single or three phase

[David Hawxhurst]

the moons have aligned, so i am looking at euro slider/shapers. the cost of the single phase and three is the same. three phase i'll have to buy a converter. the single phase is 4hp and the three phase is 5.5hp. leaning towards the three phase. on paper the three phase should be able to handle more because of the additional power, does this hold true in the real world while actually using it? is the added cost of the converter worth it? my feeling is the shaper will benefit more from the additional power.

[Jeff Duncan]

Are you buying used or new? If used then your going to be limited in your choice if looking at single phase. If new then generally speaking I say more power is better. Though in reality it comes down to what your doing. There are some things you can do with a 3hp motor and others that will bog down a 5hp motor! If you plan on doing a wide variety of stuff I would consider the 5 hp about the minimum I would want. However you also need to remember that some phase convertors will decrease the amount of power your motor puts out! So do your homework on how your going to power the shaper first....then pick the shaper;)

good luck,
JeffD

[Mike Henderson]

I'd go with the single phase. The difference in power is not going to make a significant difference. If you had three phase power coming into the shop, I'd go three phase. But if you have to convert, I'd stay with the single phase.

Mike

[Peter Quinn]

There are a few factors to consider. Three phase motors generally last longer, they are simple and have fewer parts which is part of the reason they are favored for industrial use. But at resale time it may be harder to move because the potential market is smaller. Lots of guys don't want to deal with phase conversion. Which is best for you depends on your situation. Once you have a convertor in place you can run other 3 phase motors which opens up the used industrial scene, and there are some bargains there which can balance the cost of the initial outlay.

Does 5.5 hp beat 4? Yes, and mostly as you get to the upper end of each machines capacity. Run a small cabinet set on each machine, bet you couldn't tell the difference. Put a big molding head on each, you will wish you had the bigger motor. Same for the saw. Raise the blade all the way up to cross cut a thick slab or straight line it, you want the big motor, cutting plywood, either will feel the same. So I guess I'm saying the motor size decision depends on how you anticipate using the tools now and in the future.

[Keith Hankins]

First, its a great decision to have. Me, I'd prefer the extra umph. Now if your never going to be cutting the larger stuff then not a real issue. However, I've never had a power tool that I said dang that has too much power. The other decision to make is do want to only run this one tool or have other 3 phase tools. I jumped into the three phase game last year when an opportunity for an 18" northfield planer came along for a steal but was 3 phase. I'd been avoiding it for a long time but you will find 3 phase tools (used) are more resonable due to the market being much smaller. If you plan on acquiring more 3 phase tools in the future take that into consideration. You could get a single converter for that tool or do as I did and get a larger converter to handle other tools. My planer is 5hp so I put in a 10hp rotary phase converter from American rotary phase converters and that will handle up to a 7.5 hp 3 phase tool. I purchased the panel and the idler motor from them as a package and installing was easy. If you can get your hands on a large motor to serve that purpose you can get it cheaper. I was new to the game and wanted the support so i got the package. It's been great and I don't reqret it. I have a large 16" bandsaw i'm rehabing now that will have a 2hp 3 phase motor that I will run. Again, I have started acquiring old american iron so 3 phase is a natural for me. That 5hp motor on my planer was made in the 60's and is still humming along. Anyway I put that perspective out there so you know where my opinion is coming from. I'm sure a lot will tell you its a waste for various reasons too. In the end Value is in your eyes, but don't short yourself to only reqret it later. That planer i have will take a 1/4" in a pass if needed and at top speed will spit an 10' board through in nothing flat. I'm sure that 5.5hp would be nice too, but you could get by with 4hp. What ever you decide on please post some pics. We all like toys even if they are someone else's good luck.

[David Kumm]

I think it also depends on what machine you buy and your plans for the future. I'm not sure I would go three phase for a Hammer but would not consider single phase for a higher end Felder or MM. The shaper in particular benefits from the larger motor but the quill assembly needs to handle it so the stronger the machine the bigger the motor. I'm so die hard about three phase I have three phase perfects-all used- and a Kay RPC. I think 7.5 hp is the perfect shaper motor but prefer larger to smaller. Resale may be a little better with single phase but I'm betting that in a few years most woodworkers will be comfortable with vfds, rpcs, and pp that single will be a negative for high end machines. I've been wrong before. Dave

[Rod Sheridan]

Hi, the single phase motors on the Felder/Hammer products are similar to 3 phase motors in that they don't have a centrifugal switch for starting. (3 phase motors don't need one, and the single phase motors use an external contactor for the start function, so no starting switch issues in the motor).

If you're using it for home use, how often would you need a motor larger than 4HP, even for a shaper?

If you're running it in a business with a stock feeder, maybe 3 phase.

You could also see if they'll provide it with a VFD built in, which they do for some machines so you could control the saw/shaper spindle speed and have soft start and a 3 phase machine.

Regards, Rod.

[Erik Loza]

If it's just one machine and considering it's a saw/shaper, single-phase makes a lot more sense for the home shop.

Good luck with your research.

