Update to the "Shoestring KMG" project

Daniel Koster

Daniel Koster

www.kosterknives.com
Knifemaker / Craftsman / Service Provider
Joined
Oct 18, 2001
Messages
20,978
As stated in the Shoestring KMG thread, the little motor/controller setup I put in has more than paid for itself and I've managed to save up enough to "upgrade" it.

Here's a run-down of what I got:

Inverter/Tranformer (110V Single Phase to 220V 3 Phase)
1.5 HP 3 Phase AC Motor 1725 RPM 230/460V

ordered from Friesen Electric
Cost = $440 + s/h

Comes with a 1 year warranty on the motor and drive

143TTEb.jpg

(similar to what's shown in this pic from friesen.com)


I also needed the following supplies:

Radio Shack
  • small kit box
  • SPST toggle switch (ON/OFF)
  • 10K Ohm Potentiometer
  • Knob
  • Spool of 16 ga stranded wire

Home Depot
  • 12 ft. of 10-3 stranded power cable
  • 2 ft. of 14 ga. stranded power cable
  • plug end


This was much easier to setup compared to the VDC setup. The only soldering I had to do was 3 wires to the potentiometer. Everything else is non-soldered connections (crimped, etc.)


Here's a basic wiring diagram (again, very easy to set up):

wiring.GIF





And finally, here's a lil' video I made showing it in operation:

New VFD Motor



To sum up, this is what's going on:


Power comes in at 110 Volts, 15 Amps.

The Transformer changes it to 220 Volts, 7.5 Amps (Remember, Watts is Watts.....Watts=Volts*Amps).

The Inverter changes it from single phase to 3 phase. Still AC power.

The reason for a 3 phase motor is that they are easier to make variable speed, also, they run on lower amps.

The controller varies the speed by changing the frequency. That's the red LED numbers you see "growing" in my lil' video.

The motor is rated at 60 Hz. However, the VFD can be programmed to go from 0 to 240 Hz. Since it operates at 1725 RPM when at 60 Hz, that means I can get all the way up to 6900 RPM if I want.

The other advantage to 3 Phase is torque. Very little torque is lost as RPM increases. I can attest to this....the motor is a hog at high RPM.

The motor is fan-cooled and has a standard base. I did have to order a new pulley because it has a 7/8" shaft (old one was 5/8").


I used this motor to finish up my "Lil' Moby" knife and I really like it. Easy to control, starts right up (no delay), and is very smooth.


Dan



p.s. I think there is a 1 HP version on their website for less $$ - if anyone is interested. I really liked that this one came "plug-n-play". I just needed to spend a few minutes changing settings to match what I needed and it was ready to go.
 
That is really neat Danie! Wish I had been born smart instead of good looking and I could make me one!! Truthfully, I'm not pretty either.
 
AWESOME!!!

In a few years I'll upgrade from my Sears 2x42 to a KMG. I'll have to do some checking around on a 3-phase motor! Awesome vari-speed set-up. Thanks for the video too!
 
I have a 5 or 6 horse three phase motor that we found in dad's shop after he passed away. Just think of what I can grind with that.
 
Thanks for that, I hope to use it someday on my KMG-10. 440 still sounds like a lot, is that a big savings? I though the idea was the motors were cheap, and the controlers expensive. If you wanted to run another machine, what would it cost your?

I intend to watch the video when the player stops pushing out Stairway to Heaven as butchered by Frank Zappa. It's going to be hard to follow if everyone starts ading video clips.
 
The inverter/transformer is the expensive part. $275, IIRC.

I was able to find the individual parts on ebay and surplus center for around $330, so I could have saved $100. But friesen has tested these and sells them as a package with a warranty, etc. It was worth it, in my mind.

If you were really stingy, I imagine you could get this for <$200 by waiting for used parts, scrounging for the motor, etc.

Or, if you have 220V, you don't need the fancy inverter/transformer. Just a plain ole inverter.
 
Greg - I'm debating setting it up as a buffing station. Works pretty good for that and has dual shafts.
 
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