Hi Michael,

> It will now consider these 2 to be coplanar. It did think that they were each planar before, but not that they were on the same plane.

That's interesting, so the 2 profiles were planar, I made the inner profile from circles then Boolean Union them together applied fillets then I took the whole profile and offset it outward, the only thing I can think of to check is the centres that I used for reference.

0.0000000000001 would be quite acceptable at work for precise Engineering seeing that our CAD analysis tools are set to show 9 decimal places anything after that wouldn't be seen and never had a problem even if we had a result of 1e-9 we wouldn't worry about it.

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