Sometimes, acme thread is a hinderance around harder wood sawdust. Sawdust WILL get into the threads and eventually start jamming the nut threads. Wind blown can't be effectively controlled, especially wet sticky sawdust. My table saw is partly jammed for the blade depth movement. This is why I chose winch and cable.
Winch is worm gear so, when it stops turning, it also acts like a brake. They can be found in Harbor Freight ?? for under $50.00. Just keep the gears smeared with old fashioned wheel bearing grease and a simple tin cover.
I used Surplus Center for lots of things.
I once used a 5 HP single phase 240V motor on the Peterson swing blade. It cut fairly well, just pulled kinda hard, BUT, with the tight belts, it blew the start winding.
I agree with Joasis on the farm tractor mount generators. If I lived anywhere near a junk yard, that would be my hardware supply place. A 3 phase motor will run a 3 phase motor. Motors are generators. That is not a misprint. Ebay might have cheaper priced motors. I bought a 50 HP Leeson off ebay, for my buddy down here, and it was around $650.00 brand new. Much less copper in a 3 phase motor, so, less cost. Junkyard motors, just smell them. Burnt windings stink like forever. Just change the bearings, using MOTOR quality bearings.
I used 1" acme thread for the clamp and hyd cylinder for the adjustable up/down. Used the clamp for moving logs/cants around on the bunks instead of raw me power.
Always ran tranny fluid on it to keep the sawdust washed away.
I'm nearly finished with the gasifier build, that will charge my house and shop batteries and run the new design swing mill, with that POS Honda 20 HP that refuses to run on gasoline, so, I'm a gonna stuff smoke gas down it's throat. cough cough