Hi Bart, Vincent,
compliments to your CAD skills, I guess this was quite some headscratching for designing something useful at the CAD place. My thinking you could have designed a bit more of range in the ESA for smoother operation on the road. There are two considerations I see with ESAs : Protection of gearboxes plus smoothing out the kangaroo ride with singles or twins at very low speeds.
The first aim seems not to be essential on Vincents as there are two chains in the transmission of power to rear wheel so not a harsh life for gear teeth anyway - unlike with all gears Guzzi or BMW twins. And Vincent gearboxes are designed extremely strong anway , I never have come across stories about gearbox wear even with the old non-working ESA. So this is not a point for any ESA on Vincents at all.
The second aim for smoother ride would require a bit more of range in the ESA to be felt so that is why I´d go for a bit more of range, so maybe keep your logic and reduce lobes to max. four of them and round out a bit more - bigger circle. 72 degrees at steepest spot seem quite a lot, I´d think 60 could be all you need. When going over 45 degrees at gradients you get some self-locking condition when having springs loaded onto the lot anyway, not so with the original design unfortunately, too shallow shapes there. But then I do not know, just thinking, tests will tell.
For some time I was thinking of suggesting you could find a business case here in new ESAs production as the Spares Co seems uninterested to go for real progress. But as expected when told about CAD activities at your place your design is not really great for economic machining - typical CAD ball nose cutter endless lines milling. My guess an hour or two rattling along in alu for each item, even longer for smooth finish.
Myself helpless in CAD I came to a different logic looking at the half century proven BMW ESA on all flat twins for machining both parts with standard straight end mill, using my dividing head plus encoder on it on the manual mill with DRO. That worked absolutely perfect even on the very first alu test pair. You´d do same today on a CNC lathe with milling attachment in 15 minutes for both parts and perfect smooth faces. These machines are so fast when having a standard end mill for roughing and finishing provided the part was designed for it - unlike the typical CAD line milling in small steps with ball end mills, unsuitable for mass production. In the BMW design you see two different shapes that go together, no benefit to have same shapes in an ESA, the effect will be you can machine this design at no time on a modern CNC lathe with milling head included, no mysteries about matching faces due to the logic in the design strategy. Just thinking . . . .
Vic