability to increase temperature beyond a point.

To prevent dumping heat on the printed part, which fights with your part cooling fan and greatly diminishes its effectiveness.

At the very least, the heater block needs a silicone sock. You can also use high temperature ceramic fiber or "rock wool" insulation like you'd use for an oven or kiln, and/or just layers of aluminum foil (which reflects a lot of the heat, while air pockets between layers provide insulation).
To find an appropriate sock for your hotend, search for its model name together with "silicone sock". You can also make your own using high-temperature RTV silicone (for example Permatex 81878) and a mold if you have a block with odd dimensions that nobody seems to be selling socks for.
In your question you mentioned "all metal". In the context of hotends, "all metal" generally doesn't mean that there is no non-metal insulation or other material attached or that it's not okay to attach such, just that there is no PTFE or other material that can't handle high temperatures in direct contact with the hot parts. It's perfectly reasonable (and necessary) to put proper insulation on an all-metal hotend.

depends... you can safely mount the coldend of the hotend (aka cooler body) to a plastic mount, if the cooling body below properly gets rid of the heat - such as in the e3D v6 design

@Trish: If the plastic is something that can withstand at least some minor warmth, and the hot part is sufficiently far away, I think you're right that it will work. But I still maintain it's a bad idea to run without insulation, regardless of whether (but especially if) you have a plastic mount. It will harm your printing performance (as described in my answer) and it probably makes failure conditions somewhat more severe.


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Under what circumstances are 3D printed parts actually viable with a desktop printer in comparison to other production methods?
As an engineer I was initially interested in making parts. For example I designed and printed a better part for something which wasn't available locally, and even had a client who wanted 150 of them. But print time was 23 hours per part. and I didn't have full confidence in the robustness of the part. The layer lines are a big weakness and anything less than 3 mm is so flimsy that it's a waste of time. So robust performance parts are out. As are high tolerance ones. Build volume makes it even less useful. And the design compromises you have to make are difficult to justify if there are other ways.
Then with other network parts I thought of designing the vast majority needed other bits and pieces, screws, shafts, connectors in metal that I'd need to source and assemble. Enclosures were okay, but weak, and I can fabricate those stronger and faster in other ways.
So now I mainly just print to what I perceive to be 3D printings strengths and have almost given up on parts.
Has anyone had a different experience?

Seems like a very broad, opinion-based question and not a good fit for SE in general. That said, there's probably a reason you don't see commercial 3D printing businesses using home/desktop/hobby type printers.

@FreeMan which is why I asked. A previous question and surfing around the site shows lots of answers talking about parts and precision etc,. as if it's justification for the answer or important, so I was wondering who actually makes parts. Because if they don't then their answers are irrelevant. I'm new to this site, but I intend to ask the hard questions because thats how everyone progresses together. Especially as more serious professionals start looking at 3d printing and looking for realistic information.

@ChinchillaWafers this site is about how to fix your printer? Thats not clearly stated anywhere I have seen. But if the community feels that it's out of scope (rather than just difficult to answer) then thats fine

@Kilisi in the Help Center there is a question "What topics can I ask about here?" that will give you a good idea of what is "on-topic". As to the 3D printing of parts as a business, there are companies that do that but they are using industrial grade printers. This site is more about hobbyists getting their 3D printers working or solving a problem that has occured.

@agarza so you're all amateurs?... hehe... yeah maybe  I'm in the wrong place

I don't understand the complaints about this question. Professional use of 3D printers, and whether they're appropriate for particular professional uses, is certainly on-topic for this site.

Not all that come here are hobbyists! We have members in printer design and development of high end machines. I work in aerospace R&D in which 3D printing is becoming more interesting these days. Note that you can print metals and very high performance plastics on high performance printers. One of the most challenging aspects is certification and being able to produce parts that have consistent properties. We've successfully printed non critical flight parts that are much lighter than parts that are fabricated through CNC for instance, this is viable for small quantity batches of products.

