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Starrett micrometer fix

Discussion in 'METROLOGY - MEASURE, SETUP & FIT' started by mwestcott, Feb 17, 2017.

  1. mwestcott

    mwestcott United States Active Member Active Member

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    I found what I thought was a great deal on a little used Starrett T230RL 1" micrometer. It had some old gunk on it, so I thought that was why the spindle was sticky when turned. I took the spindle out, cleaned and degreased everything, and it is still so tight I can't use the ratchet.

    Upon looking at it, it appears the spindle lock mechanism isn't retracting enough and is dragging on the spindle. It will turn to a stop and lock the spindle, but it will spin all the way around the other way and release a bit, but not enough for the mic to spin freely. I found a bit of info on line, and several mentioned that, when the thing is apart, DON'T turn the spindle lock. I'm sure I did when cleaning it. Nothing I can find mentioned how to fix this issue.

    It may be related, but it's off zero by about .0005, and I tried to rotate the barrel with the spanner, and it won't budge. Thanks for any advice!
     
  2. Tony Wells

    Tony Wells United States Vice President Staff Member Administrator

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    It's been a while since I serviced a RL series, but it seems to me there is a small pin involved in a split portion of that lock ring. If the split gets distorted by turning it when you shouldn't, the open position still doesn't "relax" the friction on the spindle. You could buy another lock ring, but no harm in trying to bring it back to proper shape. If you can't, then maybe look at buying a replacement. Or a quick call to Starrett may result in a "how to" on fixing it. I'm not absolutely positive about this., As I said, it's been a long time since I had one apart and I may be confusing it with another instrument. I have that style lock on my 0-6 set, and a few others and strongly prefer it.

    Oh, and the cal error is not related.
     
  3. mwestcott

    mwestcott United States Active Member Active Member

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    Yes, there's what appears to be a split ring in there that isn't moving out of the way. No idea how to get it or the lock ring out. There is a very small notch just in front of the ring on the barrel that I bet has something to do with it.
     
  4. Tony Wells

    Tony Wells United States Vice President Staff Member Administrator

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  5. mwestcott

    mwestcott United States Active Member Active Member

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    Thanks, I've tried that already - I get the message "the page you are looking for doesn't exist", with direction to a couple of links that go to some software company. I did find some information on another site that described my exact problem. The lock ring was moved when the spindle was out, which bends the split ring in there, which has a pin and cam arrangement. With the spindle out, the lock ring is supposed to slide out of its groove, and the split rings can be adjusted. Of course, my lock ring won't come out. I suppose the split ring was bent enough it has it locked in there. Any more force than I'm using, or going after it with a tool, will likely cause major damage.
     
  6. f350ca

    f350ca Canada Active User Active Member

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    When you figure it out post the solution PLEASE.
    Someone posted a how its made video on Starret micrometers, SO I like a kid had to see the ground thread. Looks nice but when I went to reassemble it I have your problem exactly.
    I've had them apart before to oil the threads on some old ones that had sat for decades and they went back together with no problems.

    Greg
     
  7. Tony Wells

    Tony Wells United States Vice President Staff Member Administrator

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    I'll be in the shop tomorrow. I'll take one of mine apart and report back. I've done several, but it's probably been 20 years. It will come back to me.
     
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  8. mwestcott

    mwestcott United States Active Member Active Member

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    SUCCESS! I was able to resolve this problem. The lock ring and the split ring do indeed come out directly upward, after removing the spindle. There is a little notch in the barrel just in front of the lock ring. There is a small lug on the split ring that fits in that notch. Mine was very tight, and although I knew better I finally just grabbed hold and pulled hard. It gave way and surprised me and the lock ring and the split ring and the teeny tiny little pin flew out onto the floor. I got incredibly lucky and found them all, especially the little pin (at least I hope there wasn't something else in there...). I would recommend putting the whole thing in a big clear ziplock bag or something if you do this, or so something to catch the parts in case it flies apart like that.

    At 4:30 in the first photo of the split ring is the lug that goes into the barrel notch. The split in the ring opposite to that is what causes the tightness issue apparently. I think if the lock nut is rotated when the spindle is out, the lock ring closes too much and won't spring back. I used an xacto knife to wedge the split back open. I put the split ring into the lock nut to test it and the spindle slid easily through it.

    It took me a while to figure out the pin goes into the wedge-shaped cutout in the split ring (has anyone been able to download the software from Starrett to view their exploded views? That would've really helped). Before I put it all together, I cleaned up some burrs on the split ring with a fine diamond hone. It was still really tight going back into the barrel, and a small bit of filing on some shiny spots on the split ring lug made it easier.

    Getting it back together was very fiddly. I ended up doing it a half dozen times before getting it lined up so the spindle would go through. After a bunch of tries, I reversed the lock ring on the split ring and it finally went together and now it works as it's supposed to, and I can use the ratchet.

    Now if I can just get it zeroed. It's off a half thousandth, and I cannot get it to move with the wrench. The wrench pin pulled out last time and boogered up the wrench hole, grrrrrr.... I have it soaking in Kroil now in case that may help.

    Anyway, I hope this helps someone!





    IMG_1629.JPG IMG_1630.JPG
     
    ronboult, royesses, pdentrem and 2 others like this.
  9. Tony Wells

    Tony Wells United States Vice President Staff Member Administrator

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    Yep, that's the way I remember it. I haven't had time to break one of mine down, so it looks like I don't need to now.

    The barrel is a friction fit, so soaking should help that. It isn't supposed to be that hard to turn. A little warmth like just sitting under a lamp may help. No torch or anything.:)
     
  10. royesses

    royesses United States H-M Supporter - Premium Content H-M Supporter-Premium

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    Those photo's make what you were describing very clear now. It is a one roller sprag clutch. Very ingenious design. Thanks for sharing with us.
     

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