PETG Issues
Hi all,
I’ve not printed much PETG since upgrading from a mk2 to a mk3 but never had any problems with the mk2 other than it sticking to well to the build plate, my mk3 is a different story all together 🙁
I’m currently using the supplied PETG profile with latest version of slicer PE and I’m using Prusament PETG but I’ve tried other profiles and brands of filament and always seem to suffer the same issue, poor first layer properties, poor layer bonding and general bad quality prints.
I’ve spent a fair amount of time (and filament) trying to resolve the issues and seem to have come to the conclusion that it’s to do with the flow rate value. The default profile seems to want to use a flow rate of 0.95, if I increase that value up as far as 1.35 things seem to get better but often results in poor top layer quality. I’ve attached a photo of an example print, the red section is with the flow rate unadjusted, yellow is at 1.20 and the green is at 1.35.
Ive also not been able to find the flow rate settings on the slicer profile, I can adjust the extrusion multiplier which seems to have similar results but doesn’t seem the same?
As much as this seems to help it doesn’t feel right? I’ve done a cold pull and everything seems clean, I’ve tried temp and speed adjustments but neither seem to help, nor does changing the Z height.
PLA prints perfectly every time.
Would really appreciate your thoughts.
Thanks
John
RE: PETG Issues
You seem to be printing on a textured (powder coated?) bed. If that is the case, then you really need to squish the first layer into the bed a lot, getting the Z offset very low and close to the bed. Keep in mind that some of the plastic is used to fill the pits in the texture. I doubt adjusting the extrusion multiplier (which should be synonymous to flow rate) will help, since it'll most likely negatively affect layers other than first.
RE: PETG Issues
You may want to play with first layer width (Printer/Advanced tab) - making it larger so it puts more material in layer one. And you can then save a profile for the textured bed and keep the stock profile for PEI.
Intra-layer adhesion being poor might be printing the material at too low a temperature or using the print fan during extrusion cooling the part too fast; and since PET needs time to weld into the prior layer, you can also reduce print speed to improve layer adhesion..