Plane tangent to cylindrical surface

charles_easter

In SW I often create a plane tangent to a cylindrical surface in order to cut keyways or pockest etc. Doing it this way maintains the depth irrespective of any changes to the cylindrical diameter. Any ideas how this can be done with OnShape?

brucebartlett

Only way I can see is with a sketch perpendicular to the cylinder. In the sketch draw a line from the centre of the cylinder to the surface, constrain ends to the cylinder surface and the centre, set angle as desired. Then use the line point plane. 

thomas_5

That technique can be very effective if you include dimensional controls on the sketch. It's one I frequently use even when I have a tangent/parallel solution. That way I don't have to construct a plane to be parallel (or normal to) or be locked in alignment to an origin plane.

andrew_troup

@thomas_5: by "dimensional controls on the sketch", do you mean control of the angle of the line? 

brucebartlett

Just a few more tips. To control the angle of the line delete the default horizontal constraint (tick the show constraints check box to view all constraints or just hover over the line to awaken constraints then find the one you want to delete) when the line turns blue it should be free to rotate. In Onshape you can reference dimensions to planes so by turning the right plane on I can add an angle dimension off this. 

lougallo

Here is a tangent plane FeatureScript if you want to use it: https://cad.onshape.com/documents/68455a5d522e81cd65a35211/w/deb148ff386c8a32e35e7d65/e/929b7ca8aeee162bb0f129d9