Newbe here, looking for help in identifying this tool.

There is a yearly event our family gos to each year in rural Park County Indiana.
Lots of vendors, yard sales, food, fun etc 
Picked this tool up at a yard sale and a few hours later saw another with only a 1/2 inch long machined knurled end and no slot, just a smooth butt end. I should have bought the second one too but didn't.
Our family and extended family are all puzzled as to what it is, is it for a particular industry, specific use and if it's old.
We have all done hours of online searches but can't find another example that looks like it.


So I have come to the tool knowledge mountain in hope of enlightenment.
Any help would be greatly appreciated! Thanks!
(hopefully files are attached)

Looks like a valve lapping tool.  Moving the sliding part down causes the end to rotate in one direction and moving it up should cause the tip to move in the opposite direction.

Back in the day, car engine valves had either two holes or a rectangular narrow notch on the face of the valve.  You put lapping compound on the valve or valve seat, put the valve back in the engine, inserted the tip of your tool in the notch on the valve, and proceeded to move the sliding portio of the tool up and down.  This caused the valve to rotate back and forth, thus mating the valve to it's corresponding seat.

By the way, there are dozens of different designs of this type of tool.

Mike

Agree with mike , valve lapper. It's a nice unusual one. Probably 1920's/30's era

X3- And it is quite unusual- never seen one like that.

Similar were sold with a small knurled nut at the end that tightened down on a tapered collet to hold small drills - known as Archimedean drills, they were widely used by hobbyists, especially those interested in making fretwork items in thin wood (a popular hobby in the Victoroan/Edwardian period) - the drill (about 1mm or 3/64" diameter) was just big enough for a fretsaw blade to pass through...

Possibly the second one you saw was a drill, with the bit broken off in the hole.....

For more information on drills, valve lappers and patents etc, see: http://www.wkfinetools.com/hus-bortools/zchuck/archdrill.htm

e.g.

Patent #1,131,789 March 16, 1915 W.H. Pearce "Valve Grinding Tool"

Patent #1,134,511 April 6, 1915 G.K. Carlson "Valve Grinder"

Patent #1,206,589 November 28, 1916 V. Pipshik "Valve Grinder"

Patent #1,268,309 June 4, 1918 E.B. White "Valve Grinding Tool"

Thank You Mikeswrenches, Lostmind, Papaw, Billman49!

My brother-in-law is a huge car guy. He was totally stumped.
I'll tell him how you guys helped solved the riddle but will first have to play it up a bit with a "Oh that ol' thing" story at dinner.
Should make for an amusing eye rolling time!

Again, Thanks for your help and insight!