Well, I Just Screwed Up My Spindle.

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Zoltan

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This was probably one of the dumber things I've done. :(

I had a little bit of galling on inside of the MT3 taper in my mini mill's spindle, so I bought a finishing MT3 reamer to clean it up. However, I got a little too rambunctious and ended up knocking the top of the taper 0.0005" out of alignment. It's not a huge amount, but it's amplified the further the tool is from the spindle. *sigh*

I've already ordered a new spindle from Grizzly, but it's pretty much the hardest part to replace on the mini mill.
 
That's so unfortunate,
Every last one of us has done similar, part of being human.
Good news is, pain and expense are great teachers and we generally don't do the same thing again we just move on the the next stupid thing :D
 
I wish all of my mistakes could be remedied with a couple dollars and a couple hours of work.
 
Problems are no problem for my wife, she has a easy button................... my phone number.
 
Perhaps you can skim the taper with a boring bar using the lathe's compound to true it back up. Then finish with the reamer. Did you try using the reamer under power? It should be done by hand.
 
If it's the small end of the taper that is damaged you could undercut it with a boring bar leaving that area as clearance, if you have enough taper left to drive your cutting tools.
 
Unfortunately, the whole taper is affected. At the mouth it's off by maybe 0.0001" and then progressively gets worse until it's off by 0.0005" at the top.
 
how did you manage to get it off like that?
i mean its virtually impossible to get the mouth and the top off to the same side even if you tried..
 
Last edited:
Hi Zoltan
If you are replacing your spindle do yourself a favour and get a R8 taper. Lots of tooling available anduch easier to use. Removing a collet from a R8 is much easier.
Ron
 
If you can, get an R8 spindle as Ron mentioned. Easier to tap loose.

If you have a lathe I'd try skimming the taper (or reuse the reamer using the tailstock for alignment) and see if that helps before removing it. When removing the bearings, always push them off my the races not through the balls, or you'll "Check" the bearing.
 
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