Grinder Control Question

R

Ryanol

Joined
Aug 24, 2011
Messages
778
So I picked up this grinder for dirt cheap sight unseen.


Untitled by rlibson, on Flickr

The wires have been cut and it's missing the control box?

Are control boxes manufacturer p/n specific or are there generic switches that I could wire up to see if the motor works?

I don't have the specs of the motor at hand - it's a baldor of some sort.

I'll try and update the thread when I get home and get a better look at it.
 
If you're lucky, it's 1 phase. Unless, that is, you have 3 phase power (not likely) or wish to run it with a VFD.

The motor plate should tell you what the phase, horsepower, and voltage are. The box on the side of the motor will likely have a diagram on the inside of the cover when you take it off. There will likely be six or nine wire leads coming out of the motor into the box. They will be combined into two or three bundles, which in addition to the ground wire will then be routed to your power supply. The wires should be numbered, and the diagram you hopefully find should tell you what numbers of wires to combine for high voltage, low voltage, and reverse operation. Have a look in there.
 
Some more photos - don't know my way around these things really at all - but I'm guessing 3 PH means 3 phase.

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Tomorrow I'll have more time to pull the cover off the box, remove the guard/tool holder dealie and have a better look.
 
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You've got your wiring diagram there on the side of the motor plate. That is a 3phase motor. You don't have 3 phase power, an inverter, or a VFD do you? It does appear as well that it's a fractional Hp motor... .19 Hp? If so, it won't be of much use to you for grinding steel. At least retrofitting a larger motor wouldn't be hard with the c-face motor and Lovejoy coupler.
 
Yeah I bought it without inspection but for 28 bucks I figured it was worth the gamble.

Oh well now it's off to find another motor.

What am I looking for spec wise something in the 1hp-3hp - 220 power I'm assuming?
 
Yeah, that's about right. I like 2-3 hp but 1 will be OK if that's what you can find. 220V is good if you have it. Heck, for 28 bucks you've got some good wheels there with a tracking assembly and frame you can mod for your use. Although... is that a gear reduction box the motor is driving? Might slow your belt speed down too much if that's what it is. A possible solution in that case would be to retrofit with a 3650 rpm motor, or use a bigger drive wheel, or both.
 
You don't need 220 my 2 1/2 Hp is 110 and grinds perfectly, don't know what that motor would be good for perhaps a shop fan? 
 
Sterling-
Are you sure about that motor? A 2.5HP motor running on 110VAC will be drawing a huge load. It will require 8 gauge wiring and 30-40 amp breakers. I calculate the draw at between 23 and 32 amps, depending on the motor efficiency.

Few home shops are wired to take that load. Most are wired for 20 amp circuits, and 15 amps is the recommended load for those circuits.

However, while a 2-3HP motor is great on a grinder, a 1HP will work fine. Sure, you won't be able to hog 1/4" steel down to 1/8" steel in seconds, but it will run the grinder perfectly fine. A1 Phase, 1HP motor for a 120VAC or 220VAC circuit will be easy to find, cheap, and simple to hook up.

Ryanol -
Can you verify the HP rating on the existing motor? It isn't clear in the photos, but looks like it says .19 HP??????
The grinders interesting, and is not one made for knife grinding. It has a small contact wheel and a large dust collector. I thing it was a specific use grinder for some industrial purpose. The small contact wheel is going to limit its use to some profiling tasks. The way it is setup, you can't really install a larger wheel without modifying just about the whole grinder.
Some questions-
Is it mounted on some sort of slide base?
What size belt is one it?
What is the HP of the motor?
Roughly what does the whole thing weigh?
 
Salem is right .19 hp must have been grinding something soft.

Heavy maybe 150 lbs, the whole shebang slides back and forth and perhaps side to side on a base. I haven't pulled or measured the belt but it appears to be 2 or 3 inches wide.

Definitely purpose built for something although I have no idea what?
 
Salem Straub said:
Although... is that a gear reduction box the motor is driving? Might slow your belt speed down too much if that's what it is. A possible solution in that case would be to retrofit with a 3650 rpm motor, or use a bigger drive wheel, or both.
Click to expand...

Slow speed is good for already hardened blades, particularly sharpening and stropping (running a leather belt). The slow speed retards heat build up (which can ruin the temper). Obviously if it's your only grinder and you do a lot of stock removal, then go for the faster motor. But personally I'd keep the reduction gearbox, up the power on the motor and use it for putting the edges on after HT and reprofiling.
 
