Results 1 to 4 of 4

Thread: 8" table saw motor

  1. #1
    Join Date
    Sep 2007
    Location
    St. Louis, MO
    Posts
    583

    8" table saw motor

    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

  2. #2
    Being the king of cheap, and having plenty of working motors around, I swap electrical motors constantly. To be honest with you, and in my experience, the 3/4 hp motor will not have any more real working power, if anything less.

    The old motor was hp, but was heavy due to more reasons then just the end caps. The equates to heavier shafting and overall, more rotating mass. Now you are getting into the realm of the flywheel and kinetic energy. (Trust me, as a snowmobiler I understand the inportance of rotating mass, you would not believe the difference on clutching that was needed just to add 1 pound of studs to my snowmobile track.

    The old, heavier electrical motors also dampened vibration better due to their sheer mass, and vibration sucks up power, or at the very least fails to transfer it through the belting and pulleys as efficiently.

    These are just real world experiences. Going from heavier, lower hp motor to newer lighter motors was always a disappointment. There are a ton of things I might have messed up on too though such as pulley sizing and ratios. I would still go ahead and try it. None of my power tools are not working because of a swap, I just noticed they did not work as well as they did before.
    I have no intention of traveling from birth to the grave in a manicured and well preserved body; but rather I will skid in sideways, totally beat up, completely worn out, utterly exhausted and jump off my tractor and loudly yell, "Wow, this is what it took to feed a nation!"

  3. #3
    Join Date
    Sep 2007
    Location
    St. Louis, MO
    Posts
    583
    Travis,
    I've had the same sorts of experiences in the past with "upgrading" motors. I've rebuilt a dozen or so motors and cleaned up more than that. One thing i couldn't help but noticing when i got this one back together was how silky smooth and quietly it runs - more so than your average bear. I think i'll at least swap out the cast pulleys with machined steel ones (happen to have some around). The existing pulleys have had a hard life. I tried trueing them up - something i've had luck with before, but these ones are a bit far gone.
    How's that next plane coming along?
    paulh

  4. #4
    Not good. Lots of ideas but I have been spending way too much time on my current project, a stainless steel dovetail saw. I got the case about half built, but I have a lot more to do.

    Patty and Alyson will be gone next weekend so I might be able to get down to the machine shop and start that router plane I want to make. I got a lot of other things to do to though. Like doing some more logging and looking into something for my dad and I to do together. He just got forced into early retirement, so he's suddenly bored.

    Its still snowing too so I have been riding my snowmobile some. It seems every weekend "will be the last ride of the year", but then it snows again. Anyway here is a picture of my dovetail saw in its current state in case you missed the PIP on here of it.

    I have no intention of traveling from birth to the grave in a manicured and well preserved body; but rather I will skid in sideways, totally beat up, completely worn out, utterly exhausted and jump off my tractor and loudly yell, "Wow, this is what it took to feed a nation!"

Similar Threads

  1. Delta 10" midi lathe motor
    By Billy Burt in forum Turning Tool Questions and Show & Tell
    Replies: 8
    Last Post: 10-23-2012, 03:24 AM
  2. Replies: 0
    Last Post: 10-04-2012, 12:39 AM
  3. Motor mounted "breaker" trips on my TS
    By Jim Mattheiss in forum General Woodworking Q&A
    Replies: 4
    Last Post: 07-24-2009, 02:57 AM
  4. New Motor Table saw wiring question
    By Dan Mosley in forum New Tools
    Replies: 4
    Last Post: 11-22-2008, 02:45 PM
  5. Table saw motor v mounting question ?
    By Dan Mosley in forum New Tools
    Replies: 6
    Last Post: 10-04-2008, 11:41 PM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •