Grinder Motor, hp, phase .... HELP !!!!

Battle Creek Knives

Battle Creek Knives

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Feb 23, 2010
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Sorry I'm sure this has been discussed to exhaustion but I need current help...

I've decided to build my own grinder instead of buying a replacement... I can get almost all the parts needed for free......!!!!

but I need a MOTOR !!!!

anyone with resources on a motor?? what should I be looking for, I want to plug it into 110 I will be installing multi pullys or a variable off a tread mil or something...

1 hp, 2 ?? is 3000 plus ok?? since I plan to operate pully's.....

this is a 2x72 grinder..

thanks..........I will post progress of build.... (like I need another project):p
 
I think you need 220 for 2 hp. So you will need single phase 1.5 hp. I have bought some 3 phase on ebay, but its a pain. If you use a VFD then you go 3 phase, I don't know about a treadmill.
 
There are VFD's that convert 110v single phase into 220v 3phase. I think it will top out at 2hp but well worth it imho. Ebay has VFD's from companies that sell the 110v option. Need to get on there and look. I found one from Hong Kong in about 2 minutes. Just need to email them to find out what they have. Then you can find the motor on the bay also. I picked up a 5hp 3ph motor shipped to my door for $150. Just need to look for a bit. I would recommend a 2hp motor. A 1hp would work and has for many, just cant put the pressure on it like a 2. Then I use a 5hp when I am really hogging. Good luck
 
I recently setup my kmg with a 220v 2hp and vfd and im so glad I was talked into a vfd setup!
 
Motor type needed is TEFC. A treadmill motor can be had for cheap....and won't last any time at all. You need a sealed motor for a grinder.

1.5HP to 2HP works well for a grinder. Speed is not really an issue, but the type motor you want is usually 1750RPM.

Options are:
1) To use a standard single phase motor, 220VAC being the best choice in these HP ranges, and using step pulleys to get the speed desired.
2) To use a 3Ph motor, 220VAC, and a VFD. The drive will need 220VAC single phase. 110VAC drives are underpowered and burn out fast when running these size motors.
3) To use a 180VDC motor and a DC controller ( very similar to a VFD).The controller will run on 220VAC.

For a simple and cheap setup, #1 is the best choice.
For a speed controlled grinder #2 & #3 are the best choices.
 
I just finished setting up a new motor/VFD combo. I found a new Marathon TEFC 2hp/3 phase/1725rpm motor on ebay for $100. Purchased it. and then purchased a KBAC 27D VFD from Wayne Coe. If you take your time and look, there are still some screaming deals to be had out there.

I don't know of anyone who has purchased a 1.5 or 2hp motor/VFD setup and NOT liked it. The money sometimes scares folks, but if you stick around knifemaking, sooner or later you're gona want one....so it might as well be now. :)

From experience, I would never put anything other than a 1725-1750rpm motor on a grinder. If you go with a KBAC 27D, and hook up a 1725 motor, you have the option to "double speed" the motor simply by changing a jumper on the VFD circuit board. I actually did just that with this latest setup.....and very much like the results.
 
Thanks guys!!

TEFC, that's what I'm missing... I was overwhelmed just looking for electric motor :D...

I'm wired for 220v but where everything is located is 110 and I really don't want to run more wire to the location at the moment.. so I'd like to stay 110, isn't 3 phase for commercial application?? other words, don't you have to be wired from the main for 3 phase?? or does a vfd over ride this somehow?? (most likely I'm just confused :D)

I really don't want to over complicate this (as I've read in many tech talk threads.:D) I just want something that will work, doesn't have to be super powerful as I don't hog much because most of my rough is done when I cut stock.. and forging is a whole other thing in and of itself..

I can live with step pulleys as I normally run on one speed for a while.. is there really that much of a difference with a vfd??
 
The VFD's that we use convert single phase AC to Three phase.

And, they control the frequency, which varies the speed.

I think 1.5hp is the limit on 110.
 
okay after a little searching I think that a 3 phase motor can only be run with a variable frequency (controller/drive) from single phase power but I'm still not quite sure, I like to simplify things without turning my research into a job of itself and overcomplicating the matter..

