Here's one that I have no clue about.  A friend showed it to me at a tool meet in NH in Sept.  It intrigued me so I thought I'd post it and see how you guys would do.

It is about 3 1/2 in. tall when lowered and 3 13/16" when raised.  A difference of about 7/16 in.  The pin that holds the top and bottom together is about 5/32 in. in diameter.

Around the top it is stamped U. S. PATENT.  On the base is stamped 550211 on one side and S595 on the other.  The base is oval shaped and is 3 1/8 in. by 1 13/16 in.  The diameter of the plunger(if you want to call it that) is 7/8 in.  The plunger is polished and is slightly concave.  The area that surrounds the plunger is also concave.  The area around the top, where it meets the bottom part, is convex, as you would expect. 

One would expect the 550211 on the base to be the patent no.  I was unable to find it if it is.

This is a very heavy and well constructed piece that must have been used for a precision job.  There is no slop anywhere.  The question is; what was that job?

Mike

for shotgun shells?

I'm thinking it's not for shotgun shells. I've looked at, and used, quite a few old reloading tools and can't think of any part in the process where you'd use a tool like this. It looks like it would put a pretty precisely curved edge on a disk or washer.  Whatever it must have been meant to form must have been pretty hard, given the force you would get from the threaded shaft and the leverage from the handle. And it needed to be precisely formed, jewelers dome metal disks and washers with a doming block and a round ended punch, which would be enough if you didn't need it to be precise. My first thought was thrust washers, which are both hard and precisely made, but I can't figure why you'd need to hand form them. Just my thoughts....

The type of tool reminds me of presses/formers used in making dental inserts, but I cannot imagine what would require a form of this shape.

Question: is the depth of the centre of the mould variable?? It looks as though the bottom may move up and down as the locating screw follows the helical groove seen in the fourth image, thus moving the relative position of the central spigot...

How deep is the central hole, and what diameter?? Does it correspond to any calibre of shell/bullet??

I assume from the screw that the top plate moves down, again what amount of movement is there?? Does the top locate against the bottom when fully home, thus allowing something to be compressed to a certain size? My thoughts are that if this is the case what is moulded is in the form of a powder, that then gets compressed/sintered to form the object...

Try moulding some plasticine or playdough in the recess and see what shape comes out...

It's a very cool and well made what's-it.

For setting rivets or snaps in tarps, clothing or leather? I admit I am having a hard time figuring out the movements involved in the spiral and the threaded portions. Al.

Billman,  The center post is fixed to the base, but the outside is adjustable up and down by virtue of the spiral milled in the outside.  The total adjustment is 7/16 in.  With the outside raised all the way up, the center post is then recessed 7/16 in.  Post dia. Is 7/8 in.

The screw in the "lid" also has a hole drilled in it.  Perhaps to hold a die of some type? 

For some reason I think it might a device used by watch maker's, but I can't explain why.

Thinking about this after my last post - It seemed to me that as the screw is tightened, the case will move downwards, following the milled spiral, so the centre will rise inside the case (unless you forcibly restrain it from doing so????)....