I found one on ebay but it is my understanding there should be three laps with it for the set to be complete and I’m not sure if this one has all its pieces. Can anyone tell me something about these things, how to use the tool, do they work well? Considering this one is in England, does anyone on this side of the pond have an extra to sell?

Any comments or advice would be welcome.

Thanks for your help,

Bruce

The tool pictured does not appear to have a place in the box for lap wheels. It appears to be complete. In use, the screw would be held by a collet in the runner w/the screw head exposed for polishing. With the tool frame clamped in a vise, the user would place his left hand on the runner and revolve the runner as he works a burnisher or a hand-lap across the face of the screw head. The lap or burnisher is supported by the roller on a shaft which provides some guidance to the hand held flat burnisher. With this tool, the lap would be in the shape of a file but made of brass, zinc, etc which is charged with polishing compound.

The same tool sometimes will be found with a heavy lap wheel which can be mounted and revolved upon the shaft which, in the example show, has a file rest/roller installed. The screw head is held as above, but in place of the hand burnisher, the lap wheel is employed by revolving it with a bow. The shaft or runner holding the screw head is slowly turned as the lap is revolved against the screw head. Several laps may be used with progressively fine grades of polishing compound upon them. The revolving lap wheel is best for flat screws. Dome shaped heads must be polished with hand held laps supported by the roller rest.

One other note. While the tool pictured is equipped with collets, some of these tools used other methods to hold the work. Other holders include wax chucks and brasses threaded to take the screw being worked upon, and so forth. These tools were used to hold other work from time to time, which could not be conveniently held between the centers of the turns, or bow-lathe. Of course, the modern WW lathe made both tools obsolete but they held on for many years because of the expense of a modern WW lathe and tooling.

Best regards,
Greg Crockett
IHC Charter Member 22

Greg,

Thanks for a terrific explanation. I started out by making a three legged polisher as show in Fried's book, but I can't quite get the results I want. It is a little three legged holder that uses standard 8mm WW collets and gives you a way to hold the screw perpendicular to a sheet of ground glass that act as the lap. Very tedious and slow, but the final stage leaves the center of the screw head beautifully done but the outer edges never seem to come up as brilliant as the center. I have fought with it and think I may be able to refine the tecnique, but there has got to be a better way.

I had planned on making one patterned somewhat after the picture in my first post hoping for better results, but your last comment about the modern WW lathe making both tools obsolete now has me thinking that there may be a better way. Polishing an oval headed screw is no problem, I have made concave laps and gotten pretty good results on a lathe. What I can't quite imagine is the best way to do a flat headed screw and make it come out dead flat with nice sharp corners. Does anyone know if there is a lathe attachment available that has been designed for the job?

Many thanks,

Bruce

I'm not sure why your polishing fixture is not working. Is there a chance the fixture is wobbling slightly as you run it back and forth on the glass plate?

With a lathe, you may buy a pivot polisher which would do a fine job of polishing a flat screw head. However, this is an expensive item.
Most watchmakers would use a hand held lap and polish the head flat while the lathe is turning. The last step is to clean of the polishing compoung and use a flat steel burnisher. To get a screw head plished flat with a handheld tool is not as easy as it sounds, but not impossible either.

A single or double roller rest is a good idea to help steady the burnisher as it is run accross the screw head. A fixture could be made to clamp into the T-rest socket to aid in doing this job. Bar stock the size of the T-rest shank may be cut with a slot to hold a burnisher steady as it is drawn accross the face of the screw head aiding you in preventing wobble of the hand tool. A double roller rest would accomplish the same task since the two rollers have lips upon them to limit the travel of tools such as files when used to make square arbors.

Good luck.
Greg