motor size for belt grinder

strahd71

strahd71

Joined
Jan 26, 2006
Messages
784
ok so i am thinking of getting a coote or building the NWG so i need a motor either way. i was at TSC looking and they have these GE farm duty motors and from the little info i could read there it left me uncertain as to what size i really need. they were running at 1725 rpms. these seem very heavy duty as they were stating that these could be used for grain augers and everything else. can a guy reasonably go with less than a 1HP? would a 1/2hp or 3/4hp work? not sure if it matters but i will have to wire it for 110.

thanks

jake
 
I'm looking at the NWG, too. Everything I heard seems to point to 1.5hp or more (preferably 2hp). Anything less will stall when grinding on the platen.
 
I know a guy who runs a 4x132 for sharpening mower blades and truing chainsaw bars that has less than 1 hp. It seems to bog down a little, but as long as you don't lean into the machine it should be alright. I bought a 2 hp motor for the grinder I am making, I am excited to use it!
 
I'd try to stay above 1hp at a minimum. Try to make it vs either though controller or pulleys. More is better, they say that Bob Engnath ran 5hp Burr Kings :D
 
I have a 1.5 on mine and it will bog if I push really hard on the platen. As with most equipment there is a range of powers that you could use typically the more the better in my experience. I built a power hammer that was supposed to run on a 2 hp at 1750 rpm but I didn't have one so now it runs on a 1/2 hp motor at 1425 rpm. It would work much better with the 2hp. I would get the biggest you can afford within reason of course, 10 hp might be pushing it.:)
 
If you are trying to stay within the 120V 15 amp breaker - 12 amps is your limit.
(working limit is 80%)

My Bee grinder ( a Canadian Wilton Square wheel ) has a
1 HP 3400rpm motor at 12Amps

Something about the 3400 RPM keeps it at 12 amps,
1 HP at 1740RPM is more current and therefore, needs a 20 amp circuit.

At the higher RPM, I am using a fairly light touch and have never stalled it
It is direct drive.

If i were trying to stay within the limits of the 120V 15 amp circuit and lowest cost.:
1 HP
3400 RPM
TEFC
with 5 or more steps - stepped pulleys - lower belt speeds should retain torque and be difficult to stall. (and you have the benefit of lower belt speed)
 
A lot has to do with what you want out of your grinder - what power is available to you - and what you can afford "just in case".

A 1/3 HP old furnace motor will still give you far better (more productive) results than a little 1 x 30 or a file. I belive grinding is about finesse rather than power - and 1 HP does finesse just fine thank you.

If your circuits can handle it, more power is useful for fast, production style grinding - for tapering tangs and for flattening large pieces of handle materials.

I have a lot of respect for Steve Penner's experience, but every grinder manufacturer offers 1HP 120V models. Some even offer 1.5HP. (I think those may be an adapted modification of the word HP).

Steve is certainly right that 12 AMPs rated should be the max for a 15 amp circuit.

Shop Vac offers 4.5 HP vacuums on standard 120V. Bullshit! :rolleyes: :rolleyes: IIRC 1HP = 746 watts. At 100% efficiency (and that just doesn't happen) that's about 28 amps.

Your motor should be TEFC or grinding dust will kill it quickly

Rob!
 
about the dust. the motor wasnt sealed but i was thinking could i cover the intake and fan with nylons or something
 
I would not go smaller than a 1.5hp. I changed my 1.5 out for a 2hp and it was a good choice.
 
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