How to split a circular part - my journey so far.

martin_danger

Hi, 
https://cad.onshape.com/documents/30aa714d9ba1405b6c4962b3/w/abd3881b0b7f5b4bdc438106/e/18fb9a71d18dafd488332af0
I want to split a circular part into 3 pieces. I realised that using only one surface results in you splitting the part but still ending up with only 1 part. Onshape error message at this point is unhelpful telling you to check the input.
So I try to split the part with 3 surfaces. Turns out you can only select 1 surface for a split command. 
Fair enough, then lets merge the surfaces when I create them using the circular pattern command. Using the feature option, you get 3 surfaces with no option to add. Using the part option, you get the option to add but an error occurs saying that the parts don't intersect each other (they do but being a surface must make this not work?). 
So I then go to the sketch an using circular pattern to create a sketch that will extrude 1 surface that has all 3 split locations in it. Except I can't select the spline when using to the circular pattern tool. 
Ok, I guess I could copy and past the spline. Yep, that does work :-)
Then I try to extrude that surface.....and I get another error :-(
So that's what I've tried so far. 
Next is to create a surface that intersects the circular part in 3 places without it having any intersections. It will look like a snake in the sketch. 
If that doesn't work, maybe I can create only 1/3 of the circular part and then do a negative extrude? Will have to be careful with this approach to make sure the parts will fit together.
Surely there's a way to do this that I haven't thought of yet? 

Screenshot: Catch 22 - You can't split a part if the split doesn't create a new part. But you can't split a part with more than one entity.....
Select my spline to pattern...But selecting the pattern tool deselects the spline...

eric_pesty

Probably easier to just revolve a 120 deg "sector" of the ring then do the split with the single spline and pattern the parts. then you can boolean the bits you want to be together?

glen_dewsbury

Here is an other option. Yes, the face for spitting wants to pass in one side and out the other. I split to make one part then used the assembly to put 3 together. You can make an array in the part studio if you feel the need if something changes from part to part like bolt holes. I noticed the spline used  for serrated end is kinda wonky so I made a new one more evenly spaced (still probably not optimum but cleaner). There also seemed to be something tilted by a small amount. I just started fresh and copied/paste the ring profile so didn't find out where tilt came from. Also started with cylinder centered on origin (makes some down stream items simpler to keep aligned.
https://cad.onshape.com/documents/60622a06c011915d023d16e3/w/191f3a3cd0f9bff4d7b3cc90/e/d417d399e6cd94ab2a21eae1

eric_pesty

Probably easier to just revolve a 120 deg "sector" of the ring then do the split with the single spline and pattern the parts. then you can boolean the bits you want to be together?

glen_dewsbury

Here is an other option. Yes, the face for spitting wants to pass in one side and out the other. I split to make one part then used the assembly to put 3 together. You can make an array in the part studio if you feel the need if something changes from part to part like bolt holes. I noticed the spline used  for serrated end is kinda wonky so I made a new one more evenly spaced (still probably not optimum but cleaner). There also seemed to be something tilted by a small amount. I just started fresh and copied/paste the ring profile so didn't find out where tilt came from. Also started with cylinder centered on origin (makes some down stream items simpler to keep aligned.
https://cad.onshape.com/documents/60622a06c011915d023d16e3/w/191f3a3cd0f9bff4d7b3cc90/e/d417d399e6cd94ab2a21eae1

martin_danger

thank you both for your ideas - they both work. It's good to have this forum so that when I can get some new ideas when I hit a mental brick wall and can't think of options myself.