How do I cut an o-ring grove in the face of a cylinder?

alan_brunsman706

The grove would be the shape of an o-ring but bent to the shape of the cylinder.

alan_brunsman706

Sorry, I am not asking this correctly. The o-ring does not go around the cylinder. That is too easy. The o-ring is around a small hole in the side of the cylinder. It is on the side of the cylinder. The o-ring shape would be the same if you pressed it against the side of the cylinder. 
I have tried doing this in Solidworks. I formed the curve and profile of the o-ring but I could not get it to cut the profile along the curve. no luck. It was easy to cut a flat o-ring grove but I could not put in the extra  dimension.  

mahir

I'm not exactly sure what geometry you need, but here's one way to go about it.

https://cad.onshape.com/documents/57acdfaae4b005c413ed9b6f/w/3fd585a46d3af1b3ba413c53/e/e2f1eae15625bdc140b7f720

John_P_Desilets

Something like this? 

https://cad.onshape.com/documents/16196bcaa77ee1a30bd5d217/w/0ab77b25d90e77412efc5f20/e/f28c7a869b033079f769aa54

bruce_williams

John's solution got me thinking about the newer Projected Curve.

https://cad.onshape.com/documents/18d823f88ac2b45dd10de9c0/w/7743cbf857f18503bbffe555/e/8c2ce9900185757dc7835163

owen_sparks

Model the o-ring in place, then Boolean subtract it from the cylinder with the"keep tools" option checked.

Or if you don't need the o-ring ring use a Revolve to cut away the groove.

Owen S.

alan_brunsman706

Does that cut a bent o-ring grove or a flat o-ring grove? To seat the o-ring properly I need the grove in the cylinder the same depth all round. 

Sheldon

You can either use the Revolve feature which will allow you to perform a cut around the cylinder. Or you can take a look at this: https://www.onshape.com/cad-blog/custom-feature-spotlight-how-to-use-the-o-ring-feature 

mahir

I agree with Sheldon. Just sketch a typical o-ring groove cross-section and revolve-cut it. That cross-section is typically just a rectangul with rounded corners and a specific ID/width to get proper fit and compression depending on the specific o-ring size you're using.

alan_brunsman706

Sorry, I am not asking this correctly. The o-ring does not go around the cylinder. That is too easy. The o-ring is around a small hole in the side of the cylinder. It is on the side of the cylinder. The o-ring shape would be the same if you pressed it against the side of the cylinder. 
I have tried doing this in Solidworks. I formed the curve and profile of the o-ring but I could not get it to cut the profile along the curve. no luck. It was easy to cut a flat o-ring grove but I could not put in the extra  dimension.  

mahir

I'm not exactly sure what geometry you need, but here's one way to go about it.

https://cad.onshape.com/documents/57acdfaae4b005c413ed9b6f/w/3fd585a46d3af1b3ba413c53/e/e2f1eae15625bdc140b7f720

John_P_Desilets

Something like this? 

https://cad.onshape.com/documents/16196bcaa77ee1a30bd5d217/w/0ab77b25d90e77412efc5f20/e/f28c7a869b033079f769aa54

bruce_williams

@John_P_Desilets
Very clever!  Thanks for sharing

bruce_williams

John's solution got me thinking about the newer Projected Curve.

https://cad.onshape.com/documents/18d823f88ac2b45dd10de9c0/w/7743cbf857f18503bbffe555/e/8c2ce9900185757dc7835163

alan_brunsman706

Wow! Thanks for the help. 
I have one more variable that I did not include. The cylinder needs to be tapered along the axis. A slight draft like a injection mold draft would work. How hard is that to add? The draft is on the o-ring side. Follow?

owen_sparks

alan_brunsman706 said:

Wow! Thanks for the help.

It's like that here

alan_brunsman706 said:

I have one more variable that I did not include. The cylinder needs to be tapered along the axis. A slight draft like a injection mold draft would work. How hard is that to add? The draft is on the o-ring side. Follow?

Here is my take on it.  Hopefully I've understood the direction of draft required.  Someone else may have a cleaner method but it's a start:-



https://cad.onshape.com/documents/65bfff954a1a1e427f2d5c6a/w/7528c1745d261331f48fc094/e/e5e6a6f4b839dc1e68b57d72

Similar to the previous method but:-
(a) Cylinder drafted on its initial extrude
(b) New construction plane created so o-ring center hole is normal to surface
(c) 2 surfaces are split to create the o-ring sweep path

Happy CAD-ding,

Owen S.

John_P_Desilets

 alan_brunsman706 

Is this the desired draft you are looking for? In the example from my previous document, I modified the sketch used for the remove sweep. If you activate the section view, you can see the draft angle.