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How to do ribs up to cylinders


New member
I'm just learning Solidworks. One thing that I often have problems with is creating ribs that meet round or cylindrical surfaces. Often the top face of the rib is not on one of the main planes, so I first insert a plane on which I can define the line for the rib. Then when I use the Rib feature, I get an error message which I don't know how to resolve. Rebuild Errors: The resulting rib did not intersect the existing model. Please try changing the "Extrusion direction" to fix the problem. But the extrusion direction is correct.

I then scrap the idea of using the Rib feature, and create a rectangle on the inserted plane which matches the top face of the required rib, then extrude the rectangle to the body of the existing model. This is not all that satisfactory because you have to play around with the ends of the rectangle to avoid other problems.

How do I use the rib feature in this situation?

I tried to attach an example, but the Uploader said it was an invalid file.


New member
Example of rib problem

Okay, so here is an example. In this case I was able to draw the line for the rib on the Right plane, but then got the error message. After that I had to insert the RibPlane so that I could sketch the rectangle defining the top face of the rib. The top end of this rectangle has to extend into the column, or else the rib is only tangent to the column. After the RibExtrude, the bottom of the rib sticks out of the BasePlate a little bit, so I have to do the RibCleanupCut to remove that little bit. Following that I can pattern the rib to make two more.

I think I must be doing this wrong because while it's not difficult, it still shouldn't take so many steps to do a simple rib, should it?



New member
For anyone searching this forum for an answer to the same question...

I've done some looking around and read some discussions on the topic. It seems that this is a common issue with SW - that the rib feature doesn't always work when you expect it to. The solutions offered to similar cases invariably seemed more complex than was necessary, involving lofts and whatnot. I think my approach, though requiring a few more steps than the rib feature, is the most straightforward and provides predictable results.

My thinking is that the rib feature is just a special case of a generic extrude, so if the rib feature fails, then just do what you'd do if the rib feature didn't exist - sketch the top face of the rib and extrude it to the body. Depending on the situation, you may need to extend the sketch into the cylinder to avoid 'zero thickness geometry' errors, and you may need to do some cuts after the extrude to clean up anything that sticks out where it shouldn't.

Hopefully someone will point out flaws in my solution and/or if there is a better approach.