This week we broke a few extruder parts :(
Nothing unfixable but it's taking some effort to fix (and redesign i believe).
1- Do not use plastic gears.
To move the pump, we used a small stepper motor with a 10/1 gear reduction.
The gears where taken from a printer (same as motor) and where made of nylon.
During a temperature test, we accidentaly tryed to extrude when the temperature was below melting point and the stepper gear pinion eated the nylon reduction gear.
We replaced it with a brass (or bronze) gear and pinion.
2- Clean and degrase all parts if using locktite
The pump main gear is glued to the main axe using locktite.
It's not a press fit so i glued it with locktite 640 (quite strong and support high temperature).
After running the extruder for a few minutes with a smalish (0.5mm) tip, the axe got loose.
I'll turn a new axe of a size that allow for a press fit, and i'll add some locktite to it just in case...