Starrett micrometer 436 repair

Don't have any little cleaning brushes for the insides, just going to soak for a while in mineral spirits. There's no tension adjustment that I can see on this mic. The lock is just to prevent spindle rotation as far as I know. It mostly works ok. I see no evidence of cross threading, all the threads look rather good.

I don't know how old this micrometer is, could be as young as the sixties, or as old as 1945, give or take... Steel tips, not carbide. I understand the no qtips thing, (no fibers!) but save for a squished up paper towel, or a pipe cleaner, I don't have anything to get in there. I could use a drop of M1, but I have heard that less lube is better. An ultrasonic would be great, but I don't have one. So it will soak a while...
 
Oh, yeah, I have that adjustment on the mike. You can see it in one of my pictures. It's a silver ring, not black. I haven't touched the tension setting on it. Not sure I need to, it feels like my good Mit mic right now, so I can't complain. Not loose, but not tight. I could tighten it slightly, but only by a hair. I don't have the tool for this mike, although maybe I have one for a different mike. It's just a mini pin spanner as far as I can tell.

Second reassembly, screw is so much smoother now, but I am off by 0.0035". In other words, the mike reads 0.0035 when the ratchet clicks. Ratchet isn't quite as nice as before, must not have got it quite right. Don't know why I am off by 3.5 thousandths at the moment. Cleaned the jaws with a piece of paper so it isn't grit on the anvils.

I'll have to take the ratchet off again, I bet there is a tiny piece of crud in the taper that holds the screw, that would offset the scale in the direction I am seeing. Eventually I will get it right...
 
Ratchet feels right now. The screw feels great too. Much better. However, I am off from zero by a line width, which annoys me. Is there a zero adjust? I don't want to have to clock the thimble relative to the screw, that would be a horrible iterative task, is there an easier way to do it?
 
WobblyHand said:
Ratchet feels right now. The screw feels great too. Much better. However, I am off from zero by a line width, which annoys me. Is there a zero adjust? I don't want to have to clock the thimble relative to the screw, that would be a horrible iterative task, is there an easier way to do it?
Click to expand...
so you turn the barrel with the line and markings, not the one that turns. You need a tool..
It's easy, but you need the tool.. if you have any micrometer tool check to see if it fits.
 
I had a 436 just like that. Exposed it to muriatic acid fumes accidentally and ruined it
Never keep potentially leaky acid jugs in the shop!
 
markba633csi said:
I had a 436 just like that. Exposed it to muriatic acid fumes accidentally and ruined it
Never keep potentially leaky acid jugs in the shop!
Click to expand...
All acid jugs, especially muriatic acid do that. Had that happen in the garage, rusted up my table saw.
 
woodchucker said:
so you turn the barrel with the line and markings, not the one that turns. You need a tool..
It's easy, but you need the tool.. if you have any micrometer tool check to see if it fits.
Click to expand...
Yes, I see the hole for the wrench. Ok, need to see if I can find a micrometer tool.
 
You must log in or register to reply here.
Back
Top