Okay, I give up! 20 or 30 years ago I built a boring bar holder for my Atlas Lathe from plans that I thought had been around for decades. I want to pass them on to a friend, but I cant' find them!!!! believe me, I TRIED!
This is a cylindrical toolpost that replaces the lantern style tool holder that came with the lathe. The central clamp "Bolt" that squeezes the two halves of the "clamp" around the boring bar is drilled through its side to allow the boring bar to fit right through it. This particular model has three holes in the clamps to accept 1/4", 3/8" and1/2" boring bars.
I did find a similar plan on the web someplace, but it only has one hole in its side---- for a 1/2" bar, I think.
Yah, I know, why not just scale the needed dimensions and add them to the existing plans. No, that plan is somewhat more complicated and besides, I now obsessed with the need for that VERY plan,
If someone has it, or reference to it, I'd appreciate that info. I just spent about an hour at the drop box and I can't find it there, either.
----The NEAT thing about this style of boring bar holder is that it is probably the stiffest possible way to hold a boring bar that there is.
If my arm is twisted hard enough, I suppose I could draw it up and/or add a couple of pix of it to the drop box.