Seth Clayton

Single or 3-phase?

11 posts in this topic

I apologize if this has been answered and beaten to death already, but I couldn't find anything in a search.  

I've been looking at used table saws online to consider upgrading my jobsite saw.  In my searches I started to find references to 3-phase saws.  I understand the basic advantages of the 3-phase saws (power, torque, etc...), but not sure if I would ever benefit from those advantages to justify the modifications that would be necessary to accommodate 3-phase machines.  I don't current have 3-phase service in my shop, so I would have to have it installed.  I imagine that alone is very expensive.  

If I did have 3-phase service, it would give me a broader selection of tools to pick from.  Is it worth going through the expense and hassle to have the capability installed? 

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16 minutes ago, Seth Clayton said:

I apologize if this has been answered and beaten to death already, but I couldn't find anything in a search.  

I've been looking at used table saws online to consider upgrading my jobsite saw.  In my searches I started to find references to 3-phase saws.  I understand the basic advantages of the 3-phase saws (power, torque, etc...), but not sure if I would ever benefit from those advantages to justify the modifications that would be necessary to accommodate 3-phase machines.  I don't current have 3-phase service in my shop, so I would have to have it installed.  I imagine that alone is very expensive.  

If I did have 3-phase service, it would give me a broader selection of tools to pick from.  Is it worth going through the expense and hassle to have the capability installed? 

Unless you live an in industrial site you probably cant get 3 phase.

So you would be working with a Converter anyway.

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4 minutes ago, socoj2 said:

Unless you live an in industrial site you probably cant get 3 phase.

So you would be working with a Converter anyway.

Thank you!  I'll limit my search from now on.  Unisaws are the ones that I came across with 3-phase motors.  Can I replace with a single phase or should I just look for something else?

 

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Just now, Seth Clayton said:

Thank you!  I'll limit my search from now on.  Unisaws are the ones that I came across with 3-phase motors.  Can I replace with a single phase or should I just look for something else?

 

Generally you can, but factor in another $300-$400 for a 3 hp motor it may be worth it for you to just buy a new saw by the time you get that much invested.

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Honestly you shouldnt need a 3HP motor unless your doing this stuff all the time. Like for a living. there are several 2HP motors out there, or motors that run off 220\230\240v that would work fine on a Unisaw. Some people want to have enough power to make sure they dont slow the motor down even 1RPM when ripping 4" lumber. The people who bring a timing light into the garage with them and have a buddy hold it while calibrating their saw daily... LOL
but thats just not necessary for most applications. Ive been happy with a 1.5HP motor, and have had no problems after putting a good blade on it. Before that i had no complaints about a 1HP motor.
Just do the proper calculations for any pulley size difference, check your RPM's, Voltage and HP of course and make sure it can be mounted securely to your saw

Now, with the price of the grizzly and a few other brand saws saws being as affordable as they are, it might not be a bad idea to glance for them or a used Jet saw on CL. I see them pop up all the time

Once you approach spending 800$ or so. You might as well consider buying that brand new Grizzly for just a couple hundred extra. Something with a shiny new top that has never had a beer left on it lol

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52 minutes ago, socoj2 said:

Unless you live an in industrial site you probably cant get 3 phase.

So you would be working with a Converter anyway.

Ask! So many schools and churches, not to mention fire halls etc. are built in residential areas and have no problem acquiring three phase. The hang up is more likely to be code officers if you attempt to run this route in a house rather than a shop. 

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3 phase is not typically available to single family residences. It is available to institutional & commercial properties in the area though. The high voltage underground lines that run down the residential streets where there are only houses are only single phase. To get it to a residence, it may be only 1/2 a block away or many blocks away. At the minimum, it would be very expensive. Both for the work on your property & utility company costs.

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I say ask, because three phase is on the poles in my backyard, 50 feet from my house. You never know until you ask. I have seen it both ways. A phone call never hurts. 

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In my previous wood business, I had to get 3 phase to run the bigger machines. The nearest 3 phase lines are 1 mile away. They wanted an arm, leg, both kids, and their kids also to run a line to me.

I bought a phase converter from American Rotary. The next time I need 3 phase, I will get one of their converters again.

https://www.americanrotary.com/products/view/ar-pro-series

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Having 3 phase opens up a lot of options for used equipment, sometimes significantly lower cost than 1-phase equivalent.  You can either use a phase converter (rotary or a digital like PhasePerfect) or a VFD (variable frequency drive).  With a VFD, you can control the speed of the motor and do other things like motor braking to stop the motor very quickly.  3 HP VFDs, the good ones, are about $200-250 each, and you typically would not share a VFD among many machines, but I guess it might be possible.  Phase converters vary on price depending on HP ratings (which typically need to be double the actual tool HP), but they often are used to run several machines, even at the same time. 

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8 hours ago, Waldvogel Review said:

Honestly you shouldnt need a 3HP motor unless your doing this stuff all the time. Like for a living. there are several 2HP motors out there, or motors that run off 220\230\240v that would work fine on a Unisaw. Some people want to have enough power to make sure they dont slow the motor down even 1RPM when ripping 4" lumber. The people who bring a timing light into the garage with them and have a buddy hold it while calibrating their saw daily... LOL
but thats just not necessary for most applications. Ive been happy with a 1.5HP motor, and have had no problems after putting a good blade on it. Before that i had no complaints about a 1HP motor.
Just do the proper calculations for any pulley size difference, check your RPM's, Voltage and HP of course and make sure it can be mounted securely to your saw

Now, with the price of the grizzly and a few other brand saws saws being as affordable as they are, it might not be a bad idea to glance for them or a used Jet saw on CL. I see them pop up all the time

Once you approach spending 800$ or so. You might as well consider buying that brand new Grizzly for just a couple hundred extra. Something with a shiny new top that has never had a beer left on it lol

Unisaw has a proprietary motor mount, so unfortunately his choices are limited. I believe you can get a 3, 4, and 5hp motor for the unisaw with the appropriate mount. 

 

OP, 3phase motors dont produce more torque or power per the rated motor, but they do typically last longer and run cooler. The main difference is single phase motors typically limit out around 7.5hp. To that point, a 7.5hp 3phase motor does produce more power than a 3-5hp single phase motor. 

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