Just wanted to detail the problems I have had fitting a #20 and a #15 (hammer) handpiece to my flexshaft. I have an old chrome motor from a Foredom dental outfit, but when I got the dental handpiece off of it, I bought a standard flexshaft and #30 handpiece and that all fit together fine…this was maybe 15 years ago. Last year I bought a #20 knockoff from China and it wouldn’t fit onto the flexshaft sheath… many puzzlements later, I enlarged the sleeve on the handpiece using a cylindrical grinding wheel and the #20 finally fit. A few weeks ago I bought what was supposed to be a #15 hammer handpiece off Ebay. It came in a plastic case marked “Foredom” with a set of instructions from Foredom (apparently), but it wouldn’t fit the sheath either. Having the experience with the other handpiece, I easily figured out I needed to ream out the handpiece hole again. However, after that was done, the ball bearing was too tight. I had to file off some of the bottom of the handpiece to allow the groove in the sheath end to center in the ball bearing hole. Still wouldn’t fit. I loosened the spring around the ball bearing and made the hole in it larger and the handpiece finally snapped into the sheath without heroic effort.
I don’t understand why these things don’t fit out of the box. It took about an hour to fit each of these. I could understand the knock off, $12 purchase price #20 not fitting, but I would have thought that the #15 from Foredom would have fit. Perhaps it too was a knockoff forgery, as it came at about 25% of list. Anyway, I wondered if anyone else has experienced this and wanted others to know you can get cheap handpieces, but there may be some fitting involved in getting them to work on your motor.
Other than the fitting problem, the #20 has worked well the few times I’ve used it and tonight, after relieving the edge on the anvil point and polishing it, it seemed to work OK. The little wrench for the anvil point was missing out of the box, but any little shaft substitutes for that, so no problem there. HTH, royjohn