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  #1  
Old 09-11-2012, 08:32 AM
Helicopterjohn Helicopterjohn is offline
 
Join Date: Sep 2012
Location: Seffner, Florida
Posts: 10
3 Phase Motor RPM on 2 " X 72" Grinder with VFD

Hi,

I am looking a building a 2 X 72 Belt Grinder. I want to use a 3 phase 2 HP 56C frame motor that is rated for inverter duty with a KBAC 27D VFD. This motor will be mounted for direct drive use with no jack shaft pulley setup.

What RPM motor does KMG or similar homebuilt 2 X 27 Grinders use? i.e. 1725 or 3450

Also, what size drive pulley would be required with this setup?

Any input would be appreciated on why a certain RPM is utilized with the KBAC 27D VFD.

Thanks,


John
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  #2  
Old 09-11-2012, 03:59 PM
Larry Peterson Larry Peterson is offline
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Join Date: Oct 2011
Location: I was born and raised in Spanish Fork, Utah. I now live between Manti and Ephraim, Utah. We built a home here about 10 year ago.
Posts: 79
Friend,

I use a KMG with a 3 hp motor @1725 rpm. I am using a step pulley at the highest speed advantage but it is too slow. My machine came with a 4 inch drive pulley. I am going to the 6 inch pulley but it is still not as fast as I want it to be. Eventually I will go the the variable drive.

I also use a Bader II for finishing. The motor is direct mount and is 3450 RPM. You can always slow down the 1350 rpm but the 1725 is limited. My counsel is to go 3450!

I looked at a 3.5 HP treadmill motor with the treadmill controler. The motor is not sealed like the bader and other types made for grinders and buffers and it does not have the "monster" bearings. The hp in the treadmill motor is suspect and the controler appeared to me to be very light duty.

My Bader II has a Balder motor and has faithfully served for over 30 years without even a hickup. This is no time to try to "pinch pennies." Go with the 3450 rpm.

I wish you the best of luck with your machine., Larry Peterson
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  #3  
Old 09-11-2012, 06:04 PM
Helicopterjohn Helicopterjohn is offline
 
Join Date: Sep 2012
Location: Seffner, Florida
Posts: 10
Thanks

Hi Larry,

First, thanks for your valued input.

I currently have an older Model 4103 Wilton Square Wheel Belt Grinder with a single phase 1725 RPM 1 HP motor that I picked up a few weeks ago. It has a 56C frame motor and is direct drive to a 10" Drive Wheel. I think they advertise it at 4600 SFPM. It also has a 8" contact wheel and platen attachment.

I intend to build a new grinder and put a 3 phase 2 HP 56C frame motor on it with a KBAC 27D VFD.

If I use a 3450 RPM 3 Phase Motor with the KBAC 27D VFD which size drive pulley would I need. i.e. similar to the KMG.

John
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  #4  
Old 09-12-2012, 01:49 PM
Suicycle Suicycle is offline
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Join Date: Dec 2005
Location: Trenton, GA
Posts: 154
I am running a Freq on my disc grinder and would advise the higher speed motor, you can use it to slow down and even stop the belt if you wanted to. You will have a lot of control. You could always just call and ask Beaumont metalworks and see what rpm motor they use.
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  #5  
Old 09-12-2012, 10:03 PM
Larry Peterson Larry Peterson is offline
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Join Date: Oct 2011
Location: I was born and raised in Spanish Fork, Utah. I now live between Manti and Ephraim, Utah. We built a home here about 10 year ago.
Posts: 79
Friend,

The 6 inch diameter works for me. Room on the mounting frame can be an issue when you go any wider. Suicycle is right on! I spend time almost every day in my knife shop. Having the speed and power to rough out and create is a real plus. As time goes on even cork belt and grease finishing can be a lot faster with the higher speed. The limits are getting the blade too hot and having to re-heat treat the blade. The variable speed is a real +. Good luck!
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  #6  
Old 09-12-2012, 11:45 PM
jdware jdware is offline
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Join Date: Aug 2006
Location: Merida, Yucatan Mexico
Posts: 55
John,
I just converted my older Bader Bii to variable speed. I bought a 2hp 3 ph 1800rpm WEG motor and a KBAC 27D. The Bader originally had a Baldor 2hp 3450 rpm motor. The Bader came with both 3" and 6.25" drive wheels. I pretty much exclusively used the 3" which gave around 2700 SFM (surface feet per minute) the 6.25" was a little more than double that - to tell you the truth, that high a belt speed just scared me too much!

