Having a problem with a circular pattern

paul_bartlett

I am trying to get the ribs that show on the inside to show on the outside as well. I think my axis of revolution may be wrong but I can't seem to figure it out.Anyone see what I am doing wrong.
https://cad.onshape.com/documents/36cfef7ef295ff7727e9872d/w/b71e3f3d31ec491a620f1733/e/8e7d77082e14d8a1a311a225
 

John_P_Desilets

@paul_bartlett

I tried to retrace your steps but I wasn't able to pinpoint the exact issue with the pattern. It could possibly be the line of symmetry used for the mirror.  I took a different approach and only built one section of the pattern, and based everything off a master sketch. Once the initial section was created, the remaining sections were patterned in an assembly. As a best practice, instance the parts in an assembly for faster performance and correct bill of materials.. If the parts are meant to be united after they are created, instance them in the part studio for a multi-part tooling workflow. 

Onshape Document 
https://cad.onshape.com/documents/e525cb848c794573e2e26f62/w/7cecbb0c4f5aab8c3f97eb16/e/5e1ff0580860f8b7650ff808

Master sketch  







Create a closed profile of the intended area that you want left remaining after the extrude feature. The next step explains. 



Use the extrude "Intersect option" This will use the intersection of the closed sketch profile and the parts listed in the merge scope. In this case "merge with all."


First section created. 


In the assembly, I inserted the first section and did a circular pattern around a mate connector placed at the origin. Hope this helps and good luck!

Jake_Rosenfeld

@paul_bartlett

The rib is there inside each repetition of the pattern, it is just overshadowed by the previous pattern repetition:
 
If you want the rib to show between each vertical segment, I would first get rid of the mirror (you are not using it anyway), and then decrease the number of pattern instances to accurately reflect the full angle that the segmented piece + the rib represent (# of pattern instances needed = 360 / rib angle + segmented piece angle). Additionally, the fact that each repetition has a flat back is always going to make this look jagged, which will be hard to fix up later.

The solution to something like this is usually to use rotational features from the get-go rather than using prismatic features (i.e. extrude), and then trying to make them rotational later. Here is a mockup of how I would do this (from scratch) in the minimal number of steps:
https://cad.onshape.com/documents/7f8b30c353f5c52838ed4ca7/w/fc0c9c266a31e1d7dcf8edeb/e/75dc1d3f1c5ce140e0a1b44f

1. Make some sketch representing the cross section.  Include a construction line representing the central axis, and put the divisions in there of where you want the color to change:

2. Create the rib with a revolve:

3. Hide the rib, and show the sketch (it will be automatically hidden by the revolve), then do two more revolves to create the two sets of differently colored segments.  Make sure that both of these revolves are in "New" mode so that they stay as separate parts.  Notice that since I made the rib from 0 to 3 degrees, I am going to make these from 3 to 10 degrees (Utilizing the "Two directions" option in revolve), so that they sit next to the rib, and are 7 degrees wide:

4. Change the colors so that it all looks how I want:

5. linear pattern (36 instances because I each segment/rib pair is taking up 10 degrees.  10 * 36 = 360):




Definitely not as nice as yours will be because I eyeballed it, but I think this captures your design intent well:

paul_bartlett

Thank you All. This information will  get me back on track. So Great to get this kind of help. Thanks again