Unable to sketch inside hollow part

mastrcr_derc

Hello Everyone!!

       Im new to Onshape as well as to CAD so please help. I need to create 2 tabs on the inside of the hollow surface.. as i proceed to create a sketch and select the sketch plane it dosnt recognize the inside surface of     the part. Please be kind enough to point out where i have gone wrong.

Thanks in Advance!! Have a good day!!

robert_scott_jr_

Hide the top plane. - Scotty

NeilCooke

Can only sketch on a planar face - sketch the profiles on the top plane then extrude (with starting offset) to get the positions.

martin_kopplow

NeilCooke said:

Can only sketch on a planar face - sketch the profiles on the top plane then extrude (with starting offset) to get the positions.

Well, his question is valid, though. Wouldn't it make sense to break with the tradition and enable sketching on at least certain non-planar faces such as cylinders, cones, or others that allow the use of a polar or cartesian coordinate system on them? I could have made good use of that in past projects.

mastrcr_derc

NeilCooke said:

Can only sketch on a planar face - sketch the profiles on the top plane then extrude (with starting offset) to get the positions.

NeilCooke said:

Can only sketch on a planar face - sketch the profiles on the top plane then extrude (with starting offset) to get the positions.

so if i get this ryt, you cannot sketch on any curved surface... and in this case i need to extrude from top plane with limits on starting point??

NeilCooke

Correct

eric_pesty

You could also sketch on the right plane and extrude "up to" with offset or not (depending on what you want the inner ends to look like).
A sketch by definition is a 2 dimensional object, I'm not sure how the sketch constraint would work on a non-planar surface...

You can also use the "wrap" feature to project a sketch onto a cylindrical surface but it's not needed here.

mastrcr_derc

NeilCooke said:

Correct

Man thanks a lot!! It works now!!