Horizontal Mill Flywheel

I'm overhauling a Brown & Sharpe #12 Horizontal Production Mill (more details in another thread). The main flywheel, which is not original, is craked and bent. It's about a 12" diameter double V-belt pully with a 1 5/8" bore. I've scowered our shop and found some candidates but all would need to be re-bored, plus they're all held in place with set screws and I'd like to have a clamping type hub on this flywheel (which is what it has right now). This flywheel clamps onto a brass sleeve which is pressed into a small diameter driving gear which drives a 12" or so gear on the spindle.

Now for the question: I have a 3" wide flatbelt pully about the same diameter that's a split pully, so it'll clamp, BUT it's made of riveted sheetmetal. Very old piece which came from a ceiling line drive we scraped. Do I need the weight of a cast flywheel for momentum or will this pully work? I have no qualms using a flat-belt drive. On the other hand, will a 5/16 set screw and a slight press fit be enough to hold one of the cast flywheel's on?

The power source for this machine is a 1 1/2 HP variable speed motor.

Any thoughts?

the rivited split pulley that you have should work just fine. Most machine tools didn't have flywheels. usually machines such as punches and shears needed the stored energy in a flywheel to help supply the brute force needed to forct the punch through the steel.

If you're going to transfer 1 1/2 hp through a set screw, I'd recommend a full "dog point" set screw, ... with as much of the "dog" as possible, imbedded in the brass sleeve.

If you can stick a second dog point set screw through the hub, and into the brass sleeve, at 90 degrees from the first one, ... so much the better.

I'd like to restore this mill at some future time, but for now It's just gonna keep working. But I'd like to avoid modifying any of the original parts. I'm pretty sure the gear set with the flywheel is original. If it wasn't, heck, I'd bolt the flywheel to the sucker. Mabey it's not though....
Long shot... anyone have one of these mills with the original flat-belt pullys that can post some pics? I think one guy said he did in the other thread. I'll message him.