I've got a Bosch Dremel 3000 is it the collet thread on flex extension, or the flex to tool body collar thread.?
Collet thread -. I expected a metric thread but it's a weird one, major diameter is 7.05mm, too much to be an M7, and pitch was somewhere between 0.6 and 0.7 thread gauges. Tried a UNF gauge and 40tpi gave a good fit which is 0.635 bearing out the 0.6-0.7 I thought it was.So I haven't got a clue what the actual thread is, anyone else have a clue?…..or is it a Dremel/Bosch special to stop you using other make accessories ?
Extension to tool body – is probably M19 (major measured at 18.65mm) x 2 (spot on gauge).