Here's the bolt I've been using in my latest round of experiments:
As you can see, the teeth are crudely effective. This bolt was made with a hand-held cordless drill and an M6 tap, and it shows! Also, due to the short shank, I had to insert them backwards, with the nylock in my wade's gear and the bolt head on the back- a less than ideal arrangement. If I had a lathe I could perhaps have cut the teeth straight into the threads, but that's almost impossible with a hand drill.
I think these will be far more effective, and at the very least more uniform! Unlike my dishevelled creation, these actually have a groove for the filament to ride in. The position of the hob is slightly different to mine, but some washer swapping had it lined up perfectly