3450 rpm belt it down??

M

MCoughlin

Joined
Feb 1, 2005
Messages
471
Hey guys,
Long time no talk. We're expecting our first baby at the end of the month so I've been a bit busy with related things.

Anyway, I just got my KMG grinder in the mail and I'm pumped. I have 2 motors. I have a 110V 1 horse @ 1720 rpm and a 220V 1.5 horse @ 3450rpm. I'll be getting 220v in the garage pretty soon and would like to use the 1.5hp but was wondering what size pulleys I need to tone down the speed. Any ideas?

Mike
 
The ratio of the pulleys determines the speed.For example,a 3" on the motor and a 6" on the grinder will drop the speed by 1/2.There should have been a chart with the grinder.
The formula is: Velocity ratio= input pulley diameter / output pulley diameter.
Output Speed = velocity ratio X input speed
Thus : 3"/6" = .5, .5X3450RPM = 1725 RPM
Stacy
 
bladsmth said:
The ratio of the pulleys determines the speed.For example,a 3" on the motor and a 6" on the grinder will drop the speed by 1/2.There should have been a chart with the grinder.
The formula is: Velocity ratio= input pulley diameter / output pulley diameter.
Output Speed = velocity ratio X input speed
Thus : 3"/6" = .5, .5X3450RPM = 1725 RPM
Stacy
Click to expand...

Thanks, I'll check for that chart. I would also like to be able to take it down even further for certain things. I guess I'll look for a multi step pulley. If I can't find one around here I'll have to order online I guess.
Mike
 
JMO, but speed and heat are the worst enemies most knifemakers face and are responsible for most screw up over anything else besides operator error.

I'd go with the one horse motor even if it is 120V and you'd be a lot better off. By the time it burns out you can get a 1-1.5HP 240V 1720 RPM.
 
Why don't you just ask Rob Frink?

I've got two KMGs, one with a 1725 and the other with a 3450 motor. For me he recommended matching 3" pulleys on both the motor and the machine on the 3450RPM motor, and on the 1725 he recommended a 2.5" on the grinder and a 5" on the motor. He said that configured that way, they'd both develop full torque and run at the same SFPM. I do have a VFD on each one.

If you've got a fixed speed setup, I believe he has a set of stepped pulleys that he recommends for your application.
 
J. MacDonald said:
Why don't you just ask Rob Frink?

I've got two KMGs, one with a 1725 and the other with a 3450 motor. For me he recommended matching 3" pulleys on both the motor and the machine on the 3450RPM motor, and on the 1725 he recommended a 2.5" on the grinder and a 5" on the motor. He said that configured that way, they'd both develop full torque and run at the same SFPM. I do have a VFD on each one.

If you've got a fixed speed setup, I believe he has a set of stepped pulleys that he recommends for your application.
Click to expand...

Hi,
I didn't ask Rob because I was on the forum at the time and thought I'd seek out some fellow knifemakers opinions seeing as that's my intended purpose for the machine. I don't know if Rob is a knifemaker or not but I'm sure he would be just as helpful. Thanks for your info though. Maybe I will call him and see what he thinks because my machine will be a fixed speed and I believe those step pulleys are designed for 1720 not 3450. I could be wrong but I don't think so.
Mike
 
Mike Hull said:
JMO, but speed and heat are the worst enemies most knifemakers face and are responsible for most screw up over anything else besides operator error.

I'd go with the one horse motor even if it is 120V and you'd be a lot better off. By the time it burns out you can get a 1-1.5HP 240V 1720 RPM.
Click to expand...

Thanks Mike I'm seriously considering that now:) . Do you think 1 horse will be enough power though? I've heard other makers complain:thumbdn: that it's not enough. :confused:
Mike
 
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