# Thread: Making a SOLID HELIX with a rectangle, not a circle!?

1. ## Making a SOLID HELIX with a rectangle, not a circle!?

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Can this be done? I have found a tutorial in this forum on how to do it with surface modelling, but i cant find how to do it as a solid. I have to do something similar to a circular car ramp in a parking garage. I have tried extruding along helix shaped plines, but the result is twisted and, well, wrong.

Another drawback, i am using 2002.

Can anyone help?

2. i had a similar problem of making a solid curved staircase railing. this could be solved using two lisp programs available in cadtutor. one is "helsurf". using this program we can make a helical open surface. then using the other program "m2s" the helical surface is converted to a solid. then make a similar solid again and subtract from the first one to get the required shape. remeber one thing. that is to consider the axis for the helix as the X-axis. that means a horizontal line passing through the point 0,0. we get the helix around the X-axis only by virtue of the program. rotate the helix in 3d to get the actual orientation. some trial and error method is required to establish this.

3. ## rectangular 3DSOLID spring

Hallo,
here is the description to create a 3DSOLID-model of a rectangular spring.

You can do it only using AutoCAD-command and using the 3DSPIRAL.lsp and the M2S.lsp, which are free available in www.
First it is recommended to create separate layers for the 3D-polylines, the RULESURF-surface and the 3DSOLIDs.
After loading the 3DSPIRAL.lsp you have to create the inner and the outer 3D-helixes of the spring. These helixes must be concentric and should have identical vertical slope. Notice that you only draw a full circle, i.e. the angle is from 0° to 360°.
Now you have to setup the SURFTAB1-value up to – say – 100 (the value can be between 2 and ca. 32,000 - the volume of the model depends from the accuracy).
Now set the Layer to the RULESURF-layer
Command RULESURF
Pick the starting point of the inner helix. Pick the starting point of the outer helix.
Load the M2S.lsp, start the program and pick the RULESURF-surface. Give a thickness bigger than the cross-section of the spring. The 3DSOLID laying under the surface will be created.
Copy this 3DSOLID downward by the thickness of the spring.
Use the DIFFERENCE-command to subtract the lower from the upper 3DSOLID.
COPY and UNION the turns of the spring.
Good luck and enjoy
Jochen

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Yes, by drawing a spiral line as the 'path' then extrude a closed profile.

It's possible, but the profile may twist.

I also posted up pictures of a spiral staircase a pupil of
mine drew in solids.

Nick

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