# Odd plug on table saw



## holtzdreher (Jul 20, 2016)

Last week I was given an old 10 inch craftsman table saw. One of the old heavy duty jobs. However, when I was checking it out this afternoon, I noticed the odd electrical plug. It appears to be a NEMA 6-15 or 6-30. It has the standard ground prong but the blades (which are the same size as the regular 120 15 amp blades, are turned the perpendicular to the regular 120 15 amp plug blades. (The closest I ever got to working with "phases" is being a stargazer and watching the moon. )

My work shop is not equipped for anything but simple 120, I suppose I could run a 240 volt line, but what a hassle


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## Brian(J) (Feb 22, 2016)

I think you know the options, if the motor nameplate says 120/240 and has a wiring diagram you can swap the wires around and run it 120. If not, it's run a 240 circuit or get a new motor. Or, just to include all the options, install a 120 to 240 transformer, which would be unusual.


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## Steve Neul (Sep 2, 2011)

The saw is wired for single phase 220. Rather than trying to re-wire the saw to 120v it will preform better on 220v so I would run a wire for it. Run at least a 12ga wire. If you have to go far from the breaker box I would go with 10ga.


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## shoot summ (Feb 21, 2014)

Steve Neul said:


> The saw is wired for single phase 220. Rather than trying to re-wire the saw to 120v it will preform better on 220v so I would run a wire for it. Run at least a 12ga wire. If you have to go far from the breaker box I would go with 10ga.


You are never going to get it are you Steve... :surprise2::nerd2::wink2::grin:

OP, check the motor plate, insure you have a single or "1" phase motor. Look for a marking that also indicates 120/240v or something similar. There is a high probability this is what you have but you need to check to make sure. Then you will need to pull the plate on the motor and check to see if it's wired for 120V or 240V, the plug won't tell you that. Someone could have had a special setup they used that plug for, just because it is a 240V plug, doesn't mean it's wired that way, so check.

If it is 120V, then install a new plug and you are golden. If it's wired for 240V then you need to decide if you want to run a 240V circuit, or if you have a sufficiently sized 120V circuit to run the saw.

The saw will not run better on 240V, so there is no need to waste your money on a 240V circuit, unless you want one in the shop.


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## holtzdreher (Jul 20, 2016)

Thanks every one. My knowledge of electricity and circuits is vry elementary, but I am learning. 

The manual indicates that the thing was originally 110 volt, and cautions against changing the voltage up, even though some of the OEm motors were either 110 or 220. Saw I guess it is back to the barn to see what motor is on it. My only attempt at rewiring a motor thus far has been abysmal. No motter how I wire it it runs the wrong way. So I just used the old lathe by reversing the tool rest and letting it run backwards. Got three better lathes since so that lathe will be just given away.


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## FrankC (Aug 24, 2012)

I am with Steve on this, sounds like it is wired for 220 and if you can run a new 220 circuit do it, never regretted running 220, can't say the same for 110.

Never could understand why a motor would be dual voltage when there was no advantage to running it on 220 instead of just plugging it into a common 110 outlet.


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## Brian(J) (Feb 22, 2016)

FrankC said:


> I am with Steve on this, sounds like it is wired for 220 and if you can run a new 220 circuit do it, never regretted running 220, can't say the same for 110.
> 
> Never could understand why a motor would be dual voltage when there was no advantage to running it on 220 instead of just plugging it into a common 110 outlet.


The answer is, in terms of wiring costs, it can cost less to run a 240v circuit than a 120v circuit. And, it is true that you are more likely to have voltage drop when you plug a saw wired for 120v into a 120v circuit than a saw wired for 220 into a 220v circuit.

It is also true that if the wires are sized and run correctly a 120v circuit is as good as a 240v circuit, it's all in the voltage drop. That's because a 120/240 dual voltage motor winding always runs at 120 volts, it's why you have to swap the wires around. If you run 240 into a dual voltage motor without rewiring it to reduce the voltage at the winding's to 120v it burns up in seconds.

This gets covered over and over again, so lets look at it from a practical view. If the OP has a garage someone ran a 120v lighting circuit to, and it's a long run, and maybe there is a freezer plugged into it and 300 watts of light bulbs, there will be problems running a table saw on it. So, a dedicated 240v line is run to it, resulting in a vast improvement to the saw. Is 240v better than 120v? No, but in so many real-world cases, for practical reasons a 240v circuit has solved a lot of problems.


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## difalkner (Nov 27, 2011)

And I have said this before here that I have a 2 HP air compressor that has been fitted with a 1.5 HP motor because it's all I had at the time (35 years ago but it's still running). If I run it on 120V then I have to let air out of the tank for it to run but when it is wired 240V it starts as soon as the switch calls for it to run. When I had my old DeWALT radial arm saw on 120V it took longer for the blade to come up to speed than when I wired it for 240V, so I'm sold on 240V is better. Everything in my shop that can run on the higher voltage is running 240V.


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## Brian(J) (Feb 22, 2016)

difalkner said:


> And I have said this before here that I have a 2 HP air compressor that has been fitted with a 1.5 HP motor because it's all I had at the time (35 years ago but it's still running). If I run it on 120V then I have to let air out of the tank for it to run but when it is wired 240V it starts as soon as the switch calls for it to run. When I had my old DeWALT radial arm saw on 120V it took longer for the blade to come up to speed than when I wired it for 240V, so I'm sold on 240V is better. Everything in my shop that can run on the higher voltage is running 240V.


