At the massive Brimfield Flea Market last month, I picked up this unusually well made tool. Note the ball bearings barely visible around the axle. Not only does is spin freely, but there is zero play side to side. And the wheel is very heavy.
At first I thought it was an unusual fillet, used for marking lines in leather. But it turns out it was made for the tire/ rubber industry. It is marked “The Everhard Mfg. Co.”, and is known as a beveled stitcher, used to smooth wavy edges of uncured rubber. It also bears a striking morphological resemblance to a leatherworkers wheel. Even if it can’t be usefully adapted for bookbinding work, it is still a wonderfully well made object to have.
Yikes! Have I started down the slippery slope from tool user to collector? Is this a problem?
Peachey Conservation 
You can never have too many tools.
I have one also. Now I know what it is. I also thought it was used for leather. I tool leather but it really did not look like anything I had seen before. I have a tool for cutting wetsuit material but it is beveled on both sides, and it has two handles.