The Rotary tools used to power the GC all share the same spindle thread. The thread is a .275" x 40 British Standard Whitworth thread. It was developed for watchmakers lathes over 100 years ago and is obsolete and very hard to find. I’m told Dremel began using it to discourage knockoff products. (didn’t work) It has a unique geometry and must be used.
I have found these available from China. Delivery time is 3 to 6 weeks and I have ordered them but don’t have much confidence in their tools. Being British Standard Whitworth I have searched UK websites without success. If anyone in the UK or ? can locate a non Chinese version, I would be very appreciative. Thank you in advance and please don’t go to any trouble.