Building A Boring Head — Part 4

Posted on December 18, 2011 by Jeremy

Well, chalk another one up to the scrap bin.

It certainly looks nice, but it’s wrong.

I finished cutting the threads, and when checking them with a 3/4 – 16 bolt, noticed that it was loose and seated at an angle. Not good. But at least I figured out what I did wrong. Earlier, I bored out the thread’s minor diameter to 0.7031″. That’s wrong. It should have been 0.6875″. That extra 0.015″ makes the fit sloppy, and causes the bolt to seat at an angle. So this one’s a failure. Time to start over.

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Comments

Why not just turn the shank as part of the head instead of bothering with the threads? I’m assuming you’re going to slip it into an R8 collet, right?

by K

I’m actually building two of these. One will go in an R8 collet on my mill, the other will thread directly onto a sherline spindle.