Sketch "Use tool" (project geometry) cannot serve as an anchor

mathieu_viales

Hi,

I come from Fusion 360, where I got in the habit of using the "project geometry onto sketch" feature.

I figured I could do the same in OnShape, but it doesn't appear that "Use" is meant for the same thing.

Here are the problems i'm encountering when I use the "use" feature in OnShape:

• the projected geometry is unconstrained. For example, If I project the cross section of a hollow cylinder (pipe), the resulting square is made of lines with edged that are not bound together, and I have to add these constraints myself.
• There does not appear to be any way to get the "use" tool to project all the cross-section geometry of a body, only each of its faces on a per-click basis. Working with a pipe, I have to manually select the outser cylinder face, and the two flat faces on each side.
• When building sketch geometry anchored on the projected geometry, modifying the geometry of the body use for the projection often breaks the sketch. Constraints fail to resolve, and I often have to delete the proejction, re-project and re-contrain. This has led me to designing in a roundabout way, using "proxy" construction geometry. For example, instead of using the projection of a pipe in my sketch, I create a driven variable measuring the outer diameter of that pipe and then draw a construction line of with the value. I build my sketch geometry on this construction line as a proxy for the projected geometry. Then mate the original body onto that construction line so that everything aligns. My background is not in CAD, so maybe this is the expected process rather than using the actual body? It feels like a lot of extra boilerplate.

Are the above problems expected, by design? Am I attempting to use a tool that goes against bad practices? Is this simply an area when the OnShape team hasn't gottent around to making improvemetns yet ?

Here is an example design where I've experienced these issues:

https://cad.onshape.com/documents/73b4848809bc10499f437dec/w/1a292b706c06d4986e233158/e/59145b9630d13329bc5bb145?configuration=Connector_Length_Override%3D0.0%2Bmeter%3BList_9eop9BmzEuLZ1g%3DDefault%3BList_DRkxR6QuIfx5vb%3D_45_&renderMode=0&uiState=69401a787389764c8957ae1c

It's a pipe addapter that is build off of a configurable pipe section imported two, with a hollow loft in between.

My initial design use a projection of the two derived pipes in the "Inlet & Outlet Relative position profile" sketch, but this ketp breaking when I changed configuration (especially the pipe's Angle. Going between 90° an 0° would break often)