Tool Caliper with broken screw

[Ian Moss]

Could be. Makes sense for an outfit like Starrett.

Holy shit. That Fkn thread is 78.5 thou x maybe 60 tpi. So probably an 80 thou #2 screw. Or perhaps a 2mm x 0.45 or or or.... Gunna need a better way to measure threads I can't see.

Clock makers? Any suggestions? My screw gauge is letting me down.

I suppose I could single point that but I'm not gunna. Just need to find a long screw whatever size that is!

Toolmaker's microscope...works great.

 

[ChazzC]

Could be. Makes sense for an outfit like Starrett.

Holy shit. That Fkn thread is 78.5 thou x maybe 60 tpi. So probably an 80 thou #2 screw. Or perhaps a 2mm x 0.45 or or or.... Gunna need a better way to measure threads I can't see.

Clock makers? Any suggestions? My screw gauge is letting me down.

I suppose I could single point that but I'm not gunna. Just need to find a long screw whatever size that is!

Per the exploded drawing & parts list in Post #5, it's 0.125-40. As I've noted elsewhere ( but maybe not on this forum until now) Starrett hasn't changed threads on these ancient tools to make them standard; in many cases the original toolmakers just used whatever they wanted, or made a tap to suit the single-pointed thread. I have a PT13820 "Upright Post, #196" that is (per Starrett) 0.231-28: I replicated it for a longer rod by using an adjustable 12-28 round die.

 

[Susquatch]

If you have a good place you can go in person, take the thumbnut with you and try before you buy.

I only have Fastenal here and they are unlikely to have something like that. In any event, I have not been able to get the thumbwheel off yet. So your earlier suggestion to use a bigger screw is starting to look pretty good.

If you have to order, order a bunch of sizes and use the one that fits. (shipping will likely be the largest portion of cost)

Yes, my feelings exactly. I'd prolly also order more than one and save them for a future job anyway.

If none of them fit, see my post above.

Yup, looking more and more like that's the way to go.

 

[Susquatch]

Per the exploded drawing & parts list in Post #5, it's 0.125-40.

No way. Don't care what that reference says. That screw measures 0.0785 it's not even close to 0.125! It could be 40 tpi though.

Toolmaker's microscope...works great.

I don't have one of those. But I do have a nice biology microscope I could use. If all else fails, I'll count teeth - wouldn't be the first time I've done that!

 

[140mower]

Ya, I deserved that. But I still have two words for you and they are not nice!

Whatcha mean? Everybody loves sex and travel......

 

[ChazzC]

No way. Don't care what that reference says. That screw measures 0.0785 it's not even close to 0.125! It could be 40 tpi though.

Sorry, missed your earlier post with the diameter.

Apparently Starrett changed the design of the legs to make them beefier; here is the current model:

 

[Susquatch]

Apparently Starrett changed the design of the legs to make them beefier; here is the current model:

Bet I know exactly why they did that! LOL!

 

[ChazzC]

Bet I know exactly why they did that! LOL!

Wouldn’t happen to been that the screw was too weak?

 

[Susquatch]

Wouldn’t happen to been that the screw was too weak?

Ya, it's a tiny little thing. That's prolly why mine broke.

 

[FatherWes]

My guess is it’s cheaper to make it from 1/8” mild steel that’ll bend than from a high grade steel that snaps.

 

[Susquatch]

My guess is it’s cheaper to make it from 1/8” mild steel that’ll bend than from a high grade steel that snaps.

You are prolly right, but I'm not really worried about it. It's a caliper, not a brake caliper bracket. I can't get my head around the Buffalo treatment the poor thing was subjected to. Prolly used it as a glue up clamp!

 

[Dabbler]

It looks like you might get a tap and die for a close approximation of the diameter and make your own threaded rod and thumbnut - you could even upgrade to brass for the thumnut!!

You could get a 2.5mm tap and die and that'd do the trick...