Maybe a drawing would help people see what you are intending to make.

First mark a centre line and the two hole positions 18mm apart and dot punch them.

Take a pair of dividers and mark the 10mm and 15mm external radii

Mark the 10mm and 8mm widths and join these up to get the tapered lines

An easy way to mark the internal 6mm radii is to take a short faced bit of 12mm rod hold the end onto the work and adjust the position so it is tangental to the arc and line then just scribe the 6mm radius.

To machine will depend on what you have available but

First drill the two holes, saw off the waste, make arbours to fit the holes and mount the work in a chuck on the rotary table and using a 12mm (to give 6mm internal radii) cutter round the ends stopping at the taper lines. Reverse and do the other end. Then either mill or file away whats left.

Finally use the arbour again to mount in the lathe and reduce the thickness

Of course filling buttons and a couple of files will also do the job. At the other end of the scale if you have a CAD package you can use that to get co-ordinates of the 6mm radii and just drill them to 12mm and join up between with the mill.

What does Anthony Mount say about the part?

Edit just looked at Anthonys build article and he does it as I described but say what machines and tooling you have available as there are always more than one way to do the job.

J

Edited By JasonB on 28/04/2013 07:56:25

Many parts like this (external radii) are more quickly dealt with using a combination belt sander/disk sander. It perhaps won't be as accurate as machining the part (depending on what tooling you have available) but if time is valuable to you then grinding is a good method. The finish is also very good. A rotary table with a chuck should also be high on your list of things to buy, you'll find it has many other uses apart from this type of work.

For the belt sander, make a proper table for it adjusted to exactly 90deg, and if you run the belt right up to one edge (and slightly beyond) it curves around the edge a little allowing tight radii to be formed. The disk sander (typically 6" diameter) is good for putting the final finish on the part.

This is a rather poor picture of mine, on the left, but you get the idea..

For us newbs please exactly what is a filing button and how does one get some and then how does one use them ?

Rick,

It's just a bulky washer with a screw through the middle. Some people leave them soft to be kind to the file, but I make mine from from silver steel and harden them and don't temper them.

Neil

I make mine from odds and end of scrap steel, and case- harden it with Kasenit, I,v got a whole stack of them on the window sill, some times I even find that I have old ones that fit the job. Ian S C