Wade's extruder self-tightening.

I started to have an interesting problem in the last few days. My Wade's extruder's hobbed bolt is held in place by a nut at the end. Generally that bolt became loose so I had to tighten it again. But in the last few days, it started to tighten itself instead, to the point that the gear cannot rotate after a few minutes of operation. I do occasionally dismantle the extruder so this should be due to my recent interventions but I can't understand what caused the problem. How can I ensure that the nut stays in place tight enough but doesn't tighten itself or become loose? I tried a lock-nut but that's so difficult to install due to the resistence of the nut.

What does the nut bear against? I can't see how it would self tighten if it was only touching the moving part of a bearing. If it's touching the outer, non-moving part of the bearing then you need to add a spacer that matches the diameter of the inner part. Thread locker will prevent the nut from coming loose, but use the right strength to make sure you can undo it again when you need to.

Are you using a single nut to keep it all together? Usually it's 2 nuts that are tightened up against each other and hold each other in place.

Or use a nyloc nut

I think the problem was with the nut I used. It is difficult to find an M8 washer with a small diameter. I was applying a lot of force to the bolt so the nut was restricting the movement of the bolt and also tightening itself. I changed to a smaller diameter nut (still M8 but it is a nut used to lock other nuts, so it is thinner) and things are ok now.

A nyloc nut would be ideal as it won't come loose or tighten itself but it is very very difficult to install or remove. Requires a lot of force. If the setting was permanent, I wouldn't hesitate to use it but I change extruders from time to time so I need the system to be practical).

I second the Nyloc Nut suggestion. Every printer I have owned came with one.