PM66, 3-Phase, Need Help!


Michael Sloop

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Hello All,

 

I found a 1989 PM66 with a 5Hp, 3phase motor that appears to be in pretty decent shape.  Owner is asking $1,300.  Only problem, I don't have 3 phase at my house. Based on my research my options are to (1) pay the power company to install 3 phase, (2) get a phase converter, and (3) replace the motor.

 

(1) I'm waiting on a quote for this, but I hear its expensive.

 

(2) I have read that the phase converter will cut the power of the saw by 1/3, which I guess is ok for my situation.  Or, I can get 7.5Hp converter, but thats expensive from what I've been reading. I'm also not clear on what phase converter is appropriate for my situation.  I see a bunch on eBay. 

 

(3) I've been looking at the Baldor website and a 5Hp, single phase motor costs over $1K.  i can't afford that.  I looked on eBay and there are a bunch of Baldor motors for less than $400, but I'm lost about which one to buy for the saw.

 

Does anyone have any experience on suggestions on what to do?  In particular, can you provide the specific type(s) of motors or Phase Converters that would work for this saw, so I don't price out the wrong one.

 

Thanks in advance for any input that can be provided.

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Thanks wtnhighlander, I'll look into that.

 

In response to the others, I've definitely been thinking about just getting a new PM2000, its just too much money for me.  I'm hoping not to spend $2k on this one, instead talk them down to closer to $1,000 and spend a few hundred on a solution. 

 

On a side note, I've talked to two folks who sell PM2000 and they have said the PM66 was a better machine and that I should get that if I can.  Surprised to hear that from a distributor, but I have been told that.

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I think you have a little give and take. The newer saw will have the updated blade guard and riving knife. The  66 was a great saw but is really no better than the 2K, build quality may have been slightly better. With a 3 phase saw I would be a little concerned that it was used commercially and will probably need some work. If you can find a local electrical shop you may be able to pickup a rebuilt motor and use yours as a partial trade. I did this with my bandsaw and save a bunch of money.

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Alright, so i talked to the guy and explained my situation with the three phase limitation. Unbelievably he offered to sell it to me for $600. He turned the saw on and it ran so smooth. No vibration, no run out, no bad sounds. Cut wood beautifully. Cast iron top was in great shape. No rust or pitting. I'm gonna buy it, no doubt about it.

Now I have to figure out where to go from here. I'm gonna look at what highlander sent for the converter, thanks again highlander.

I also want to look at a new motor. does anyone know exactly what motor I need? I want to look at the 3 and 5 Hp options, single phase of course. I'm gonna wire my shop up for 220, so no concern there.

Thanks all.

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Unfortunately the converter previously linked will not be big enough. The converter needs to be able to take single phase input and put out at least 5hp of output. The previous converter only took single phase input up to 3 hp. 

 

I have looked before and I looked again and I can find no one who makes a single phase input 5 hp 3-phase output VFD. This means your cheap options are likely out of luck. Your next step is to either build yourself or have built for you a 5hp RPC. (rotary phase converter). If your electrical skills are half decent this can be done cheaply by buying an old 5hp motor and wiring in a box etc. Of course at that point you might as well just buy a used 5hp motor for your saw and call it a day.

 

If you look at the motor tag on the saw you will see all the needed particulars for buying a new motor. You need to know RPM, frame, and you will also need to measure the diameter of the spindle (where the pulley is). If the pulley's are cast iron then getting them off with a pulley puller is a piece of cake. If they are not cast iron I would go ahead and order some new pulleys in the same size that are cast iron for your new motor. This saw is 25 years old so you should probably replace bearings. Just because it spins smooth to the touch doesn't meant the bearings arent bad or in need of replacement. And if they are bad they will destroy your saw within a few years of going bad.

 

Good luck!

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Unfortunately the converter previously linked will not be big enough. The converter needs to be able to take single phase input and put out at least 5hp of output. The previous converter only took single phase input up to 3 hp. 

 

I have looked before and I looked again and I can find no one who makes a single phase input 5 hp 3-phase output VFD. This means your cheap options are likely out of luck. Your next step is to either build yourself or have built for you a 5hp RPC. (rotary phase converter). If your electrical skills are half decent this can be done cheaply by buying an old 5hp motor and wiring in a box etc. Of course at that point you might as well just buy a used 5hp motor for your saw and call it a day.

