I'm trying to dial in bridging settings for HatchBox PETG on a MakerGear M2E. I started by doing a calibration for the extrusion multiplier using a single wall cube, and came up with 0.86. This is with a 0.35mm nozzle, shooting for 0.45 mm width with 0.25 mm layer thickness. This was a bit tricky, because 3 of the four walls were quite consistent, but the 1st wall printed was always significantly thinner. I ended up getting 0.45, 0.45, 0.46 & 0.36 mm.
In any event, I started with some bridging parameters from the MakerGear forum:
Unsupported area threshold: 5 sq. mm
Extra Inflation Distance: 1.0 mm
Bridging extrusion multiplier: 140%
Bridging speed multiplier: 125%
I downloaded a bridging test file from Thingiverse and fired off a print. The results were pretty horrible:
In addition to the giant loops, I noticed that the bottom surface wasn't fully filled in. There are lots of tiny holes, which suggests I'm under extruding. The walls of the bridge areas don't look too bad, it's the interior bottom fill that isn't working. I looked at the preview in S3D, and I think the loops are the result of the zig-zag fill unraveling because the ends never stick to the perimeters:
I tried a couple more prints, increasing the extrusion multiplier first to 0.88, and then to 0.90. The holes closed up a little, and the loops got a little better, but it's still pretty awful.
So, I have two questions:
1) How do I reconcile the single wall calibration that gets me the right wall thickness (3 out of 4 times...) with the fact that I'm clearly not getting enough extrusion to get a good fill?
2) How to I tweak things so the ends of the zig zag fill on the bottom of the bridges actually connect to the perimeter walls?
Thanks!