John S very kindly send me a Cut3d generated file which I have just tried to machine.
The wheel should have been finished in 2 raster passes at 90 degrees to each other.
Unfortunately, 3/4 of the way through the first finishing cut, my Z axis lost about 5mm worth of steps and I couldn't rescue the part.
My machine still has an acme leadscrew on the z axis and can't run very fast without stalling. I have a ballscrew to fit but the machine will need a lot of modification to accomodate it. A gas strut might help to take a lot of the weight of the knee.
The first picture shows how it cut and how the fillets on the spokes look. They look very good and don't show the problem that the Aspire wheel showed! (Strange that Cut3d and Aspire are both from Vectric!)
The next picture shows the steps which are produced by rastering. The second finish cut (at 90 degrees to the first) would have cleaned these up.
John estimated 51 minutes - Mach3 told me 1hr 14minutes which is probably down to my slow z axis.
There is one feature in MeshCAM which ensured a good finish to the rim and the inside of the spokes - it has a 'waterline' finishing feature which runs round following the profiles in steps . It also has raster finishing in either one or two passes.
I don't know why MeshCAM needs to do the inside of the spokes in many passes as the sides are vertical and would machine just the same in one pass. I've asked the question of the software developer as I may be missing something in the settings.
I'm doing no more in the workshop today.