Mini Mill R8 spindle

jrkorman

H-M Supporter - Gold Member
H-M Supporter Gold Member
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Jan 22, 2017
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Bought a HF mini mill a few days ago (lightly used), so got it home and have torn it down and am cleaning and
relubricating as I go. I've got to the spindle now and am noticing that the shank will go in about an inch or so
then is very hard to insert any further. When I was taking things apart it was a bit difficult getting the shank out
of the spindle.

So is this in the range of "normal?"

I've looked at the shank and it appears to be well finished, smooth with no burrs or such. When shining a flashlight
into the spindle bore it looks as if the surface finish is a bit rough!

I'm still cleaning other parts and probably going to wait until I get the belt drive kit before I do much with this machine.
Any suggestions on how to attack the problem would be appreciated.

Thanks,
 
Might need to see some picts on that....
 
Might need to see some picts on that....

I'll see what I can do - lighting might be interesting
DSC_1508.1_141.JPG


Think I may have found it. After looking at several pictures, I went back out and tried several more times.
I've noticed that it starts to "drag" about a 1/2" after the locking grove makes contact with the pin (upper left).
I ran my finger along the grove again (not the first) and noticed that there is a burr from there at least a couple
of inches. Still very tight, but guess I've more work with the file to do.

Putting a very light chamfer on the edge of the grove shouldn't cause any problems that I can see!
 
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Does the R-8 bore in the spindle have the small metal post that engages the R-8 collet? Is it lined up?

Be curious how rough the bore is.
 
Does the R-8 bore in the spindle have the small metal post that engages the R-8 collet? Is it lined up?
The post is fine and the shank inserts past that. Seems to be binding up as the straight portion of the shank gets further in. I cleaned up the grove and that has helped a bit. Feels like trying to insert a shaft into a very tight fit.

Be curious how rough the bore is.

See the picture above.
 
Is there a way on that mill to adjust how far the alignment pin sticks out of the sidewall of the spindle? If so, you might try backing it out a hair and see if that helps.

Tom
 
Sometimes either the pin is rubbing because it sticks out too far. Or the groove in the collet is too narrow causing a binding. To find out if it is the pin or the collet I would try a couple collets. If they all bind a bit then it probably is the pin causing the problem.
 
I would take the pin out, so it is not in the way. And GENTLY with a brass fox tail brush (the correct size) and WD40. Clean out the hole. Then get back us…Dave
 
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