What's an easier way to sketch concentric closed shapes?

skybrian

Making concentric circles is easy, but what if you have a more complicated shape, like an irregular polygon? I'm currently sketching concentric shapes by hand, but it's getting old. Any tricks?

This is to make a sort of box, where the walls stay the same width but move in and out as you go up, like a candlestick. I'm currently extruding or lofting each wall section separately. Maybe there's some other way to do that?

eric_pesty

A good way to do this is to pattern a variable referencing itself. For example something like in this example: i created configurations to grow either linearly or exponentially for each step.

https://cad.onshape.com/documents/b1ec68dff06d55ff179d8bc7/w/dc0ae0007b32017045650876/e/3f39a038645434881e565b7e

I used a move face to create the change but you could also use a transform feature to apply x and y scales

You could get creative and use sine function or some other formula to make it more varied.

If you can't easily describe it with an equation, you could just pattern the shape and manually apply different scale features to each section, that would be faster than manually sketching the shape over and over!

EDIT: more details on how this works: https://www.onshape.com/en/resource-center/tech-tips/tech-tip-how-to-use-variables-in-patterns-to-vary-features

S1mon

The sketch offset tool seems like the most obvious answer. It can easily select a bunch of entities at once. It’s also possible to extrude a surface and then offset that. In Solidworks I would sometimes find this approach to be more robust. 

What sort of shapes are you dealing with? What issues are you having?  

steve_shubin

@skybrian

When people post questions, sometimes it’s all about trying to interpret, what it is, that they’re trying to accomplish.

Something that stood out in your post was the shape of a candlestick

MAYBE, drawing the shape at the bottom of your box first, and then drawing a profile to sweep around this base shape, well maybe that might accomplish what you’re looking for

Take note that there are two different Part Studios in this document. Look for the two tabs at the lower left

https://cad.onshape.com/documents/fa5f80e8d9466a1a9180b16a/w/2579123d01b71b1064a8589a/e/5333d91e327c42d8b7e1b8acWe 

steve_shubin

@skybrian

I added another part studio

See the document in my post directly above

In Part Studio 2, which is the one I just added, I swept a SURFACE and then THICKENED it to come up with a consistent wall thickness

Here is a section view that shows the wall thickness being the same throughout

skybrian

Thanks everyone! For what I'm doing, learning to use the Sweep tool seems promising. (Somehow I hadn't thought of using it to sweep along a closed curve.)

S1mon

Keep in mind if you sweep, you can sweep more than one curve and create multiple surfaces or parts at the same time too.