Difficult geometry

stephan_sonnenschein

Is there a way to model this in Onshape? What would be the approach?

EvanReese

Aw, Michael you beat me to it with Contour Spiral, but I did model it out. This is a very challenging model, but once you get the workflow it is fairly flexible. You could shell it after the pattern to get the hollow spiral parts. Mine is just a workflow proof of concept. It's not meant to be perfect.

https://cad.onshape.com/documents/9158f5120f43a70cc7da6d25/w/97409d83725eab473231455f/e/27eb13f7d047644019cdce18

MichaelPascoe

Hey @stephan_sonnenschein,

There are multiple ways to do something like this. Here is one approach you could take:

• Create the base piece with a sketch profile and a Revolve.
• Create the main body using Loft. This will require a start and end profile, any in between profiles, and some guide profiles. Alternatively, you could use the custom feature Variable Section Body by @Konstantin_Sh to make this part more precise.
• Use the Shell feature to shell the lofted shape.
• Boolean add the lofted shape to the base collar.
• The square holes will be tricky, you will most likely need a custom feature for this. I recommend Attractor pattern by @Evan_Reese.

https://cad.onshape.com/documents/1ddacd6cd265a0a76e218577/w/cc9eabd418726825da2ced4d/e/dcb32fd7967e...

stephan_sonnenschein

It get's even more complicated. The wrapped ribs actually need to be hollow because that's where the water flows.  So I guess the Attractor patter won't help here. I've seen a video of somebody doing it in Solidworks and part of the solution was using a twisted loft I think that could be a way but so far I haven't had success doing this in onshape.

nick_papageorge073

stephan_sonnenschein said:

It get's even more complicated. The wrapped ribs actually need to be hollow because that's where the water flows.  So I guess the Attractor patter won't help here. I've seen a video of somebody doing it in Solidworks and part of the solution was using a twisted loft I think that could be a way but so far I haven't had success doing this in onshape.

I thought this looked familiar. Was that video on youtube where the youtube guy had hired 3 remote cad modelers to attempt to make this?

stephan_sonnenschein

Yes, exactly. Actually he wanted to test what offerings he would get from people offering their service and most didn't even want to take this on and two did with different quality of the result.

MichaelPascoe

Hm, in that case, you will probably need some sort of Contour spiral or 3D Spiral that follows the path. @Konstantin_Sh wrote this one as well. It should be possible to spiral along the path then split the surface. From there you can thicken the surface inward and then hollow the final part.

It might also be possible with a normal Loft and a single profile. You would have to match the connections so that they twist. Not sure this way will work.

Another way may be to have several profiles and loft them. Each one slightly more twisted.

stephan_sonnenschein

Thanks Michael! I'll investigate a little more, will try the spiral approach and will also try a little harder if a loft twisted via defining the connection points would work. I'll probably report back tomorrow...

EvanReese

Aw, Michael you beat me to it with Contour Spiral, but I did model it out. This is a very challenging model, but once you get the workflow it is fairly flexible. You could shell it after the pattern to get the hollow spiral parts. Mine is just a workflow proof of concept. It's not meant to be perfect.

https://cad.onshape.com/documents/9158f5120f43a70cc7da6d25/w/97409d83725eab473231455f/e/27eb13f7d047644019cdce18

MichaelPascoe

@Evan_Reese, Knew you could do it! I was having trouble implementing it. Looks like the feature pattern did the trick.

nick_papageorge073

It's funny in the youtube video I think the guy payed something like $100 for the model. IDK, that just dilutes everything. Can you imagine how much experience one needs to model this?

stephan_sonnenschein

 Evan, -Amazing!! That’s it. Had a quick look at it late at night. I’ll study the steps in every detail tomorrow. I’m glad it can be done in onshape, I was a bit in doubt for a while. Thanks again, Michael Pascoe too

EvanReese

stephan_sonnenschein said:

 Evan, -Amazing!! That’s it. Had a quick look at it late at night. I’ll study the steps in every detail tomorrow. I’m glad it can be done in onshape, I was a bit in doubt for a while. Thanks again, Michael Pascoe too

I mean, to be honest, my first thought was "Onshape isn't the right tool. I'd use Rhino for this", which might actually still be true, but Onshape can do it. Rhino would allow me to model it straight and bend it later, which is much easier, but not as updateable, and would move it out of my main development tool, which both have major downsides.

GWS50

wow that's impressive....I wouldn't know where to be begin! Lovely job.