PET printing problem
Hi!
I'm completely new to 3D printing (this is my first 3D printer ever) so the answer to my question may be obvious 😀
While the first attempts were promising (ignoring some printing quality issues reported here already, e.g. the messed up Benchy bow) when I tried PETG I ran into my first major issues with failing prints.
I'm attempting to print a Raspberry Pi case. While the bottom went fine the top ifs failing every time. I'm not sure what the problem is (model works fine with PLA), but hope some of you more experienced guys can give me a hint what Slicer settings I have to change or if some other things (new calibration because different filament?) are necessary. Here's a picture:
As you can see the first layer appears to be fine, but then it doesn't seem to stick any longer? 😕
I used the default MK3 Slicer settings and I don't consider the model to be especially difficult.
Disclaimer: Due to being clumsy I ordered the assembled version of the printer, so I hope there aren't any build issues...
Thanks in advance!
Re: PET printing problem
It seems to me layers are not sticking to each other.
Thats usually when you're not printing hot enough
Re: PET printing problem
Regarding the temperature, did you change filament type in the plater meny?
Here is the settings in Slic3r, firstlayer/other layer.
PLA Extruder 215/210°C Bed 60/60°C
PET Extruder 230/240°C Bed 85/90°C
Bear MK3 with Bondtech extruder
Re: PET printing problem
I think I changed filament type in Slicer and the correct temperatures are in the gcode (as far as I can tell):
M104 S230 ; set extruder temp
M140 S85 ; set bed temp
M190 S85 ; wait for bed temp
M109 S230 ; wait for extruder temp
//snip
;AFTER_LAYER_CHANGE
;0.35
M104 S240 ; set temperature
M140 S90 ; set bed temperature
Maybe the nozzle isn't reaching the set temperature? Is there a way to check actual temp without an IR thermometer?
Re: PET printing problem
Try bumping the print temperature a few degrees and see if that helps. There can be some variation in the actual print temperature from machine to machine, and each filament will have a slightly different optimal temperature too. I've found that PETG in particular really wants to be dialed in to exactly the right temperature, so you can't assume the default filament profile for PETG is going to work for the particular spool you're trying to print in your specific printer.
Re: PET printing problem
Thanks for the hint! I raised the default temperature slightly from 240 to 245°C which allowed the print to complete, yeah!
Somehow I assumed if I get the filament from Prusa as well everything would be tuned in nicely and the default profiles would work out of the box, well, now I know better.
However, despite the print completing which is nice I now got some burn marks:
Is that to be expected or can I tweak some other setting to avoid those?
Re: PET printing problem
I think those burn marks are possibly blobs of PETG that get rubbed of the print and stick to the side of the nozzle. Then they burn and drop off into the print. Have you calibrated the extruder to see if you need to tweak the extrusion multiplier
It can be different for each material and brand, for me the PETG from rigid.ink was spot on .45 walls however the PLA was over extruding and needed to be tweaked to 0.91. My K value was 57 for the linear advance where as the default was 45 for PETG so you may want to test that aswell
https://mattshub.com/2017/04/19/extruder-calibration/
https://mattshub.com/2017/10/02/linear-advance/
PS dont forget to edit the temperature for the PETG if you download matts Gcode
Re: PET printing problem
Yea... usually you always have to tweak a bit to get it perfect. And PET can be really picky sometimes.
Those burn marks are like Jason said most likely..
I can see you have a few strings here and there.... Those strings attach to the nozzle when the head is moving and they eventually burn... and sometimes they stick to the part and leave a "burn" mark.
Are you using Z-lift??
Z-lift is Known to make those really small strings.... you could try disabling but you need to check if the part you're printing has areas where it can curl up and hit the nozzle as it passes.
Re: PET printing problem
PETG is probably the worst filament for scorch marks. I think it's because it gets really sticky when melted, so tends to stick to the extruder more than ABS or PLA. I get very few burn marks with ABS, but a fair number with PETG.
Check that your nozzle is clean before you start the print. You can also try one of those silicone socks for the hot block. I don't know if that will help but it can't hurt.
Re: PET printing problem
Oh, that’s a lot of advice!
I watched closely, and the burned blobs are definitely from material building up on the nozzle, burning and finally dropping into the print.
I’ll have to read up more on the different parameters to fully understand what each change will do, but now I have a few options I can try, thanks!
Still like the output of a PETG print more than PLA, so I’ll try to get it right, maybe try a second spool or different manufacturer as well.
Re: PET printing problem
If you get blobs building up, try reducing the filament multiplier to say 0.9 instead of 1.0
Regards Joan.
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK