OK. Here's a Spree variator that someone should be able to make from off-the-shelf stuff, with a lathe, welder, grinder, and some balancing tools. No special molds / dies required. Please excuse the poor drawings.
It's not dimensioned:
x is the diameter for clearance to crank (probably +.001" to crank size) and
y is arbitrary, though some of the
y need to be bigger for clearance to rotate. You can figure it out.
First image is the stock pulley. You'll need a lathe. Machine out the inside, enlarge center hole, remove outer boss. Drill and tap for screws to attach rear cover.
![Modifications to stock pulley](./download/file.php?id=710&sid=f44bb61c44781753c51d9a06f18d820e)
- Modifications to stock pulley
- stock pulley.jpg (65.57 KiB) Viewed 3736 times
Second shows the blow-up. Ramp plate is not well detailed. Note flat variator back, of thin sheet steel. Simple to fabricate. Center bushing can be off the shelf or made on lathe. Weights could be ball bearings or rollers.
![Variator blow up](./download/file.php?id=711&sid=f44bb61c44781753c51d9a06f18d820e)
- Variator blow up
- modified pulley.jpg (63.7 KiB) Viewed 3735 times
Last, detail of ramp plate. Since the variator outer is simple, the ramp plate is more complicated. It needs to have channels to hold the weights in place. Not sure if this will work without channel guides on the variator outer, but since the throw is short (1/8") if the balls are larger than that (say 1/4") then they shouldn't be able to fall out. I think you make the guide from steel U-channel, then weld it together in the cross-shape, bent back. You will want to balance (probably dynamically) this part when you're done, as it needs to rotate fast. The cross-design is arbitrary; it could be a three-channel design as well. I think it would need to be tapered as you go out (thicker in the center,) but it's beyond me how much or what it would look like complete.
ERROR IN DRAWING: That center hole should be
x, not
y. Otherwise it won't work. And for that matter, all the variator back needs to do is keep the ramp plate inside the variator outer. Center hole could be larger, as needed.
![Complicated ramp plate](./download/file.php?id=712&sid=f44bb61c44781753c51d9a06f18d820e)
- Complicated ramp plate
- variator ramp.jpg (29.03 KiB) Viewed 3736 times
One thing I forgot to design are the guide sliders for the ramp plate (the ramp plate would not rotate with crank as shown.) You could weld fins to the variator outer and let the ramp plate slide on that. You would then need to balance the variator outer as well. Probably should do this with the whole thing assembled and without the balls.
This can all be made from off-the-shelf parts and materials, but will require some skills with machine tools. But there's no expensive one-off tooling to buy.
If anyone builds this, I'd like to see it. Have fun!