Hi, I am printing with PETG at 228-230 degrees/70 degree bed temp. I have a BMG extruder and Ender3 hotend setup Bowden style.. I am working to dial in my Simplify settings for it. Currently have retraction set at 7.8 with extra restart, coasting, and retraction speed of 55, otherwise I seem to get blobs where ever a new layer starts.
My first layers go down very well - like glass actually. When it starts to do infill (currently set at 45%) - I get weaker , partially bonding lines that the second pass ( alternate angle) seems to fix but leaves the surface bumpy. This is set to a rectilinear fill.
I have read a number of the print quality guide suggestion. So far nothing has resolved it. Wondering if anyone had any tips.
Thanks
Re: First infill layer weak - Second seems ok?
I'm guessing your first layer prints slower. If you're getting good fill but faster layers seem to underextrude, I'd increase temperature.
Different brands of PETG print differently, but I rarely go below 240 nozzle temp and print some as high as 260. You'll probably get better layer bond strength at higher temps too.
Different brands of PETG print differently, but I rarely go below 240 nozzle temp and print some as high as 260. You'll probably get better layer bond strength at higher temps too.
Re: First infill layer weak - Second seems ok?
Thanks for the quick response. Yes - my first layers print at 50% speed. I have been printing with this PETG with other printers at the same temp successfully. That said, the others are not bowden style, and have Micro swiss Hotends. I will give the temp increase a try. I will also see about slow down the print, increase my infill line width, and d a slight Z adjustment to see if my autolevelling / mesh is a confounding factor. Not all at once of course. Working the variables. 
