Machinist gauge/micrometer?

[Zrxrunner]

Found this in an old machinist box I'm clearing out. I know previous owner worked on old ford's and model T's, not that it matters all that much specifically. 4649 is only model or mfg. Everything else looks like graduation marks. Assuming it's part of a bigger set, but Google lens won't help much either. The sale i got it from had lots of good precision tools, but they were scattered everywhere! Ended up with half a truckload in order to make sets of anything! Anyone have a good idea of mfg or specific use of this?

 

[cvairwerks]

Looks like a cylinder bore gauge.

 

[d42jeep]

I agree although I haven’t seen that exact one. There is some resemblance to these Starrett ones.

 

[RoninB4]

Looks like a micrometer head from a specific fixture for checking some specific piece. Normal micrometer heads don't extend that far or have a spindle that looks quite like that. It's possible that cvairwerks is correct or that this is an inside micrometer but I'd have to see the other end of this too. That spindle looks odd to me and I've seen very many different brands both old and newer.

Edit: I looked at the photos closer and must have missed the end on one photo. I agree it's likely an inside mic or bore gauge, not just the average mic head because there's no collar for mounting like they usually have. Still think the spindle looks odd.

 

[Zrxrunner]

I should have put a few more specs in too, fairly large piece...overall 6.75 inches long when adjusted to 2.5 setting. 2.25 inches of the gauge shaft sticking out at that setting. It's about 1.25 inches diameter at thickest section of the tube. 3/8" diameter of the smaller shaft that would do the measuring

 

[Provincial]

That could be a tool for setting a cylinder boring tool cutter. Mounted in the head with the groove in the shaft locking it in place with a screw, it would be used to read the actual cut being made. The the cutter could be adjusted without removing everything from the cylinder block.

 

[txvwnut]

I haven't touched my cylinder boring setup in forever but I remember it having a mic head similar to the one listed. You would dial in the amount of cut you needed then set the tool in the boring head and adjust the cutter.

 

[grannyknot]

I've rebuilt more than a few engines, I use my dads old cylinder bore gauge.