Grinder motor???

R

Ratking20

Joined
May 2, 2017
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Looking at options for a grinder motor. Its for a 2x72 that i plan on building soon. Im just starting out. So i want to keep it simple. I figure a 2hp would be good. Any recommendations or tips. I want to keep it as simple as i can for now. I dont mind buying used. Would rather not have a vfd. But if i have to i will. From what i read i will have a hard time getting it slow enough without a vfd. Is that correct? Any help would be great. Thanks.
 
You can use two step pulleys and put the motor on a hinged board for a Adjustable speed motor.

A TEFC motor 1750 RPM is best but i used open motors I bought used and just blew the steel dust out with a compressor and never burned one out
 
IronHorse is one of the best new in box options, aside from N.O.S./surplus motors. As for the VFD, I can't recommend it enough. As somebody who used a step pulley for years, when I did finally get a VFD, I immediately regretted not pulling the trigger sooner. The KBAC-27d is the standard recommendation for a quality VFD, though if you want to save some money, the chinese VFDs on ebay are a decent option, as long as you make provisions to keep the dust out of them.
 
So def a 1750 rpm over a higher rpm?

Do i have to look for anything specific to have it work on 110v?

I looked at some online. Is it the general purpose motors?
 
Yes! a 1750 rpm is what you want, other wise you will not be able to slow it down enough for use with Pulleys! I ran a 3400 RPM motor years ago when I was a new maker and didn't know shit! I separated the rubber off an 8" wheel from running it too fast! If you can afford it? Get the VFD if you can afford it or go with two step pulleys if you can't
 
If you only have 110, you are limited to 1.5Hp. do some research, there are many brands out there. look for one that will run on 110v and 240V.
you have 2 options. get a 1Hp VFD and motor right now, should be able to do that for less than $300. OR run 240v to your work area, at least 20amps, get a 2Hp VFD and motor, should be able to do that for less than $500 + the cost of wiring, junction boxes, circuit breakers and other related stuff.
another thing to look for drive wheels. a 3" drive wheel at 1720rpm is 1350 fpm belt speed. a 5" drive wheel at 1720rpm is 2250fpm. it takes 5 minutes to change wheels, most of that finding the spare wheel and the right allen wrench.
 
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I've use a 1 1/2 HP on 110 for years on three different machines and never had a problem with lack of power.
 
You may be able to get by with pulleys for the time being, but eventually you will want VFD. The problem is that will require a new motor as well as the VFD. Buy them now and you will only buy a motor once. Often, three phase motors are cheaper.
 
Ratking20 said:
So def a 1750 rpm over a higher rpm?

Do i have to look for anything specific to have it work on 110v?

I looked at some online. Is it the general purpose motors?
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1725-1800 RPMS is the typical recommedation depending on set up. Voltage range and motor type will depend on what exactly you decide on. If you're going with a VFD, you'll have to get a 3 phase, inverter duty motor. A lot of guys will get an 1800 RPM motor and double speed their VFD for a higher top end speed with more torque on the lower speeds. If you're going with step pulleys or a single speed, then a 120V, single phase motor will work, up to 1.5hp. No matter what setup you go with, you'll want a TEFC frame (Totally Enclosed Fan Cooled) to keep the metal dust out.

A quick note about they lower cost VFD's: They're typically set up to only run on 220vac.
 
If i go the step pulley route. Does the motor have to be single phase. Or will single or 3 phase both work? What should i expect to pay for a used 1.5 hp motor. Im gonna take a look on ebay
 
Ratking20 said:
If i go the step pulley route. Does the motor have to be single phase. Or will single or 3 phase both work? What should i expect to pay for a used 1.5 hp motor. Im gonna take a look on ebay
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either motor would work. but to run 3 phase you are going to need an inverter/VFD. if you go with 1Hp, you have many choices in a 110 input VFD, TECO, Fuji, Allen Bradley, Leeson, KD and others. you will also have a large selection of new and used motors. as said, you can find a new 1hp motor and new 1hp VFD for $300 or less.
 
Either motor will work with pulleys. But you need 3ph supply to run a 3ph motor.
3ph is either supplied by your utility (unlikely if your workshop is located at a N.America residence) or you generate 3ph yourself using a VFD or single ph to 3ph converter.
Bottom line,
If you go with pulleys, then decide pulleys suck, you will have to get 3ph motor & VFD.
 
Ratking20 said:
If i go the step pulley route. Does the motor have to be single phase. Or will single or 3 phase both work? What should i expect to pay for a used 1.5 hp motor. Im gonna take a look on ebay
Click to expand...
Used motors are all over the place price wise, but on average, for a single phase TEFC, expect to pay about $100 to $150, depending on age, brand and condition. Check your local craigslist, and any surplus or motor repair shops. When I built my first grinder, I found a nice 1.5hp single phase TEFC motor for $75, and it's still going strong. I've seen them for more or less, it just really depends.
 
knife to a gunfight said:
Used motors are all over the place price wise, but on average, for a single phase TEFC, expect to pay about $100 to $150, depending on age, brand and condition. Check your local craigslist, and any surplus or motor repair shops. When I built my first grinder, I found a nice 1.5hp single phase TEFC motor for $75, and it's still going strong. I've seen them for more or less, it just really depends.
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That's exactly what I did, a friend here on the forum spoted a Baldor 1.5 reconditioned on Craigslist for $75 close to me! There out there, just need to be patient and keep checking!
 
thanks for the help! last questions?

does shaft size matter?

and some on ebay say the 210v - 460 v.... is any 1.5 capable of running on 110v or does it have to say 110 in the description
 
Shaft size (OD) does matter for when you order your drive wheel. OBM has several sizes for shafts, i.e. 3/4", 5/8", 7/8".

Yes, you will need to ensure it states on the motor the voltage you plan to use.
 
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Liquidators, like HGR auctions, sell NIB 3 phase motors for pennies on the dollar. The ones in the sizes that people want often go for much higher than ones that are larger or smaller. Right now there is a new 3Ph, 5Hp, 230VAC, TEFC Baldor at $23.00. I have bought several 1Ph 1Hp motors fro $30-40, and DC 1.5Hp motors for $50-70.


UPDATE: the motor sold for $49.
 
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Ratking20 said:
thanks for the help! last questions?

does shaft size matter?

and some on ebay say the 210v - 460 v.... is any 1.5 capable of running on 110v or does it have to say 110 in the description
Click to expand...

The standard preferred size for knife grinders seems to be around 5/8" which would be a 56 frame. Guys also use motors with 3/4" shaft. 5/8" and 3/4" are the most commonly available bore sizes for off the shelf drive wheels. If you're making your own, or are willing to spend a little extra for a custom size, you can go a little more or a little less.

As for voltages, not all motors will run on 110.
 
direct drive means a face mount motor. the most common bolt pattern lets you use 56C(5/8" shaft) and 143TC/145TC(7/8" shaft). I know Oregon Blade Maker and knife Grinder Parts on eBay have drive wheels in 7/8", same price as 5/8".
 
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