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Discussion Starter #1
Just got done searching the site/threads for related information. Got some generalities now for some specifics please -

I have a Craftsman model 113.12130, 1/2HP 1725 RPM 115V motor running my drill press and probably the same type on my band saw.

After looking over the related threads it looks like I will need a 1/2 HP 3 phase motor with a VFD single phase input and 3 phase out put to control the speed of my tools.

Could someone give me some specific model/type motor and FVD to make this work out? Looking at some of the sites it's kind of confusing to choose from what's available.

Thanks,
Terry
 

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Here is one from grainger that I believe would work.

http://www.grainger.com/Grainger/FUJI-AC-Adjustable-Frequency-Drive-4RG31?Pid=search

You could also call grainger or your local electrical supply house. Ask for city desk. Tell them what you are trying to do and they should be able to help with VFD and motor selection.

The above VFD is around $400.00. Motor would be extra.

Also extra would be any electrical supplies you would need to properly wire this for your use. Simple guess would be under $1000.00 for entire project. Worth the cost to do what you want?

Keep in mind. The supply wires for the VFD and the Motor feed wires need to be in separate conduits. You cannot mix them in the same conduit.
 

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Discussion Starter #5
Motor speed control

I do have pulleys to change the speed on the drill press, but not on my band saw. Don't have room for pulleys on it. Beside I am a gadget guy within my means. I like to build my own video transmitters rather then buy one...it's a lot more fun. I just built a really neat Jumbo Digit Thermometer kit from an old Nuts and Volts article.

I just think it would be neat to be able to control the speed of these tools for different project.
 

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Discussion Starter #6
I noticed that VFD output was only 2.? amps the present motor is about 7 amps, put its AC too, not sure if that make a difference or not. I probably would not buy from Granger, they are extremely expensive, but when I get an good idea of what I need, I'll check Amazon or E-Bay.
 

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I noticed that VFD output was only 2.? amps the present motor is about 7 amps, put its AC too, not sure if that make a difference or not. I probably would not buy from Granger, they are extremely expensive, but when I get an good idea of what I need, I'll check Amazon or E-Bay.
Your present motor is single phase, correct?

You would be changing to a three phase motor, correct?

This drive would be for a 3 phase, 1/2 HP motor. Which should draw around 2 amps at 240V. this drive would accept 240V single phase input.
 

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Another thing to remember about VFDs and power tools; a typical electric motor will produce about 2 - 3X its rated horsepower for a short time when it's connected to utility power. With a VFD, the figure is more like 1 - 1.5 times, unless you grossly overrate the VFD.

For example, a 1HP motor operated on utility power will produce about 2 or 3HP before it rapidly loses speed. A 1HP motor operated on a 1HP VFD might produce 1.1 or 1.5HP before it loses speed. A 1HP motor operated on a 3HP VFD (yes, the VFD can be way oversized) will produce 2 - 2.5HP before it loses speed.

True enough, most shop equipment isn't overloaded much, but one notable exception is a table saw. To get a table saw to rip the same wood, you'd need to go up at least one HP size, and use a VFD that's 2 or 3 times the motor HP.

Also note, only 3 phase motors are speed controllable. Single phase induction motors cannot be controlled by a VFD.

Further, most inexpensive VFDs don't do well with rapidly changing loads. They take a while to 'catch up' to the change in load.

Rob
 

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I had to buy a VFD for my Bridgeport mill and ended up converting my bandsaw and drill press to 3 phase as well. Those 2 machines are perfect candidates for a VFD. Sometimes I will change the pulleys for a heavy slow cut but for the most part I never have to fool with them anymore. I bought a Mitsubishi VFD about 20 years ago when they were very expensive so I just have the one VFD working all 3 machines with a disconnect (motor rated toggle switch) and simple potentiometer at each machine. With the prices so reasonable now, I would probably just buy multiple VFD's.
 
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