Dead CNC lathe -> EMC Special purpose machine
Have you tried, or would you mind trying if you have a minute, a profile with a flat section? I'm a little concerned that it will be difficult to produce an actual flat facet like in my sketch. Precise flatness is probably not critical for my application, but it would need to at least look right. What are your thoughts?
Flat facets should be possible (they make cams using vaguely similar machines) but you will need to do some clever maths to figure out the axis position for each angular position.
The end-mill as you show it is equivalent to a flat cam follower. A shell mill running axially would be equivalent to a roller follower. I have seen the equations for both types in books. Your end-mill would need to be at least as wide as the flat.
With the single-point lathe tool it should still be possible to create a flat, but tool clearance angle will be an issue. If you consider the point where the tool it at the very beginning of the flat, if the angle of the flat to tool is greater than the tool clearance, then it can't be cut.
I think that the maximum flat width is twice the base length of a triangle with the tool clearance angle at the apex, and the hypotenuse being the material radius.
Tools with large clearance angles do exist though, as they are needed for boring tools. I have not found any with an angle >20 from a cursory inspection though.
Time to do some reading up on EMC2. Hopefully I will have some hardware ordered in the next week or two!
Thanks for your help!
I'll look at this in a couple of weeks as I only just started making things on my lathe yesterday. - a three week retrofit!
The gui pgm I refer to is "Dewey's tcl" program.