does anyone know how to draw a helix (spring)?thanx

I've made them with Amorphium, you can probable make one with a nurb modeling app, but it is rather difficult. ( compared to Amorphium )

It depends on how fussy you are. You can't make a perfect one. You can fake it though. Use tori booleaned in half and lined up, and stacked high. That will look a helix from some angles, but looks bad from others. Of course, if you boolean the tori down to quarters or smaller, you might have something better, but it's a bit more geometry. The Pythagorean theoreum will be helpful if you're gonna try that. Or you can make a path in spiral shape, and multi-replicate metaballs so it appears to be a helix. Here's a quickie I did with half tori. You'll see that at some angles it's really good, some it's really bad. But, if it tracks the camera, that might not be so bad....

Rhino has a helix draw function, not double helix though. A good double helix can be made in Rhino by twisting a pair of bars, and twisting them again, and again, and again .....

you could also use cylinders. rotate them on the z axis, use the edit palate to resize the y dimention, rotate back until the bottom of the cylinder is parallel to the ground, move on the x axis away from 0, put the object's origin at zero, duplicate, put the new object on top of the first, rotate around y so the sides line up, and use the y offset and the rotation to multireplicate. the shorter the cylinders are the better the helix looks close up, but it also takes up more memory.

Try this free tool for producing helix meshes, it's quick and easy to use, and it's er... FREE! http://www.evolve.co.uk/helixir/ Oh yeah, it only outputs in *.pov and *.unc, which bryce can't read so you'l need this FREE file converter as well, use it to convert the mesh to *.dxf or *.3ds. http://home.europa.com/~keithr/crossroads/

Boing!!! I love freeware:),especially when it is this unique. http://www.abbott.demon.co.uk/knots.html Peace all.