Orientating the coordinate system to a sketch plane

Andy_Mayo

I am trying to generate a part from a combination of photogrammetry and a laser scan which have different coordinate systems. The object is a clutch bellhousing and I created a surface mesh which I then imported as a reference to identify hole positions which I could then place in actual Onshape parts.

The technique worked pretty well but wasn't quite accurate enough, and photogrammetry surface when imported had not relationship with the coordinate system of the part studio. I then got better hole position data using a CNC set up, and I now want to use that to improve the hole positions on the face of the part I have already generated.

As such I need to have what in AutoCAD would be called a User Coordinate System defined by the existing plane and hole geometry I have. I have created a sketch plane using a mate connector aligned to the part, both normal to the plane the holes are in and it appears aligned to two holes that are aligned along the Y axis of my new data, but I can't measure orthogonally in this new plane - everything is referenced to the World Coordinate System (WCS) in the part studio which is irrelevant.

Any ideas?  We are a charity building a hovercraft to be used in Madagascar to transport teams of doctors (hoveraid.org) and I need to get this right so I can install a custom made drive shaft out of the clutch. Cheers - Andy

Andy_Mayo

Andy_Mayo

The image above shows the issue - the part isn't aligned to the coordinate system in any way and I need to work on the plane shown with a local/user coordinate system that is orthogonal to it.

NeilCooke

Can you not just transform it to the origin csys? using the mate connector you created?

Andy_Mayo

I can't reorientate the mesh, that's the root problem - so reorientating the part wouldn't take the mesh with it. I don't see a way of connecting a mate to a mesh - any ideas? If I can then I may be able to do as you say

NeilCooke

A mesh is treated like a part so you can associate a mate connector to it.

outstanding

@Andy_Mayo wrote:

I have created a sketch plane using a mate connector

Just want to thank you for those words!!! I had struggled to create a local coordinate system to my liking, and those words opened my eyes. Mates can be used for this. Thanks!

Project: https://cad.onshape.com/documents/02c303679e6677195f7b884e/w/76c098413a81818bbe72f9c2/e/34d5b38a40f029b8189e846b > ”Aligning a sketch” tab