[toastydeath]

We have a lathe with a C axis encoder, but no indexing. It's a high accuracy machine, and was used for turning radially asymmetric objects (for instance, an oval bore). It had a very old tape control that was broken and from the early 70's, so using that is out. We're adding an aftermarket control that supposedly has the ability to provide the same asymmetric motion, but the control and the manuals are not in.

Assuming all the codes are there to provide the desired motion, how do I mathematically map out and program a radially asymmetric part by hand?

Thankfully, these parts are simple with only one feature, period. We want to use the lathe to put a large radius on a flat. The spindle nose is 20" in diameter, and we want to do 50"-100" radii on blocks held on a faceplate.

How would I come up with a set of formulas to synchronize the X axis movement to the C axis position? Said another way, the C axis will spin at a constant, and based on the angle, the X axis will reposition itself. I just don't know what math to use to get the motions.

[Al_The_Man]

My background is not machining, but wouldn't this be better suited to a mill operation, or is it because you only have the lathe.
With modern controls there is special Lathe G codes that perform involute and other specialized G codes using a combination of the C combined with the X axis etc. That takes away alot of the mathematical calculations necessary.
You may want to find out what is included on the new control.
Al.

[toastydeath]

This is a special lathe designed for aspheric turning, and the original control is fried. We have mills, but the lathe is more accurate and provides a much better surface finish.

[WayneHill]

Something like a prescription contact lens or glasses that is turned on a special lathe? But on a larger scale?

[toastydeath]

Kind of, but the math for those is a good deal more complex than what we're doing. Think of things like off-axis bores, elliptical bores, turning a square, etc.