When making no-mandrel bushings..

[mikemac]

how do I get the tapered hole to 60 degrees?

I drilled them out with a #4 center drill, but when mating them to my live or dead center.. I don't think they are cutting at 60 degs.. if I remember my high school shop, I think they are at 62.5 degs, or something like that...

Or does it really matter? Will they self center, if they fit properly into the tubes, and flat against the blank, once squared?

.. and I thought a wood lathe was a learning experience ... :embarrassed:

 

[johnnycnc]

Mike, #4 center drill sounds okay.Industry standard would be 60°,
not 62.5°. There are other included angle center drills to be had,however.
So be sure of what you have.And no, they won't self center if things aren't correct.The center seat and both diameters must be concentric.

 

[gwilki]

Mike: I bought a 60 degree countersink at Legere in Ottawa.

 

[mikemac]

Thanks all!

 

[Paul in OKC]

Mike, #4 center drill sounds okay.Industry standard would be 60°,
not 62.5°. There are other included angle center drills to be had,however.
So be sure of what you have.And no, they won't self center if things aren't correct.The center seat and both diameters must be concentric.

Yep. Angles available I think are 60, 90, and 82, or something like that, so make sure you get the 60 degree ones. And like said here, all diameters and center spot have to be concentric when made, or else.......! If you can't make it all in one step, be very careful when putting the bushing back in the chuck to center the end. If you are using a mini metal lathe, .003 is usually about as close as they get, but if you have more than one place for the chuck wrench, indicate the bushing trying each spot seperately, or all three in an order, and mark which one is the closest and always end up on that one. Usually you can get things pretty close that way.