PETG Overhangs (Beginner's Question)
Hi Guys!
i am new and inexperienced so take it easy on me 🙂
I have a Mk3S+ and a satin print sheet. I am using Prusament PETG.
Generally everything is working fine. However, regarding overhangs, I run into the layer issues as seen on the pictures attached.
What am I doing wrong? The prints do not indicate, that supports are necessary and I printed them in PLA just fine without supports.
Thanks so much!
Gonzo the Great
RE: PETG Overhangs (Beginner's Question)
Have you tried adding support? I know it says it is not needed.
The other option is to increase cooling and slow the print down.
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Chuck H
3D Printer Review Blog
RE: PETG Overhangs (Beginner's Question)
Those first layers are not low enough. Especially noticeable on the black part. So the filament is being dragged over when it printing the circles. Live z can differ for different materials and generally does need adjusting between pla and petg.
Also your strings being pulled across look like they are on the lower layers. PLA filament profiles have the fan kick in at after the first layer, petg ones usually kick in after layer 3. That may be causing you some issues with this design. Without a project to get a proper understanding of the slice details its just guesswork but the part looks like its using chamfered edges, the bottom of a chamfer is a near perfect overhang until it gets higher around the curve. So layers 2, 3, 4 etc will be largely unsupported. With pla and the fan this may just be good enough for it to print ok. Change the filament properties and the fan and the results will differ. As you are seeing.
If you want better help then please save and attach a zipped up PS project file. File>Save project as in PS. This will save a .3mf file that contains your objects as well as all the settings and modifiers applied. It allows us to study things in detail and use the tools in the slice preview to get a better understanding of how its being sliced.
It has to be zipped or the forum wont allow the file to be attached.
RE:
I agree with my esteemed colleague Neophyl, with one small comment. Swap "chamfer" for "fillet". A chamfer is a straight line transition between two faces, usually at a 45 degrees angle. A fillet is a rounded transition. So if you have a fillet on the base of your model, the overhang angle changes from 90 to 0 degrees and the first few layers are usually unsupported. With a chamfer, you have more overlap from layer to layer and it's easier to print because a constant 45 degrees overhang should be easy to handle for your printer.
Now for this specific model, the red one looks like the filament scraper I have printed at least six times. Never had any issues with PETG, with PC Blend a few loose strands. As Neophyl suggested, try adjusting the fan. Or just put the trusted heat gun to good use and blow away those small wisps of filament.
RE: PETG Overhangs (Beginner's Question)
I often get those 2 mixed up lol.
RE: PETG Overhangs (Beginner's Question)
Thank you very much for this insight!
So, as I understand it, there are three problems:
1) Live Z needs to be lower. I readjusted it today, but that alone, didn't help (see picture below)
2) The fan is starting too early. I would assume, this is bad because PETG has to be printed hotter.
3) The model is using a fillet instead of a chamfer.
The black thing is a Raspi 4 Case and it is quite possible, that it was intended for PLA. The orange print is indeed the scraper
I have attached my project for the black Raspi 4 Case. rpi-4-case.3mf
