Constraints in 3D

fst

Hi,

Solid Edge has a feature that allows to define constraints like driving or driven smart dimensions on history-less geometry (that was e.g. imported from a STEP file). This is super helpful to make models that were not initially created in that CAD program parametric and make precise changes.
Does something similar exist in Onshape (or is this on the roadmap)?

eric_pesty

I don't think you can quite do this but you can define a "Move face" with an offset: for example to make the thickness adjustable you do a move face with condition "up to" the other side and add an offset that becomes the thickness.
I think that ends up being pretty close in functionality?

S1mon

Not exactly, but you can do a lot of cool things with the direct modeling tools (e.g. move face, replace face, delete face, modify fillet) to make precise changes which can line up with all kinds of references. There are no 3D constraints as such, but you can move face up to another vertex or face or offset from a face. I've done a fair amount of this as we transitioned from Creo to Onshape, and needed to make modifications to complex geometry. The tools are build on top of the Parasolid kernel, which is used in NX and Solid Edge. With many of the direct modeling tools you can chose to keep or delete fillets automatically. These options don't always work, but when they do, it's pretty amazing, at least coming from Solidworks, where that's not possible.

https://learn.onshape.com/courses/direct-editing
https://www.onshape.com/en/resource-center/videos/tips-tricks-for-working-with-imported-models

eric_pesty

Also worth noting that you can quite easily get a "flattenable" sheet metal model from imported stuff as well.

fst

Thanks or the hints! Will try this "move face" with "up to" condition.
3D constraints would imho be a great addition in future versions! (Of course it would be even better if companies could settle on a common interchange format like STEP - but with construction history. But I doubt that will happen for both commercial and technical reasons... So good direct editing and easy re-constraining would be a viable alternative)