Trueing Spindle Bore

[epanzella]

If you can't sleep now, what do you think will happen if you screw up your spindle doing a job that didn't need to be done. The factory didn't make the bore perfect because they didn't need to. If the 5MT is concentric that's all that matters.

 

[higgite]

Speaking of opening a can of worms, maybe I should go fishing instead of wrecking my lathe.

To butcher Thoreau’s quote a little bit, “Everyone should believe in something…. I believe you should go fishing.”

Tom

 

[Tozguy]

I’m all dressed up with no place to go.

That Thoreau fella sounds pretty smart. I believe it is Gene Fowler who is credited with saying “I am glad that I paid so little attention to good advice; had I abided by it I might have been saved from some of my most valuable mistakes.”

It would certainly be a mistake to true the spindle bore on my lathe; one that even Gene would not want to make . Total run out of the bore at the front is .090” and since spindle i.d. is 1.490” and o.d. is 2.145”, that is a relatively huge amount to take off of one side of the bore. If I persisted in wanting to true the bore it would only prove that I have a bad case of ‘tunnel vision’.

The fish weren’t biting so I went back to the lathe and decided to take just a token cut somewhere that would not hurt anything. It looked like the entrance to the bore could use a bit of chamfer so I started putting the boring set up together.

Cutting the chamfer at the entrance to the bore allowed me to confirm that the boring approach I used can actually work even if it looks like a pipe dream. It was a boring afternoon but I have never had so much fun.

Here are some pictures in case anyone is interested.

 

[Tozguy]

Here is the chamfer and proof of chips.

 

[4GSR]

Did you measure any of the OD's of the spindle to make sure you have meat to work with?

 

[Tozguy]

Ken, yes, dimensions are given above. I only chamfered the entrance to the bore that is 5.5" in from the nose (pic above). It was a very light cut just to prove the boring set up. I did not attempt to true the bore as originally planned.
Since the run out of the MT5 taper at the front of the spindle is less than .0001" it would have been ridiculously reckless to do more than I did.