Turning a small diameter?

Hi Nigel, If you can imagine an end mill, with a hole all the way through, held in a drill chuck and simply applied to the end of your material. If the hole is the size you want to end up with your new screws can be cut in one go. I have a number of commerially made ones for various BA screws, great when making lots of screws with a die head You can make one yourself from silver steel if you have "steam engine problem" equipment, just think counterbore but without the pin. Good luck, T.W.

You do not tell us how long the reduced portion is, but assuming fairly normal dimensions ie about 20 mm x 2 mm dia, I would male a twin turning toool with a bush, this is a tool with two tools set at 180 degrees to eachother so they both take an equal cut, by setting them in this way nthere is no cross force on the component. You can get away with a single tool, but it is not quite as good, in front of the tools you can fit a bush which is bar size, this keeps the whole thing central. This tool would have been fitted into a capstan turret, howewver you could put yours ito a tool post and the die (or coventry diehead) in the tailstock. In my experience roller boxes are not to good at brass or very small diameters.
Peter

'Roller boxes' for brass generally use vee guides rather than rollers, as brass chips tend to build up on the rollers.
Tim

Agreed, though I found that a simple Knee tool with a bush did most things . Peter

You certainly can produce lots of bits, ALL exactly the same size, by making some BOX CUTTERS. I use a Unimat 3 and have made two box cutters, sizes are 10 BA and 12 BA, for making hundreds of coach-bolts, that I use for the models that I make. There is an article on how to make the box cutter, it's in the Workshop Practice Series # 14, Making Small Workshop Tools by Stan Bray. I had a look at this article and then worked out that what I needed was a very small one, to do the job required, so I drew up my own plans and these are what I came up with. The hole in the end plate is the same as the material that I use for the small bolts that I make. The toolsteel position can be clearly seen and the way they are affixed to the toolpost. You don't need to be a rocket scientist to be able to draw one up, just work out if you need an adjustable roller or have a fixed size hole in a plate, the rest is easy.
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regards radish :D