@0scar yeah I saw something about a planes internal paneling being 3D printed a few month ago. Wasn't a desktop printer though, the panels looked at least a metre long per section.

Whilst interesting, this question seems to be opinion based, and there is no right answer... "Everyone's a winner"! Personally (and I may be wrong), I think it should be closed as it will end up inviting wishy-washy opinionated answers. However, in order to preserve the already existing interesting answers, it might be more suited to Meta.3DP.SE and could be moved there, maybe???

@Greenonline I see no need to move it, or assume it's only going to attract opinion based answers. It has 5 answers already

Under what circumstances

When your part has internal geometry that would be difficult and expensive to reproduce using other methods. For example fishing lures which need internal water channels. Fittings or covers that would normally require several parts to be sealed together could be simplified to a single part and gasket.
When your part is a complex shape but has no need to be particularly robust because it doesn't come under stress.
When you need a part that you can design with a specific weight and shape you can control the weight with the infill percentage and other factors.
When your part is a niche one that goes with 3d printing strengths. Such as short term or single use items like name plates for conferences, key ring giveaways. Items of novelty value etc,.
When the part is not just functional, you may want a simple functionality in an ornate part for promotional, branding, or other reasons. I was tasked to create a container of certain dimensions. I could have done this a number of ways. But they also wanted their logo and a bunch of designs along a particular theme incorporated into it. Only with 3d printing was this able to be accomplished.

A production run of parts is generally a bad idea.  The 3d printed part works as a proof of concept, testing measurements and tolerances even if the printed part can never take the load/pressure of the proper part.
The costs are also significant - filament is ridiculously expensive for what it is, and the power costs of running the heaters for 23 hours per part add up too.
You can also rapidly iterate on a design without having to wait days/weeks for a fab shop to cast/machine/make it out of metals.
I find myself integrating 3d printed parts into a larger build using other items.  Example, 8x printed blocks with holes sized to epoxy to metal tubes, then covered with stitched fabric held down by hook&loop to the frame.  Buying those parts would be okay, if they existed to find in the first place.

If you're under time constraints for something and can't wait for the proper item to arrive from a supplier.
Sometimes "good enough"  is literally true.
To paraphrase... When it's after midnight and I need this part right now goshdangit!

Good answer, unless you print to 3d printings strongpoints in which case a production line will work

As an engineer I was initially interested in making parts.

First of all, a lot of people who need "parts" (I'll define that term as something playing a physical functional role in the operation of the thing it goes in or becomes a part of) are not engineers, and don't have routers, lathes, saws, drill presses, etc, available to them. A decent 3D printer is comparable in price to a couple small low-end power tools, but the range of what parts it can make is a lot broader, and it can make them with a lot less tool-use and safety expertise necessary.
But a 3D printer is also potentially a very useful tool here even if you are an engineer and even if you do have access to a large toolbox:

When you need the part in quantities larger than one, but too few to make by injection molding or other mass production techniques, 3D printing is one of the few solutions that's not prohibitively labor intensive.

Some types of parts are difficult to produce with techniques other than 3D printing due to geometry that's not conducive to molding or subtractive manufacture techniques.

But print time was 23 hours per part.

3D printing has a reputation for being slow. It doesn't have to be that way. At present, unless you're willing to become an expert with the tool or spend a lot of money buying something high-end, you're probably stuck with it being slow. But this is changing.

I didn't have full confidence in the robustness of the part. The layer lines are a big weakness and...

This is another area where the field has progress to be made. Weak layer adhesion and inconsistency of part strength are problems caused mostly by a mix of bad slicers, bad slicing setting defaults, and bad extruders. The first two can be mostly mitigated with some expertise using the slicer; the latter is a matter of spending more on the printer or knowing what to upgrade on a cheap printer and doing it.

...anything less than 3mm is so flimsy that it's a waste of time. So robust performance parts are out.

