Twister bulb - cant sweep along spline?

Hey, I'm pretty new to Autocad and I'm trying to draw one of those new energy-saving lightbulbs in 3D. It's a Phillips Mini Decorative Twister bulb to be exact. I'm trying to make it as accurate as possible. I have the base done and I did the spiral/middle part of the bulb, but I ran into a problem when I tried to do the bottom of the bulb where it meets the base. I used a spline since the bottom part of the bulb meets the spiral part at an odd angle, then curves at almost 90 degrees and goes straight to meet with the base. The problem is when I tried to sweep a circle along the spline Autocad wouldn't let me. If someone can help me with this or give me some tips on how best to do the bottom and top parts of the bulb, it would be much appreciated. Thanks.

Have you tried the loft command?

I suppose it could be done that way, it just seems like it would be more of a pain in the you-know-what. I was hoping to do it with sweep. But I'll give it a go with loft. Thanks.

You could try a helix as well, but you should be able to sweep along a spline. Make sure that what you're trying to sweep is perpendicular to the path at the starting point. Here's an example:

Sweep won't cooperate if during the operation, the new 3d object intersects itself. You may have to fudge the shape a little if that's whats happening. Could be that the radius is too tight where you make your 90° bend into the base. You can test this by sweeping a very small circle along the path...if that works, then you'll know. if it doesn't, then you may have to find a different way to create it.

Sweep won't cooperate if during the operation' date=' the new 3d object intersects itself. You may have to fudge the shape a little if that's whats happening. Could be that the radius is too tight where you make your 90° bend into the base. You can test this by sweeping a very small circle along the path...if that works, then you'll know. if it doesn't, then you may have to find a different way to create it.[/quote']

 

I remember in the old days I would remove half a Torus and rotate and copy to make a 3D spring. If I recall correctly, I think the old Helix.lsp worked a little better than the HELIX command in AutoCAD 2008.

...If I recall correctly, I think the old Helix.lsp worked a little better than the HELIX command in AutoCAD 2008.

Not even close is my recollection.

You can get some pretty good results using 2 helix's rotated and 180 and copied. Then manipulating the UCS a litte you can use filleted polylines to make the bends.

This is not a perfect example but it only took a few minutes. You can get a pretty accurate model with a little time.

KC

This is not a perfect example but it only took a few minutes. You can get a pretty accurate model with a little time.

 

KC

Show off!

Hello,

I did an experiment with a helix exploded and converted in spline, and later converted in smoothed 3dpline.

The conversion of spline in 3dpline that eliminates "sharp edges" that prevent the sweep.

However the solid obtained has no a "clean" geometry as shown in the zoom.

Regards,

When you use sweep or loft pay attention to the geometries you get.

If they are not "clean" can make you ugly jokes.

When I closed my file, my deformed bulb has become a tropical flower!