Circle Pattern

fernando_villa837

I am trying to create a pattern where the center circle's diameter is .309 of an inch and successive circles are increased by (x) where x =  +.003.  so, the next circle is .312 of an inch, and so on.

S1mon

You can use variables and expressions to do all kinds of math on each iteration.
https://www.onshape.com/en/resource-center/tech-tips/tech-tip-how-to-use-variables-in-patterns-to-vary-features#:~:text=Variables%20in%20Onshape%20can%20be,get%20further%20from%20the%20center.

Evan_Reese

Here's a quick example. https://cad.onshape.com/documents/9241f53d45ee7ee408507709/w/388af2dd85f58ca07166c43a/e/d87594f61ad5f709c9b1d9af

fernando_villa837

Thankyou both for out standing solutions.  

To get to my Idea solution, I need to add one more element to the design, all circles have to be Cocentric but not necessarily extrusions or holes.

I will study your solutions close and try to expand the model to fit my idea solution.

Evan_Reese

Glad to help! The same idea works with all kinds of setups. I added a tab to that same document showing how to make it like this too

robert_scott_jr_

Evan, I took a look at your document and I have two questions. First, in both examples I don't find the 'increment' variable being used in any feature although it seems to have indeed been used. Second, why the creation of a composite curve? - Scotty

eric_pesty

@robert_scott_jr_
The increment is used "indirectly".
The key for this to work is you have to define a variable in terms of itself. In the circle example #size is first defined at 3mm then it is defined again (just before the pattern) as itself plus the increment (#size+#increment). Using a separate variable for the increment is not necessary but it does make it more intuitive to make adjustments (i.e. the second definition of size could just be #size + 0.3mm).
The composite curve is not actually necessary but it does make the circles easier to see without all the overlaid sketch circles. You can see the result without the curves if you "show" the pattern feature itself and hide the curves.

Evan_Reese

@robert_scott_jr_Eric nailed it on both questions. #size calls itself + #increment, so each time the features loop, it grows by the increment. The composite curve was just for cleanliness. If you did like 100 circles, it would get really hard to see them.

fernando_villa837

Thanks again, I got my sample working.

how do I extrude each circle of the pattern?  I tried adding the center circle extrusion to the linear pattern.  You know the results did not work for me.

Evan_Reese

Add the extrude into the feature stack before the Linear Pattern, then make sure you select the extrude feature in the pattern. You could also increment the extrude height if you want, like this.
https://cad.onshape.com/documents/9241f53d45ee7ee408507709/w/388af2dd85f58ca07166c43a/e/b2cc9a8b3683fa855e89024b

fernando_villa837

Reese,

fantastic, works now.  

Solid extrusion "New" worked.  Evidently, I can not use Solid "Add".
unless you know how to make Solid "Add" work.  I did get what I want from your examples.  Thanks.

Evan_Reese

If you want to do it with "Add" you need to give the first extrude something to merge to. Here's an example where I just made a small body first so that the first extrude "Add" would work, and the rest of the pattern works now too. https://cad.onshape.com/documents/9241f53d45ee7ee408507709/w/388af2dd85f58ca07166c43a/e/285f2a9af98c04a21cd037fb