Paul Hubbman
Member
- Messages
- 582
- Location
- St. Louis, MO
I'm rebuilding an old Atlas 8" table saw for a friend of mine. I just finished up the motor over the weekend and am moving onto the saw itself. It's in good shape and is a solid little saw EXCEPT for the trunnions - made out of pot metal. The original trunnion bracket on the back side of the saw had broken, i was told, when the saw fell backwards onto the ground (was used as a job site saw until a couple of years ago and was setting on unstable ground). It landed on the motor hanging out the back, which transfered the shock to the trunnion bracket.
I was lucky enough to find the parts i need on line (now there was a needle in a haystack!). My question is about the motor. I just rebuilt the motor. It had lost its spec plate. I put it back together and reved it up. According to the amp meter, it's drawing 5.5 amps - about 1/2 hp. It's an old cap start motor with the iron end bells. It weighs quite a bit. I can put it back on the saw, but i happen to have a totally enclosed cap start, fan cooled, 3/4 hp motor which is newer and weighs a bit less. I think it would be easier on the trunnion assemblies. The downside is that it spins at 1750 rpm, not the 3450 rpm of the original motor.
I know, in theory, i should be fine by adjusting the pulley size to get the same rpm at the arbor, and that lower rpm motors have greater torque than their higher rpm counterparts. The torque at the end of the 4" arm of the blade should still be greater than with the 1/2 hp motor. On paper, the saw should work better with the 3/4 hp motor. I wanted to know if anyone out there can see a downside to using the more powerful motor. I like the fact that it weighs less and will be a lighter load on the trunnions. I also like the fact that it's totally enclosed. I suppose i can always try it with both, but thought i'd ask around a bit first.
Any real world experience with this?
Thanks in advance,
Paul Hubbman
I was lucky enough to find the parts i need on line (now there was a needle in a haystack!). My question is about the motor. I just rebuilt the motor. It had lost its spec plate. I put it back together and reved it up. According to the amp meter, it's drawing 5.5 amps - about 1/2 hp. It's an old cap start motor with the iron end bells. It weighs quite a bit. I can put it back on the saw, but i happen to have a totally enclosed cap start, fan cooled, 3/4 hp motor which is newer and weighs a bit less. I think it would be easier on the trunnion assemblies. The downside is that it spins at 1750 rpm, not the 3450 rpm of the original motor.
I know, in theory, i should be fine by adjusting the pulley size to get the same rpm at the arbor, and that lower rpm motors have greater torque than their higher rpm counterparts. The torque at the end of the 4" arm of the blade should still be greater than with the 1/2 hp motor. On paper, the saw should work better with the 3/4 hp motor. I wanted to know if anyone out there can see a downside to using the more powerful motor. I like the fact that it weighs less and will be a lighter load on the trunnions. I also like the fact that it's totally enclosed. I suppose i can always try it with both, but thought i'd ask around a bit first.
Any real world experience with this?
Thanks in advance,
Paul Hubbman