Hi.  I'm new to the forum and starting off with the question that brought me here.   I found this tool/device (image attached) at a yard sale a few months ago and bought it because I was felt that I had seen one previously and thought that it might come in handy.  As you might imagine I have never figured out what it is even though I've been all over Ebay and also run several image searches on every descriptive term I can come up with.  I even uploaded a photo and used that as a reference.  No luck. 

The device is made of cast iron and the three "feet" at the bottom have been ground so that it sits solidly on a flat surface.  The dial is set on a shaft, the bottom half of which is threaded.  The dial/shaft will rotate multiple times, but obviously you're only supposed to be interested in about a quarter turn either way from some starting point.  As the dial turns the shaft comes out the bottom and it is long enough to touch the surface that the tool sits on.   Also, the bottom of the shaft is not flat, but domed inwardly as if it could sit atop something - or not.  At the dial end of the device there is a screw which I assume will lock the dial in place.  The shaft coming out the top is grooved.  Whether that is to facilitate turning by fingers or to hold a knob or attachment I don't know.

Anyone have a clue?

Thanks!

Hi Tom, and welcome!

I don't know what you've got there, but there's something stamped at the bottom of the thing... I can see the digit "1" for sure, but what else is there?

It could be the letters AC touching one another, or it could be a C with a line coming out the front side of it... -C.  The C and line are clear, but my eyes sort of make out the form of an A.  Both letters are smaller than the 1, and offset a little higher off the baseline.  Without my glasses on I would never have seen them if you hadn't mentioned them.  For that matter I forgot the 1 without my glasses.

Oh, and it's about 11 inches long.

Thanks.

looks like something to check the depth of a depression, or high point.
flat on 3 legs & screw tip into depression/high point.... is scale in +/- .001"? .010"?
I think the scale can be set to "0" first, then grind & check high point from "0"
sometimes used with surface plates & bluing...

Yes, the scale is +/- 10 corresponding to +/- 0.10".  The dial has a hole in it and is held to the shaft by a clip, so if you were to tighten the set screw in the end of the tool and insert something in the hole you could spin the dial to zero it.  Sounds like you are on the right track.

Off to search some more...

Thanks.

the only thing is the bottom tip is concave? normally it would have a ball tip to fit in a small spot, & used with a dial indecator (i.e. mounting rod for indecator & foot)

Yep, the bottom tip is concave and not smooth at all, it has a lot of concentric rings like it was turned on a lathe rather than drilled. 

Looks like some sort of leveling device - possibly to set the depth of cut on a wood planing machine???

I think Billman may have hit it,  I knew I've seen these but couldn't remember where.  Sears used to sell a jointer setting kit,  I'll check some older Craftsman catalogs to verify.

Yep, that would be it.  A jointer knife setting gauge.  Found a Craftsman model identical to it (in all but color and markings) on ebay with the original box, so no question about it.  What a relief to finally know what it is.   

Thanks all! 

More info here: http://vintagemachinery.org/photoindex/detail.aspx?id=6796

Dooo!  I should have called it.  That is the way that I sharpen my jointer blades. Use a flat bottomed stone in a router.  I screw a  piece of 5in x10in 3/4 in. mdf with a notch that clears the stone to the bottom of my router.  I raise the infeed table up level with the outfeed table.  Turn one blade so that the sharpening side is parallel to the infeed side. Jamb the rotor with a wood wedge. Level the infeed table to the blade with a straight edge. Slide the board along the infeed until the stone is over the blade. Set the depth so that it just touches the blade.  One hand on the board keeping it down on the table and the other hand on the router. Count the number of blade passes you make across the blade. Rotate to the next blade and make the same number of passes. Check it with a dial indicator or the nifty Sears Guage. Correct any that are unequal. If I was a perfectionist, the mdf board would have three feet like the guage tool. It takes a while, but I don't have to change blades.

Tom, here is a link to the instructions for the gage.

http://vintagemachinery.org/pubs/222/4745.pdf

Thanks, that could come in handy.

I can't believe the this site sometimes, the knowledge here is incredible.