In my last post regarding the saga of the part of many attempts, I mentioned my intent to try an “old school” technique for rounding off the ends of the part. The obvious approach would be to center up the part on the rotary table and mill the ends. This has challenges. The small size of the part makes any error in centering very obvious, holding on to the part while still getting in there with an end mill is tricky, and so on.
I was especially leery of messing things up at the final stage for what is a cosmetic feature so I elected to go with hand filing. I am no master of the file so just marking out the curves and having at it was not going to produce a satisfactory result. Enter the filing button. Filing buttons are a form of filing guide that provides something to file up to centered on a hole. Other filing guides can be used for more elaborate repetitive shapes but all I needed was a circle. One usually makes the guide out of a harder material so that the workpiece goes well before the edge of the guide.
I made a pair of buttons out of O-1 drill rod since that is much harder than brass. I could have heat treated the results to get something that the file could not scratch but this is a one shot use and I wanted to avoid extra wear on my file. I made a pair with matching center and hole so that I could clamp the forks of the workpiece in the vise and not bend things.
After dropping and finding the button parts several times, it was just a matter of filing away all the bits that didn’t look like a rounded end. It probably took me three times as long to make the buttons as it did to use them but I found it relaxing to use files because there was little to no chance of a catastrophe. I am pleased with the end product and even enjoyed making it. Onward (finally) to the next part!