3 phase is just that, 3 phase.. which means has to be run from 3 phase power, most homes have single phase power...

my question now, ON THE CHEAP...........

wouldn't a Variable Frequency (controller) as found in a treadmill work?? I'm thinking this has to be a little more technical then a dimmer switch :D and probably may not be enough to psyche a 3 phase motor into running>>>??????????

with that said... anyone use TECO Drives?? I've found a drive for $200 that will run a 3 phase 2 hp motor...

after reading some, looks like a may be pulling some 220 to my work station after all :( the bright side however I'm just going to branch off of existing and run it approximately 20' where I have my bench..
 
Curious as to whats stopping you from running a single phase, 1.5hp (or lower), with pulleys. That way you can run it off a normal household outlet, have variable speed (via the pulleys) and it is quite a low cost option.

I'm assuming you are on a fairly tight budget (I'm going to be building one soon and will be pinching every penny I can). A brand new motor can be had from http://www.waynecoeartistblacksmith.com/Motors___VFDs.html. He even sells the wiring kits with cords/switch. If you really want you could order a VFD from him too.

My setup will be: 4 step pulleys, 1.5hp 1800 RPM single phase. From what I've looked up it's the most cost effective for me, even if I do decide on a brand new motor.
 
I typed this this afternoon, and we had a cable outage, so it didn't send.

The normal voltage coming to your house is a center tapped 220VAC single phase. This is referenced to the neutral (center tap) line from each end, and gives you two separate lines of 110VAC. if you go from end to end, you get 220VAC. All that is still single phase.
Commercial power is often three phase, allowing more options for drawing off the power. If you use all three legs you get a higher efficiency in turning motors. This is real important when industrial motors run from 1HP to 500HP.

In order to run a three phase motor on a single phase line, as would be the case in most homes, you need to convert the current to three phase. This can be done with a static converter, which uses two motors ,one to turn and one to change the voltage from leg to leg, thus artificially creating three phase. This is not a good setup for a small shop, so we use the neater, cleaner system of a VFD - Variable Frequency Device. This uses electronics to change the phasing of the single phase input to a three phase output. Some VFDs are also made to allow three phase circuits to be made variable speed. These are called three phase to three phase VFDs. The input and output voltage are determined by the electronics and are usually not adjustable, so you want to get a VFD for the desired motor and voltage you have. The most useful ones are 110VAC input, single phase - 220VAC output, 3 phase. Trying to run a 1.5HP motor on a VFD at 110VAC input is not a good idea.

The main advantage to us is that the VFD can change the frequency from about 120 hertz to 10 hertz. This allows the motor to be slowed down , but maintains the torque. This is done by a thing called volts/hertz ratio.
 
wolffbite said:
Curious as to whats stopping you from running a single phase, 1.5hp (or lower), with pulleys. That way you can run it off a normal household outlet, have variable speed (via the pulleys) and it is quite a low cost option.

I'm assuming you are on a fairly tight budget (I'm going to be building one soon and will be pinching every penny I can). A brand new motor can be had from http://www.waynecoeartistblacksmith.com/Motors___VFDs.html. He even sells the wiring kits with cords/switch. If you really want you could order a VFD from him too.

My setup will be: 4 step pulleys, 1.5hp 1800 RPM single phase. From what I've looked up it's the most cost effective for me, even if I do decide on a brand new motor.
Click to expand...

nothings really stopping me from 110, but this thread has got me thinking about running my 220 to my work station just in case.. currently I don't need a bigger motor for hogging as I have other grinders, bandsaws I use for profiling.. I'm upgrading my shop so yes I have to keep my budget in mind.. especially since I'm having my pontoon boat re-upholstered, landscaping my house, fixing my bobcat, painting my house, prepping my tractor for sale, concreting my driveway.......

so budget for upgrading my shop is on the very back of the 'back burner' :D and is completely on hold as is every knife project :( I was hoping to build my grinder for free but, doesn't look like its going to happen......... I will be welding together my grinder next week little by little as I sneak away....

I'm gathering parts/materials in hopes to have time to slap everything together and be back in business once my life slows down...

Stacy thanks for info I appreciate it.... I'm still curious however if I go the 110vac route if I could use maybe a variable speed box from a treadmill or even a dimmer switch????????????? curiosity..........
 