If you drag that compressor over to the panel and run a 120v circuit to it with #12 wire it would probably run better than it does now with 240v. Clearly there is a voltage drop issue with the 120v circuit you have available. But it's working for you on the 240v wires and that's great.


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## FrankC (Aug 24, 2012)

Many years ago when I bought my first radial arm saw I had it sitting 10 feet from the panel and was trying to run it on 110 volts, I was ripping 1 1/8" plywood and the saw was continually overheating and cutting out. I went to the local service center to see if there was a chance of installing a larger motor so I could get some work done. The serviceman laughed and handed me a 220 volt plug and outlet and told me to install it the way it should have been done in the first place, worked like a charm.


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## Jammer (Jul 15, 2009)

Steve is right.


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## difalkner (Nov 27, 2011)

Brian(J) said:


> If you drag that compressor over to the panel and run a 120v circuit to it with #12 wire it would probably run better than it does now with 240v. Clearly there is a voltage drop issue with the 120v circuit you have available. But it's working for you on the 240v wires and that's great.


Can't disagree with that at all, Brian. But when it was wired for 120V it was sitting where it is now, 8' from the panel, and wired with #14. I need it sitting where it is and running so 240V was the quick and easy solution.


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## holtzdreher (Jul 20, 2016)

Again, the saw manual warns against wiring for 240 volts, however, I do not know if it is the original motor. The manual warns against using motors that are the wrong rpm, so it looks like I have quite a bit more investigation to do. (And here I thought I would just have to replace the blade) 

My shop is currently split between the pump house and the barn. I laid wires to have 240 volts to the barn's sub panel, but the electrician that hooked things up did something that resulted in only 120 volts to the barn. The barn is 125 feet from the main panel. I remember the underground 4 wire was gosh awful expensive, 8 ga perhaps. The pump house has 240 volt service but is cramped at only 8 x 13 ft. so when I am done investigaing the motor, I may have to switch the saw to the pump house. 

When I have the motor figured out, I suppose it is time to correct the problem with the wiring to the barn as well.


and all I wanted to do was cut some wood!


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## TomCT2 (May 16, 2014)

I'm curious as to why it cost less to run things on 240/220 volts.

I pay by kilowatts; watts = volts * amps.

240 motors have more starting torque/etc - but in the end it takes a certain amount of power to saw a board - 
whether it's 3 amps @ 240 volts or 6 amps @ 110 volts seems to matter very little except for a possible slight difference in power factors.
other factors - size of wires=pounds of copper needed for more amps, line loss, etc apply - but outside of factory size shops, how much difference does this really make?


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## Steve Neul (Sep 2, 2011)

TomCT2 said:


> I'm curious as to why it cost less to run things on 240/220 volts.
> 
> I pay by kilowatts; watts = volts * amps.
> 
> ...


A motor uses magnetic fields to make it rotate. If only one field is used as in 110V it draws more amperage to get the job done than if it used two magnetic fields as in 220. You can tell this by the the heat the motor generates. It's the load you put on it doing woodworking. If the motor was on a bench not hooked up to anything the amperage would be the same either 110v or 220.


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## shoot summ (Feb 21, 2014)

holtzdreher said:


> Again, the saw manual warns against wiring for 240 volts, however, I do not know if it is the original motor. The manual warns against using motors that are the wrong rpm, so it looks like I have quite a bit more investigation to do. (And here I thought I would just have to replace the blade)
> 
> My shop is currently split between the pump house and the barn. I laid wires to have 240 volts to the barn's sub panel, but the electrician that hooked things up did something that resulted in only 120 volts to the barn. The barn is 125 feet from the main panel. I remember the underground 4 wire was gosh awful expensive, 8 ga perhaps. The pump house has 240 volt service but is cramped at only 8 x 13 ft. so when I am done investigaing the motor, I may have to switch the saw to the pump house.
> 
> ...


I hope it's something better than 8ga for 125'...

#1 is most likely for a 125A sub panel.


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## shoot summ (Feb 21, 2014)

Steve Neul said:


> A motor uses magnetic fields to make it rotate. If only one field is used as in 110V it draws more amperage to get the job done than if it used two magnetic fields as in 220. You can tell this by the the heat the motor generates. It's the load you put on it doing woodworking. If the motor was on a bench not hooked up to anything the amperage would be the same either 110v or 220.


Steve, all fields are used whether it's 120V or 240V, please try to absorb this, it's been covered a lot now.

All fields are used, the difference is how they are supplied, at 120V the circuit supplies all of the fields, at 240V they are split across the different 120V legs. That's why the current draw is 2x at 120V.


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## Steve Neul (Sep 2, 2011)

holtzdreher said:


> Again, the saw manual warns against wiring for 240 volts, however, I do not know if it is the original motor. The manual warns against using motors that are the wrong rpm, so it looks like I have quite a bit more investigation to do. (And here I thought I would just have to replace the blade)
> 
> My shop is currently split between the pump house and the barn. I laid wires to have 240 volts to the barn's sub panel, but the electrician that hooked things up did something that resulted in only 120 volts to the barn. The barn is 125 feet from the main panel. I remember the underground 4 wire was gosh awful expensive, 8 ga perhaps. The pump house has 240 volt service but is cramped at only 8 x 13 ft. so when I am done investigaing the motor, I may have to switch the saw to the pump house.
> 
> ...


125 feet is a long way to go with #8 wire. It's really only rated at 40 amps and going that far you may only be getting 35 amps. It really depends on how much you have going at once. If you have a lot of lights and or equipment you may be starved for power. You probably should have used #1 wire. You just need to add up everything you might have going at the same time and add a little. 

Yes wire is expensive. It's why there are so many people going around pulling wire out of empty or abandoned houses.


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## shoot summ (Feb 21, 2014)

difalkner said:


> Can't disagree with that at all, Brian. But when it was wired for 120V it was sitting where it is now, 8' from the panel, and wired with #14. I need it sitting where it is and running so 240V was the quick and easy solution.


#14 is the issue, even at that distance it should have been #12 for a 1.5HP motor.


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## Steve Neul (Sep 2, 2011)

shoot summ said:


> Steve, all fields are used whether it's 120V or 240V, please try to absorb this, it's been covered a lot now.
> 
> All fields are used, the difference is how they are supplied, at 120V the circuit supplies all of the fields, at 240V they are split across the different 120V legs. That's why the current draw is 2x at 120V.


Nothing to absorb, there are two individual fields on a duo-voltage motor. You have the main winding and the auxiliary winding. When one is positive the other is negative when running at 220v. On 110v only the main winding is used for power.


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## shoot summ (Feb 21, 2014)

Steve Neul said:


> Nothing to absorb, there are two individual fields on a duo-voltage motor. You have the main winding and the auxiliary winding. When one is positive the other is negative when running at 220v. On 110v only the main winding is used for power.


Wrong Steve.

All windings are active regardless of the voltage, there is not a primary, and auxillary. All windings run at 120V regardless of the supply.

If only half are active, how do you explain the current difference? 

It should be the same, and the HP should be less running on 120V if only half are active.

So yes, there is something to absorb, and you still haven't...

Explanation - The windings of a single-phase dual voltage 120V/240V motor are 120V rated windings. They must be put in parallel on 120 so that they will be connected at their rated voltage. Likewise, if put in series on a 240V supply, the 240V divides across the two equal resistance windings, so 1/2 of the 240V (120V) is applied across each winding.

If you put the windings in series on 120V, you would only receive 60V on each winding, which would not be enough to provide the proper magnetizing effect to develop turning torque.

If you put the windings in parallel on 240V, you would be putting the full 240V on each 120V rated winding, and you would burn the windings up.


A good read:

http://www.thewoodnerd.com/articles/motorRewire.html


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## TomCT2 (May 16, 2014)

>>If the motor was on a bench not hooked up to anything the amperage would be the same either 110v or 220.

aye, and there's the rub.
"the same amperage" at 110v is "the same wattage"
"the same amperage" at 220v is "twice the same wattage"


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## Brian(J) (Feb 22, 2016)

TomCT2 said:


> I'm curious as to why it cost less to run things on 240/220 volts.
> 
> I pay by kilowatts; watts = volts * amps.
> 
> ...


Hi Tom,
You may be replying to my post, I meant the cost to install the circuit and not the cost to operate the tool. And you are correct it doesn't make a lot of difference really.


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## shoot summ (Feb 21, 2014)

TomCT2 said:


> >>If the motor was on a bench not hooked up to anything the amperage would be the same either 110v or 220.
> 
> aye, and there's the rub.
> "the same amperage" at 110v is "the same wattage"
> "the same amperage" at 220v is "twice the same wattage"


Red is an untrue statement, not sure where you got it.

A 1HP motor draws [email protected], and [email protected] The wattage calculates to be the same, as does the HP.

P(W) = PF × I(A) × V(V)


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## TimPa (Jan 27, 2010)

holtzdreher said:


> I laid wires to have 240 volts to the barn's sub panel, but the electrician that hooked things up did something that resulted in only 120 volts to the barn. The barn is 125 feet from the main panel. I remember the underground *4 wire* was gosh awful expensive, 8 ga perhaps.


4 wire absolutely should have resulted in 240 volts being available. H-H-N-G. it may be as simple as adding a two pole circuit breaker in the sub-panel. or, both hots were not connected to a 2 pole cb in the main??


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## TomCT2 (May 16, 2014)

where I got it?

quoted from a preceding post.....


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## TomCT2 (May 16, 2014)

Brian(J) said:


> Hi Tom,
> You may be replying to my post, I meant the cost to install the circuit and not the cost to operate the tool. And you are correct it doesn't make a lot of difference really.


not really a reply to any specific post - just the on-going "theory" that 240v stuff is cheaper to run. this thread, multiple other threads, etc etc.

it's an old wives rumor that will not short out.

I personally don't pay per volts or per amps; I supposed some utilities might charge somehow other than watts - or perhaps we're missing a magic cold fusion 220v sub-panel. but power is power and it's quite normally sold in watts.


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## Stevedore (Dec 28, 2011)

Steve Neul said:


> Nothing to absorb, there are two individual fields on a duo-voltage motor. You have the main winding and the auxiliary winding. When one is positive the other is negative when running at 220v. On 110v only the main winding is used for power.


 I've never heard of main/auxiliary windings, although some might refer to a starting winding as an "auxiliary" winding, as it drops out of operation when the motor reaches a certain speed. Dual voltage motors have 2 separate windings, but both are used. They're in series for 220 operation, parallel for 110.


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## Brian(J) (Feb 22, 2016)

TimPa said:


> 4 wire absolutely should have resulted in 240 volts being available. H-H-N-G. it may be as simple as adding a two pole circuit breaker in the sub-panel. or, both hots were not connected to a 2 pole cb in the main??


Tim,
Exactly right. If the OP will tell us-
1. the number of wires
2. the size of each wire
3. Copper or Aluminum
it would help develop a solution. And it might be an easy one.