I use printed herringbone gears that are just 4 mm thick, with pitch of pi mm (making tooth thickness about half that), in my printer's extruder drive train, which is a fairly demanding application with momentary speeds up to about 4000 rpm. And that's without any "engineering" plastics, just basic materials like PLA and PETG.
Aside from that, I use a lot of other printed parts for less-stressed roles on my printer, and outside of my printer, I have printed housing for various electronics, custom fluid hose couplers, replacement door closer mounting brackets, replacement soft feet and end caps (TPU) for patio furniture, impact-protection phone and tablet cases (in TPU) for models where it's hard to obtain mass-prouced ones with necessary features or fit for where the items are being used, etc. I'm not sure what of this qualifies as "parts" to you, but I think most of it meets the definition I opened this answer with.
One particularly underappreciated class of parts I'd like to highlight here is soft parts made with TPU or other flexibles. TPU is extremely durable, and at hardness 95A or above can even be quite rigid when printed at 100% infill. It holds up really well under abrasion, exposure to weather, and exposure to oils etc.

Build volume makes it even less useful

This is really dependent on the scale of things you're working with. 3D printed parts seem more appropriate to me at the scales where build volume is not a limiting factor. Most of the people I encounter using printers with large build volume are using them mostly to do whole plates of parts at a time (for example, parts for building printers) rather than single large parts.
When you do need large parts, however, 3D printing can still play an important role, producing jigs or molds to use with other tools and materials.

I'm talking abut 'real' parts that you could confidently sell to the public without worrying about irate customers in the next few days.

@Kilisi: In mass production or being sold to customers for low-volume or single-unit-custom equipment?

Small production, obviously single unit is worth doing. Mass production would depend on product and market

@Kilisi: I think replacements for almost any plastic gear (and some metal ones even) are something you could easily print and sell without worrying about irate customers. Just make sure you use a material appropriate for the load.

Have you done it? I can make a useable toothpick that would be suitable, but doubt I'd find a buyer

@Kilisi: I don't have a business doing that or customers, but what I'm saying is that if I did, I'd feel confident selling them a printed gear.

ahh.. ok.. I get what you mean. Just realised you expanded your answer... nicely done

Like, if I were doing repair as a business or as repair-culture-building service, and someone came to me with an old piece of equipment they wanted to get working again that was out of service because of broken plastic gears, I'd feel pretty confident that I could take a few caliper measurements or a 2D scanner image from the old gear or the one it's supposed to mate with, model the replacement in CAD, and get a working durable replacement in an hour or so.

Outside of hobbyist objects the only commercially useful use of 3D printing that I can think of is in support of prototyping new parts or products that will ultimately be produced by other methods.  If an engineering team is developing something new that may require a few iterations to get form and fit perfected, 3D printing is a viable way to make changes relatively quickly as the design process progresses.
Things that support mass production methods such as molds, dies, jigs, CNC scripts, etc. are expensive and time consuming compared to 3D modeling and printing and typically must await a finalized design.  Prototyping with 3D printed parts is a reasonably rapid way to get to that point with the assurance that a hold-it-in-your-hands prototype provides.
Another thought has occurred to me - geocaching containers.  Geocaching - stashing things in odd places for others to find using published GPS coordinates, clues and hints - is a popular pastime and custom containers are always a welcome change from the usual pill bottles or food storage containers. I've made dozens for a friend who hides geocaches. I'm not entirely certain whether this market would be commercially viable but it's a big hobby. As I understand it there currently are over 1 million active geocaches in the US and probably tens of thousands of enthusiasts hiding them and/or seeking them out.

I've only just started my journey in 3d printing, but I have a little hobbyist experience in other forms of "structural crafting". I can see a few ways you can use 3d printing to enhance other techniques - the main one being that a printed part can be used to make a mold, which you can then use to cast aluminum, bronze, or whatever else.

True, but you could also 3D print in metal directly, with the appropriate printer.

