Old gauge or what

[FCEng]

I have a number of interesting things and was hoping someone could help me figure out what they are. I have a number of short steel rods with center drilled ends, various diameters. Some have a size stamped on the end, some do not. This one is a good example. Stamped 1/2. But the rod itself is not really 1/2 in diameter as seen from the end measurements. These look to me to be manufactured items, not something someone made on a lathe. Any idea what these are supposed to be used for? As we can see, stamped 1/2, but actually a taper from end to end. These are part of a bunch of old tools that I have with an old lathe and mill.

Thanks!

 

[The Cobbler]

pictures of the entire item may help

 

[FCEng]

The full thing! And the end - both are the same. Both ends that is. small drilled conical hole. I thought maybe they were to place between centers on a lathe and check runout, but why the taper?

 

[WAS Jr]

Mandrel. Use on a lathe. Precise hole in work, slide on to the mandrel, now you can turn its outside to whatever diameter you want. Mount a lathe dog on the flat of the mandrel and turn the work using a faceplate. The taper allows you to tap the workpiece off after you turn the outside diameter. Half inch hole, a set includes all the nominal sizes.
Bill S.

 

[tombell572]

It's a tapered lathe mandrel. if you have to turn the O/D of a workpiece such as a flat belt pulley on a lathe and the part cannot be easily mounted in a chuck. a mandrel of the correct I/D (1/2" in your case) is inserted and the pulley pressed on until it is forced firmly against the tapered diameter of the mandrel. The mandrel is then mounted between lathe centers and the part turned to the desired O/D. The mandrel is mounted with the smaller end at the tailstock so the cutting tool continues to force the workpiece in the direction of the cut toward the headstock.

Tom B.

 

[FCEng]

That makes sense - Thank you both for the quick identification. I have a lot to learn about these things! Appreciate the information! I probably have a set - accumulated over time, as they are not all the same markings.

 

[RoninB4]

Put some light oil, not WD-40, on them including the center holes. Those are precision ground surfaces to be protected from the rust that appears to be forming. Don't use ANY abrasive to clean them up, not until you know how to do this correctly. Nice bit of tooling to have.

 

[FCEng]

Thanks - they are well over 70 years old, probably older, and have been neglected for most of that time. Will oil them right away.