Saving a Unimic

mercredi 12 novembre 2014

I've been after a Mitutoyo UniMic for a while now, and finally got one sent over from my friends over in German ebay. The price was "ok" and it arrived quickly, but when it arrived it was frozen solid. I was able to eventually free it, but it really took some doing, and it was clear it had been that way for a long time. To cut a long story short I stripped it down and got it running fine. I was just about to call it good to go, but I like my mics to run quite loosely as I typically don't use the ratchet and prefer the feel from my finger tips. I was trying to loosen it off a little but instead I found myself getting the thing increasingly out of shape until I saw disaster had struck and the thread body was cracked (whether it was like that all the time I'll never know). Unavailable as a spare part so it was either bin the thing or press out the thread body and make a new one. It was a bit fussy so thought I'd post the process here.

Here is the thread body, together with a brass dummy I was originally going to use. It pressed out of the rest of the housing ok.

Thread body.jpg

For the real deal I started with some 12L14, I figured that should run ok against the hardened spindle, and the original was some from unhardened steel. It was then spot drilled and reamed to 1/4", the spindle size. It is a metric Mitutoyo mic, yet a bizarre mix of threads. I tend to use my collet chuck quite a lot now, and it's ideal for this type of work.

12L14 steel.jpg Spot drilling.jpg Reaming.jpg

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