1. I had another idea. Try this curve in the equation.

x = diameter/2 * cos ( t * 360 )
y = diameter/2 * sin ( t * 360 )
z = amplitude * sin ( t * 360 )

It should give sinusoidal motion and if you set 'amplitude' to 1" you will get a +1" and -1" motion once every revolution of the shaft. What we have been playing gives two every revolution or the weird looking curve (flatish one side, curved the other) you were talking about. Anyhow, its another option.

Cheers

2. yeah i was thinking, i need a parabola shaped curve instead. the sin wave gives me a bell shaped curve which leads to flat spots on the +- transition instead of a straight line. i would need a new equation then?

3. How about this. If you can map out your desired axial position / velocity we can make a curve that reflects what axial position / velocity you require.

Just like mapping the lift on a cam.

For example

Degrees Rot. Axial Position

0 0.000"
5 ???
10 ???
...

90 1.000"
...

180 0.000"
185 ???
190 ???
...
...
270 -1.000"

350 ???
355 ???
0 0.000"

I gotta go (it's 11pm in Oz) but I'll keep an eye on the thread and if I can help more I am happy to. What is your application for this groove?

Cheers

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