Modeling O-rings

After some fiddling, I figured out one way which was to sketch a construction circle the nominal diameter of the o-ring as well as a line representing the depth of the groove. The o-ring center corresponds to the midpoint of the const. line. Locating the the o-ring center was just an equation from the groove dimensions.

Maybe there is a more logical or universal technique?

Everybody I talk to seems to have a different method based on the application. One of the easiest to work with is to just model the o-ring to the gland dimensions (square profile). Then in your case you would need a different configuration for face or axial seals. Or, you can you some variation on contruction lines in layout sketches as you've already tried.

Myself, I model the gland, then drop in the o-ring just to fill the BOM.

Like Dale said, everybody seems to have their own preference on this. I show mine the same way I always did on the board. I have modeled them as ellipses with it tangent to a plane. Then for a static seal that plane is conincident to the sealing surface. For round inserts, I use a different mating scheme, but the o-ring is still shown as an ellipse. This indicates that it is under compression.

YMMV

jk

krupnikas,

I use a revolved ellipse. The minor is the compressed height and I exaggerate the ellipse major to show the ID and OD as being squashed.

Ken B.