Mixed opinions - what size motor for 2x72 grinder

JRNP said:
:confused: Wow a DC 1.5 HP motor should be any thing but easy to bog even with a big flat wheel. I am curious about your controller. Does it have IR compensation adjustment? If so you might try tweaking it a bit. It might be worth wile for you to upgrade your controller. A DC motor with good controller will maintain constant speed very well and the lower the speed the higher the torque, at least in theory. Of coarse you could just be over powering the motor:D
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You might have something there. It's an older machine, not a digital controller. Thanks, I will consider that.
 
As someone who almost exclusively flat grinds, I have a 2hp 3phase 3600 rpm motor powered by a VFD. I find it's plenty of power 99% of the time, but I have stalled it about 3 times in the near year I've had it. Those were all during heavy flat grinding on the platen or during tang tapering.

I also have a Grizzly 2x72" with what I believe is a 1hp motor, and I can trip the breakers on it anytime doing just about anything.

1.5 is minimum. 2 hp is gravey. 3 hp is the cats meow. I think the only reason someone has to choose between 1.5 hp or 2 hp is the available current in their shop. If you don't have 240V service, 1.5 is about as big as you can run. If you have 240V service, the cost difference between a 1.5 and 2hp motor is almost negligable except for the cost of a VFD if you go 3 phase.

--nathan
 
silver_pilate said:
As someone who almost exclusively flat grinds, I have a 2hp 3phase 3600 rpm motor powered by a VFD. I find it's plenty of power 99% of the time, but I have stalled it about 3 times in the near year I've had it.
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AFAIK I'm running the exact same 2-hp motor as Nathan on my KMG... driven by a KBAC-27D VFD. Like Nathan, I can stall my motor if I am flat-grinding. For me, this mostly happens when I am using finer grits at low RPMs with too much pressure.


silver_pilate said:
1.5 is minimum. 2 hp is gravey. 3 hp is the cats meow. I think the only reason someone has to choose between 1.5 hp or 2 hp is the available current in their shop. If you don't have 240V service, 1.5 is about as big as you can run. If you have 240V service, the cost difference between a 1.5 and 2hp motor is almost negligable except for the cost of a VFD if you go 3 phase.

--nathan
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+1 to what Nathan said. If you have 220v available and you are planning on running a VS setup with a VFD, there is no reason not to go 2hp instead of 1.5hp. The cost difference is barely noticable. If you go 3hp, you'll likely end up paying a bit more for a larger VFD.

Erin
 
Well, against many recommendations I decided on the 1 HP Baldor for the time being. It is already wired with a switch and 110 cord and the price was right. I'll try it out and see how it works - I'm a newb so anything is better than hand files. Worst case scenario, if it turns out to be massively underpowered I'll save up for a better set up down the road.

I'll let you know how I make out once the NWG is actually built (hopefully by year end :)
 
Hey man, there's no way you can ever have too many electric motors! :D You did good. If you end up upgrading your NWG, you will use the Baldor for something else, trust me. :) Everyone I know is under standing orders to watch garage sales for any electric motor 3/4 hp or larger. Neighbors show up with motors that aren't always ideal and I have quite a little collection started, but -- you can never have too many electric motors...
 
ddavelarsen said:
Hey man, there's no way you can ever have too many electric motors! :D You did good
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That's what I figured. From the same guy I bought the 1HP Baldor I also bought a 9" flat disk grinder wired so it's bi-directional. He's a knifemaker that lives about 5 hours away (Tom Haslinger - makes some beautiful stuff!) THe goodies should be here next week :)

So once I get the disk grinder and the NWG built I shouldn't need anymore tools for a while.... ;) (ya right)
 
hammerface said:
(Tom Haslinger - makes some beautiful stuff!)

So once I get the disk grinder and the NWG built I shouldn't need anymore tools for a while.... ;) (ya right)
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Yeah man, I've seen his stuff and you're right!

But as to 'shouldn't need anymore tools for a while' -- I'm sorry, you are so wrong... :D
 
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