Glen,

I posted on this around January. I had mine built up with WELCO 14 BARE

nickel silver alloy. I just got my 9" running last week and the halfnuts I

rebuilt with this procedure are as good as a new set if not better. Here are

a few added thoughts in addition to the article.

1. I did all my work on a Bridgeport mill. This procedure can be done on the

lathe as in the article but the mill setup is sturdier

2. I bored the original threads out to .85 dia. I reasoned this would leave

.05 of alloy to act as a "base" for the threads.

3. The halfnuts appear to be made from a single casting and split down the

middle with a 1/8 cutter after all factory machinery is complete. When I

sized and cleaned up the silver solder I left the center portions heavy so

there would be .005 or less between the two nuts when in the fixture. (In the

fixture the nuts are in the engaged position on the lathe.) In hindsight I

believe this step was the basis for my threads coming out as good as they

did. I'll explain. I purchased a new tandem acme tap for this project and

during tapping I had to add clamps over the threaded portion of the nuts as

the casting would flex away from the tap. I tapped about 1/4 turn and backed

out. I did this while advancing 1/8 to 1/4 turn each time. By having a full

diameter of metal around the tap I experienced none of the "breakout" that

would have been felt with the 1/8" gap between the nuts. Also, you can

purchase a single stage acme plug tap for about 1/3 the price of a tandem.

Don't even try to do this with an acme plug tap. I think the nuts would break

from the forces required to remove all the metal with the single thread

former on the plug.

I have spent the last year rebuilding my 9" and at some point in time I plan

to post pictures in the files sections so the group can see my toys. In this

was to be pictures of these nuts and the fixture. If you have any questions

feel free to contact me.

Keep turning!

Ed

9" Model A

(Broken file)

(hacksaw)