Machinist

[Lawrence London <lfljvenaura@gmail.com>]

http://www.practicalmachinist.com/vb/general/how-make-277084/index2.html
You can use most any boring bar that will fit in a 3/8" hole (your first hole.) Typically a 1/4" boring bar or tool will fit in a 3/8" hole. A 3/8" boring bar will not fit in a 3/8" hole because you need some clearance. You don't even need carbide tooling. HSS tooling will work fine and is cheaper and more forgiving of mistakes. Strangely enough you may find that most boring bar sets of equivalent size will cost 2X to 4X as much for HSS as for brazed carbide.

But... I found just the right tool for this job for you: Tool Bit, 1/4" Boring Bar Presharpened - LittleMachineShop.com at $6.50 esch. Get two or three. It will clamp directly in to one of your regular tool holders as long as it will hold a 1/4" tool.

Use a light touch and touch it up on a whetstone when needed and a couple of those little HSS tools will last far longer than a whole set of the cheap brazed carbides.

Here is an image of the operation you will be doing with that tool: http://www.sherline.com/images/lathfg11.gif



You should also get a book called 'How To Run A Lathe' (It is a basic reference manual that many of us learned from.) It is a bit dated and the most recent copies will be more up to date. The first edition is from about 1914.