Motor advice needed.

Forgedog

Well-Known Member
Its time to upgrade the old grinder.

Im thinkng I want to get a 5hp motor.
I would like a three phase but my shop isnt set up for three phase.
Also im curious if these motors can be run on their side with the drive shaft sticking up.

Heres the options ive found in my area and in my price range. Canadian dollars.

Mostly wondering if these will work.
 

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Steer clear of the "Drip Proof" (also know as "open") motors, and stick with TEFC (Totally enclosed fan cooled)..... otherwise in a grinder application, steel dust and other grinding swarf will quickly get into a Drip Proof type motor and cause it to burn out.

If you don't have 3-phase power in your shop, the way to do it for a grinder is with a VFD (Variable Frequency Drive). I'm not sure you'll find a quality VFD to run a 5hp motor. My grinders are setup with 3hp, 3 phase motors, and KBAC 29D VFDs. The VFD is powered by/connected to a 220V, single phase outlet/circuit, and the VFD converts it to 3 phase power to operate the motors. It also allows for variable speed on machines...which is something you'll wonder how you ever got along without...once you use it.

I'm not sure where to purchase in Canada, but here are some links to the motors/VFDs I use on my grinders......

http://www.electricmotorwholesale.com/10001-KBAC-29D/

http://www.electricmotorwholesale.com/LEESON-132595.html

You might need a different motor, depending on the mounting configuration.

Hope that helps!
 
My philosophy has always been to buy tools or machinery UP TO the quality you need for the tasks you KNOW you are going to need it for. That way the money you didn't spend can be used to buy either, other tools and machinery you do need, or materials to use with the tools and machinery you have.
 
I would get something bigger then a 1.5 hp. I have one and it does work but it's pretty easy to bog down. I would go with at least 2hp 2.5hp would be even better and 3hp would be the cats meow!
 
Daniel, you mention preferring a 3hp - you full time? I can maybe see a full time maker like Ed wanting a 3hp so the motor isn't running heavy loaded. For myself, I've got a 2hp with VFD and with it cranked up 100% I'm not sure I could choke it down on an 8" contact wheel. Even the platen which pulls more hp it'd be hard to choke..... OK, I just went to shop and tried to choke with a 50 grit VSM ceramic belt on an old rasp that is 1.5" X 3/8" holding rasp flat so the full 1.5" X 3/8" is being ground. Crank the VFD to max of 3800 RPM for about 4,000 SFPM belt speed and couldn't choke motor - but it sure was throwing some sparks! When I say I couldn't choke there was a max amount of pressure I could apply because the grinder would lift on stand. Had stand been bolted down - maybe I could have choked motor - not sure.

For the price point I don't see any reason for more than 2hp on a 2X72 grinder - especially for the part time maker. Full time is a totally different matter. I'm not full time so will bow to Ed's experience since he's been full time and makes more knives in a week or two than I do in a year.

If I had a 1-1/2 hp motor laying around, or found one cheap I wouldn't hesitate to use it. If buying new, the cost difference in 1.5 vs 2 hp is only $12 for a 3600 rpm IronHorse motor. Of course, the 3hp 3600 rpm motor is only $50 more than the 2hp.
 
No sir not full time at all. I should have worded it a little differently. If I had MY choice it would be a 3hp. I can bog down a 2hp. Granted it's hard and I'm not generally that heavy handed but I do go real hard when cleaning up scale and Billetts and stuff. I've run a 3 hp a handful of times and can't touch that one. A 2hp would do just fine.
 
To answer the Hp question... Im a HUGE fan of overkill... But having said that, 3Hp might actually suit me better.
 
I agree that 5hp is definite overkill for a belt grinder, and honestly, 3hp is more than most makers will ever need.

I'd stick with 2 to 3 hp. VFDs are readily available for both.

The other thing to keep in mind is your frame and shaft sizes. Most grinders now days use a 56 frame, which will have a 5/8" shaft. You'll find plenty of drive wheels available with that bore. The first motor frame you listed has a 1-1/8"shaft, and you'd have to custom fit an off the shelf wheel for it.
 
I do go real hard when cleaning up scale and Billetts and stuff.

Thinking about that statement I expect it would put more load on a motor because the billett would be laying flat exposing MUCH more surface area than the 1.5X3/8" area I was grinding. The more surface area to grind, the more power it will take. Daniel (and other fans of 3hp), I now see your point and do agree 3hp just might be better for that purpose.
 
I can slow down a 2HP if my speed on the VFD is very low, but past 20% I’ve never been able to do it. Even at low speed I have to be jamming something very bulky into the belt and using a tool rest. Freehand grinding? Forget about it.
 
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