Proxxon Micromot 50/E Miller/Driller run-out.

[David BridgenParticipant @davidbridgen77862]

The machine hasn't had much use, but when I came to use it again a few days ago I noticed some run-out when using the keyless chuck 28 941 and, to a lesser extent, the steel collet set 28 940.

I don't remember having seen this the last time/s I used it, but that may be due to an ageing memory.

In desperation I bought a new 50/E unit, which was supplied with another collet set, and a new chuck.

I discovered the same problem, run-out.

A bit of experimentation revealed that if I tried inserting a drill bit or milling cutter at various depths into the chuck I got different results. And I find the same with different insertion depths with the collets.

I placed the detached chuck, jaws down, on the bench and pushed down with a rod on the washer, inside the rear, which pushes the jaws forward as the chuck is screwed onto the drive shaft. The movement felt very rough (reminding me of John Gardener's recent post "Chuck binding&quot.
It "feels" as if the inside of the chuck body has circular machining marks around the circumference on the inside.

On examining the front of the chuck after doing this a few times I found that one jaw wasn't always fully bottomed along with the other two.

I there any way I could attempt to smooth the machining marks off the inside of the chuck body? I don't even know how to disassemble it or what I might do if I could.

Now, as regards the collets. I found that depth of insertion of the bit significantly affects the results, and it is possible with a bit of fiddling to reduce the run-out so that it just about disappears.

All in all very disappointing though.

Oh, an additional note. On the first 50/E I bought, the collar around the drive shaft, around which the tool is clamped in the drill press, was of cylindrical, i.e. parallel sides, and was made of black poly-whatever.

That on the new 50/E has a parallel sided section and then it tapers, and it's made of aluminium. A mistake in the assembly shop, or a crafty way to make one buy a different tool?

[David BridgenParticipant @davidbridgen77862]

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