The workings of the Formula Curve tool are still a bit of a mystery to me. Nevertheless, the other day I needed to model a curtain & decided to figure out how to make a sine wave with it.

Here's what I came up with:
[attachmentid=1886]

This will give you a sine wave that is 60 inches long, with about a 2 inch wave (crest to trough.)

Then I copied the resulting 3D curve up to the desired height & used Ruled Surface to make the curtain.

(Note: Some end values work better than others. 50 works good, but 51.75 gets messed up toward the end.)

-Mike

Great Mike,
Would you by change know how to make this circular. I need to create a stitching pattern on a round case.
Thanks
Tom

Not sure if I understand your geometry correctly or not tom (something like a wavy washer?), but it sounds like you need to switch to polar coordinates, change the first available "expression" to a constant (the radius) and set the Z (height) to some trig function (i.e. sin([# "bumps"]*t) (see the sin washer attachment).

Of corse, if you are trying to get the line on a sphere (not a cylinder), then your Radius equation will need some more thought....

And the more times I read you post, the more I think I gave you bum info. If you want the thing to be planar, but have a "sine wave following a circle" type geometry, do something like the second attachment (flat sin washer)....the radius equation becomes: "[radius]+[bump amplitude]*sin([# of bumps]*t)"

Thanks Mike T

I managed to bypass the formula using the 3D curve and "tracing" over the cylinders edge incrementally. Then I select every other point and move down to get a wave effect. Believe it or not, it really didn't take along time to do, I was surprised ( not really )

Anyway, I will try your second option also. Not a trig major (oh well).

Thanks
Tom
[attachmentid=1972]

Tom-

I think you want the first option.... the second one will have the "stitch" in the wrong plane.

Go Polar, Go "Degrees", set your radius (first expression) to the stitch radius, and set the second expression (height) to something like:

[stitch height]*sin([# of stitches]*t)

With that being said, there is something extremely wacky going on with the interpritation of trig equations...I think a bug report is in order here.

Can someone repost the seetings to get the sine wave. The images are missing. tx
t