Yes, molds are another viable use.


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Are there printer firmware specifics when adding printer profiles to slicer software?
In this question, I was struggling with my printer not recognizing sliced files. Switching from ChituBox to Lychee solved the issue until the printer stopped recognizing the .ctb files sliced by Lychee as well. Something clicked and it occurred to me that perhaps I shouldn't have set up the Saturn profile and print on a Saturn S. (I'm currently printing on the smaller Saturn build plate since my Saturn S build plate is currently out of commission.) I switched to the Saturn S profile initially set up. Lo and behold, the printer was recognizing the file again!
I figured the printer profiles in slicer software simply adds optimized print settings (like exposure times, retraction settings, build volume, etc.) to serve as a solid starting point and the user could tweak from there as needed. However, since my sliced files were not being recognized using the Saturn profile, it seems that there's more to these profiles than just print settings. Do any firmware or hardware considerations go into creating the .ctb files? It reminds me of compiling code to specific architectures back in my computer science days.

I reached out to Lychee (didn't even think to ask Chitu but the answer is probably something similar). The guy's response was basically:

The ctb file has some data inside that allows it to be printed only on a specific printer. V4 is even encrypted... To add a pinch of fun for us. Supporting it was not an easy task.
Anycubic for example use the ctb format too but each printer has its own file extension to avoid any confusion.

So the file does have model-specific parameters so one has to match the correct printer profile to the physical printer model, even if the printers are only slightly different as is the case with Elegoo Saturn and Saturn S.
In Lychee and ChituBox, one can set the build volume. So instead of using the Saturn profile for the smaller build plate, add a new printer, select Saturn S model, rename it to something that reminds you that it's the smaller build plate, then change the build volume x and y values to match the build plate. In Lychee, the x and y dimensions can be edited even in the free version (the pro version is required to change the z dimension).


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Can't get rid of horizontal layer lines?
I have an Ender 3 V1 3D printer. When I first got the printer and assembled it, I was able to get very good prints. My post is specifically about horizontal layer lines, and initially with my printer, I didn't see any horizontal layer lines.
Here are some pics of my last good print:

Then, I introduced some changes to my printer. Namely, I got the SKR mini e3 V3.0 and added some other things like a rear electronics box, Octoprint with a Raspberry Pi, an LED light strip, and more. During the time of these upgrades, my printer was down until I completed all of the upgrades, which also included the disassembly of some parts of the printer.
Ever since completing those upgrades, I've had uneven horizontal lines on my prints.

I've tried so many things, it's unbelievable. I've printed hundreds of calibration cubes and have adjusted many things.
My upgrades:

Yellow bed springs
Metal extruder
Glass bed
SKR mini e3 V3.0
BLTouch
Octoprint
LED light strip
Flexible Z-rod coupler
Anti-backlash nut

Things I've tried:

Lowering flow rate, including dramatic changes
Bed PID autotune
Hotend PID autotune
E-steps calibration
Flow rate calibration
Acceleration calibration
Cleaned the Z-rod many times and re-lubed it to varying degrees
Tried a different Z-rod
Printed a Z-motor spacer
Checked alignment of the Z-rod in terms of distance
Tightened the belts many times, to varying degrees to test what produced the best results. Everything from very tight to loose
Adjusted the eccentric nuts in many ways, from less tight to more tight
Changes the wheels on the X and Y axes
Tried Prusa Slicer and Cura Slicer
Tried multiple different rolls of PLA filament
Tried some different slicer settings, like increasing the minimum layer time
Tried different hotend printing temperatures
Levelled my bed many times
Put my 4.2.2 board back, and produced horizontal lines as well
Increased stepper currents
Changed the extruder tensioner spring
Changed the nozzle many times
Changed the PTFE tube
Made sure to the best of my ability that the PTFE tube was well seated with the nozzle
Linear advance calibration
Tried turning off linear advance
Rebuilt my printer twice using CHEP's video
I've followed Teaching Tech's calibration guide
Tried printing from the SD card instead of Octoprint
Use my own custom Marlin. But also tried BTT's pre-compiled firmware

