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Starrett No 700 questions

texasgeartrain

Titanium
Joined
Feb 23, 2016
Location
Houston, TX
I picked up a Starrett No 700. It is missing a thumb screw from the back side of one of the jaws. Its called a locking knob, in one search I did, however I don't know exactly what its locking. The mic functions fine, the jaws don't move around. It also appears there is another thumb screw on the end, jaw side, not sure if its a permanent fixture, or maybe is removed for cleaning and disassembly.

Would anyone happen to know the missing screws thread size, or other info. Would be appreciated.

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Looking at Starrett's page for the inside mic, they show a factory use parts kit. The last part in the list is labeled "SCREW, .100-56 LOCK X .250 LONG". Wonder if they just rounded up on that diameter.
700A Inside Micrometer Caliper

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Clicking on the part, there is no option to add to cart. Not sure if contacting them will help, might give it a go.

McMaster Carr has some options in the #3-56.
McMaster-Carr
 
It doesn't seem that they rounded up any other sizes. I wonder if it would have been made of brass. Quite often, screws that are made to lock a quill or spindle are made of brass so as not to mar the spindle.

JH
 
Starrett uses/used many non-standard thread sizes on their tools.

I highly doubt that a screw that measures .002 OVER nominal size is a #3 screw. Screws will measure AT MOST the nominal size, and usually are smaller.
 
I've had to replace a few Starrett screws and rarely does a standard thread size fit. They're almost always a bastard thread (from my experience). To be honest though, many companies that were around during the turn of the century did the same as "standards" were still evolving and when threads did become standard, the proprietary threads ensured that customers would go back to OEM for replacement parts.
 
I have both 700 micrometers. the 1 and 2 inchist range. I would contact Starrett they might have be able to supply the screw. I also have a broken 1 inchist. Not sure if I want to sell it, one side has the tab broken off. I was thinking I might want to modify it. I did contact Starrett and was told they would not sell the part I needed. Can't remember if they said I could return it for quote to regrind it. Found another on ebay, while looking found a newer B&S. I like the B&S better. Have the older B&S models but new model is better.
 








 
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