Mitutoyo Digit Micrometer

[sparky961]

I just received this in the mail today after a recent late night eBay shopping excursion...

Mitutoyo Digit Micrometer

After opening the package and trying them out, I notice that the barrel is a little bit sticky and I'd like to disassemble and clean everything.  Can someone tell me whether I should expect little springs and gears to go flying everywhere, or how I take this type of micrometer apart?  What about a light oil on reassembly?  Yay or nay?  How about calibration?

Thanks!
-Sparky

[sparky961]

Update!

Ok, I couldn't wait.   I did a bit of exploration and came up with what looks like 2 grub screws under the little rubber/plastic cap.  The two screws on the desk are from the counter cover.  I haven't taken out the grub screws for fear of messing something up.  Looking at how they're moving though, it looks like there is some relationship to the stickiness/binding that I'm feeling when turning the barrel.

Mitutoyo Digit Micrometer

Mitutoyo Digit Micrometer

[philf]

Sparky,

You can get an exploded diagram at http://www.mitutoyo.com/TerminalMerchandisingGroup.aspx?group=1099

I have a 0-25 and 25-50 and have taken both apart with no springs or other parts flying through the room.

They're excellent micrometers but I still always check the reading on the barrel - to make sure of the last digit. (There's always a little bit of backlash.)

Cheers.

Phil.

[sparky961]

Thanks, Phil.  That helps a lot!

[sparky961]

Well, I was able to take everything apart for cleaning (with alcohol).  Then I put everything back together while figuring out exactly what each part did in terms of adjustment.  There are a lot more parts to one of these than the more economic Craftsman one that I've been using for the past few years.

I decided on a very light coating of silicone grease on the threads upon reassembly and was able to take almost all of the backlash out of the dial without having noticeable drag on the thimble.

Initially I was a bit worried that I might have gotten a dud, but now it feels like one would expect from something brand new!

Oh, and if you're trying this yourself, DO NOT DROP THE SETSCREW!  The one is not much bigger than a grain of pepper, and after muttering a few choice words I spent 15 minutes on my hands and knees with a flashlight.... lol

-Sparky

[Paddy OFernichur]

I've got a couple of different types of those Mitutoyo 22x-xxx series mechanical digital micrometers. I congratulate you for the work you did on yours. I wouldn't dare crack mine open to fix them if they needed it. Too many small parts for my aging eyes and a general ineptitude on my part for that type pf rocket surgery. 

I have a mint condition #222-125 0-1" blade (a.k.a groove) micrometer, which I picked up off of the local Craigslist for $90.
Mitutoyo Digit Micrometer

A recent addition was the #223-125 0-1" disc micrometer. I also picked up that one from a Craigslist seller for just $10, but it had problems. While the numeric digits worked fine, the threads in the thimble got tight and crunchy as I opened up to 1". I brought it to the local Holt's Instrument Repair facility, as I didn't have time or parts. They hit me $125 to completely recondition it. They even made the mistake of giving it a NIST-traceable calibration certificate, for which they refunded $25 of my mney because I never asked for it. (But they can't take it away!)
Mitutoyo Digit Micrometer

I will be slowly, over time, be converting much of my collection of 20 different micrometers to all be the Mitutoyo Absolute digital electronic IP65 styles. My Starrett No.734XFL-1 will be serviced one last time and sold, as I picked up it's replacement from yet another Craigslist buy yesterday. It's #293-348 0-1" friction thimble type that I got for $100, in absolutely mint condition. I have the 1-2" already, from Ebay for $77.50, but its the ratchet style. Here's the new one:
Mitutoyo Digit Micrometer