TableSaw Motor for a grinder

G

goalie098

Joined
Feb 13, 2015
Messages
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I have been debating building a grinder and looking through some previous threads I see a lot of discussion about motors in the 1-2hp range. I just bought a new table saw and the old saw isn't really worth selling or giving away but the motor is still strong. The specs from the Manufacture are:

MOTOR:
AMPS 13
VOLTS 120
RPM 5,000

Good motor for a grinder or not? I was thinking if it is I would use step pulleys for speed. You expertise is much appreciated.
 
Pictures are everything.


It's pretty fast


I would bet real money that it's an open framed motor and that's bad
 
I would say go for it. Step pulleys and appropriate belt handling gear would be perfect, and reasonably priced.

Larry
Tinkerer
 
Most grinders start in the 1750 RPM range for a motor, just as a point of reference.
 
I agree with the guys here. Table saw motors are light duty motors, grinders need Farm duty motors, and 1750 rpm is best, faster and your asking for trouble.
 
I am currently using a table saw motor. It's a craftsman, open frame, 3450rpm and 1 hp. It is fast. I keep it blown out with air. It did flare up once and that's when I started blowing it out. But hey, $40 is a good deal.
 
I would wonder what type of table saw motor that is - a direct drive motor where the blade mounts direct to the motor? As said before, 5,000 RPM is really spinning. With a 2"X4" step pulley to half the shaft speed, and using the standard 4" drive wheel you belt speed would be around 2600 SFPM.... Pretty fast for the slowest speed. Even with a 2"X 5" pulley setup you'd still have 2000 SFPM, then if you could make a 3" drive wheel, you'd have about 1571 SFPM as the slowest speed.

The open frame isn't a big deal for a hobby maker, just keep it blown out as Matt says and it will last longer than you'd expect. When it does short out, no biggie - it was free anyway. When building a grinder, the motor is the cheap part anyway. New 2hp 3 ph, TEFC motors are from $130 to $160 shipped depending on RPM.

Ken H>
 
i have run a 1hp open frame motor off a table saw for the last 3 years. mine was a 1750rpm though. You could step it down to half speed with pulleys and get closer to a useful range. its not ideal and its not going to last forever with the metal dust, but if its free and it gets you grinding and working until you can upgrade then i see no reason not to use it for now. Mine was still working after three years but i scored a 2hp 3ph baldor for free so went the VFD route now. The speed will be an issue but with pulleys that can be adjusted. The only thing i would advise against is building a grinder specifically to accommodate the motor. as long as your grinder can be switched to a proper motor in the future, i would go for it.
 
With the specs you gave I would NOT use it. Table saws and grinders are different creatures. That motor does not sound like it would make the transfer well.
 
Great Info! thanks everybody. I thought it might be too fast from all the other info I have read on this forum. Maybe I will just put a Dado stack in and leave it. I did see a vid where a guy upgraded his dust collector and built the fan out of wood.
 
You know you can get just about any size pulleys that you are likely to need? USA Bearings and Belts had 1.75" up to about 7" with 1/2 5/8 or 3/4" bore balanced cast iron pulleys for pretty reasonable prices. I'm sure there are others - this is just where I got pulleys and bearings for my project.

A little bit of effort with a spreadsheet and you can translate just about any motor speed to whatever SFPM you want.
 
The motor he describes is almost surely a direct drive saw motor. It is made to bolt on a saw blade....it isn't made to have a pulley. Running at 5000RPM, even the most minor balance issue could be a serious problem. The best pulleys in the world would not be likely to run smooth on a threaded shaft at 5K RPM.
 
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