As I mentioned in the last post, after building up the extruder/hot end assembly I tried to feed some filament into it as you would in normal use. I noticed that this could only be done by opening the tensioner and having to use a screwdriver to push the filament so that it lined up with the teflon tube.

Shaded area represents the straight path

Even once you have done that, because of the forced curve in the filament around the gear, it is very tight to push the filament down through the hot end.

The basic issue is that hole in the extruder body which fits the teflon tube and the hole in the top where you insert filament are offset from the surface of the hobbed gear. I am going to guess the the MK8 hobbed gear is a slightly larger diameter than that the body part was designed for.

I have already filed the left side hole out in these photos

By drilling/filing out both holes I have reduced the problem considerably, moving the filament is a lot easier but it is still not great. I know that the extruder stepper and driver already are a bit limited on power so the additional friction cause by this situation isn’t good.

I will see how it works once I start printing. There are solutions, but nothing that simple. You quickly run out of material around both holes if you drill out anything more than 5mm. Also there is then nothing holding the teflon tube in place.

We shall see….