I'm not sure on this, but I think treadmills usually have a DC motor. The controller will not be compatable with an AC motor. Also the treadmill will most likely have an open air motor which means it is not sealed from environment. Grinder dust will soon collect in the motor and short it out.
Dimmer switch is really out of the question. They are not intended to handle that kind of current draw, and only vary the voltage. This means your motor will lose torque faster than it looses speed. By the time you turn it down to 1/4 speed, it will barely be useable for sanding fingernails.
I got lucky and found some 2 hp 3 ph motors on craigslist for really cheap. I did the math, and found that setting up a 3 ph motor with VFD was just a little more expensive than buying a 110 v motor and all the step pulleys needed to get the speeds I wanted ( 4 in all). (plus the VFD will give me all the inbetween speeds as well)The current draw on the 3 ph 220 is by far less than a 110 volt motor of comparable size and therefore cheaper to operate as well. Even a 220v single phase will draw less than it's 110v cousin.
In my researching I found that for motors 1 hp and above, 220v 3 phase was cheapest, followed by 220v single phase with 110v single phase being the most expensive. That same order seemed to follow with concerns of current draw and availability with 110v single phase being the most difficult to find and highest current draw.
If you can't get 220 to your workstation then 110 with pulleys is the only answer. If you can then your options are wide open.
 
little mac said:
I'm not sure on this, but I think treadmills usually have a DC motor. The controller will not be compatable with an AC motor. Also the treadmill will most likely have an open air motor which means it is not sealed from environment. Grinder dust will soon collect in the motor and short it out.
Dimmer switch is really out of the question. They are not intended to handle that kind of current draw, and only vary the voltage. This means your motor will lose torque faster than it looses speed. By the time you turn it down to 1/4 speed, it will barely be useable for sanding fingernails.
I got lucky and found some 2 hp 3 ph motors on craigslist for really cheap. I did the math, and found that setting up a 3 ph motor with VFD was just a little more expensive than buying a 110 v motor and all the step pulleys needed to get the speeds I wanted ( 4 in all). (plus the VFD will give me all the inbetween speeds as well)The current draw on the 3 ph 220 is by far less than a 110 volt motor of comparable size and therefore cheaper to operate as well. Even a 220v single phase will draw less than it's 110v cousin.
In my researching I found that for motors 1 hp and above, 220v 3 phase was cheapest, followed by 220v single phase with 110v single phase being the most expensive. That same order seemed to follow with concerns of current draw and availability with 110v single phase being the most difficult to find and highest current draw.
If you can't get 220 to your workstation then 110 with pulleys is the only answer. If you can then your options are wide open.
Click to expand...

That was absolutely hilarious !!! its a good thing I wasn't drinking anything or my screen would be wiped out... :D

you've pretty much pushed me over the fence, I've just been looking around again since I last posted and I'm really thinking I may go the VFD route, I have a good lead on a motor locally I may pick up this week, but I still have plenty of time to sort through everything..
 
Lil'mac had the answers to your questions and some good advice. I think you are making a wise decision.
 
On VFD's....

Teco has had mixed results from my research here. For the most part they work reliably. They are not NEMA4 rated(dust,splash resistant).... Do a search with Teco here on the forum and you'll find several threads regarding them.

I've seen them successfully used by placing them in a box with filters, and by placing them outside the room where the grinders are. Grinder dust is the enemy of the TECO VFD's.... Salem Straub uses one I believe, has it in another room and ran a potentiometer to the grinder from the VFD to control his speed at the grinder.

I am finishing assembling a 2"x72" GIB from Polar Bear Forge. I bought a 1.5Hp 1725RPM 3Ph TEFC motor from Wayne Coe and a KBAC 27D VFD from Wayne to go with it. I'm running it off of a 110v power source so I'm using the VFD to convert my single pahse power to three phase for the motor.

I also used a feature on the VFD to run it at 2x speed for 3,450 RPM's max with a speed control that allows me to adjust the speed from 100% almost to 0% with full torque across the range.
Call Wayne and He'll be able to educate you on choices. I went with the stuff from him as it's new, and I was able to buy the cable glands, switches and everything needed from one source.

http://www.waynecoeartistblacksmith.com/Motors___VFDs.html
 
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