Installation of a tachometer in an LMS mini-lathe

And today is a new day! Upon reflection, and the fact that I only had cut 0.25mm deep threads, and full depth threads are 1.3mm, I decided to flip the gears on the B/C shaft. And cut some threads. Apparently have a bit of deflection due to the home made bar and HSS cutting bit.

What that last sentence really means is the nut didn't fit! Can't say I am surprised. (Just because I had a perfect fit twice in a row, doesn't mean it always works!) It's pretty close, but not quite deep enough. I suspect the tip of my tool bit is a little flatter, or missing a tiny piece at the tip. There's a flat spot where there shouldn't be. For some reason my grinds leave the HSS weakened. That's a topic for a different post. The ID seems to be about correct, maybe the major diameter isn't correct due to the blunter tip. I can line up the pieces, but it just shows no inclination to start threading. Yes, I measured the spindle pitch, and it matches the 1.5mm pitch I cut.

I can see why people make a male test piece - so you don't have to take the nut out of the chuck. Going to do that now. Have a piece of 1.25" OD 1144 that would work. After a few iterations, I got it. Used thread wires to measure the spindle thread and cut until the test piece matched. Wish I could internally thread as well as these external ones came out.
PXL_20211002_234940043.jpgPXL_20211002_235032218.jpg
 
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