Help a Beginner with PETG?
Hello,
Complete newb here. I have a new mini+ and am having issues printing PETG (turqouise/light blue purchased from Prusa).
PLA using PrusaSlicer defaults prints beautifully. All test objects and misc things that I printed worked great! Changed to PETG and am having troubles.
FIRMWARE 4.3.2
Using Prusaslicer 2.3.3 -0.15 Quality Defaults.
Filament Settings - Prusa PETG -All default except extrusion multiplier set to 1.05 due to lines way too thin. This seems to have corrected that problemPrinting on textured plate - first layer is sticking very well.
I'm printing a series of cookie cutters. What is strange is that I'm getting the occasional glob of "snot" (burned globs of plastic) and there are areas that are not printing correctly. 90-95+% of the items seem to print just fine. Attached are examples of the issues with my cutters. What can I try to tweak? I've tried adjusting the nozzle temp ~5 degrees each way, and get similar results.
Thank you for any help!
Best Answer by Lupin:
Here's a rather poor picture of the right edge of the more complex part. The two tabs have slight deformation at the beginning. Higher up they are ok. This was printed with quality settings.
So what i think of this so far:
Lowering the temperature by 10 degrees (230 at first layer, 240 after that) helped most. If I print this in draft setting, especially with these lower temperatures, there are no deformations. Other settings don't make much difference. I have not tried to turn it 180 degrees, i.e. chin towards back, that might help with these side tabs (cooling reaches them more easily), but turning would likely cause similar defects near the top of the "head", where the continuous perimeter would shadow the tabs from cooling.
I'm at loss on how to get perfect print out without tweaking so many parameters and doing test prints ( I have done only 5, but I feel this is enough for now).
I don't know why the lower part of the tabs are worse, but can speculate. Maybe the print below and the heat bed warms up enough that these parts heat up too much, perhaps the coolers breeze does not reach near the surface so well (maybe redesign blowers output?).
Anyway, with these settings the part comes out good enough that it can be used, I think. Those deformations are very slight and likely won't cause any problems in use.
I will cease printing these unless someone comes up with a good suggestion on what to try next.
Meanwhile I likely change the nozzle to E3D Nozzle X, and replace PTFE tubing with Capricorn's PTFE tubing. (Slight tweaks to my mini). These changes have only little effect on printing (I hope). Most notably I need to raise the printing temperature 5 degrees or so because the Steel nozzle is not as good heat conduct as brass.
leak and extrusion
You might have a leak from your hotend and a low extrusion issue. Look around the heatblock and see if there is any plastic being release between the heatblock and heatsink.
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Chuck H
3D Printer Review Blog
Retraction issue
If there are no leaks, it could be some weird retraction issue. Form the picture all of those paralel side tabs have an issue. Maybe the printer/slicer tries to prevent stringing and it gets worse every time there's a short tab to print. This is just a hunch, but you could try to shorten the retraction distance to about half of what you have currently configured and reprint. If it is perfect leave it, but remember that you might need to adjust it back on some other parts. If it gets little better, but these still are problems, shorten the retract distance once more. If the print is perfect but you get stringing, you might want to lengthen the retraction distance just a bit.
If this kind of adjustment works, you'll might have to settle on few hairs here and there as long as the print is otherwise fine. Nothing a hot air gun won't fix in a jiffy.
This theory is like this on your issue: Once the printer has printed a layer of a tab, it moves to another close by tab and retracts the filament during move. Once on the next tab, it prints so little filament, that the retracted part just barely comes out. Then comes the next tab and so on. The retracted filament starts overheating and does not come out evenly, getting worse on every subsequent tab where the after retraction and not printing enough filament out after it. Eventually the parts of the retracted plastic that haven't gotten out overheat, and on some point when there's enough output, it comes out as brownish blob.
I might be wrong, but it might be worth a try. The adjustment at first (cut the distance to half) is to see if this has desired effect. Based on your print you need to rethink, is this a step in the right direction? Do you need to tweak the setting further? Note that if the print does not get any better, reset the retraction distance setting and start analysis over.
I'm a newbie who prints solely PETG (currently, might change). There was a discussion of this kind of "against the logic" retraction tweaking, that discussion sounded like it might help in your case. But naturally, check your printer fist as @cwbullet suggested. If there are leaks then fix them first.
Thanks for the Ideas
Thank you for the explanation! I will definitely try that out. I printed a different cookie cutter overnight...one that is much simpler without the small notches and details. It printed flawlessly. So it looks like I'm in for more trial and error with the C3PO one.
RE: Thanks for the Ideas
Remember to report back on your findings, with pictures especially if you run into problems. That way we all learn and can perhaps suggest something other to tweak.
Many members here are experienced old timers (like cwbullet), but even them won't be able to give proper advise without enough details. I'm far from expert. Mini is my first 3D printer and I use it as a hobby tool. There are members who have plenty of these as a part of a print farm. But still, one can create a model that will be problematic to print with default settings. You can disable retraction altogether, but that will likely cause some hairs or stringing with PETG as it tends to ooze out a bit.
If shortening retraction does not help, you could try the opposite, but I cannot see how it would help in this particular model.
