I picked up a Starrett 436 in a smoking deal on Fleabay (not that I needed one, but you know...) and as a kicker, it came with a 221. I had no idea if the 221 worked, I know it's a different animal- but since what I paid was a fraction of the what the 436 alone is worth I had nothing to lose.
The tenths spindle wasn't operating correctly at all- so I located a parts schematic and proceeded to disassemble/clean.
Starrett 221 micrometer | 3D Warehouse
The exploded view doesn't show exactly how the motion amplifying lever fits together with the sub-spindle and the fine spindle cap; but I can find only one way where once fitted it allows the 90 degree travel needed for the fine spindle. The MA lever fits onto a pin protruding from the top of the sub-spindle, and the tiny pin on the underside of the fine spindle cap "snaps" down into the center of the MA lever when the pin is aligned with the notch and snapped down into place. This does allow for the 90 degrees of rotation, but it's REALLY "sticky" at the last couple of tenths on each end of the travel. Everything has been cleaned and degreased, no visible burrs. I can load the spring tension on the cap no problem (though I have no idea what the spec is for this)
Wondering if anyone's had one of these apart and re-assembled before, if I've got this right- and what might be causing this. I've calibrated it to a 1" standard, but would like to get this running correctly if possible. No- I'm not going to send it to Starrett; it's just not worth a repair bill the size of a new digital mike (which I don't need more of anyway).
Ideas on what might be causing this and how to fix?
The tenths spindle wasn't operating correctly at all- so I located a parts schematic and proceeded to disassemble/clean.
Starrett 221 micrometer | 3D Warehouse
The exploded view doesn't show exactly how the motion amplifying lever fits together with the sub-spindle and the fine spindle cap; but I can find only one way where once fitted it allows the 90 degree travel needed for the fine spindle. The MA lever fits onto a pin protruding from the top of the sub-spindle, and the tiny pin on the underside of the fine spindle cap "snaps" down into the center of the MA lever when the pin is aligned with the notch and snapped down into place. This does allow for the 90 degrees of rotation, but it's REALLY "sticky" at the last couple of tenths on each end of the travel. Everything has been cleaned and degreased, no visible burrs. I can load the spring tension on the cap no problem (though I have no idea what the spec is for this)
Wondering if anyone's had one of these apart and re-assembled before, if I've got this right- and what might be causing this. I've calibrated it to a 1" standard, but would like to get this running correctly if possible. No- I'm not going to send it to Starrett; it's just not worth a repair bill the size of a new digital mike (which I don't need more of anyway).
Ideas on what might be causing this and how to fix?
