3d spiral issues

Barry_van_Wijk

Hi,

I have 2 questions, which are maybe related.

I'm using a 3d spiral FS
https://cad.onshape.com/documents/f437577a13ebbc350129b4a0/w/1873523e917e24872187e57a/e/3818058990e621d97e65afc3
to create a bending twisted loft.

Situation 1:
The 3d spiral is following the spline. 

But the spiral points do not end up at the profile sketch, which give problems with piercing the profile sketch.
The spline needs to be 100% vertical. But how do i do that? 
A solution is to use a sketch line and connect a spline. But the FS does only work with a spline.


Situation 2: 
I have the problem that my helix doesn't start and end on the same axis points:

I don't know how to fix this? 

I have made my situation public:
https://cad.onshape.com/documents/4e225d938e08997721242a8b/w/b84dd15a33cf99a5324034e0/e/b3d1711686f659df427c4e2b 

Note1: The profile sketch is in this example not the end profile sketch.

Note2: Anyone with a better topic title?

Thank you!

konstantin_shiriazdanov

You using two different features of different authors - Helix^2 and 3DSpiral, moreover 3d spiral doesn't linked from original source. I just made an enchancement for 3d spiral so it should work as you expect and allow multiedge chains.

https://cad.onshape.com/documents/59007ff281e43510ea3797a2/w/a6cb15bca8f1b2bf6e312ccd/e/7517d8bd0162caff9f9cb2a7

steve_shubin

@Barry_van_Wijk
@konstantin_shiriazdanov

The two spirals around the inverted J caught my attention. I thought — how hard would it be to loft. Turns out that all you have to do is, select the Surface button in the loft dialog box, and then, select the two spirals

Thanks to Kostantin for his updated tool

Barry_van_Wijk

@konstantin_shiriazdanov
@steve_shubin

Thank you for your support! 
I have updated the 3d spiral and sketched the related profile .
But it stil doesn't work  .
I think I tikked all the boxes to make it work, but no....

Maybe you guys can find the problem?




New link: 
https://cad.onshape.com/documents/67807a66f42ae204984ee5c6/w/78b69b8e83dc4982e1803d33/e/095337ee6fb7756a19d7dcfe

S1mon

Have you tried much more simple versions of the sketch you're sweeping? Or much more simple versions of the spiral guides? 
You may also have much better luck with sweeps instead of lofts. I might try 6 spirals, each at the center of their respective cable.

In theory your loft should be able to work. In practice, many CAD systems don't handle even the complexity of sweeping one circle along the spiral path well. They often over simplify and rebuild the path curve in a distorted way and therefore you'll end up with self-intersecting geometry which Parasolid doesn't like.

konstantin_shiriazdanov

So I played a while with this problem and here are my thoughts: it is closer to be made by using sweep rather then loft, but that sweep should have option to rotate cross section, and because of this you dont't actually need spirals, just center line, cross section profile on one end and rotation law along path. I made some example using my Variable section sweep feature.

https://cad.onshape.com/documents/2d81c59d7fc5df36ecbaecf3/w/a2de18e932e02a4bd51d3af3/e/011d093280067e6e7e0b1263

Barry_van_Wijk

I did it....

I used the loft function and cut it up in several parts. Then the computer will not find it too difficult .

Only downside is that you can see the transitions ...

john_marentette

I cannot find the 3D Spiral function??

steve_shubin

@john_marentette said:

I cannot find the 3D Spiral function??

https://cad.onshape.com/documents/59007ff281e43510ea3797a2/v/a32c98e33ad3fdfd68973e79/e/8695694c2f658a05d1fb7da2