Hey all,
I found this tool for $2 at a local country store... They had 2, one a little fancier- but they had no idea what either of them were. For $2, I had to figure it out.

First photo- Tool at rest. You can see "No100" stamped into handle, the only mark

Second photo- Back (or front???) at rest.

Third photo- Tool with lever pressed.... Little triangle tipped rod comes up just a tiny bit

Fourth photo- as far as the rod goes up

Fifth photo- Top of tool has opening ...

You have a saw set for setting the teeth of a saw when sharpening or changing the set.

Definitely a saw set !   But not one that I would want as a user unless I had it set for a particular saw.     The set adjustment is a bit crude, and would be tough to change the set for the # of TPI or PPI  for multiple saw types.

Thank you! When you say saw... I take it you mean for straightening teeth, like for a sawmill type blade?

Saw sets come in all sizes for all types of saws, from big mill types to small hand saws. Failure to set the teeth properly makes a saw almost unusable.
Google saw set, sawset, saw wrest , you'll see.

For instance on a two man crosscut saw you would set the teeth different for cutting pine than for cutting oak.

Or you could be crude like me and use horsepower and carbide ....*ducking*

Gawd we have gotten spoiled these days....

Using a 1/4 horsepower to cut a piece of wood with a wide kerf blade that probably can be cut with a properly set thin blade with 1/100th of a horse power in not much more time...

oh,well, progress....

Amen Rusty well said.  When I first started as a climbing arborist, we only used hand saws because chainsaws were too big and didn't have any safety features.  When we first started using chainsaws in the trees we would detune them so they would not idle.  If the saw kicked back we would just throw them and they would go dead by the time they got to the end of the safety lanyard.  We now use super hand saws that have the teeth sharpened three ways.  We now only use chain saws for take downs and to cut large limbs.