And probably many other things that I just don't immediately recall.
Another thing to note is that I really haven't printed much with this printer. I got it a few months ago, and I haven't printed much with it. So there are not many hours on it.
I'm at a point where I don't really know what to do. I have some parts on the way to do the following:

Dual Z-Axis upgrade
Petsfang V2 cooling duct upgrade

I really don't know what to do at this point. I've been genuinely considering buying a brand new printer and throwing the one I have out the window. I'm really frustrated that I can't get a good print anymore.
I've posted multiple times on some other places, and I've gotten good advice that I've applied. That did not fix the problem.
I would appreciate any insight into the problem. If I can't find a solution here, and the above two upgrades don't do anything, then I'm not sure what I'll do with the printer and hobby in general.

It's a silly question, but did you do all of these prints on octoprint or did you try using the SD card too? It's been a few years since I used octoprint, but I do remember there being some funkiness printing off of it, like sending a line of gcode at a time or something (which SHOULDN'T affect print quality) and it's one more potential source of errors.

@LuxClaridge It is reported that older Raspberry Pi's and Pi zeros aren't fast enough to produce good prints. So, that is a possibility.

Thanks. I did try printing with the SD card only. The print looked identical to the Octoprint one.

Did you introduce a "Flexible Z-rod coupler", and what kind? These are known for creating problems. Furthermore, you have an Ender 3 printer, you can't expect Ultimaker quality prints. I see the banding in the cubes, but to say that it is printing badly... The Ender 3 is a popular cheap printer with design flaws, but, it has some good design features with respect to the previous generation that had acrylic frames.

The coupler I am using is this one : https://tinyurl.com/2p88atez. I bought the coupler in response to the banding. So the issue was there before. The print quality was pretty much identical after adding the flexible coupler, as compared to a solid coupler that came with the printer. To be fair, that was expected, since I aligned my z-rod pretty much perfectly. So I didn't expect the flexible coupler to do any 'flexing'.

That's a fair point. However, I used to get really good, consistent layer lines. Also, I see the cubes and benchies that others share, and they have pretty much perfect layer lines. Like literally perfect. Their benchies and cubes have just unbelievable consistency in the layers. It seems like it's possible and some of those posts claim to be fully stock. So I've been trying to aim for that.

@geekgeek4 Those couplings are springs and do not constrain the Z motion. These are the ones most people would skip using or replace when the printer comes with these, for me they gave me inconsistent printing results also. I'm using Oldham couplings nowadays. See this answer for details. There are other alternatives using e.g. axial or thrust bearings to fixate the Z movement.

If you only changed the X and Y whels, it seems plausible that the Z ones are at fault. Especially if you played with the eccentric nuts and overtightened them at some point, the wheels may be imbalanced/not perfectly round as a result of being left compressed in a particular orientation, and that may in turn cause this sort of wobble.

Note that on the Ender 3, the lead screw and nut are not terribly relevant (or at least not dominant factors) to Z wobble or other Z axis issues because the main source of tension constraining the motion of the carriages is the wheels against the V slots.

Also, check for play in the undriven side of the gantry. It's possible that it doesn't reliably follow the driven side, but instead moves upward an inconsistent and unreproducible amount that varies by layer.

Thanks for the suggestions. I have ordered some wheels. I only replaced the X and Y wheels because that's all of the wheels I had on hand. I also felt some slight hesitance at some points when moving the X and Y. As for the undriven side of the gantry, the dual z upgrade should fix that, but it does seem to move appropriately and is tightened.

I also ordered parts for this upgrade : https://www.thingiverse.com/thing:4857627. I thought it was pretty interesting and seems like it could possibly work well for me.

Did you look at Combing? Check the Travel Lines in Preview.

