Hello all,
Finished a little project and thought I would share. In the process of making various tiny screws, grinding and polishing the top surface can be a bit tricky. I had first made a jig, called a 'frog' or 'bolt tool' (depending on the text). It consists of a clamp with two rear leg-screws which are positioned level with the object to be polished in the clamp. The difficulty lies in leveling these leg-screws for polishing something only a fraction of a millimeter thick. I could have made some improvements, for example a smaller screw pitch, but I decided on a better designed tool. A source of information on the bolt tool can be found here (
http://www.bhi.co.uk/aHints/frog.html)
Photo of the old tool:
In Henry Fried's book, "Bench Practices for the Watch and Clockmaker" he provides a diagram for a screw polishing tool which has three stationary legs, i.e. a tripod. This omits the need to make the tool level for each use. The object to be polished is held in a collet (8mm watchmaker's collets in this case), and an adjustment for height is provided.
I made a drawing and machined the components from brass plate and hex rod, drill rod, and 12L14 steel rod. It consists of a tube to fit a collet with a nut to draw-tighten the collet. This tube is keywayed and fit into a larger tube, which has a set-screw to mate with the keyway (this arrangement allows for the height adjustment). I made the legs to fit into bushings which will allow small adjustments to be made to the tool to keep it level over time.
For additional information, I detail the construction process on my website (
http://watchmaking.weebly.com/screwhead-polisher.html).
The finished components:
The assembled tool:
Thanks for looking,
Jere