 

If you look at the motor tag on the saw you will see all the needed particulars for buying a new motor. You need to know RPM, frame, and you will also need to measure the diameter of the spindle (where the pulley is). If the pulley's are cast iron then getting them off with a pulley puller is a piece of cake. If they are not cast iron I would go ahead and order some new pulleys in the same size that are cast iron for your new motor. This saw is 25 years old so you should probably replace bearings. Just because it spins smooth to the touch doesn't meant the bearings arent bad or in need of replacement. And if they are bad they will destroy your saw within a few years of going bad.

 

Good luck!

I think the Lenze SCF series drives go up to 5hp with a single phase input... but I wouldn't recommend one to anybody who is not already familiar with VFDs.  They are not exactly "user friendly".

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I did just what you are talking about 2 years ago.  I purchased a used 3-phase 5hp grizzly saw.  I weighed the same options you have and i decided I would purchase a vfd off ebay I want to say it cost around $100.  It does drop your hp by 1/3 but I have not ever had any problems with it.  Once I overheated the vfd and it shut down but that was hot summer and I was running a dado for several hours working the saw hard.  Let it cool for 30 minutes and went back to work.  I figure if I ever buy more 3phase machinery I will purchase a rotary phase converter.  

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So, I talked to Phase Craft and they strongly discouraged the VFD route. Jim suggested I go with a rotary phase converter and idler motor. He has a $189 rotary phase converter. Now I need a 5 Hp, 220-240V, 1700-1800 rpm, 3 phase motor. Jim suggested I call a scrap yard, which I'll do. Any other suggestions?

For those that have gone the rotary phase converter and idler motor route, any feedback on how that's worked out?

And for the record, I read a lot of great stuff about Jim on various forums. So far, he's really been great to deal with. Super responsive and very informative.

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RPC are the best way to go to get 3 phase power hands down. If you plan to have more 3 phase machines in your shop I would highly suggest it. If this is the only one then it will likely be several hundred dollars cheaper to buy are used 5 hp single phase motor that can fit that saw. Or a 3hp motor used or new that can fit the saw if you don't need the extra hp.

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I would certainly wait to see the feasibility of getting 3 phase service before taking the plunge on a converter. For me, it would make more sense, and probably cost less. In your location, maybe not, but certainly it is worth checking. Let us know what you find out, I am curious to hear how utility companies treat such situations in different parts of the country.

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HI-I have a pm66 that I bought at the irs woodworking auction for 800. Its 5 hp 3 phase 230 and I run it with a rotary phase converter.If you only have one 3 phase tool you can run it off a static phase converter which is much cheaper than the rotary or look on ebay for a used sgl phase motor.The rotary phase converter I have is a 10 hp model that I paid 1000. but I have 5  3 phase tools that I am able to run with it.gary

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Highlander, I'll let you know what I find out.

PJtang, do you have an idler motor to accompany your rotary converter! Phase Craft sells a 10 Hp rotary phase converter for $189, but Jim with Phase Craft explained to me that I need an idler motor too that is 5 Hp, 220-240 V, 1700-1800 rpm, 3 phase. I'm not clear on where to find one of those cheap. Jim indicated they can usually be found at scrap yards for $150 to $200.

I checked Powermatic and they still sell the motors for the PM66. A new Baldor motor, 5 Hp single phase is $800.

One option I'm considering is buying the new motor, then selling the 3 phase motor. If I could sell the 3 phase motor for $200, then I'd only be spending $200 more for a brand new motor than trying to use a converter ($200 for converter + $200 for idler motor + $200 for selling 3 phase motor).

What do y'all think of that approach?

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Hear is what Phase Craft sent me.

If you want to get the full 5-HP out of your table saw, you definitely want a rotary converter. As far as it turning on automatically when you turn on your saw, all rotary converters must be started before you turn the saw on. This is because they use a separate "idler" motor to generate the three phase power. Until the idler motor is running, you don't have a three phase output to run the saw. On the other hand, static converters work automatically when you turn a machine on, but they don't give you true three phase power, and you lose about 1/3 of your horsepower. If you're concerned about wasting electricity when the idler motor is running, a typical 5-HP three phase motor, when used as an idler, only draws around 3 or 4 amps with no other load running. When you're actually running your machinery, it will go up correspondingly, but will probably never reach the full rated amperage shown on the nameplate.

