KMG Motor - Another Specific Question

H

Hypocrite

Joined
Apr 23, 2008
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This question is kind of an extension of the question posted by Silver_Pilate on THIS thread.

The stock 2hp VFD package that Rob sells uses a motor spinning at approx. 1800rpm and a 5" motor pulley. Like Silver_Pilate, I am considering purchasing the 2hp 3600rpm motor from Grizzly (the price looks right). Now, if the motor rpms are doubled, it makes sense that I should halve the size of the motor pulley to 2.5". Grizzly does not sell a 2.5" pulley, but sells both a 2" and a 3". It looks like Silver_Pilate has decided to go with the 3". I am wondering whether it makes more sense to go with the 2" or the 3" motor pulley. Seems like the 2" may give a bit more low-end torque with the VFD, while the 3" will give my a higher top speed. Which is more important? Which would you choose?

Thanks in advance. Erin
 
I chose the 3" pulley for higher top end belt speed for hogging. When I'm working at lower belt speeds, it will be for more detail and finishing work where you're not leaning into the grinder as much, thus less torque is required. That's my reasoning, anyhow. I think with a 2hp motor, the torque drop won't be significant over rpm range for most people unless you grind heavily or work with a lot of large blades.

--nathan
 
I've been through 4 or 5 drive pulleys over the years. Not because they wore out, but because as I got better at grinding, I wanted the belt to run faster. Pulleys are cheap, so start with something that will run a little slower until you're comfortable with everything and then go to faster if it fits your developed style of work. I learned to grind from J. Neilson who grinds like a gorilla, and so everything runs fast and hard in my shop too....It's more about the style you develop than anything else.

-d
 
Thanks deker... I am a newbie, so slower may be good for learning this grinding business. Maybe I need to get me some paint sticks.:D

Erin
 
Erin, mete brought up a good point. I grind on a Grizzly which runs pretty damned fast right now. With the VFD, I'll be able to go MUCH slower than I could dream of at the present. Since it is all I've ever had, I've learned to grind on the Grizzly, so I'm used to handling a fast belt. However, a slower grinder would be easier to learn on, you just won't have that super high speed for quickly hogging material. That's probably a good thing as you want to be able to take it slow when you're first learning. At like $7 a pop for a sheave, you can definitely change your mind without hurting your wallet.

--nathan
 
For that matter, I think it would be fun to hear from anyone else who is taking advantage of Rob's customer appreciation sale to buy a new grinder. What goodies and gadgets did you get?:D How long will your wives/significant others be giving you the "eyebrow of justice"?

(edit: Maybe better in a different thread)

Any other thoughts on 2" vs 3" pulley on 3600rpm 2hp motor?

Erin
 
You may get more responses in a new thread, but I'll throw my $0.02 here anyway. :)

I ordered the 10" KMG package which comes with the 10" contact wheel, work rest, and platen assembly, the 2.5" the grinder pulley, a drive belt, an extra tooling arm, the small wheel attachment with 1" wheel, the base plate, and the tooling rack.

I'd love to get a rotary platen and a MAP arm/work rest, but those will have to wait for another day and another bonus. :D

My wife was actually really cool about it all. I got a decent bonus from the hospital, and with some of the debt I've piled up over the years and my old house being on the market, I had expenses I needed to cover. I offered to use my bonus to cover some of those costs, but my wife told me that it was my bonus, and that I needed to get something fun for me. What a great gal!!

--nathan
 
I'd consider the three inch pulley. Either would be fine, but I'd guess the the vfd would be able to dail down the the the speed to any comfortable range that you'd want. The 2" pulley may seem like it's pretty slow on the top end, and you might appreciate the faster hogging speed to get you to the more detailed dial down part.

Congrats on the new grinder, Craig
 
My wife was pretty cool about it... I spent money that I had made on some of my woodworking projects. But she was hoping for a big screen TV I think. Plus, it's her opinion that I spend too much time in the shop and not enough time with the family. I offered to buy them all respirators... ;) (do they make respirators for 4-month olds?)

Thanks for the info on your grinder. I went with the 8" wheel and two spare tooling arms. Bought the small wheel attachment and a couple of wheels.

I also would love a MAP arm, but I think that the next shop purchase will be a heat-treating kiln... after all, I have 5-gallons of Parks 50 sitting around doing nothing.

Erin
 
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