Another "First time printing PETG" - questions
I tried printing with PETG for the first time tonight and it did not go well. After a few tiny test prints that went well I tried to print a 4x4x2 (inches) box and lid. The first layer went just fine and everything looked good. I walked away and came back 20min later to find that the nozzle had a large glob all over it and the subsequent layers were partially ripped up.
I'm printing with Overture PETG. I may have been printing too cool at 230C. Bed temp was 85C.
Any advice? I've basically perfected printing with PLA for my needs. PLA prints always come out perfect, but I want to use PETG going forward.
RE: Another "First time printing PETG" - questions
If you save your part & settings off in a project 3MF file, zip it and upload it here, helpful suggestions on your settings may be forthcoming.
and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan
RE: Another "First time printing PETG" - questions
If you save your part & settings off in a project 3MF file, zip it and upload it here, helpful suggestions on your settings may be forthcoming.
Here you go.
RE: Another "First time printing PETG" - questions
I found that PETG doesn't want to stick to a bed that has PLA residue on it. So when switching filaments clean the bed with soapy water, and after that apply windex/gluestick.
RE: Another "First time printing PETG" - questions
Over the last few days I printed a lot in PETG. I’ve been amazed by the quality of prints, using the Generic PETG filament profile in PrusaSlicer and AmazonBasics filament. Until I switched to another, old spool of filament, and all hell broke loose. Pretty much exactly what you described. I tried a few things, no luck. Then I switched back to the AmazonBasics filament, and everything was back to great again. Might be worth checking out another brand of filament if you have access to it.
Formerly known on this forum as @fuchsr -- until all hell broke loose with the forum software...
RE: Another "First time printing PETG" - questions
Over the last few days I printed a lot in PETG. I’ve been amazed by the quality of prints, using the Generic PETG filament profile in PrusaSlicer and AmazonBasics filament. Until I switched to another, old spool of filament, and all hell broke loose. Pretty much exactly what you described. I tried a few things, no luck. Then I switched back to the AmazonBasics filament, and everything was back to great again. Might be worth checking out another brand of filament if you have access to it.
This is the very first spool of PETG I have bought (Overture) and I have my doubts about it. I'm happy to try other brands but feel like I need to make sure I'm not doing anything stupid with the print settings first, hence my question here.
RE: Another "First time printing PETG" - questions
I found that PETG doesn't want to stick to a bed that has PLA residue on it. So when switching filaments clean the bed with soapy water, and after that apply windex/gluestick.
I cleaned the bed with acetone and then applied windex. About the only good thing that happened was that it appeared the first layer stuck well, but still came off properly. It felt just like PLA in that regard.
RE: Another "First time printing PETG" - questions
I'm pretty sure that I need to raise the nozzle a bit for PETG from where I have it set for PLA. I know I can do this with live adjust z, but is there a way to automatically raise the nozzle when using a PETG profile? I'd like to keep my settings for PLA because it prints perfectly.
RE: Another "First time printing PETG" - questions
I raised the Z height a little bit and my test prints come out fine. The test prints are just smaller versions of the image below, but when I try to print the real thing this is what starts to happen after the first layer or two.
RE: Another "First time printing PETG" - questions
I raised the Z height a little bit and my test prints come out fine. The test prints are just smaller versions of the image below, but when I try to print the real thing this is what starts to happen after the first layer or two.
The first thing I'd try is dialing speed back 50% using the front knob. If the problem clears up, you just need to slow down speeds above Layer 1. Infill speeds are often a bit too high in some of the profiles. Also check to see if cooling is kicking in after layer 1. PETG will tend to have poor inter-layer adhesion with too much cooling, which can add to this sort of problem.
and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan
RE: Another "First time printing PETG" - questions
The first thing I'd try is dialing speed back 50% using the front knob. If the problem clears up, you just need to slow down speeds above Layer 1. Infill speeds are often a bit too high in some of the profiles. Also check to see if cooling is kicking in after layer 1. PETG will tend to have poor inter-layer adhesion with too much cooling, which can add to this sort of problem.
Thanks, this gives me some things to try.
Regarding cooling, my filament cooling settings are:
"Keep fan always on" - enabled
"Enable auto cooling" - enabled.
These are the stock settings and I haven't changed anything there. I can hear the fan kicking up at times.
Regarding the speed settings, my solid infill and infill speeds are set to 80mm/s, again as the defaults that I haven't changed.
I feel a bit foolish, but it appears as though the problem may have been the actual model. It's a simple box/enclosure with a lid. The model design has a small radius that is applied to the edges of the box so it didn't have a sharp edge. So the model had a slight upward rounded edge on the bottom coming off the print bed. (I have used the same thing for PLA prints which were fine). I removed that rounded edge on the bottom and now the print is going good. I'm on layer 5 and so far it is looking perfect; the gyroid infill just started so I'll see how that speed goes.
I do wish I could have that bit of a rounded edge, but if it's messing up the print it's worth it to get rid of it.
Again, many thanks!
RE: Another "First time printing PETG" - questions
A rounded edge (fillet) is in effect a steep overhang at the start of the curve. Depending on size and or material you can often get away with it. If you use a chamfer at something like 45 degrees at the edge or even at the start of the curve it is usually much more reliable for printing. One of those design for 3d printing tips to be aware of.