The Taming of the Screw

Broken saw screws, what to do? Especially the nice of brass split screw variety? Given that they were on the clapped out Spear & Jackson, I should just throw them away and put on some chrome Great Necks. But I just can’t. For some insane reason, I want to keep things somewhat original looking (given what I’m thinking about doing to the handle, this is truly unexplainable). After kicking some ideas around, I decided to just go ahead and make some.
This things are not simple and look like they were made with a hammer (nothing round or consistent), so measurements have a lot of slop. I don’t know what the thread started out as (it is possible that the saw is old enough that it predates thread standards), the threads are two messed up to measure but 8×24 seems close enough to work. Not a die I have. But a metal working lathe I do have.
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The slope on the shoulder seems to be 20 degrees (I originally measured 30, fixed that later).
One thing I learned later is that the original screws didn’t have enough threads. Through dumb luck, I have enough thread, plus the relief gives me room for wood shrinkage.
Threads turned on the lathe, checking until I got a good fit.

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I moved to the mill to cut the shoulders, a file would have worked just fine but why have tools if I don’t use them? A square collet holder allows me to cuts square shoulders – put in vise, cut one shoulder, unclamp, rotate 90 degrees, clamp, cut, repeat. Remove, measure, cut some more (getting a caliper under the chunk is a pain).

 

 

 

 

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Cut the screw off the rod and dressed the head.
Did some test fitting and tweaking (this is where I went, “hmmm, that angle seems to be too steep”) and done, better than new. And it only took two hours. Yeah, two hours to make a little bitty screw. But in the saw it does look like a factory new replacement.  Better yet, that bent one busted as I was test fitting, that is how I know wood shrinkage wasn’t taken into proper consideration (the nut bottomed out and twisted off the almost dead screw). Oh well, I know what I’m doing now, it should only take me half the time for the next ones.

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One Response to The Taming of the Screw

  1. Pingback: Brooksbank backsaw rehab | ZK Project Notebook

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