On the new setup I'm using the 6.25" drive wheel, so I'm still at around 3000 SFM at top speed. The KBAC has a jumper inside that will double the motor speed, so I could get up to 6000 SFM for rough grinding and hogging, if I choose to.
J

JDWARE KNIVES
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  #7  
Old 09-13-2012, 07:43 AM
Helicopterjohn Helicopterjohn is offline
 
Join Date: Sep 2012
Location: Seffner, Florida
Posts: 10
Thanks

Hi Guys,

Many thanks for your valued input.

I have been doing some further research and like the Wilmont Grinder design as it is easily converted from vertical to horizontal grinding with little effort. Another friend of mine is already in the process of making his own homebuilt grinder similar to the Wilmont.

Hi J,

1: Have you tried the 2X speed option on the KBAC27??

2: If so, did you notice any loss in the torque of the motor?

3: Also, when in the 2X speed option will it go to near Zero RPMs?

Guess, maybe questions 2 and 3 are for KBAC, but thought I would ask.

John
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  #8  
Old 09-13-2012, 08:27 AM
jdware jdware is offline
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Location: Merida, Yucatan Mexico
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Haven't tried the 2X option yet. I also had some questions for KBAC and called - the tech was very helpful.

J

JDWARE KNIVES
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  #9  
Old 09-15-2012, 01:05 PM
Suicycle Suicycle is offline
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Location: Trenton, GA
Posts: 154
I never knew of the 2x option. I rarely run over 70% though. Normally about 20% to 50% is my normal range, but I am running a disk too.
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  #10  
Old 09-16-2012, 06:13 PM
Helicopterjohn Helicopterjohn is offline
 
Join Date: Sep 2012
Location: Seffner, Florida
Posts: 10
KBAC 27 Inverter

Hi Guys,

I talked to the technical support engineer at KB Inverters a couple of days ago and found him to be extremely helpful.

We discussed the 2X option.

He said that the 3 phase (Inverter Duty) motor would have to be capable of running at 120 HZ to utilize the 2X function. I personally have never seen a 3 phase motor that had 120 HZ on the name plate.

Have any of your guys run a 3 phase (inverter duty) motor utilizing the 2X option on a KB27D inverter? If so, was the motor rated at 120HZ and what was the original rated RPM on the motor i.e. 1750?

We also discussed the new High Efficiency (Premium) motors that are mandated by some new governmental regulation.

I was told that these High Efficiency (Premium) motors do not behave that well in a (No Load) situation like we would have on our grinders when utilizing the KBAC 27 inverter. I think he said they make some type of noise when not under load. I asked him if they would offer any type of upgrade kit for the KBAC27 when these High Efficiency motors become the only style offered by the manufactures. The answer was NO. I think he said that currently only motors 3HP and over are mandated but could not tell me if any of the manufacturers have converted all their motor lines to the new High Efficiency type.

He suggested that I contact the individual motor manufacturers for information on their products.

I hope I have all this straight as there was a lot covered during our conversation. I have his phone number and extension if anyone has any further questions.

One of my other friends is going to call Baldor tomorrow and talk to them about the ability of their prior High Efficiency (Premium) motors to run at 120HZ.

I would appreciate any additional input form anyone that has been there and done that.

John
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  #11  
Old 10-19-2012, 04:20 AM
Taz575 Taz575 is offline
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I will check mine when I get home. I got one of the KMG's with the 1.5HP VS setup. It uses a Leeson 1.5HP motor 3ph 220V. The Genesis KBAC speed controller converts the 110V power single phase to 220V 3 phase. IIRC the RPM on the motor is the 3450 and I got the motor and drive wheel pulleys from KMG, they are both 3"diameter IIRC, so it is a 1:1. I think I have the KBAC27D?? The 29D may be better for the 2hp motor, but I don't know much about that stuff? I know that you can't run it on a Ground Fault protected circuit, either.
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  #12  
Old 08-24-2013, 10:01 PM
Helicopterjohn Helicopterjohn is offline
 
Join Date: Sep 2012
Location: Seffner, Florida
Posts: 10
2 X 72 Grinder

Hi Guys,

It has been a long while but I finally am getting back to my DIY Grinder build. My friend finished his DIY Grinder. He is running a 1 1/2HP 3 phase motor with a VFD and loves it. He said that it has been one of his most rewarding projects.

I will start a new thread to show you guys my progress.

John
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