motor swap: 3phase to 1 phase

[Bill Leonard]

I purchased a Powermatic model 26 shaper with a Baldor 5 hp 3 phase motor and a PM66 with a 5 hp 3 phase Baldor motor at auction about 5 years ago for next to nothin', less than $300 for the pair. I've been running them with static phase converters quite successfully on a routine basis since purchase. I make sawdust between beers, I am not a professional
The converter on the shaper decided to go toes up today and stopped all shaper production, not a real problem- time for a beer. Here's my quandary and need of counsel:
I am involved in an internal debate with regards to purchasing a new static converter (~ $240.00) or biting the bullet and drop in a 3hp single phase motor. Both Baldor and Leeson are real proud of their motors and seem to be reluctant to part with ownership without a title to the first born son ( I have no problem with son ownership, but his wife might) . Another static converter at $200+ seems like a short expensive step to a recurring long term problem. A new single phase motor appears to be approaching a grand +.
Here's my question for you graybeards:
Is there a reasonable "no name motor" solution out there for both the shaper and saw??? I include the PM 66 as well, since one converter failure may well portend the second.
3 horse is adequate, since that's about all I'm getting with the current arrangement, and I am satisfied with the performance. I am also aware that there will in all probability be additional expense with switches and such.
I do not have any real heartburn over the expense, considering the initial cost of the equipment; I just don't want to do it again in the near future, and slap my forehead and say " Why didn't you do ___".
Any and all counsel will be appreciated.
Bill

[Dennis Aspö]

No expert so keep that in mind, but as I understand it, a static phase converter does not supply all three phases with power, only during startup to get the ball rolling, so basically you're running the 3ph motor as a 1ph one which i can't imagine is all that good for it anyway.

What does a VFD cost where you are? If it's cheaper than a new 1ph motor then it seems the obvious way to go, it supplies true 3ph power and you get to keep the motor which is superior to a 1ph motor and a VFD gives you other options such as RPM control and I think motor breaking. I've read though that RPM control to make the motor run at anything but what it's rated for under load is also quite bad for it so it might not be such a great feature, the ability to supply true 3ph is.

[Erik Manchester]

Bill,

Given your investment in quality 3 phase motors I would stick with them and either buy another phase converter or a VFD which will do much the same as the static convertor.

The trick to longevity is to make sure that the converters/VFDs are well ventilated and not buried in dust or chips.

There is lots of advice available on VFDs but the prices are so low that they are very affordable.

I have a 15 HP RPC as well as a number of VFDs and am very pleased with the 3 phase solution. Where I do not require speed control I wire the tool directly to the RPC and this powers multiple tools at the same time.

This is just my experience, and you can certainly go single phase, but those motors will cost much more than VFDs.

[Matt Day]

I've always heard that for multiple machines an RPC is the way to go, and single machines it's a VFD. that being said I only have one 3 phase machine right now and have a VFD. It would be nice to have the variable speed on a shaper wouldn it?

BTW, nice stealth gloat! Sounds like my dream auction score!

[Mike Cutler]

Bill

Personally, in your situation, I would buy another rotary phase converter. You're looking at $500+ dollars each to replace those motors if you go brand new Leeson's or Baldor"s. This is assuming that the mounts will be compatible, pulleys won't need to be changed because of the smaller arbor size, motorized mechanical contractors and thermal contractor can be reused, magnetic switches can be used again. Putting in a new motor is the easy part, it's the wiring changes that can be problematic.
There are cheaper motors, but that's what they are cheaper motors. If you have the juice to your shop to run the phase converter, I'd go that route. The only compelling argument I can make to swap the motors would be for resale down the line. Single phase motors have a larger "buyer pool" than three phase. Which is why three phase equipment can sometimes be bought pretty darn cheap.

[Bill Leonard]

Wow!
That was quick help. Thanks.
Now, can someone lead me down the rotary phase converter road?
I flew airplanes for a living and know more Greek than electric, and actually know no Greek.

[Bruce Wrenn]

Find a used three phase 5 HP motor, and make your own RPC. Visit "Practical machinest" web site for plans and ideas. You have basically two choices for starting RPC, pony motor, or capacitor bank. Both work. In my case, I was lucky to find a Herbisz dry motor, which voltage appears on one of the windings when motor reaches speed. I used this lead to operate the latching relay which applies voltage to RPC motor. If power is lost, RPC drops out. Salvage yards are a great source for used three phase motors. Most I have bought need bearings, which cost less than ten bucks. I buy them by the POUND, somewhere around $0.25 a pound.

