I'm printing some change gears to check the fitment of the gear train on a banjo. I have been fighting with this particular brand of PETG trying to get a clean and accurate print since last week.
Notice on the 2 20T gears the poor bores and under extruded 5 layer top surface. They were printed with a hardened .40mm nozzle on a Bambu A1 Mini. They do NOT fit the spindles on the banjo at all.
Now look at the larger 80T gear. Clean teeth and bore with proper flow rate on the top surface. (Yes the infill is showing a bit due to the mere 3 top and bottom layers I printed it with to save on filament). This gear fits as it should right off the plate.
Same exact filament, same printer, same exact slicer setting. Just a hardened .60mm nozzle swapped for the hardened .40mm nozzle. And dried to 14%Rh for days and I printed directly for the dryer.
Soooo much time and filament wasted calibrating and recalibrating for that .40mm nozzle and it still failed. All I needed was the .60mm nozzle. But, still a new and interesting phenomenon to learn from for me.
I seldom use a .40mm nozzle much anymore since I mostly do functional prints like these gears. I have found the .60mm nozzle is a good compromise for speed in printing, better strength, and good accuracy.
Interestingly enough, a .40mm will print nearly or as fast as a .60mm nozzle on Bambu printer in general. This because Bambu optimizes their slicer setting for the .40mm nozzle. What it does give up a bit is between layer strength. This is due to to the smaller contact area difference between layers. I can get the same strength with 2 perimeters using a .60mm that would take 3 perimeters with a .40mm nozzle.
Very interesting, thanks.