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## shoot summ (Feb 21, 2014)

To the OP, would be good to get some background on the saw if you can. Both 6-15 and 6-30 are pretty common in IT, if the person had access to surplus they might have used them in a pinch instead of the correct plug/recep. At this point I wouldn't assume anything on a used piece of equipment you haven't seen, or heard run.


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## holtzdreher (Jul 20, 2016)

I had a look at the motor this am. It is a Dayton, 3450 rpm. I had a wiring diagram for both "low" voltage and "high" voltage.

Seems for now it would be easier to rewire for 120 volts.


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## woodnthings (Jan 24, 2009)

*easier?*



holtzdreher said:


> I had a look at the motor this am. It is a Dayton, 3450 rpm. I had a wiring diagram for both "low" voltage and "high" voltage.
> 
> Seems for now *it would be easier *to rewire for 120 volts.



Are you saying that it is currently wired for 240 volts? so "rewiring" it for 120 volts is easier.... than what? ... new running a 240 line? Cheaper for certain, but you must still have large enough wires for it to run efficiently on 120 volts I.E, no. 12/12 GA. 

If you plan to do much more woodworking it would pay to get a 240 volt working line to the barn and since the wires are already there, it should be a simple fix.


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## FrankC (Aug 24, 2012)

holtzdreher said:


> I had a look at the motor this am. It is a Dayton, 3450 rpm. I had a wiring diagram for both "low" voltage and "high" voltage.
> 
> Seems for now it would be easier to rewire for 120 volts.


Why not "for now", if you are happy with the performance then that is the end of it, if not at least you can cut some wood in the meantime.


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## holtzdreher (Jul 20, 2016)

I should have corrected the statement to It had a diagram for low and high voltage operation. I am building a new shop about this time next year and it will have a subpanel supplied with 240. For the time being, I have a corner of a pole barn to work in and only two circuits available. Trying to limit the loads. After all. I can only run one machine at a time. add lights and a fan and I am done. The new shop will hopefully have better facilities.


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## woodnthings (Jan 24, 2009)

holtzdreher said:


> Again, the saw manual warns against wiring for 240 volts, however, I do not know if it is the original motor. The manual warns against using motors that are the wrong rpm, so it looks like I have quite a bit more investigation to do. (And here I thought I would just have to replace the blade)
> 
> My shop is currently split between the pump house and the barn. I laid wires to have 240 volts to the barn's sub panel, but the electrician that hooked things up did something that resulted in only 120 volts to the barn. The barn is 125 feet from the main panel. I remember the underground 4 wire was gosh awful expensive, 8 ga perhaps. The pump house has 240 volt service but is cramped at only 8 x 13 ft. so when I am done investigaing the motor, I may have to switch the saw to the pump house.
> 
> ...


33 posts later and I still don't know if the motor is wired for 120 volts or 240 volts and why the 4 wire run to the barn can't be "corrected" so you have 240 volts out there. If you intend to do any serious woodworking you will want the 240 volts for 3 HP motor and larger.
A 3 HP motor will just not work on 120 volts. I have five 3 HP and larger motors all run on 240 volts. 

Why can't you check the motor wiring diagram to see how it is wired, never mind the plug on end. You don't have a receptacle for that plug anyway, so which ever way you want to run it, you need a different plug. 

Enough talk, just wire it up and "cut some wood" ..... :smile3:


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## Rick Christopherson (Jun 27, 2016)

Steve Neul said:


> Nothing to absorb, there are two individual fields on a duo-voltage motor. You have the main winding and the auxiliary winding. When one is positive the other is negative when running at 220v. On 110v only the main winding is used for power.


I am sorry Steve, but you are incorrect on this one, as was pointed out by another member. The internal windings on a dual voltage motor are either in parallel or series, and that is the only reason why there is a difference in the current when the motor is reconfigured. The individual windings neither know nor care which way they are configured. They always see the same 120-volts internally.

Within the motor, there is no change in power, nor heat, nor energy savings, nor dollar savings. It all boils down to what is easiest to supply within the building.

Back to the original poster, yes, your description suggests a NEMA 6-15 plug. You have a choice of either running a new 240-volt circuit to the saw, or reconfiguring the motor for an existing 120-volt circuit. The choice should be made on which is the easier method for getting the motor powered.


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## Steve Neul (Sep 2, 2011)

Rick Christopherson said:


> I am sorry Steve, but you are incorrect on this one, as was pointed out by another member. The internal windings on a dual voltage motor are either in parallel or series, and that is the only reason why there is a difference in the current when the motor is reconfigured. The individual windings neither know nor care which way they are configured. They always see the same 120-volts internally.
> 
> Within the motor, there is no change in power, nor heat, nor energy savings, nor dollar savings. It all boils down to what is easiest to supply within the building.
> 
> Back to the original poster, yes, your description suggests a NEMA 6-15 plug. You have a choice of either running a new 240-volt circuit to the saw, or reconfiguring the motor for an existing 120-volt circuit. The choice should be made on which is the easier method for getting the motor powered.


You say this but this was explained to me by a company that rebuilds electric motors. Then as far as power and heat I have seen this from first hand experience operating the same saw at 120v and 220v. There is a definite reduction in the saw motor generating heat at 220v and you can feel a slight power increase. There is a definite benefit to operating a saw at 220v if it is equipped.


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## woodnthings (Jan 24, 2009)

*what size motor?*



Steve Neul said:


> You say this but this was explained to me by a company that rebuilds electric motors. Then as far as power and heat I have seen this from first hand experience operating the same saw at 120v and 220v. There is a definite reduction in the saw motor generating heat at 220v and you can feel a slight power increase. There is a definite benefit to operating a saw at 220v if it is equipped.


