How do you make a concave shape in a cylinder?

[HMF]

How do you use a ball turning fixture or other tool to machine a fairly accurate concavity in the end of a solid cylinder- such as a depression where a sphere could rest. (think "egg cup")?

The diameter of the "sphere" is 1.5".

Thanks,


Nelson

 

[Tony Wells]

It seems to me I read a method of cutting concave radii by using a rotary table and boring head or fly cutter and tilting the head. Don't have a link to describe the method, however.

 

[cyrusb]

Depending on your application you could bore a series of step diameters and then go at it with a graver and a t -rest. Many hobby operations can be done without specialised tooling. If you don't have a t- rest and some gravers, whip some up. With some practice it's amazing how accurate you can be. And doing it "by hand" is very satisfying.