How can I create something like this in Onshape?

paul_britton

How would I go about creating something like this in Onshape?

https://cad.onshape.com/documents/d92d80069f785d65b6606001/w/1310ce0438cdc4020d6936ae/e/d3ad5cbe97550525c27c1044

This is a mesh imported from an STL created by OpenSCAD.

Or even just a helix around a torus? Which I can then sweep a thread around?

ilya_baran

I think at this point for these types of shapes, I don't know a way to do it without using FeatureScript.  See the Parametric Curve (and Surface) features here: https://cad.onshape.com/documents/578ff8b3e4b0e65410fcfda3/w/d33395f174e5b38f4abd6097/e/cc0c3d5644a78b1b64d6c3b4 and here: https://cad.onshape.com/documents/57a62df8e4b03de4c9fcf154/w/f6d71f3d862b522902efcd68/e/ece65382fcd820281a9ee704

billy2

Paul-


I'd would try to use the user interface 1st. If you're a mathematician then define it with equations.

-The 1st thing is to orient and position the mesh relative to the origin. Use translate and 2 mate connectors.
-The 2nd would be to break the pattern down to one element and work on it.
-The 3rd would be to create the element. This isn't trivial. Like Ilya said, you can use the mesh to build your curves, and then use curves to build surface lofts, then thicken surfaces to a solid and lastly pattern the element around origin to complete the design.

Can Onshape build this?, absolutely. Is it easy?, depends on who's doing it.

What is it a ring? If you were good at parametrics you could define a circle as a datum, build geometry referencing the circle and end up with a ring that'll change size for the various ring sizes. If it's not a ring, then you'd end up with something that'll change it's diameter.

I think what Ilya is showing, is that Onshape can create any surface shape. Which is true. If the curve is continuous around the origin and you can figure out the equation, then you could build this with a few equations. But I see discontinuous curves and patterns. I think I'd build it with the user interface.

paul_britton

Forgetting this actual part for the moment, what about just sweeping/lofting a helix around a ring (or part ring)shaped solid? I don't see a way to do that (helix tools fails for me)

konstantin_shiriazdanov

@paul_britton you may take a look at this 3D Spiral feature script
https://cad.onshape.com/documents/59007ff281e43510ea3797a2/w/a6cb15bca8f1b2bf6e312ccd/e/8695694c2f658a05d1fb7da2
it can create spirals along different smooth curves

paul_britton

Wow.. thanks... that looks like it will probably do the job (as long as OS can use these to sweep along!)

I'll have a play  experiment... 

looks useful for modelling lightbulb filaments too!

Rootentity

konstantin_shiriazdanov said:

@paul_britton you may take a look at this 3D Spiral feature script
https://cad.onshape.com/documents/59007ff281e43510ea3797a2/w/a6cb15bca8f1b2bf6e312ccd/e/8695694c2f658a05d1fb7da2
it can create spirals along different smooth curves

haha, I was just going to post a link. I told you this would come in handy!

Jake_Rosenfeld

@konstantin_shiriazdanov

Wow! These spirals are so cool.  I would love to link your custom feature and use them to 3d print something.  Can you make a V3 on your document so I can link to the 3D spiral and Evolvent features? I currently can't add them to my toolbar because there is no version that contains them.

konstantin_shiriazdanov

@Jake_Rosenfeld - done, I should notice that for now it doesn't create closed spirals for closed curves, I was pleasantly surprised that it generally works with closed curves

Jake_Rosenfeld

@konstantin_shiriazdanov

Thanks!  Here is a proposal for a code change that will allow your code to create closed splines

https://cad.onshape.com/documents/590390dc51bde5111182a458/w/fe92a4d9fcab25c6b4ab15aa/e/d631772c7e759d36921f0a56

See the change before the 'try' that executes opFitSpline

Edit: this does close the spline but it isn't a perfect spiral... best I could do on short notice.  If you bump the point count way up it's unnoticeable (I used 10000 but that may be overkill)

konstantin_shiriazdanov

thanks @Jake_Rosenfel, i've also added test for curve being closed

Jake_Rosenfeld

Another side note: after allowing the spline to be closed it seemed like it was harder for us to sweep over this path.  Maybe provide a check box for closing or not closing the spline? That way a user can leave it open if the sweep is being fussy.

konstantin_shiriazdanov

@Jake_Rosenfeld i thought of this too and decided to add a 3d point in the initial point of the curve for closed cases. so one can add a construction plane using it and the spline stay closed

Jake_Rosenfeld

Nice!

philip_thomas

OOOO - i want to play. Did this for another customer, but this group might have some fun with it.
(similar to the others posted here but with a lot more control over pitch, resolution and start angles)
Ilya - we need a much better way for users to be able to find and contribute custom features.

https://cad.onshape.com/documents/f437577a13ebbc350129b4a0/w/1873523e917e24872187e57a/e/3818058990e621d97e65afc3

barry_gibson

Your just showing off now. all the same very very nice.

NeilCooke

@konstantin_shiriazdanov can you add a flip button to 3D Spiral to make a counterclockwise helix? Asking for a friend...

konstantin_shiriazdanov

@NeilCooke I'll add it in a few days

andrew_putrello

Fantastic!