This week we broke a few extruder parts :(

Nothing unfixable but it's taking some effort to fix (and redesign i believe).

Lessons learned:

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...