Millrite spindle play in not a problem

Mar 12, 2007 2 Replies
J

One question that came up during the "Table jumps around when drilling with an end mill" saga (starting 24 Feb 07) was if the spindle on the Millrite was loose, and Jon Elson suggested measuring the radial motion when a 50# sideload is imposed on a bar clamped in the spindle collet. I did this with 18.3 pounds (the weight of an iron block I have) and a



1/2" drill blank clamped in the brand new 1/2" R8 collet, with a pulley and rope transferring the load from the dangling iron block to the spindle, and the spindle moves slightly less than 0.001", so the spindle bearings are not a problem.

Joe Gwinn


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J

I was also trying to point out that there will be some clearance in the bearings, themselves, which will be taken up by lube when the spindle is running. There is also some clearance in the quill, which won't be taken up except maybe when the quill is clamped.

I don't bother with exact forces or weights and pulleys, I just lean on it with my hand, that is good enough to see these clearances.

Jon

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J

True enough. Hmm. I'm not sure I clamped the quill. I'll have to redo the test.

Anyway, the threshold question was answered: One theory was that the table jumped around because the spindle was loose, and this does not appear to be the case here.

I did that too, but with a known weight I can compute the actual stiffness, and compare it with published values. The intent is to hang a number on "stiff enough".

Joe Gwinn

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