Basically you offset the rotary table centre relative to the cutter path to get the spoke width and tweak the actual angle setting to get the taper.

So using round numbers and assuming the cutter is of zero diameter to make it easier to see what’s going on. Think laser cutter I guess. If the spokes were parallel and 0.100″ wide you’d offset the RT centre by 0.050″ to one side and go round cutting one side of the 18 spokes. Move it over 0.100″ so the RT centre is 0.050″ offset the other way and cut the other side of the spoke.

As the spokes are tapered set the offset for the wide end and adjust the angle on the RT so the line of cut is deeper on the narrow end giving the desired taper.

In the real world you have to add a further offset of half the cutter diameter to get the cut line in the right place.

If your trigonometry and geometric visualisation is less than wonderful this is the sort of thing that is likely to net you a whisky bottle size hangover headache without the pleasure of emptying the bottle first.

Playing with CAD makes it all much easier.

Good idea to mock things up on paper with pencil or slender felt tip pen / sharpie in the spindle and a suitable backing board in the RT to support the paper. Draw out something simple, four spokes are plenty, and try to trace over it. When the penny drops after 3 or 4 goes you will wonder what the problem was. But until it does …

The trigonometry involved is fairly straightforward. I imagine Jason or one of the other CAD jockeys can easily show you that. My trig is well up to such things but I found getting the visualisation straight for the moves needed first time through tricky.

Clive

You really need to give hub diameter and inside of the rim diameter

But angle wil be approx 0.7deg either way and offset 0.041″ plus half cutter diameter.

Bit of CAD soon gives the numbers but confirm those two diameters or exactly where those widths are taken and the cutter diameter being used and I’ll give it more accurately.

No need for fancy machines, a basic rotary table can do it as that is all I have used in the past

Playing with what the ID of the rim may be and how far towards the hub you can get with a 1/16″ dia cutter this is what you will likely end up with. Angle is between 0.6 and 0.7 deg so I would be inclined to use 40mins as it’s an easy number to read off the R/T. But give the numbers I asked for and you can have it exact but will have to wait until the morning.

Driving wheels have an oval shaped hub to fit the crankpin. Trying to cut them from solid without CNC is not something I would undertake