I've seen motors under 1 or 1.5 HP and 2 HP that have dual voltage wiring diagrams, but none of my 3 HP motors, if I recall correctly, will run on 120 V. They are all factory wired to run on 240 v. only, so this discussion is not applicable to a 3 HP motor. 

I had a 2 HP Baldor motor on my old Craftsman 10" table saw wired to 240 volts years ago. It would rip anything I ran on it easily, barely even slowing down. I parted out the saw, but still have the motor. :smile3:


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## Steve Neul (Sep 2, 2011)

woodnthings said:


> I've seen motors under 1 or 1.5 HP and 2 HP that have dual voltage wiring diagrams, but none of my 3 HP motors, if I recall correctly, will run on 120 V. They are all factory wired to run on 240 v. only, so this discussion is not applicable to a 3 HP motor.
> 
> I had a 2 HP Baldor motor on my old Craftsman 10" table saw wired to 240 volts years ago. It would rip anything I ran on it easily, barely even slowing down. I parted out the saw, but still have the motor. :smile3:


I figure they make a dual voltage motor so if a person can't or is unwilling to wire to to 240 can opt to use lesser power at 120v. If the voltage made no difference then they could make the motor cheaper by building it a single voltage 120v motor. As far as I'm concerned a 120/240 volt motor is designed and intended to be operated at 240 volts.


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## GeorgeC (Jul 30, 2008)

1 hp = 745.7 watts X times 110 volts = 745.7 watts X = 6.799 amps

2 hp = 1491.4 watts X times 220 volts = 1491.4 watts X = 6.799 amps

X times 110 volts = 1491.4 watts X = 13.558 amps

3 hp = 2237.1 watts X times 220 volts = 2237.1 watts X = 10.168 amps

X times 110 volts = 2237.1 watts X = 20.337 amps

You get slightly different figures if you use 120 volts and 240 volts for your equations.

Regardless, a 2hp motor or any hp motor used the same number of watts whether it is wired for 110 or 220 volts. That 2hp is 2 hp is 2 hp the world over.

As you can see for the 3 hp motor the current just gets too high to run on 110 volts. The cost of the larger wiring required for that hp and larger just prohibits using the lower voltage motor. That is why industrial motors are always run at 220 or higher voltages, not because of any gains in efficiency in the motor itself.

Then you bring in the phase of the power and the explanation gets more complicated.

George


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## Rick Christopherson (Jun 27, 2016)

Steve Neul said:


> You say this but this was explained to me by a company that rebuilds electric motors. Then as far as power and heat I have seen this from first hand experience operating the same saw at 120v and 220v. There is a definite reduction in the saw motor generating heat at 220v and you can feel a slight power increase. There is a definite benefit to operating a saw at 220v if it is equipped.


Unfortunately you were misinformed, but it's not uncommon. Rebuilding motors is a mechanical occupation. They don't need any electrical background. The same is actually true for electricians. Most (but not all) have very little electrical knowledge. 

This is not a new topic. I wrote Electricity in the Woodshop 20 years ago because of it. I invite you to read that, as it covers and explains all of the points you just stated. There was a time that if you Googled the word Electricity, this article was the first hit.

Because the windings are switched between either series connected or parallel connected, the voltage and amperage through each winding is the same regardless how they are configured to external configuration.


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## woodnthings (Jan 24, 2009)

*What a surprise!*

I have often referenced your articles on static or explosions in dust collector systems in response to inquiries here. Thanks for showing up on this forum and please stick around. You have a wealth of knowledge to share. :thumbsup:


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## Brian(J) (Feb 22, 2016)

Rick, I was once firmly in your camp, and I do have some experience with motors. But my thinking is shifting. The reasons are somewhat complex and completely off topic, so I posted those to a new thread, and I hope you will consider commenting.


http://www.woodworkingtalk.com/f12/wiring-120-240-motor-240v-examined-detail-144018/


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## holtzdreher (Jul 20, 2016)

Well I had the chance to check the wire to the barn. 10-3. I was certain I purchased 8 ga wire and was so puzzled by it that I would have dug through old tax records for the wire receipt, except they were lost in a fire. I remembered that I had some extra wire stored in the back shed. I went digging and found a part of a spool of 8-3. Not enough left to run to the barn. So I did purchase 8-3, I just don't know what happened to it. Anyway, I am stuck with a 125 ft run of 10-3 to the barn. So. I will have to watch my amps draw a little closer. (In the winter, I run up to two water trough heater ats 1500 watts each.) The lights have all been changed to LEDs so that draw is minor. 

So I guess i will need to rewire the connections to the motor to 120 volts and limit what is used simultaneously.


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## Steve Neul (Sep 2, 2011)

holtzdreher said:


> Well I had the chance to check the wire to the barn. 10-3. I was certain I purchased 8 ga wire and was so puzzled by it that I would have dug through old tax records for the wire receipt, except they were lost in a fire. I remembered that I had some extra wire stored in the back shed. I went digging and found a part of a spool of 8-3. Not enough left to run to the barn. So I did purchase 8-3, I just don't know what happened to it. Anyway, I am stuck with a 125 ft run of 10-3 to the barn. So. I will have to watch my amps draw a little closer. (In the winter, I run up to two water trough heater ats 1500 watts each.) The lights have all been changed to LEDs so that draw is minor.
> 
> So I guess i will need to rewire the connections to the motor to 120 volts and limit what is used simultaneously.


1500 watts is 12.5 amps. With two of those heaters running with lights at that distance you are using up all of the 30 amps of power you have. You probably need to check the wire coming in from time to time to see if it's getting hot.


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## woodnthings (Jan 24, 2009)

*which is it?*



holtzdreher said:


> Well I had the chance to check the wire to the barn.* 10-3. * I was certain I purchased 8 ga wire and was so puzzled by it that I would have dug through old tax records for the wire receipt, except they were lost in a fire. I remembered that I had some extra wire stored in the back shed. I went digging and *found a part of a spool of 8-3.* Not enough left to run to the barn. *So I did purchase 8-3,* *I just don't know what happened to it. Anyway, I am stuck with a 125 ft run of 10-3 to the barn.* So. I will have to watch my amps draw a little closer. (In the winter, I run up to two water trough heater ats 1500 watts each.) The lights have all been changed to LEDs so that draw is minor.
> 
> So I guess i will need to rewire the connections to the motor to 120 volts and limit what is used simultaneously.


!0-3 would not make sense for such a long run when you installed it. JMO.


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## Steve Neul (Sep 2, 2011)

Rick Christopherson said:


> Unfortunately you were misinformed, but it's not uncommon. Rebuilding motors is a mechanical occupation. They don't need any electrical background. The same is actually true for electricians. Most (but not all) have very little electrical knowledge.
> 
> This is not a new topic. I wrote Electricity in the Woodshop 20 years ago because of it. I invite you to read that, as it covers and explains all of the points you just stated. There was a time that if you Googled the word Electricity, this article was the first hit.
> 
> Because the windings are switched between either series connected or parallel connected, the voltage and amperage through each winding is the same regardless how they are configured to external configuration.


That statement won't wash that a technician that has been rewinding and repairing electric motors for more than 40 years doesn't know how electricity works in a motor.


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## Brian(J) (Feb 22, 2016)

holtzdreher said:


> Well I had the chance to check the wire to the barn. 10-3.


When you say 10-3, do you mean Black-White-Green(or bare copper) or do you mean Black-Red-White?


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## Brian(J) (Feb 22, 2016)

Brian(J) said:


> When you say 10-3, do you mean Black-White-Green(or bare copper) or do you mean Black-Red-White?


The cables you refer to are generally called 10-2/G or 10-3/G, the G refers to a bare ground wire. To an outbuilding, perhaps it's direct-burial wire, but in any case a bare copper wire isn't needed. Instead you drive a ground rod at that building and connect the ground wires from the outlets to that. And where the white wires and the green or bare wires all go to the same buss-bar in the panel of the main building, at the outbuilding the white wires are kept separate on their own bar.

If you have 10-3 that is Black-Red-White you've got 240 and a capacity of 7,200 watts. If you've got Black-White-Ground you have 120 and 3,600 watts.

By code you're supposed to de-rate motors and heating circuits to 80% of those numbers.

If you've got 240, and the saw runs 240, with no other load your voltage drop would be 1.2%, and you are fine.

If all you have is 120, and the saw will run on 120, the voltage drop will be 4.9%, the saw will run OK but you'll want to take it easy and avoid loading the motor with heavy cuts one right after the other. Keep the saw running idle for a bit between cuts.

Above assumes copper wire.


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## TimPa (Jan 27, 2010)

good write up brian, 


additionally, notes for anyone calculating or using voltage drops.


if using the formula E = I x R for calculating the drop, the wire resistance/foot is multiplied by the total distance traveled by the current, which is out and back for both 120 volts AND 240 volts systems.


Since motors should always be kept below 5% voltage drop, large amperage loads when configured for 120 volt are typically wired with a larger wire gauge to compensate for voltage drop.


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## GeorgeC (Jul 30, 2008)

Brian(J) said:


> The cables you refer to are generally called 10-2/G or 10-3/G, the G refers to a bare ground wire. To an outbuilding, perhaps it's direct-burial wire, but in any case a bare copper wire isn't needed. Instead you drive a ground rod at that building and connect the ground wires from the outlets to that. And where the white wires and the green or bare wires all go to the same buss-bar in the panel of the main building, at the outbuilding the white wires are kept separate on their own bar.
> 
> If you have 10-3 that is Black-Red-White you've got 240 and a capacity of 7,200 watts. If you've got Black-White-Ground you have 120 and 3,600 watts.
> 
> ...


There are several ifs, ands and buts about that ground rod. I seen people try to use and stores sell, 4 foot ground rods. These are not adequate under any conditions.

A minimum of a 10' copper rod is needed. In some soils even that is not sufficient. Where I live it is not adequate. On Eglin AFB we have even gone to the extreme of digging a 110' deep well to bury a ground place. And then the soil was salted to further increase the effectiveness.

I brazed together three 10' copper pipes and jetted them in to 30 feet deep to supplement my house's ground.

George


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## Rick Christopherson (Jun 27, 2016)

Steve Neul said:


> That statement won't wash that a technician that has been rewinding and repairing electric motors for more than 40 years doesn't know how electricity works in a motor.


So, a well known electrical engineer tells you that you are mistaken, and you want to continue arguing that your sources are reliable? Got it. You can lead a horse to water, but I stopped trying to force them to learn a long time ago. But you would be well served to pay attention and do some additional research as needed.


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## woodnthings (Jan 24, 2009)

*Not necessarily so*



Steve Neul said:


> That statement won't wash that a technician that has been rewinding and repairing electric motors for more than 40 years doesn't know how electricity works in a motor.



The ground crew mechanic who works on the plane, can't fly it. The computer wizard at the Best Buy can remove your virus, but can't write programming code. The auto mechanic who replaces the broken parts at the dealership can't fix/repair/rebuild them. The carpenter/house framer who builds the home can't design one. 

