If you don't have a mill they are used to file square, hex etc flats onto a round bar using simple indexing of the spindle.

Never seen mention of them being used to file round work parallel and all have twin rollers, one either side of the work so the file stops cutting the work as it runs on the rollers.

I made my filing rest back in the 70/80s from I think a G.H. Thomas design. To be honest it doesn't get that much use but it is quite useful when putting flats on round stock. On one occasion a triangular head on a bolt that needed to be tamper proof.

What is suprising is how quickly one can achieve things like this as opposed to removing the stock from the chuck and transferring to the mill, not forgetting all the set up time.

Phil

Jason

They don't all have twin rollers, in fact the majority of ones for watchmakers lathes only have one roller. I dont see how they can be used with any accuracy or repeatability though.

I have just managed to get hold of a twin roller one myself, its main use for me will be "reducing" the size of hexagons on small commercial BA bolts, or making them from scratch using round stock. I think doing each one in the mill might be very time consuming, so I am going to try this method first.

Phil

I had my tongue in my cheek. I am 100% sure I have seen comments about using them to remove taper in round work. They could also clearly be used for final sizing and polishing. As I haven't done either I can't comment on the practicality but given that they are made with sufficient accuracy / adjustability I really can't see why it shouldn't work out.

I have also seen designs with one roller as Phil mentioned and not for watch making as well.

John

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Probably one of the simplest filing rests that one can make, is something like the one I made for my Unimat a few years ago, based on an idea in another forum.

Here are two views. Partly disassembled and assembled.

To use it, simply mount it in the lathe toolpost rotated about 30 to 45 degrees from the vertical. The crosslide is then used to adjust the filing depth. This photo of it being used to file a flat on the end of a rod should make it clearer.

Although it doesn't get much use, it is handy on occasion, and far faster to set up than setting up the milling attachment.

I have subsequently made two changes to it since the photos were taken: I replaced the socket head screws with countersunk screws allowing it to get closer to the chuck, and I also reduced the diameter of the thick washers which hold the rollers on and also act as a stop for the file as they limited the maximum diameter of the work piece.

Clive