This picture from "Aviation Mechanics Made Easy" Vol. 4 pg. 526 (c1942) shows a clamp in use on a control cable. It also shows the other tools needed to form the splice, a marlin spike, rawhide mallet, and wire cutters. You also need a hardwood block to pound against when tightening up the tucks.
This clamp is from a 1944 Supply Division catalog pg. 75. That same gallon of Berryloid dope was then $2.65 although a new Sensenich prop. for a J-3 was only $35.
The one I've decided to use as a model to make my own is one I borrowed from Rich Wilbur who is restoring 2 WACO NINEs. He made this one in A&P School so it seemed like something I should be able to copy. I've had this for a year but couldn't find a piece of 1" steel to make the holding block on the vise end. While making some tools for the Cessna 140 project I realized this block could be made from 1/2" x 1" mild steel like the clamp base piece. All I need to do is screw 2 pieces together to make a 1" block. In the end this is probably a better idea since it solves the problem of how to install the bushing which holds the block and clamp base together.
The 2 block halves were cut 1-1/2" long, ground smooth on one side, and squared up on the ends. The Base piece is also cut from 1/2" x 1" mild steel 3" long. The Jaw piece at the end is the same size but cut from 1/4" thick mild steel. The pivot bolt is 3/8" - 24 UNF x 3" long. The 2 Slider bolts are 1/4"-28 UNF with a grip length of 2-5/8". The threads need to bottom out in the Jaw plate. The ends get ground off smooth and staked in place.
I decided I needed a wheel closer to 2" in diameter with nice big knurls for a good grip. I also wanted to keep it 1/4" thick to have a reasonable number of threads. If it wears out I may need to make one from 3/8" thick steel.
The only piece of 1/4" steel I had was on some tools for making wire ferrules for the WACO internal bracing wires. I decided it would be fine with a 2" hole in the base since I just clamp the base to my work bench.
I located a pilot hole for the 2" hole saw then used the saw to draw a centerline to layout a pattern of holes for the knurls. It certainly took the guesswork out of where the center of the holes should be.
I center punched a pattern of 12 holes, pilot drilled them with a 3/16" drill and finished them with a 5/16" drill.
To round the edges of the holes, it makes more comfortable knurls, I countersunk the holes with a 1/2" center drill, steeper flutes. Then I lightly countersunk then with a 1/2" twist drill. It really makes a nicely rounded edge to the holes.
Back to the 2" hole saw to cut out the wheel. I cut half way from each side and when it got close just pounded it out with a light hammer blow. I didn't want to risk this 1/4" slug flying around.
It's looking like a thumb wheel.
I cleaned up the outside radius with the belt sander and the chamfered the edge at 2 angles, sort of like with the hole edges.
The remaining burs were cleaned up with the small sanding drum on the Dremel tool. It needs to feel good in your hand and no sharp edges.
The hole was tapped with a 3/8" fine thread to spin on the center bolt.
I had a little trouble getting the 3 bolts apart since I had put Loctite on the threads and cut off the head of the 3/8" both after tightening it in the clamping bar. A little heat took care of the Loctite. I greased the threads and the pivot with Molykote to keep the friction low.
A much nicer wheel.
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