Sketching on an Angle and Normal to a Curved Surface.

michael_ingmanson

I am working on a part which has a front and back curved surface to it. My goal is to subtract two sub-flush holes into the curved surface while keeping the holes normal to the curve. I can't figure out what menu option to use to accomplish this?



So far I've only been able to create a sketch and subtract the volume if I use one of the three primary axes. I read this post as well, but it did not give me enough info to solve my problem. I'm assuming that I need to create a sketch normal to the surface, but that's the part I can't sort out.

Thanks in advance,
-Michael
  

MBartlett21

@michael_ingmanson

The plane feature that you need to use is called line angle

I have created a copy of your document with the plane in the right place here:
https://cad.onshape.com/documents/fa3481d8ee4217c213a7a5e1/

mahir

Are you trying to create a hole feature? If yes, you can create the desired holes with a few extra steps.

1. Create a plane parallel to the Top plane that is the desired distance from the flat top/bottom surfaces. 
2. Start a sketch on that plane and use Intersect on the curved surfaces. 
3. Draw a couple lines that are normal to the these intersected curves. Keep in mind for convex surfaces you'll have to offset the endpoint of the line so that the hole feature has room to start. Otherwise, it will generate an error. 
4. You can now use those lines to create a normal construction plane using the Curve/Point option. Draw a sketch point on those normal planes that can be used with the Hole feature.
5. Create your holes.

Here's an example.
https://cad.onshape.com/documents/57acdfaae4b005c413ed9b6f/w/3fd585a46d3af1b3ba413c53/e/b151d128f65e19706a48270c