I decided to make a bench key for my watches. When I started filing a square on the end of a rod,it quickly became evident that I am not as steady as I used to be, and needed to use a double roller filing rest. Since I don't own one, and couldn't find any to fit my WW tool post on Ebay, I decided to make one from some scraps of aluminum and brass I had lying around. The center plate is 1/4" plate. The slide is 1/8" plate. The brass "rating" nut is 1/4" square stock. Side screws are 4-40 and set dry, so that I can remove the slide plate for cleaning if necessary. The rolers are on 6-36 machine screws, cut slightly short, and held in with a dab of fingernail polish in the recess formed at the back side when screwed in. (Here again, so it can be disassembled if need be.) The rollers are 1/4" OD #6 spacers I found while digging through a 50 Lb box of Westinghouse floor sweepings my father had. I was actually looking for "6 ss pan head screws for another project.) I don't know what material they are, but they weigh very little and are HARD!!

Nicely done, if you need something, make it.
The sign of a true machinist.
Mike

Of I had it to do over, I'd order a very fine thread tap, so that I could have more control in the vertical adjustment. As it is, that is a 32tpi screw thread, so with the hex nut on top, I can only tell about 1/12 turn, or an advance of .0025" or 0,075mm. It is really a little coarse for watch work, but will work to make such things as stems or the odd sized bench key, provided I am judicious as I approach the desired size. (It will be ideal for small clocks such as those size 37 Waltham car and aircraft clocks.)