[jack forsberg]

+1 what Bruce said. Just for those that are confused about the difference between a static and RPC a static does not have an idler motor and is just the start circuit of a RPC. and as such your 3 phase motor is only single phasing(runing on two of the 3 legs of power) and so will only ever give you 2/3 the HP of the motor and run hot. Its not really necessary to use a static any more these days as a VFD is so cheap now why would you. VFDs give in many cases cleaner than line 3 phase power from your utility to your machine motors and full hp with motor over load protection .they are your motor control as well. many other things that a spindle moulder would benefit from as well.

Here is all i would get and its less than the SC. A vfd is so easy to wire a monkey could do it.

eBay item# 261057784425

you need to read up on it.




Find a used three phase 5 HP motor, and make your own RPC. Visit "Practical machinest" web site for plans and ideas. You have basically two choices for starting RPC, pony motor, or capacitor bank. Both work. In my case, I was lucky to find a Herbisz dry motor, which voltage appears on one of the windings when motor reaches speed. I used this lead to operate the latching relay which applies voltage to RPC motor. If power is lost, RPC drops out. Salvage yards are a great source for used three phase motors. Most I have bought need bearings, which cost less than ten bucks. I buy them by the POUND, somewhere around $0.25 a pound.

[Mike Schuch]

I have a 10hp rotary phase converter I built myself and 3 VFD's. VFD's are best for 5hp and under. The rotary converter is best for over 5hp motors. The reason I say the rotary converter is best over 5hp motors is because VFD's rated for more than 5hp get quite expensive. If you can find a good price on a larger than 5hp VFD I would go that route over a rotary converter. A rotary phase converter is pretty much a static phase converter with a idler motor (A motor that just runs without any load on it to generate the third leg of 3 phase). A rotary phase converter should have an idler motor 50% larger than the largest production motor the converter is going to drive.

A friend purchased one of these drives and has been running his powermatic cabinet saw on it for over a year now with no issues:

That is a pretty bottom end drive but it has been working very well.

I have a couple Hitachi drives and an Allen Bradley drive. They are higher end units but the end result is the same.

The soft start that pretty much all VFD's support is really nice for bringing tools up to speed instead of BAM motor is at speed with a rotary phase converter or true three phase.

[Steve Peterson]

A friend purchased one of these drives and has been running his powermatic cabinet saw on it for over a year now with no issues:

That is a pretty bottom end drive but it has been working very well.

I have a couple Hitachi drives and an Allen Bradley drive. They are higher end units but the end result is the same.

The soft start that pretty much all VFD's support is really nice for bringing tools up to speed instead of BAM motor is at speed with a rotary phase converter or true three phase.

That looks like a decent option. Soft start is nice. Variable speed might also be good for the shaper.

Another option is a 5hp single phase Leeson motor from ClearVue. They have them for $375 plus $55 shipping.

Steve

[Bradley Gray]

I have no experience with VFD's - the motor speed control sounds interesting.I have used a homemade RPC for 38 years. I run 10 machines on an 8 HP idler that I start with capacitors. I have built several converters for others that use a small single phase motor on a slip clutch to bring the idler up to speed. I also have machinist friend that runs his whole shop from an idler that he spins with his foot to get up to speed. The point is, an idler of some sort will get the machine running cheapest and also cover future machine acquisitions.

[Peter Quinn]

I've been in a similar position with a shaper, swapping motors is almost never the best option unless somebody gives you the right motor. I also have a PM66. Problem with the PM66 is its a real specific motor mount, not many cheap Chinese options there. You might find a replacement for the shaper. But if the 3Phase motors are functional, why bother, they will outlast any cheap replacement you might find if properly powered. Looks like the VFD's (variable frequency drives) have come down a lot at the 5HP range, used to be anything over 3HP was cheaper to go rotary convertor. In any event I'd skip the static convertor option, that may have the added effect of premature motor failure. Get either two VFD's or a good RPC like American Rotary or Phase-a-matic sized to run both machines if you use them simultaneously or one at a time if you don't, and keep making saw dust. And drinking beer.....but not at the same time.