Difficulty repairing Foredom handpiece

Wreck™Wreck said:

Thanks, my wood working experience is limited. Much like a flexible shaft die grinder I suspect.

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It's biggest market is watch and jeweler service. but has many uses. The three machine shops I have worked in had one. Can be used as a die grinder along with many other things. I have used mine in a boring bar holder as a tool post grinder.

Years ago I worked for a dental supply company. The dental laboratories that make dentures, crowns and the like used Foredom equipment extensively. We serviced tons of their stuff, I don't remember it being all that difficult.

For the sake of sharing...
I decided to further dismantle the spindle on my #44 handpiece. I thought the shaft was pressed into the Collet chuck, but it was in fact a taper fit. (Some of you may have known that, I didn't.) That was good news. But careful measuring with a DI, surface plate, etc indicates that the collet chuck is indeed not right. Specifically, the taper is not coaxial with the hole for the collet. I still contend that this was a factory error given how stout the collet chuck is. The spindle shaft is pretty thin and a little bend there isn't a surprise. And the taper fit feels a little egged as well. So, I will make a close fit expanding mandrel (approx 13/32") for the lathe and regrind the little taper in the collet chuck. Anyone know the taper specs? If not I'll dope it out as best I can. I'll regrind the spindle shaft anyway so they match. I'm surprised this shaft assembly isn't available from Foredom!