VFDs can be troublesome, particularly if you install a switch between the VFD and your saw. The VFD will probably shut down, and could be damaged. I'd strongly recommend that you avoid them, as your saw was designed and built to start quickly, and it's not going to damage your motor to start it the way it was intended to start. If you're contemplating adding other machinery later, I'd recommend that you get my model 10-HP-18, and use it with a 10-HP 220-240 volt idler motor. The idler should be three phase, and with an RPM between 1700-1800. Most people buy a used motor for this purpose, which you can usually find at a metal scrap/recycle yard for around $150.

You can run more than one machine at a time if you ever want to, but it depends on the horsepower and type of machinery you plan to use it with. Table saws are easy. Planers, belt sanders, and shapers are more demanding.

-Jim

- phase-craft

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Here is the exact response provided by Phase Craft, a great explanation.....

If you want to get the full 5-HP out of your table saw, you definitely want a rotary converter. As far as it turning on automatically when you turn on your saw, all rotary converters must be started before you turn the saw on. This is because they use a separate "idler" motor to generate the three phase power. Until the idler motor is running, you don't have a three phase output to run the saw. On the other hand, static converters work automatically when you turn a machine on, but they don't give you true three phase power, and you lose about 1/3 of your horsepower. If you're concerned about wasting electricity when the idler motor is running, a typical 5-HP three phase motor, when used as an idler, only draws around 3 or 4 amps with no other load running. When you're actually running your machinery, it will go up correspondingly, but will probably never reach the full rated amperage shown on the nameplate.

If you're contemplating adding other machinery later, I'd recommend that you get my model 10-HP-18, and use it with a 10-HP 220-240 volt idler motor. The idler should be three phase, and with an RPM between 1700-1800. Most people buy a used motor for this purpose, which you can usually find at a metal scrap/recycle yard for around $150.

You can run more than one machine at a time if you ever want to, but it depends on the horsepower and type of machinery you plan to use it with. Table saws are easy. Planers, belt sanders, and shapers are more demanding.

-Jim

- phase-craft

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Someone with experience will have to chime in but I think you are misreading that. The idler is the rotor in every rotary system I have seen built. Ask him if he is referring to two devices or simply comparing rotary to static.

One other thought, if this is just for you, I would ask how important a full 5hp is. There are many guys thrilled with 3hp. I know I am a go big or go home guy, I just want to be sure to caution if it is warranted.

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I think my understanding is correct, as verified by Phase Craft below. Read the rest email from me below, then the response from Phase Craft.

-------------------------

Dear LM

Yes, you've got a pretty good understanding of how it works. Turn on the converter, use your saw, shut down the saw when you're done, and then turn off the converter... super easy. The model 10-HPPB-18 control panel for $219 will work fine, but you could also use the 10-HP-18 for $189. The only difference, is how you turn them on and off. The more expensive one uses push button start and stop controls, while the other one uses a toggle switch. For unattended machinery like air compressors, for instance, you'd want the push button model in case the power ever went out while you weren't around. That one would not try to restart itself and the air compressor both at the same time when the power was restored. You always want the idler motor running before anything else. The toggle switch model would try to automatically restart when the power was restored, but that's not an issue with attended machinery like a table saw, which you'd never leave running if you weren't there. In your case, if the power ever goes out while you're using the converter, you simply snap the red safety cap down on the side of the converter. That shuts it down, and that's all you need to do. When the power is restored, you just start the converter back up, then your saw.

- phase-craft

-------------------------

Ok, so I see a $219 10Hp rotary converter of yours. Is that the correct one? Am I also understanding correctly that you suggest I buy a used 10Hp, 3 phase motor, 220-240 V, 1700-1800 rpm motor at a scrap yard to use as an idler? So I'll run 230v single phase to the converter, connect the idler to the converter, then the converter sends 3 phase to the saw?

Thanks

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