3D spiral

Is it possible to extrude a circle or any shape along a 3d spiral as for a coil spring or a handrail for a spiral staircase.

I have tried solids and surfaces but nothing works.

Any help would be appreciated.

Thanks Richardb

HiHo; Use "Rhino" from

Thanks for your help. I may try to get Rhino but does this mean that AutoCAD cannot handle spirals?

Regards Richardb

Try this spiral lisp routine:

Conny

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Hi

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Ofcaurse AutoCAD do Spirals, you just need an application or, just one spiral that you then make into a block , and then insert in different scale, that way you can make many different spirals from one. But a Lisp application will do the first spiral you need , and such app can be found with a search. Realy, I would try a poverfull search engine and try search for "spiral.lsp" ;)) P.C.

Yes, get a different cad program. Turbocad will do that with great ease.

Yes. That is only one of many things it can't handle.

No, you can make railings without twisting the profiles. I wrote a LISP to do that. In case of interest ask me. regards Jochen

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I have a few drawings done just send me the coordiantes needed i will be able to come up with a dwg in cad 14 extension file

Regards

Rich, There is a way to do this in cad. Now, i havn't done this in a while, but i can give you the basic concept. (for what its worth)

Fist off, create a circle at the desired radius/dia, use the trim command to cut the circle in half. now you need to rotate the ucs so that the Y axis is in the direction of the former Z direction. Figure out the slope or angle in which the spiral will accending. now rotate the half-circle so that it is angled upward at the desired slope. now copy, and rotate the half-circle 180d (using the original ucs) use osnaps to connect the two halves. (so that they form a spiral) once you have gotten the spiral at the approprite height and angle, you need to change the ucs once again so that one of the endpoints (top or bottom) is perpendicular with the ucs. after that all you need to do is join all the line segments to creat one line. Create the shape that the actual handrail "grip" looks like, and make it into a region. Once it's a region, it's just a matter of extruding the shape along a path, which would be the spiral.

I hope this helped a little more than telling you to buy new software. Good luck!!!

Daniel Sandy

Say, why not to use a "Torus" tool from Solids toolbar to do that? Or draw a cross section of the desired handrail/spring and use Revolve

This would give a helix not a spiral. (Constant diameter in Z direction.)

Wait.......that's what he asked for: a helix. But isn't there another problem with this approach? Don't you end up with an ellipse in plan?

Dear Jochen,

Thanks for your reply.

You wrote,

Yes I am interested. I would like to learn how to extrude any shape especially a rectangle/square, channel, UB beam etc along a 3D spiral/coil/helix without twisting. Circles are not a problem now.

I have tried a few other suggestions by others but I did not explaine my problem well enough as their suggestions might be OK for simple presentation drawings.

Looking forward to your reply Thanks again Richardb

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Hi Richard,

thank you for your interest in my ideas.

some times ago I started to develop programs to make SOLIDs from surface-models, i.e. to get a general solution for the "unexplode"-command for SOLIDs. And now I've found a first solution for SOLIDs bounded by plane faces (REGIONs). But for your problem about untwisted profiles it is quite enough to use my RS2S.lsp. Using it you can create the SOLID laying between 2 RULESURF-surfaces having equal SURFTAB1-values. I take the first 4-point- surface( it must not be a plane one) and the corresponding 4-point-face from the second RULESURF-surface and create the HEXAEDER laying between them. It consists of TETRAEDERs and PENTAEDERs. Finally I unite these single SOLIDs and the results you can see from the appended examples- see especially the GELAENDER1.DWG (i.e. railing). The accuracy is depending on the value of the SURFTAB1, i.e. it is up to

256. Beeing correct I have to say that you really cannot create twisted surfaces in AutoCAD as I know - depending on the ACIS-kernel but the results got by triangulation seem to be sufficient. Other Informations you will see from my ( unfolding , PEDIT3D). Regards from good (c)old Germany Jochen PS. The attachment was not transferred please contact me via snipped-for-privacy@t-online.de

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