Chief Delphi - CAD for Spiral Cam

Chief Delphi (http://www.chiefdelphi.com/forums/index.php)

- CAD (http://www.chiefdelphi.com/forums/forumdisplay.php?f=168)

- - CAD for Spiral Cam (http://www.chiefdelphi.com/forums/showthread.php?t=125056)

Re: CAD for Spiral Cam

Quote:

Originally Posted by araporta (Post 1486687)

Thats the first place I looked, and it doesn't really help. I can see how to enter a parametric equation, such as that in post #5 above, but I don't get how to enter Ether's equation in post #8, which is not parametric? Its probably trivial, but I just can't see how to do it.

r1 = starting radius at theta=0,

r2 = ending radius (at theta=alpha),

k=log(r2/r1)/alpha,

r = r1*exp(k*theta),

x = r*cos(theta),

y = r*sin(theta)

...

So for r1=25, r2=5, and alpha=2*pi, you would get:

x = 25*exp(-0.11124453*t)*cos(t)
and
y = 25*exp(-0.11124453*t)*sin(t)

Re: CAD for Spiral Cam

Are you sure you want a constant-slope spiral, and not a constant-torque one instead?

Re: CAD for Spiral Cam

Quote:

Originally Posted by Ether (Post 1486771)

So for r1=25, r2=5, and alpha=2*pi, you would get:

~~x = 25*exp(-0.11124453*t)*cos(t)~~
and
~~y = 25*exp(-0.11124453*t)*sin(t)~~

I should have used my CAS.

x = 25*exp(-0.25615*t)*cos(t)

y = 25*exp(-0.25615*t)*sin(t)