Hi all,
I've got a pair of components in which we've modelled an involute spline explicitly, using an equation curve.
The modelling approach is as follows:
Generate one involute curve from the base circle up to a diameter beyond the final tip diameter:
Extrude this, by Projecting it into a sketch, mirroring it, and adding a root fillet between the two flanks:
The involute equation includes an offset angle, which generates the clearance between the two parts by effectively rotating the offset about the origin. If I measure the angle between the two curves at any diameter, I get a constant angle, as I expect:
However, when I measure between the actual solid geometry (and this is what our analyst noticed when running FEA), the angle is not constant, and the OD is closer than the ID:
It appears to affect both flanks, regardless of whether it's the 'original' or mirrored side, so I don't think it's caused by the mirroring op. A curvature analysis also suggests that the mirror is good, although it does show some worrying unevenness:
Is this an accuracy issue? I've tried tightening the accuracy (absolute) but without fixing the problem. Has anyone else experienced anything similar?
Thanks!