Simon, what about a simple temporary makeshift wood lathe for the pulley vee -- like you used for the sander drum.
I've actually done that with a piece of 1/2" pipe for an arbor, screwed into a 1/2" pipe floor flange as a faceplate. Attach your pulley blank to the floor flange with wood screws and turn the pulley true with an improvised tee rest and add vee groove using a chisel, or home made form tool.
You can run that arbor in wooden bearings for the temporary lathe setup. And lag it right to the benchtop for a temporary rig. Actually, oiled hardwood bearings work very well even long term if the speeds are reasonably low -- as wood lathe speeds are for this size work.
I mention this because, well, that router table rig does look scary the way you're using it, and also, not everybody has that tooling either.
I think my hands were fairly clear of the router bit, it was a tight fit around the spindle and didn't risk spinning freely, I wasn't climb milling, and I was taking small cuts with each pass. The biggest risk seemed to be the clamps holding the board to the table vibrating loose and allowing the thing to dig in. With the flat cuts I doubled up the clamps to reduce the risk, and with the groove the router bit had a bearing that would hopefully prevent total disaster if the clamps came loose.
There's alot of ways I could've cut the part. One idea was to cut a temporary pulley on the motor, drilling the 3/4" hole out to 20mm, and using the setup to cut the drum itself as a lathe (driven by the temporary pulley) to cut a nicer one. Although the only 20mm drill bit I had was a spade bit. A plug of wood could've filled the hole but it couldnt be cut with a hole saw/ hole cutter due to the hole in the middle. So careful work on a bandsaw cutting a tall but narrow 3/4" inch plug, which seems like a fairly dangerous thing to do.
But then another safety concern is using chisels to cut deep grooves. With chisels you don't get the leverage you would with real turning tools, and making fairly deep grooves seems like a bad idea with a chisel and I wouldn't want to do it more than once.
I still think, outside of using the metal lathe in any way, the router table was the most convenient and the safest way to cut the part I had available.
