Need Grinder motor reccomendations

H

Hoplophile

Joined
Feb 23, 2001
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435
Ok, F I N A L L Y, I have a place to set up a shop. I have a KMG-1 that I need a motor for.
1, 1.5, or 2HP?
1725rpm TEFC.
Shaft diameter? Or does it matter?
What does "capacitor start" mean?

I want something that I plug in and then switch on, so 120v single phase?

What pullies do I need? (and where)

I'm wantin to have "black boogers" by the middle of April.
 
I picked up a 1.5hp Lesson off Ebay. The same one Rob sells. It is a 5/8" shaft. Just make sure it is a TEFC.
 
If you're going with 115V, 1.5HP is probably going to be a good bet. As for speeds/pulley sizes, if you look here, you'll see my dissertation on figuring out your speeds. I'd recommend a pair of step pulleys so that you have some control over your belt speeds. I tend to want the belts going a lot faster now than when I started out (and I blame J. Neilson! :D) but there are still things it's good to slow down for.

I believe the ones that Rob sells are 3450RPM. With a good set of step pulleys you'll be in good shape.

-d
 
My set up is a rubber coupled driven 3" drive wheel. A 1.5hp @ 3450 RPM motor.
Its very adaquate but if I build another I would go for more hp and a veriable speed motor. Good Luck:)
PS, USE A DUST MASK for your own sake not mine!!!
 
You will want 1725 rpm, the slower speeds keep your belt moving slower and give you more controll. You will need to wire the motor yourself and add a switch. The capacitor starting coil is already built into the motor.

You will need to check your electric pannel and see what sort of circuits you have in your house. In my case I only had 15 amp circuits through the house, in which case I was limited to a 1hp motor, because a 1hp motor draws about 13 to 14 amps when running on 110v. A 1.5HP single phase motor will draw 18 amps running at 110v, and if you only have 15 amp circuits, you will be constantly tripping your circuit breaker when you turn the motor on.
 
I guess I should really check that. Thanks for the info. Keep it comin.
It's goin in a glass blowing studio, so I might have 220 as an option.:)
 
If you do use a 115 volt motor, you may need to use a time delay fuse for the circuit. Starting draw is very high and will often trip out standard breakers or standard fuses.

If you can go 220V you will have the added bennefit of reduced electricity consumption. 220V motors tend to run cooler, and use less power to operate.
 
According to the electrical code I learned.

The maximum continuous load on a rated circuit is 80%
This means on a 110 V 15 amp circuit, you have 12.0 amps maximum

Of the motors you linked to, they are all switchable between 110 & 220 based upon the wires you use on hookup (diagram inside the plate)

The largest motor I have found to fit a standard circuit is a 1 HP 3400rpm at 12.0 amps

(not 1725 rpm, it draws too much)

However if you have to install anyway, 110v larger than 15 amps, or 220
As has been said 220 is better.
220 single phase is almost every home everywhere (electric clothes dryer, kitchen stove....)
Inside the box you pick off one red and one black

You will need:
Empty space in the breaker box
Breaker single for 110, double for 220
Wire suited for the purpose
(ask electrician about the gauge - needs to know length of wire from the box & load Amps
Additional length requires heavier wire, keep it shorter = cheaper)
switch ( make sure its rated for the motor )

Optional outlet & plug, or hardwire it directly to motor. Outlet & plug = $ & convenience


All the motors on your link are capacitor start.
The capacitor is under the rounded cover on the top.
(Removable and movable if needed to fit your grinder)
It stores a charge and provides surge power on startup to improve starting under load
(Not a big startup load on a grinder compared to a water pump...)


Unless you stay at 1 hp or less you will need to spend $ on hookup.

The bee grinder (Canadian square wheel) comes standard with 1 HP 3400 rpm.
I can slow it down if I try & lean into it.
I would go with the 1 hp 3400 and stepped pulleys to allow SLOWER speeds.
This would increase your torque and controllability at low speeds and allow you to maintain the ability to plug it in anywhere you find an outlet.

On the other hand, if you know you want higher HP, go big
The difference from one to the other is very small now compared to changing up later and having to buy 2 motors & redo the hookup twice

First pick the HP you want and then figure out what you need to hook it up.

Steve
 
The design goal of the KMG was to keep it as versital as possible in all aspects including the motor that you use to run it. There are an infinate number of choices.

To narrow them down a bit....since you want to run this on 120V..you are limited to 1.5hp. Don't fall into someone's marketing scam where they boost some crazy peak HP like 7.5. Physics dictate this pretty well. It takes about 17 amps of electricity at 120V to produce 1.5 hp. You home/shop electrical outlets have 15 or 20 amp circuit breakers...so you can't get anymore power without rewiring something. If you decide to rewire...go to 220V.

With that in mind, my preference is 1725rpm and use step pulleys with a 4",3",2" diameter. This is what the KMG was basically designed around for knifemaking belt speeds.

Get a Totally Enclosed Fan Cooled (TEFC) motor which is required for your dusty and gritty enviroment around the grinder.

Any frame size will work...and the frame size dictates the shaft size. The most popular frame in this HP size will be a 56, you might also find a 145 which is a bit larger and will have a 7/8 shaft.

So here are my suggested specs to look for:

1-1/2 hp
110V
1725 rpm
56 frame
TEFC
CW/CCW rotation

BTW, this is the most popular set-up for the KMG.

Good luck,
-Rob
 
Just a small thing to clear up. 220 does not exactly use less energy than 110 (ignoring better motor efficiency).
A motor that would draw 15 amps at 110V will draw 7.5 amps at 220V. The power consumption is the same, 1650 watts. The big advantage is the much lower draw on each leg. You can wire 220 with 10 gage wire and run a BIG motor. The same wire in 110 would burn up.
Stacy
 
I'm actually of the opposite mindset of many it seems. I like my belts going as fast as possible. I use 3M 977 ceramic belts from Pop's Knife Supply in 36 and 60 grit and they cut longer and better the faster you run them and the harder you push....I think they were made for me. :rolleyes: My blades are about 85% finished by the time I finish with the 60 grit and everything else is clean-up. With care and practice (lots of practice) you can grind just fine at higher speeds as long as you are again careful and keep your blades cool. That said, I use a KMG with step pulleys and do slow the belt down to mid-speed when I get to 600 grit (600-800 grit is where I usually finish my blades on the machine). If it's possible I'd try to visit a few people's shops who work differently and try them out, see what you think. I know it's not always possible but, it's a good idea.

Just my thoughts.

Oh yeah, my buffers run fast, too.
 
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