How to create an extrusion with angled walls

logan_merriam

I'm extruding a shape and I need the walls of the shape to be angled inward. This is a complex shape so it can't just be scaled down scaled down uniformly, the final face of the extrusion has to be "shrunk" or inset relative to the the original shape. I'm including a mockup to illustrate. Any ideas how to do this?

MichaelPascoe

Here is an approach you can try if the walls are all the same angle:

• Extrude with a draft angle

https://cad.onshape.com/documents/eb90c042dbe320afa990d2db/w/5747d25f0e014f7774e7ecd0/e/08dbe387e4b62af81e84d8f4

logan_merriam

MichaelPascoe said:

Here is an approach you can try if the walls are all the same angle:

• Extrude with a draft angle

This is exactly the tool I'm looking for! Unfortunately, I'm extruding a much more complicated shape than my simple illustration into a volume and it seems that it can't resolve the draft angle at anything over 1 degree (and I need to go closer to 30deg). It has no problem doing the reverse angle and growing from the original shape, but it can't seem to resolve a significant draft angle that shrinks the inset shape. Here's a pic of the shape I'm extruding.

Prachi

Looks like the draft is trying to close the bottom opening creating perhaps non manifold geometry or some thing!!
I tried using separate extrusions for main and take away with a Boolean subtract and got a better result but the bottom is closed at larger draft angle.
You can make a draft that eliminates the second end of an extrude as long as nothing over laps.

https://cad.onshape.com/documents/44300b8443e31a8a7552cb4e/w/9ece92663a727e60560de254/e/7065876524fb33db90d58e16

MichaelPascoe

@logan_merriam, There are a few more complicated techniques that will probably work. It will be most helpful if you share a link to your model with us.

Something else that is best practice. It looks like your sketch was an imported dxf or something that did not convert to smooth splines and arcs. Try tracing the shape within onshape to ensure smooth lines for the extrude. This helps the calculations for some features.