A technician is not an engineer. Electrical theory is more complex than most can appreciate. I had a few structural engineering classes in college and when it came to calculus and differential equations a whole lot was over my head, but I squeaked by with a new appreciation for engineers. :smile3:


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## FrankC (Aug 24, 2012)

It is also possible that from practical experience the guy that has been rewinding motors for 40 years has discovered that despite the specs given by an engineer there are other factors that come into play for a better or more reliable repair. He will not be able to prove why on paper to justify his method, he just knows it works.


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## GeorgeC (Jul 30, 2008)

FrankC said:


> It is also possible that from practical experience the guy that has been rewinding motors for 40 years has discovered that despite the specs given by an engineer there are other factors that come into play for a better or more reliable repair. He will not be able to prove why on paper to justify his method, he just knows it works.


Do not see what that has to do with the current subject? I have also seen just the opposite happen.

George


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## Rick Christopherson (Jun 27, 2016)

FrankC said:


> It is also possible that from practical experience the guy that has been rewinding motors for 40 years has discovered that despite the specs given by an engineer there are other factors that come into play for a better or more reliable repair. He will not be able to prove why on paper to justify his method, he just knows it works.


A motor technician has no idea what is behind the design of the motor. All he does is remove the existing coils of wire and replaces them with identical new coils. His two primary concerns are whether he used the same wire gauge and the exact same number of turnings per coil. It is purely a mechanical job.

But that's not even the point. According to Steve, his motor "expert" incorrectly described how a motor even functions in the first place. That is an inarguable sure sign that his "expert" doesn't have a clue as to how a motor works. 

No offense to either, but it is not a point that can even be argued. It's a failure of freshman or even high school electricity, and not even close to understanding magnetic principles of motors.


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## woodnthings (Jan 24, 2009)

*I mentioned this before*

For anyone who is interested in the various issues in woodworking,....electricity in the woodshop, getting square cuts, static in dust collectors, climb cutting vs normal with a router check out this site linked above in Ricks signature.

Great information: http://www.waterfront-woods.com/

Also check out the expanding round table build. :thumbsup:


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## Brian(J) (Feb 22, 2016)

GeorgeC said:


> There are several ifs, ands and buts about that ground rod. I seen people try to use and stores sell, 4 foot ground rods. These are not adequate under any conditions.
> 
> A minimum of a 10' copper rod is needed. In some soils even that is not sufficient. Where I live it is not adequate. On Eglin AFB we have even gone to the extreme of digging a 110' deep well to bury a ground place. And then the soil was salted to further increase the effectiveness.
> 
> ...


Yes, there are always the details and the exceptions. In many, perhaps most parts of the US two 8' ground rods 72" apart are now required, with bare copper between them. So you get 16' of galvanized ground rod and 6' of #4 copper


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## Brian(J) (Feb 22, 2016)

FrankC said:


> It is also possible that from practical experience the guy that has been rewinding motors for 40 years has discovered that despite the specs given by an engineer there are other factors that come into play for a better or more reliable repair. He will not be able to prove why on paper to justify his method, he just knows it works.


Steve, I've seen your posts around this site and for me you've got plenty of street cred. I never get the idea you are just pasting in some info you got off the net somewhere, it feels like you've been to the rodeo quite a few times. Where I'm ignorant, like wood finishing, I would consider your counsel carefully. But I'm surprised that what a guy told you 15 years ago and that one experience has become the gospel in spite of any information to the contrary.

FrankC, your point, that practical experience may prove more accurate than some theory, great. But in my case, when I became an electrician I went to night school for three years, motor school was three months. My instructor got his training in the Navy and ended up the chief electrician on the battleship Missouri, he had some stories to tell. We built a couple different crude but working motors, and then that profession became my life's work for 15 years. Lots of problems with lots of motors. I'm pretty sure I know what was going on with Steve's motor and why getting it on a 240 circuit fixed the problem, and 120 wasn't the problem, but that's just speculation.

I think the only way to get Steve, and maybe Frank, on board is to set up two identical tablesaws side by side, 120 and 240, don't tell them which, and let them try to tell the difference. I wait for the results.


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## Jammer (Jul 15, 2009)

Who's the "well known electrical engineer"?

I've never heard of any of you.

Is he new?


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## Steve Neul (Sep 2, 2011)

Rick Christopherson said:


> So, a well known electrical engineer tells you that you are mistaken, and you want to continue arguing that your sources are reliable? Got it. You can lead a horse to water, but I stopped trying to force them to learn a long time ago. But you would be well served to pay attention and do some additional research as needed.


The problem with your argument is what my guy told me was tried and proven. It's difficult to buy a different story.


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## Rick Christopherson (Jun 27, 2016)

Steve Neul said:


> The problem with your argument is what my guy told me was tried and proven. It's difficult to buy a different story.


Yeah, and my mom told me if I didn't stop I'd go blind....>

But that's not what you said your friend told you, and it certainly wasn't proven. But c'est la vie. A wise person would continue learning. I can't fix that.


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## Steve Neul (Sep 2, 2011)

woodnthings said:


> The ground crew mechanic who works on the plane, can't fly it. The computer wizard at the Best Buy can remove your virus, but can't write programming code. The auto mechanic who replaces the broken parts at the dealership can't fix/repair/rebuild them. The carpenter/house framer who builds the home can't design one.
> 
> A technician is not an engineer. Electrical theory is more complex than most can appreciate. I had a few structural engineering classes in college and when it came to calculus and differential equations a whole lot was over my head, but I squeaked by with a new appreciation for engineers. :smile3:


In this case motors are brought to this guy on a daily basis. He has to diagnose what is ailing the motors and determine a fix. It's inconceivable he could do this work without knowing what makes the armature go round and round. I have no doubt there is nothing about electric motors this guy doesn't know. Anyway when it comes to electrical theory it's difficult to find two people on the same page.