I absolutely applaud your dedication and perseverance.. My CR10 is being finicky and I almost just threw it out and bought a new one... All of this trial and error won't go without reward too. I'm sure you've learned a massive amount.
I'll place my question and suggestion in the answer box.. Well, maybe 2 suggestions.

Have you found solution? I also have the same printer, upgraded to skr mini, and i tired to find solution..

I had the exact same-looking layer lines, and the problem was multi-factorial, but mainly in the Y-axis concentric nuts being too loose.  In the Ender 3, the Y-axis wobbles very easily because it only has the thinner rail, the Ender 3 pro has the wider 40x40 aluminum rail on the Y-axis and it makes a world of difference.   It sounds like you have dealt with this, just make sure to double-check that they are indeed as tight as recommended by CHEP.
The other issue was the extruder motor shaft/brass geared wheel that is on the shaft.  If the motor shaft is slightly warped or the brass gears are worn or some of the gears are full of filament, etc., you will get a consistently uneven extrusion that gives weird layer lines; I had to replace the gear.
Finally, the end of the X-axis that does not contain the lead screw came way too tight from the manufacturer, which leads to uneven lines.  This was not apparent from simply moving the gantry up and down.  It required taking apart the X-axis gantry so that the wheels on that right side were independent of the lead screw side and then adjusting those concentric nuts so that the little 3-wheel part would glide up and down the rail with no resistance at all, and then reattaching it to the rest of the gantry. It is a different technique than tightening the other concentric nuts because you don’t care if a wheel seems too loose, just that it flows up and down the rail (I wish I had the time to find the YouTube video that explained this technique because it solved the last of my problems).  I know you are waiting for a second lead screw but could try this adjustment while waiting.
Finally, you said that you have changed nozzles, but where are they all from the same company and batch? I got a batch from Amazon that all seemed to give me gimped prints so changing the nozzle to one from a different company might still help.
Good luck.
BTW, I am also using the skr V3 with no problems, in one Ender 3 printer (other upgrades are just Capricorn tube and filament runout sensor) and the other Ender 3 has the original 8-bit board and they both print about the same quality with regards to layer lines - which is similar to your original pictures.


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Method to easily connect objects that are slightly spatially separate in .obj file
I am interested in printing a brain that contains 696 parcels (i.e., chunks that break up the total brain).
The .obj file was created such that each of these parcels are spatially separate. Do you have recommendations for printing these parcels such that they are slightly connected, i.e., having the parcels be connected yet still being able to see most of the grooves in between them? I hard coded the .obj file in R/Python. Do you have recommendations for easy redesign of this 3D file to accomplish this goal?
I would like for all parcels to be one solid piece when printed.
Here is an image to get a sense of the object.
Thanks. I am new to 3D printing so any advice would be appreciated.

"Do you have recommendations for printing these parcels such that they are slightly connected?" is one question, directly related to how to print.
"Do you have recommendations for easy redesign of this 3D file?" is a second question, related to how to model a change. Do you want two answers or focus on one of them?

Two answers, please. I included both in case their solution was shared.

The "How to print" portion of the question is vague and should be addressed in a separate post, with much more detail, such as your type of printer (resin or filament), perhaps your slicer software, print settings, any problems you've had with making  a print to function.

If it doesn't need to come apart again then I'd just boolean union them with some spheres so that they're one object. With the spheres all internal so you keep all the outside detail.
All 3d software I have seen can do this although the specifics vary.

@Kilisi, I also considered to place something between the "loose" parts. As you've noted, many modeling programs will easily accomplish this.

@fred_dot_u yeah, I just use spheres because they're easy

@Kilisi Considering the quantity of pieces (348 slightly separate mesh objects per hemisphere), I was wondering if there was a way to avoid inserting (many) new spheres. I am currently using Fusion 360 but have access to most software. Would there be a way to slightly scale each separate chunk (i.e., mesh object) such that adjacent chunks would overlap, and then apply some boolean union? When I try to scale all 348 mesh objects in Fusion 360, the problem is that the same gaps are maintained, as the objects get new center points as they scale with respect to the origin of the entire brain.

