Coach Bolt Hack

The M8 bolt in my BfB extruder hasn't been gripping the filament well. I've tried the standard tricks, sharpening the thread, increasing the force (until I cracked the acrylic), but I'm still able to pull the filament out by hand against the thread. While shopping around, I came across some coach bolts with much deeper, sharper threads. Simple replacement of the M8 bolt was difficult - there aren't nuts that fit and it was impossible to attach the existing gear or provide vertical support.
I needed a bolt with m8 at one end for the gear and bearings, and coach bolt screw at the other for the filament bite. So I made this:

From Coach Bolt drive

It's soldered together ( see pictures for more detail of how), but if I had an extruder I could easily have made a coupler, since the joint is in compression.

From Coach Bolt drive

It seems to fit OK into the BfB assembly, with a little modification of the bearings (one bearing, rearranged nuts to fit). It grips the filament lovely now, and hand-winding the gear drives the filament well.
I then attached my rebuilt extruder nozzle.

From Coach Bolt drive

I'll post later when I've tested the nozzle.