I'm still a noob but I've got one of those cheapie HF 1X30 that seems to do an alright job with the smaller finishing touches.

@salem Im not very mechanically inclined - I could test the gear reduction box by marking both the shaft and the wheel with a sharpie and turning them to see if one rotates more than the other - right?
 
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You could check it that way. If it's much of a reduction it'll probably be pretty obvious just by turning the shaft and watching the wheel.
 
You have a three phase Baldor motor. That is a very good thing. If it was driving the machine before, I would guess it would still work. You will most definitely be able to have the motor fixed. Take it to a Baldor service center. There's probably something minor that's keeping it from working. Baldor motors generally don't fry. They are expensive, and worth every cent.


0.19hp? Can't you tell exactly what hp a motor is by the amps it draws, knowing everything else? It looks like maybe it's a 4x48 with a 3" belt on it to me. I just can't see an underpowered machine here. It's industrial in every way.

A very cool thing about 3 phase motors is that they work perfectly with a VFD and 220 power. The "gear box" or whatever could quite probably be the speed control. That would certainly be my first guess.

It looks like you've got a very industrial duty machine. I would be thrilled to find something like this. I've spent as much as $100 getting an old Baldor to sing.

Or you could just buy a new TW-90, and I will gladly double your money on the old machine. :D
 
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That motor on there is rated at 1725 RPM I would not put 3600RPM motor on there are guys that make phase invertors on ebay to use to start the motor.
 
It does look like a bigger motor than .19 hp. However, from what I can barely make out on the spec panel, the amp draws appear to be fractional too. That would tend to make me think it's a smaller fractional hp motor, as well.

The gearbox would be single speed, probably pretty high reduction, and would increase the torque of the small motor as well.

It's an odd machine. I almost want to think it was some kind of wet grinder, and the position of the dust collection doesn't make sense unless the belt was running upward, or if the grinder is meant to be oriented a different way than pictured. (upside down of the top pic?) Thoughts?
 
grizzled gizzard said:
You have a three phase Baldor motor. That is a very good thing. If it was driving the machine before, I would guess it would still work. You will most definitely be able to have the motor fixed. Take it to a Baldor service center. There's probably something minor that's keeping it from working. Baldor motors generally don't fry. They are expensive, and worth every cent.


0.19hp? Can't you tell exactly what hp a motor is by the amps it draws, knowing everything else? It looks like maybe it's a 4x48 with a 3" belt on it to me. I just can't see an underpowered machine here. It's industrial in every way.

A very cool thing about 3 phase motors is that they work perfectly with a VFD and 220 power. The "gear box" or whatever could quite probably be the speed control. That would certainly be my first guess.

It looks like you've got a very industrial duty machine. I would be thrilled to find something like this. I've spent as much as $100 getting an old Baldor to sing.

Or you could just buy a new TW-90, and I will gladly double your money on the old machine. :D
Click to expand...

It is superduty and industrial for sure. It might carry a hell of a tune but I can't tell as it's missing parts/wires.

Here are the downsides - all wires were cut (power supply and controls) and I have no controls/VFD, The only room w/220 service is my laundry - mama's gonna be pissed!
 
Salem Straub said:
It does look like a bigger motor than .19 hp. However, from what I can barely make out on the spec panel, the amp draws appear to be fractional too. That would tend to make me think it's a smaller fractional hp motor, as well.

The gearbox would be single speed, probably pretty high reduction, and would increase the torque of the small motor as well.

It's an odd machine. I almost want to think it was some kind of wet grinder, and the position of the dust collection doesn't make sense unless the belt was running upward, or if the grinder is meant to be oriented a different way than pictured. (upside down of the top pic?) Thoughts?
Click to expand...

It's definitely right side up the base is pretty stout - not sure which is the front and which is the back, and whether the top dealie is a dust collector or some sort of tool/fixture holder.
 
Your answers were what I thought they would be.
While I can only speculate what function this did in a factory, the basic process was:
1) To slide forward and make contact with some material, probably plastic. This was probably done by a pneumatic actuator that kept a constant pressure.
2) Then another actuator, probably a screw drive, would pull the contact wheel down the material slowly and evenly as the belt cut a groove....basically an automated hollow grinder.
3) At the end of the cut, the grinder would pull away from the material and return to the starting spot.

Sadly, because of the way it is made, it won't be able to do much for you as a knife grinder.
Since you haven't filled out your profile, no one can volunteer to come over and look at it and offer advise on modification, or trade you for something you can use.
Modifying it would be difficult and expensive.
 
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