I do not understand what you mean by "grinding a toolbit to match the original Mantua worm". Does your lathe have a controllable carriage motor? I am guessing that is the only way it would work. I am not machinist, but rather a hobbyist and I do have a Taig micro lathe that I use for brass turning and milling, but for the life of me, I cannot imagine how you would turn a worm on the lathe.
Thanks and regards,
Date: Tue, 18 Oct 2011 12:08:15 +0000
Subject: [HOsteam] Re: New member...Saying Hello and with request for information
Bill, I spent many years as a machinist before retiring, so grinding a toolbit to match the original Mantua worm was not too difficult for me. My home made worms (I've made several over the years) are never quite as smooth as NWSL's, but if I can't find one of their's to fit the situation, the "home mades" are smooth enough!
Incidentally, when I have a metal to metal worm gear set (typically a steel worm and a brass gear), I usually improve the mating fit by polishing the assembled set (in the locomotive) with abrasive lapping compound, followed by a thorough cleaning then run it again with jeweler's rouge polishing compound (often for several hours, over a period of days), then more disassembly, cleaning and finally lubrication. The difference in smoothness and noise level is usually dramatic!
That being said, I've found that this procedure doesn't seem to work with the Micarta / Fiber worm gears commonly found in older engines. Not sure why this is. They remain noisy after all the polishing and cleaning work! Maybe someone on this list can explain why.
I've never bothered using this polishing technique on Delrin or Nylon worm gears because I've always found them to be smooth and quiet right from the start.
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