Monday, January 9, 2017

Improved Thumb Wheel for the Cable Splicing Clamp

After using the Splicing Clamp to make about 10 cables, for my Fly Baby, I decided I needed to stop and make a larger, easier to grip, tightening wheel.  I originally made the wheel from the same 1/4" x 1" bar stock used for some of the parts.  It seemed clever and would work fine with flexible cable.  With the non-flexible 1x19 cable it was just too hard to get the cable tightened against the thimble.  You could do it but it took a lot of wiggling the cable while turning the wheel.

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.

I'm ready to make some more cables.  Much nicer wheel.

I'll go back and add this to the original posting.

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