Cyma Curves

[xaviervasco]

I just wanted to pin this thought somewhere. I do a lot of work in classical styles, and as a result I’m always dealing with cyma curves. I generally try to consult historic literature for techniques in drafting, which results in me attempting to decipher highly ambiguous line work. From everything I have read, two principle ways to drafting cyma curves reappear:

Both produce pleasing curves, but I am interested if anyone has a preference of the two (maybe someone with a mathematical basis), or even an alternative?

Initially A and B seem to produce very similar curves:

When the pitch is more extreme the differences between the two becomes more apparent:

[DaveR]

One way I do it is like this:

[xaviervasco]

That’s neat. I assume the ability to set the chord proportion means it generating a truly continuous curve and not just splicing two arcs together. I will definitely give that a try.

[davidheim1]

Dave, what’s the name of the extension you’re using?

[DaveR]

Cyma Curve Tool by TIG from Sketchucation.

[davidheim1]

Thanks.

[napperkt]

So glad I read this! Another plugin that I didn’t know I wanted but am so getting! Actually got stuck with this problem myself more then once!

[tweenulzeven]

I’m wondering if the segmentation of the circles has something to do with the different outcomes…

[xaviervasco]

Nah its equal segments. The two methods create different arc centres and so the curve is different

[tweenulzeven]

@xaviervasco

Initially A and B seem to produce very similar curves:

@xaviervasco

The two methods create different arc centres

They can be the same…
Cyma curve.skp (1,4 MB)