I'm printing on a TAZ 6, with PETG at temp 235: bed 77 with 20% fill and 10 top layers with fan off. There appears to be randomly placed un-poped bubbles that show as bulges in the top finished layer. Any suggestions on eliminating them.
I would agree with slowing down your print speed but I would also suggest making sure your filament is dry. PETG has a tendency to absorb a lot of moisture and it can cause serious printing defects like bubbles.
It's likely to be one of two things -
Delamination due to it being extruded too cool (the surface will have a matt/silk-like finish) - try 240-245°C ,
or moisture - dry a full 1kg reel in a food dryer/dessicator at 55-60°C (or a preheated electric fan oven) for at least 6 hours.
I made the changes suggested so far, to no avail. I hope this photo shows the problem. Keep in mind that except for top layers all other parts of the part works great
PETG sags a lot (does not bridge well). This includes bridging over sparse infill; it just sags down into the gaps.
Recommend you increase infill density, and increase number of top layers when using PETG. Specific to the print in your photo, I’d suggest doubling the infill density. Thicker layers also helps, but denser infill and more top layers are the key.