New Information
OK, new information / update: I tried drying my filament out in a dehydrator and that didn't seem to help. Will keep it in mind though. I've also tried checking for clogs, cleaning the nozzle and playing around with the temperatures. Some of those changes helped a little, but not much. I tried a couple of other rolls of PETG too, different colors, same problem. I went pack to PLA to rule out some other issue and to make sure I didnt have a clog. It still prints perfectly (side note: I printed my first lithophone...very cool!). Problem seems to only exist with PETG, perhaps.
What DID work is trying to print another model. What I've learned is that solid or thick objects (object without thin walls) print pretty much spot on, with default settings (and a small extrusion multiplier bump). Here's what I've learned: when I try to print cookie cutters with lines/walls that are no more than two "layers" thick (so, no infill), thats where I get the problem that I've pictured. Whats weird is the problem doesn't exist on most of the thin wall perimeter. Just about a 0.5 -1 inch vertical section of the wall (so maybe a seam or something?). I printed another couple of cookie cutters that have thicker walls (so there is a small amount of infill used in the walls) and they come out perfect. Does this new info help identify what may be causing the issue?
It sounds like you may have designed walls that are thinner than your nozzle can extrude accurately. With the default 0.4mm nozzle you have to begin taking extra care below 2.4mm thick...
Either redesign a little thicker or try a smaller nozzle.
Cheerio,
Looks like you found the situations in which you're seeing issues but I still don't see the root cause. I print two or three perimeter wide walls all the times for game inserts I design, no problem. Did you calibrate your extrusion multiplier using a hollow box (eg as described in @bobstro's notebook)?
Calibration?
I didn't. Would you mind pointing me to that or instructions? Not sure I've heard of @bobstro's notebook before, but certainly willing to give calibration a try.
Looks like you found the situations in which you're seeing issues but I still don't see the root cause. I print two or three perimeter wide walls all the times for game inserts I design, no problem. Did you calibrate your extrusion multiplier using a hollow box (eg as described in @bobstro's notebook)?
Check out https://projects.ttlexceeded.com/3d_printing.html.
Bob has collected a treasure trove of high quality information about the Prusa, from hardware to software.
Thanks
Ok, great. I will definitely check it out. Thanks!
Check out https://projects.ttlexceeded.com/3d_printing.html.
Bob has collected a treasure trove of high quality information about the Prusa, from hardware to software.
RE: Help a Beginner with PETG?
@norwegianblue care to share your project, e.g. in 3mf format? I could take a peek and perhaps try to print it with my mini. I think stl will work too. gcode does not offer much to work with (easily I mean).
I don't have use for cookie cutter, but currently my mini is idle (I have other things to do), so I guess I can donate some PETG for this. Those perimeters don't seem so thin to me, but what do I know, I'm a beginner too.
STL file
Hey, that would be great! Here's the file in STL format. The only thing I did is import it, and scale it (locked) to 5 inches on Y. Here's the link:
@norwegianblue care to share your project, e.g. in 3mf format? I could take a peek and perhaps try to print it with my mini. I think stl will work too. gcode does not offer much to work with (easily I mean).
I don't have use for cookie cutter, but currently my mini is idle (I have other things to do), so I guess I can donate some PETG for this. Those perimeters don't seem so thin to me, but what do I know, I'm a beginner too.
RE: STL file
Got it and printed it. I had moist filament and the only problem was stringing. I printed only the more complex part in draft mode and it came out just fine except for the stringing.
I had "Detect thin walls" on in print settings. I dried the filament over night and another try out is in progress where that "Detect thin walls" is disabled.
RE: STL file
Printed it now with quality profile without the "Detect thin walls" setting. Now I have similar defects on both pieces as on your pictures. The thin tabs are now about 0,75 mm thick (with slight variation) versus the about 1,00 mm when printed with "Detect thin walls = enabled".
I'll print this once more with quality profile but this time I'll enable the "Detect thin walls" setting in Print settings -page.
RE: STL file
I think I goofed the last print, it looks identical to previous, same defects and same thickness of those thin walls. Oh well, I guess I'll try again.
Thank you!
Really appreciate you trying to help!!!
I think I goofed the last print, it looks identical to previous, same defects and same thickness of those thin walls. Oh well, I guess I'll try again.
RE: Thank you!
No worries. As I said, my mini is idle as I have other things to do, so this kind of helping, slicing the model, printing it and reporting results does not disturb me much. The one thing I value in Mini is that it is for most part a "fire and forget" type of printer, since the SPINDA upgrade. I can give the model to printer and just go out and do something else. When I come back several hours later, I can marvel the finished piece on print sheet.
Anyway, next try out is in progress, I'll report back.
Really appreciate you trying to help!!!
Update
Looks like the only way get passable print out is to use draft. And that might mean there is particle cooling problem. I will try again later with tweaked setting in cooling and perhaps print speed.
RE: Update
Printed again just the more complex part. I.e., I took the parts separately, modified in the filament settings/Fan Settings/max speed 100%.
Printed with quality profile on dry Prusament PETG Carmine Red. Looks good. I will post pictures later in the evening. Don't know which change did it, printing separately or raising the fan speed.
Anyway, to me it seems you cannot print this without adjusting something. I also had the "detect thin walls" enabled.