Building A Boring Head — Part 2

And so it begins.

I cut off a couple 1.25″ lengths of the cast iron bar, and faced the ends to make them pretty. The big thing about this cast iron bar is that it isn’t round. So although the ends of the bar are flat now, they aren’t necessarily perpendicular to the length, or even parallel with each other.

I popped one in the 4-jaw chuck, and faced the end again. I now have an end that’s flat and straight as long as it’s in the same setup. I then turned down a section to 1.395″, as called for in the prints.  That section is now actually round and perpendicular to the faced end. This end of the workpiece is now a datum, a reference that I know and can work off of for my next operations.

This end of the stock gets threaded 3/4 – 16. So I started by drilling out to the largest diameter I have, which is 1/2″.

And I then bored it out to 0.7031″, which is the required diameter for putting in 3/4 – 16 threads. Since the bore was done in the same setup as the facing and turning, the bore is concentric with the outside diameter.

And now I face a conundrum. I don’t have a 3/4 – 16 tap. And I don’t have an internal threading tool. I have some broken cutters I could grind into one, but they’re all carbide, which my aluminum oxide grinding wheel just can’t handle. So I’m stalled until either I buy one or think up how to make one. Stay tuned.

And so it begins. I cut off a couple 1.25″ lengths of the cast iron bar, and faced the ends to make them pretty. The big thing about this cast...