Yes, no need for lots of spheres, they're just easy. You could just use one and sculpt it into shape. Or if you're using software that can do it. Just export as stl then remesh the stl.


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How thin should I print a logo so that it is flexible enough to wrap around a curved object?
I want to print out a flat object without any support structure straight onto the build plate of my ender 5. It's going to be PLA and I need it to be thin enough to still be flexible.
I don't have a picture available, but imagine that I wanted to print out the Coke Cola and then wrap it around a bland soda can, so that the logo is raised up slightly?
Alternatively, what is the best layer height to use, and how many layers should I use?

This isn't an answer because you specified you want PLA, but TPU works really great for this at a thickness of around 1-2 mm and it's indestructible. You don't have to worry about bending it too sharply and creasing it, or about it being brittle from being so thin.

I'm really new to 3D printing, so I'll ask a naive question: Why not just print it to the desired curve in the first place? Or, is flexibility the purpose, and the Coke can example was simply a way of saying it needed to be flexible?

@FreeMan printing flat negates the need for supports and is stronger and faster with zero chance of failure regardless of complexity. So you could print a 5cm high logo on it's edge with a curve, but that is 250 layers and if it was thin would be a problematic and brittle print. Or you could print it flat faster, stronger and cheaper.

@Kilisi thanks. As I said, possibly a naive question. That mostly makes sense.

@FreeMan You're welcome, we all have to start somewhere

For text such as the Coca Cola label consider a negative image, i.e. a thin, flat, rectangular piece with letter shaped holes.

This question makes little sense, each material is different. It takes very little time to print test samples and try. Do that.

@FarO the OP specified PLA

With PLA you can just heat it to curve around the object. I've done this with up to 2mm. Real easy with 1mm.
I haven't tried thicker but assume it would work ok.
You'd have to glue it though to make it stick. My attempts were just to shape the prints, I didn't want them sticking so I shaped them around a glass bottle.
If you want it flexible in it's own right, then I suggest 2 * 0.2mm layers. I have a large 2 layer print in front of me that bends easily.

This can be rolled up into a tube, but as soon as you let go it will return to flat.
1 layer is even more flexible but tears along the lines with a bit of effort. So if you want it really flexible I suggest you print 1 layer at slightly lower than normal nozzle height to really get the lines melded together. Or a bit hotter than normal.

+1 for the heat reference. You'd be able to wrap something approaching 2-3 mm with enough heat. The thicker parts may experience some distortion. Leave a PLA part in a hot summer car and watch how much flexibility results!

@fred_dot_u Yeah, I've bent PLA around quite a bit for various reasons, usually to avoid layer line weakness or fasten things together. You can even make quite strong PLA rivets.

2x 0.2 mm layers will flex very nicely, but will crease and crack if you bend them sharper than a certain limit.

@R..GitHubSTOPHELPINGICE yes, they'll take quite a bit of abuse though, well within the parameters of the question. I use it often enough that I have a sheet lying around so I can cut pieces off it when I need to.

1 layer, of whatever thickness your device can print.
I did something like this to print letters for a flat sign.  The letters were 1mm thick and didn't bend, but I'd accidentally printed quite a lot of brim lines which were a single layer thick, and they'd merged into each other.
The brim worked superbly as a "net" to hold the letters in place, so in theory you could print as little as one layer thick.

Nozzle height will have to be exactly right to merge the lines together.  There are no lines crossing-over on the next layer to help bond them all together.
Let the print bed cool to ambient before removing it from the bed, to help keep the lines connected.  Could take an hour or so.
Use a wide flat scraper to pull job off bed - you might want to design in a "tab" that can be damaged while getting the tool started, and trimmed of later.