Erik Loza
Minimax USA

[David Kumm]

Rod, Felder does offer an internal vfd with their variable speed option. Makes difficult electronics almost impossible to repair IMO. I think most would be better off spending the extra grand or so for an rpc and simplify life. I'm a used guy and wonder about the resale or repair of ten year old machines with the internal vfd. Most electronics are modular now so replacement is much easier but so far the choices for the internal vfd are more limited. $1000-1500 buys a new rpc or a used PP. Dave

[Peter Quinn]

Just FYI, I went three phase because I was offered a minimax shaper used for $900 that I see selling regularly for close to $3k. Like Kieth, I installed an American Rotary 10HP RPC, came with a Baldor shaft less idler and a very user friendly control panel. Purchase price plus the wire/ boxes/switches to install, cost me just over $1000. I have since added two more 3 phase machines, similar cost savings on purchase price. I sized the convertor to start a 7.5 HP medium load motor and run a large shaper +feeder. That puts some numbers out ther for comparison. I did the RpC install myself, if you need an electrician add that to the equation as well.

[Mike Heidrick]

the moons have aligned, so i am looking at euro slider/shapers. the cost of the single phase and three is the same. three phase i'll have to buy a converter. the single phase is 4hp and the three phase is 5.5hp. leaning towards the three phase. on paper the three phase should be able to handle more because of the additional power, does this hold true in the real world while actually using it? is the added cost of the converter worth it? my feeling is the shaper will benefit more from the additional power.

Really depends on the machine. Some slider shapers have independant motos so that would be multiple VFDs (there are some ways to control more than one motor but I digress). A nice Kay Perfcet or American Rotary or my dream a phase perfect will cost quite a bit more. If that is no problem and you have the infrastructure to power the converter and machines then the 3phase setup has long term benefits in more machines if sized correctly.

Also if it is only one motor a 5hp or larger VFD can get quite expensive. Plus you will have to rewire the reversing control and power buttons etc if you convert yourself.

We really need to know more specifics on the models you are looking at to prepare you for the work you will need done.

[Matt McColley]

I have plans and collected all the parts to make a rotary phase convertor (which is basically, just a three phase motor with a circuit of start capaciors to get the motor going, and a circuit of run capacitors to balance the generated third leg with the house voltage supplied first two legs)... but I lost steam on the project and scrapped the 3 ph cyclone DC I had salvaged.

The main reason for abandoning the project was the issue of insurance. Though I was 98% confident I knew what I was doing.... I wouldn't risk having an electrical problem only to find out my insurance company was denying any claims because I had an "unapproved" 3ph power system installed by an "unlicensed" electrician.

Even if you buy a commercial rotary phase convertor.... you should look long and hard at having a licensed electrician install it and wire up your 3 ph panel and circuits for you.

And this from a guy who wired his own house!

[Larry Edgerton]

I went from a shop with three phase coming in to running off of a RotoPhase and I want to get a Phase Perfect. I don't mind with the planer and shaper, but with the RAS, drill press,band saw and tablesaw its a pain in the butt. If I want to make one little cut I have to start the converter first so its an extra two steps, turning the converter on and off. I hate the noise the converter makes at idle so I do not leave it on, and it is suggested in the manual that you do not leave it idling anyway because of heat generated at idle.


In your situation, factoring in the loss with a converter, I would think seriously about single phase. Now, if you were willing to spring for a Phase Perfect, that may be a different story. A Phase Perfect makes little noise, and can be ready to go with no harm to itself. One is in my future.

Larry

[Keith Hankins]

Were you impressed like I was at how quiet that Baldor Motor was? I figured some noise but it purrs like a kitten. I installed mine myself directly under my service panel and it was pretty easy (although I do most my own stuff anyway.

[Matt McColley]

two things many people don't realize about 3 ph motors....

1. they run smoother at a more consistant rpm.

2. they do not have a large curretn surge when starting (since there's no capacitor in the strarting circuit).

[Rod Sheridan]

two things many people don't realize about 3 ph motors....

1. they run smoother at a more consistant rpm.

2. they do not have a large curretn surge when starting (since there's no capacitor in the strarting circuit).

Hi, a 3 phase induction motor, like a single phase motor runs slightly slower than synchronous speed (1,800 RPM for a 4 pole machine at 60 Hz). This is called slip, and it reduces speed as load is applied, to induce current in the rotor bars. (Hence induction motor).

A 3 phase motor is smoother with respect to torque impulses ( there are 3 times as many), than a single phase motor.

As for starting currents, they can range from 3.15 KVA/Hp for class A, to over 22.4KVA/Hp for class V motors, assuming we're talking about NEMA motors.

To generalise on startup currents, that's approximately 3 to 22 times normal current for startup currents for 3 phase motors.

Regards, Rod.

[Peter Quinn]

Were you impressed like I was at how quiet that Baldor Motor was? I figured some noise but it purrs like a kitten. I installed mine myself directly under my service panel and it was pretty easy (although I do most my own stuff anyway.

I sure was. I have left it running for brief periods because I forgot it was on! When everything else in the shop is off I hear it but otherwise not so much.