You’ll find a bit more information and a few photos of that particular “slip-on” needle cutter and the machine it’s mounted on here…
Far more information about the development of the “slip-on” flywheel can be found here…
This printed flywheel had several advantages over the shaft-mounted versions… the motor/cutter assembly could be made shorter and more compact, it made for much easier needle attachment, and it was smoother running (easier to balance). The main disadvantage was that the printed flywheel needs to be a custom-fit (it’s a close friction fit) to the motor bell of whatever motor you’re using for your cutter. If you can 3d print and your printer is pretty well dialed-in, the fit is pretty easy to attain within a couple of tries and the print time is quite quick.
I’m pretty much out of the needle-cutting business now (old, tired, retired, etc) and haven’t been keeping my ear to the ground as I once did but there have been a number of variations on a theme built by folks still actively needle cutting foam. The FliteTest thread referenced above is very lengthy but, if you’re determined/persistent, you should be able to find quite a bit more information that could be of help. I did put my FoamRipper alternative carriage design out on TV and it includes the last flywheel I developed for the CF2822 motor I was using. There is also a more recent design – EZ-Flywheel by @sirjaymz – that may be more suitable for ERC TimSav users… similar/better needle attachment but shaft-mounted.
Hope this helps… and good luck! – David