Assembly: wrong mating of cones about freecad HOT 4 OPEN

To achieve what you want, it needs a distance joint of 0 between the 2 conic surfaces.

And currently distance joint doesn't work between 2 conic surfaces as the solver currently doesn't have this.

Another solution would be to make it possible to select the cones 'top' points. ie when selecting the conic surface, the JCS would position itself at the 'top' point. Then you would be able to match 2 cones by making a fixed joint between the 'tops'. This I think I should be able to do.

Now after thinking about it, the distance joint between 2 conic surfaces, is basically a distance between the tops points. Maybe I can cook something.

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If you know the distance between the point ($\ell$) and the angle ($\alpha$, equal for both cones), you can calculate the distance between the two surfaces ($h$) using this simple relation: $$h=\ell\times\sin\alpha$$

The distance $h$ is closer to the intent of the user.

If the angle is different for both cones, it’s harder. Let $\alpha_m$ and $\alpha_f$ the angles of the male and female cones respectively.

If $\alpha_m<\alpha_f$, you need to determine the minimum diameter of the conical hole on the female geometry, and determine the position of this diameter on both cones, then set the distance $\ell$ so that the intersection of the two cones is a circle of the same diameter. If $\alpha_m>\alpha_f$, then you need to determine the maximum diameter of the conical shape of the male geometry, and adjust the distance cones the same way. You will then have contact with the two parts.

If you want clearance the same way as defined for $\alpha_m=\alpha_f=\alpha$, more calculations are needed to determine $h$.

Ideally, the solver should do this. If we go for a temporary workaround, I think that implementing only the case when the two cones have the same angle is sufficient.

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Ah yes its simple only if both cones have the same angle. And only to make distance between them when they are aligned.
But cone distance is actually much harder than this indeed. The cones don't even have to be aligned.

So what I can do for now, that would solve the case you describe, is that when you select a cone, the JCS position itself to the top point.

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Seeing your picture, I think that there should be a distinction between mating joints and tangent joints. Both can have a distance. They can sometimes be equivalent. Mating is for moving both surfaces to make them overlapping, while tangent is for making them touching each other.

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