Plane defined by the edge of revolve?

alexander_potochkin

Hello everyone!

Could you help me to define a plane by the edge of the revolve in the following example:
https://cad.onshape.com/documents/497294dde6d7430daccb07c4/w/35ba91b8cf2c45b49165a3a1/e/fba4be4331de47d78cf99bfd

I need a plane going through the revolve's edge where the sphere touches the cylinder.

Onshape does highlight the ring there but doesn't accept it as a source of the offset plane for some reasons.

Am I missing something trivial?

Thanks!

3dcad

Do you mean like this @alexander_potochkin

https://cad.onshape.com/documents/d29ff8e74a0f49809e533f48/w/48fedb2064cc4f30a27ee6e8/e/afb6d1d1d9914b7aae49f229

andrew_troup

Plane definition is one of the weakest areas in Onshape, @alexander_potochkin , in my opinion.

I often find myself wishing for the same thing you are asking for here. And many others to do with plane creation. I personally think they need to start again, and build an "Onshape-quality" toolset which is simple, elegant and powerful.

When the circle in question is not at an orthogonal angle, I have found it quite a tricky proposition to create a plane containing that circle. If we had 3D sketches, we could simply convert the circle into a sketch, snap three points to it, and create a plane through those points.

In the meantime, I wonder if anyone has come up with a cunning workaround? The only ones I can think of are laborious and/or unreliable.

3dcad

Do you mean like this @alexander_potochkin

https://cad.onshape.com/documents/d29ff8e74a0f49809e533f48/w/48fedb2064cc4f30a27ee6e8/e/afb6d1d1d9914b7aae49f229

andrew_troup

@3dcad
Imagine the same combination of shapes, but the cylinder arising (separately) from an extrude from a sketch disposed at an oblique angle, and the sphere being a complete sphere.
It seems a current limitation that entities such as the circular edge where those two bodies intersect, despite unambiguously defining an infinite plane in geometric terms, cannot yet be used to define that plane directly in Onshape.

alexander_potochkin

Hello 3dcad

The extra line does the trick, thanks!
However why the extrude edge is not accepted as a source of an offset plain?

Doesn't it define the plain itself?

Thanks again

3dcad

I agree that we should be able to create planes anywhere 'mouse snaps'. This particular case workaround was only extra line but in more complex shapes it can require a lot of extra work as @andrew_troup pointed out.

I too find plane creation sometimes a bit laborious, for example just a plane in say 45deg angle should not require any sketch to run. But I also think that currently we can manage with planes and should get back on this when big things are finished. 
 

alexander_potochkin

Hello 3dcad

I understand the situation, thanks a lot for your efforts!

Have a nice day

_Ðave_

You could create that plane with the existing sketch that was used for the revolve. Use the line point option in planes and select the cylinder OD line and the end vertex of that line.

karthikr_r

Add a sketch with just a Line coincident with the revolved edge. Use this sketch line to define the Plane with LINE-ANGLE, just as in the example given by 3dcad

I had Scaled my model with TRANSFORM, and had great difficulty in defining the plane, till i saw 3dcad's example

Thanks a ton!