turning a parabola

[Peroni]

Fellas I got a job here that requires turning a parabolic face on an acrylic cylinder. I rough the shape on the mill then transfer to an asg machine for finish diamond turning. Right now a NURBS spline is the geometry that drives the tool and it outputs nc as G1 moves. I have the linearization tolerance as small as it will go (.00005). This works and makes a good part but my boss thinks the spline can be converted to arcs and the nc output changed from linear G1 moves to G02/03 arcs.

 

Can this be done and how?

[John Summers]

I think I can help. Can you send me the parabola formula? I'm not sure it will make much difference, but we can try. It depends on the control. How many places can it read?

[MotorCityMinion]

This may help. In the milling side of things, I would run a BNE along the spline, or the entire chain, with comp set to off and no lead in, turn the filter on, then back plot and save as geometry. Careful with the tolerances though. Now use that geo to drive the lathe side.

[John Summers]

I have put a file PARABOLA ARCS.MCX in FTP site MCX_FILES. The arcs are tangent to each other. I can make a file for your parabola if you want to test it out, or you can run the algorithm yourself.