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## Rick Christopherson (Jun 27, 2016)

Explain to me again what you think is happening inside of a dual voltage motor. I'd be happy to discuss what is correct or incorrect with you.


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## woodnthings (Jan 24, 2009)

*I know what you mean*



Steve Neul said:


> In this case motors are brought to this guy on a daily basis. He has to diagnose what is ailing the motors and determine a fix. It's inconceivable he could do this work without knowing what makes the armature go round and round. I have no doubt there is nothing about electric motors this guy doesn't know. Anyway when it comes to electrical theory it's difficult to find two people on the same page.


I had to take my lathe motor to a shop that was highly recommended by another motor shop and there were motors from floor to ceiling and on every bench top. These guys knew all about motors I'm sure and I didn't question their expertise. My motor was wired correctly and ran great for $40.00. 

What I'm saying is that above that level of expertise is the "theory" and the difference is between book smart vs street smart. Some times it doesn't make any difference, other times it does. And the best is a combination of both skills. :wink2:


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## shoot summ (Feb 21, 2014)

Rick Christopherson said:


> Explain to me again what you think is happening inside of a dual voltage motor. I'd be happy to discuss what is correct or incorrect with you.


It's been explained to him a dozen times, but he refuses to believe it from anyone here, only the "motor god" that worked at the shop has any creds. You will be ridiculed by Steve and Frank as a paper pusher, they don't believe that formulas correlate to this in any way.


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## Rick Christopherson (Jun 27, 2016)

_Woodnthings, I started writing this off-line before you made your posting, but since you just used the word, I felt I better point that out._

This is just food for thought.

People use the word "theory" to describe any topic which they don’t personally understand, with the implied assumption that if they don't understand it, then no one else could possibly understand it either. Something isn't "theoretical" just because one person or group of people don't understand it. 

Motors fall well within the known group. They are well known and well defined. There is no "unknown theory" behind them. Even the current and voltage relationships within a motor are precisely modeled mathematically, and the only reason why some people assume it is just "theory" is that they don't know the non-simplified versions of those equations. Those are the equations that contain variables that most people have never heard of. But those variables are well known to the engineers that design the motors.


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## Jammer (Jul 15, 2009)

Actually, among educated people, the words "theory" and "theoretical" both have a specific, defined meaning. They are words used in science, to distinguish several modes of thought from other modes.

Until I read your post, I thought electricity fell into the realm of science.


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## woodnthings (Jan 24, 2009)

*Rick, sorry for any confusion*

What I was getting at was "how a motor works" is different than "why it works" A technician may know all about how it works, but may not know why in some cases .... I donno?

I would suggest anyone who doubts your credentials to go to your website and read the articles as I have done. I have known about you for years, having come across the site when researching static and explosions in shop dust collectors, and respect your opinions.


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## Jammer (Jul 15, 2009)

Oh, man, is this that guy who was selling see-through cyclones like they were something new?


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## woodnthings (Jan 24, 2009)

*Nope*



Jammersix said:


> Oh, man, is this that guy who was selling see-through cyclones like they were something new?



That would be Bill Pentz. Clear Vue Cyclones:
http://billpentz.com/woodworking/cyclone/cyclone_plan.cfm


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## Jammer (Jul 15, 2009)

Ah, that's him. So this other guy _is_ new?


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## woodnthings (Jan 24, 2009)

*Nope*



Jammersix said:


> Ah, that's him. So this other guy _is_ new?



Only "new" to you and to this forum. He's been around for years. He does amazing work... the "expanding round 
table" on his site. You did check out the link I posted....?

http://www.waterfront-woods.com/


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## GeorgeC (Jul 30, 2008)

Rick Christopherson said:


> _Woodnthings, I started writing this off-line before you made your posting, but since you just used the word, I felt I better point that out._
> 
> This is just food for thought.
> 
> ...


Well, you are certainly correct.

Electric are long past the "theory" stage. Every aspect of how they operate has been well known for many, many years.

Many people use the word "theory" incorrectly. It is commonly used in place of "principle." ie. Please tell me the theory/principle of of electric motor operation.

George


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## FrankC (Aug 24, 2012)

shoot summ said:


> It's been explained to him a dozen times, but he refuses to believe it from anyone here, only the "motor god" that worked at the shop has any creds. You will be ridiculed by Steve and Frank as a paper pusher, they don't believe that formulas correlate to this in any way.


The problem with your formulas is they all start with "if", in the real world these situations begin with "when".


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## Jammer (Jul 15, 2009)

In theory, there is no difference between theory and reality.

In reality, there is a world of difference between the two.


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## woodnthings (Jan 24, 2009)

*So then....*

In reality, this is a theoretical discussion. 0




Jammersix said:


> In theory, there is no difference between theory and reality.
> 
> In reality, there is a world of difference between the two.


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## Jammer (Jul 15, 2009)

woodnthings said:


> In reality, this is a theoretical discussion. 0


Well, theoretically, anyway. :grin:


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## TimPa (Jan 27, 2010)

the great thing about the internet is that there is a large variety of folks participating, every color of the rainbow. of course, everyone will not agree with everything said.


say your piece, and move on!


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## Jammer (Jul 15, 2009)

Or stick around.


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