thoopid pulley size/power/mojo question

Folks -
Lawdy! I am still futzing with my old craftsman 6" jointer and am going to swap motors out for MORE POWER. The spare motor I had laying around is 1.5 hp. It's an old GE unit, probably weighs 80# - capacitor start, ALL cast iron.
Anyway, the original jointer motor is 1/2 hp at 3450 rpm and has a 2.5" D pulley. The GE motor is 1.5 HP at 1715 RPM. It has a ~4" D pulley. Now, I know that should get a 5" D pulley, but live in a small town, and darn it, the local hardware store just doesn't have a huge selection of pulleys with 7/8" bore... none, in fact...
So, I'll go with what I have for now - knowing that the cutterhead speed will be a bit low. My question is that WITH a 5" pulley, will I only have an effective HP or Torque of 3/4 HP since I am doubling the output speed?
I am also wondering if 1.5 HP may be a bit rich - the bearings in the jointer are okay and all... I don't use do face jointing of boards so I don't think I'd be putting that much of a load on it, but with the existing 1/2 HP I could easily (very easily) overload it edge jointing 6/4 oak.
Final question - the motor data tag says it'll run 110/220, but I have *NO* idea how it is currently (no pun intended) wired, and have no manual for it. How can I tell how it's wired?
Whatcha'll thimk?
John Moorhead
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http://grainger.com for pulleys direct to your door.

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It will still be 1.5 hp, even with a 20 inch pulley. But easier to stall. Shouldn't be a problem with a 4 or 5" pulley. My lathe has several pulley size configurations but no noticeable change in power, just speed of the second shaft. There is often a wiring diagram inside the cover where you connect the wires. I can't remember the configuration offhand, but could pull a cover and look if you don't get a good response from someone else.
John Moorhead wrote:

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Gerald Ross, Cochran, GA
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www.grainger.com or www.mcmaster.com

No. it is stillthe same hp/

Remove the plate covering hte wiring. It may be printed on the inside. Often the motor plate has it on the outside.

A little Rube Goldberg, probably overkill on the power, but if it works and it is cheap, good for you.
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The data tag most likely has a schematic showing the proper connections for low/high voltage.
Jerry
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On Thu, 19 Aug 2004 23:40:49 GMT, "John Moorhead"

the bearings were sized by some engineer somewhere to handle the forces that can be put through them by the 6" blades. if it's an old enough craftsman that engineering was prolly ok. your new motor may or may not be able to exceed that- it sounds like your old motor was way undersized. but it doesn't matter if the motor is oversized- you still can't put more force through the 6" blades than the bearings can take, unless you start using the thing regularly to take full width 1/2" deep cuts or something. I doubt you will be using it like that....
what you do need to worry about is belt tension and cutterhead speed.
bearings are rated for a max speed. exceeding it will greatly reduce their service life. underrevving is no problem.
applying too much belt tension will also smoke your bearings, and the bigger the motor the more tension needed to transmit full horsepower. so don't overtighten the belt. you might even want to switch to different type of belt- different belts slip at different tensions. I'd adjust it as loose as possible and still not slip at the deepest cut I'm likely to make, and will run without belt flutter.
if there is extra HP, it will simply be unused, which is really not a problem in your case and with that machine. if this was a big machine and in an industrial situation, the current draw of an oversize motor would have financial repercussions, especially for a machine that is run 7/24.
besides, I don't think one anna half is oversize for a six incher annyhow.
    Bridger
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