Helix about a helix

[tmayer]

I am trying to wrap a coil around a helical or spiral path. Does anyone have a sugestion? Creating a spring is no problem, but trying to wrap this spring around another is causing me some trouble. Any help would be greatly apppreciated

[Anonymous]

I think Rhino can wrap a spiral around a curved
path.  That is some very tricky geometry.  To fake it you can try
applying a bitmap to a coil.

Pat

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"tmayer" <
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I
am trying to wrap a coil around a helical or spiral path. Does anyone have a
sugestion? Creating a spring is no problem, but trying to wrap this spring
around another is causing me some trouble. Any help would be greatly
apppreciated

[Anonymous]

I have posted a technique into Inventor Customer files. Perhaps you can
figure out the math / trig to make it work. Basically, it is a
patterned array of coils along a helical path. If it is possible to
make it more "precise" it will require real numbers and formulas.

tmayer wrote:

> I am trying to wrap a coil around a helical or spiral path. Does
> anyone have a sugestion? Creating a spring is no problem, but trying
> to wrap this spring around another is causing me some trouble. Any
> help would be greatly apppreciated

[RogerJames]

Charles,

Cool use of the pattern along path option. Very elegant.

I have another possible method but it requires MDT. (see files posted as reply to Charles’ file post in CF)

Using the old Spiral.lsp file (circa R12) you can create a 3Dsprial. Use this as the path for a swept surface or native AutoCAD solid (assuming you want a spring around which to wrap the second helix) Now take this same helix path and convert it to an augmented line and twist the vectors to the desired pitch. Now draw the cross section of your second helix. Sweep this cross section along the augmented line as a surface. If you create trimmed surfaces at each end of the resulting surface, you can stitch it into a solid. In the example I posted (I think I posted it properly), you will see that the cross section of my second helix is not quite round. This is because I did not rotate the plane on which I drew it to be perpendicular to the path. To do this, the math needed is found in my Machinery Handbook 25th edition page 1856. I’ve used these same formulas for helical gears.

I was able to translate these into IV but because I didn’t stitch the surfaces in MDT, I had to promote the surfaces up from the construction environment.

Does anyone know the legality of posting the sprial.lsp file since it came with an old version of AutoCAD and may be copyrighted? Or, where it might be found?

I hope this helps,

Roger James
Motor City CAD

[tmayer]

I greatly appreciate your sugestions, yet I need to do this frequently and easily. Using another software or autocad solids is not an option for me. I work in the medical field (and regretfully on Solidworks) and have this problem at hand. I was hoping to sugest Inventor as a solution, but if is not a straight forward, simple solution, I will have a difficult time proving my case. Maybe the developers will include the solution with IV7? Just another wish list item from a HUGE Inventor fan.

Thaks for your sugestion guys.