# Difficulty repairing Foredom handpiece



## ericc (Feb 18, 2017)

My Foredom handpiece was making grinding noises when spinning freely. The company sent a reply saying that the bearings were probably bad. Because it was difficult and expensive to repair their old style handpiece, it was recommended to purchase a new one. The newer style was supposedly easier to repair. There is a video on foredom.net showing how to do this,but there are some warnings on the internet that the older style has a bearing that is difficult to press. I told the responder that an arbor press is available, so it should be easy. Also, a lathe and mill are also available, so how difficult could it be? Turns out, very difficult!

The first problem was that the end cap was too tight to unscrew. The video shows a pair of jawed pliers unscrewing it, but this would mar the finish. So, I arrogantly made a wrench to unscrew it. This arrogance will surely lead to disaster later as things get screwed up even worse.  Anyway, here's the wrench. It worked great, leading up to the fall later.


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## chips&more (Feb 18, 2017)

Hang in there! I did it once, can’t remember it being any big problem.


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## David S (Feb 18, 2017)

Hey C&M please don't keep this secret.  Information here could help others.

David


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## ericc (Feb 18, 2017)

From the site video, it appeared that the front bearing should be pushed towards the rear. It was put in an arbor press and it moved a bit, and then just stopped. Uh oh. Something's wrong. Better push from the back. Uh oh. Won't move. Put some penetrating oil on, but now I know the end of the story. It will end up in little pieces. I should have thought a little bit more about the hole in the middle of the handle and understood what that had to do with the inner race spacer in the video.


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## ericc (Feb 21, 2017)

I just received an e-mail from customer support that I should have listened to them when they suggested that I return the spindle to them for repair rather than doing it myself.  Even though I have an arbor press, that doesn't mean that everything will be OK.

Here's how to press out the bearings on this old style Foredom handpiece.  I searched all over for this information.  Hopefully, someone looking for it will find this post.  Completely disregard the video.  It is for the new style.  The customer service rep told me this *AFTER* I failed.  That was a lot of help...NOT.  Actually, the bearings are not pressed out.  Both bearings are blocked from pressing out in either direction by an inner shoulder in the spindle housing.  They are not meant to be pressed on.  So, don't use any sockets or bushings to press with.  Instead, the shaft is pressed from the rear.  That is because the shaft is pressed on the inner race of the front bearing up to the boss behind the collet, and it is not possible to get a tool in there, even if you wanted to.  This is considered poor machine practice, since the inner races of both bearings will not be supported when the shaft is pressed forward.  I guess it doesn't matter, since the old bearings are destined for replacement.  The shaft will press out of the rear bearing, and maybe out of the front.  If the front bearing comes along, it will have to be pressed off the shaft with some wedges, which can be fabricated on the lathe.  The shaft will not come completely off the first bearing because the hole for the tool changing pin will have a burr on it.  This bur has to be ground off before the shaft will pass through the front inner race.  This has to be done every time the unit is disassembled.  Finally, the rear bearing can be pressed or pulled out, but again, it will have to be by an unsupported inner race.

Now, I have to figure out whether to turn a replacement spindle body or just give up.


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## mws (Feb 21, 2017)

How timely is your post!  Just yesterday my son went to use our Foredom Hand piece with a larger carbide 1/4" burr. We usually leave it with only 1/8" bits.  He tells me he bent it. Bent it? I don't think so.  Well, to make a long story short, after hours of dismantling and checking the spindle on V blocks and DI it turns out that the collet chuck body, where it's bored to press onto the spindle shaft, is off center by 0.0045.  It's NOT bent, I could fix that.  I guess I could send it to Foredom. They don't sell replacement spindles for the #44A either.  But it sure diminished my opinion of Foredom.


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## Wreck™Wreck (Feb 22, 2017)

What exactly is a Foredom hand piece?


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## brino (Feb 22, 2017)

Wreck™Wreck said:


> What exactly is a Foredom hand piece?



It's like a replaceable, interchangeable, reversible, repairable dremel tool on steroids......see:
Foredom® #30 Handpiece: http://www.leevalley.com/en/wood/page.aspx?p=31033&cat=1,130,43409,43410
Foredom® #44T Handpiece: http://www.leevalley.com/en/wood/page.aspx?p=31036&cat=1,130,43409,43410
Foredom® #8AD Handpiece: http://www.leevalley.com/en/wood/page.aspx?p=31035&cat=1,130,43409,43410
Foredom® #28 Handpiece: http://www.leevalley.com/en/wood/page.aspx?p=45490&cat=1,130,43409,43410,45490

They all work with the motor unit: http://www.leevalley.com/en/wood/page.aspx?p=65681&cat=1,130,43409,43410
some rebuild parts: http://www.leevalley.com/en/wood/page.aspx?p=31032&cat=1,130,43409,43410

A useful tool.

-brino


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## Wreck™Wreck (Feb 22, 2017)

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


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## ericc (Feb 22, 2017)

That's it. Kind of like a more serious version of a Dremel.


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## kd4gij (Feb 22, 2017)

Wreck™Wreck said:


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




 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.


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## ee-lee (Mar 12, 2017)

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.


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## mws (Mar 14, 2017)

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!


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