# Please help with table saw motor



## Janderso (Aug 30, 2020)

My son bought a Craftsman ( Sears and Roebuck) table saw. It has a dual voltage 1.5hp Lessen motor.
First off, the motor was wired wrong. 
They had T3, T5 and T8 on #2.
I now have T3 and T5 on #2 and T2 and T8 on #4.
Please see the pics. We are going for low voltage.

I have the chassis grounded.
Where does neutral go?


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## Maddogmech1 (Aug 30, 2020)

Picture of the data tag on motor?


Sent from my iPhone using Tapatalk


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## Packard V8 (Aug 30, 2020)

Low voltage (115v) supply cord should have three wires; L1 hot (black), L2 neutral (white) and ground (green)  The green ground can go to one of the screws holding on the cover plate.

jack vines


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## Janderso (Aug 30, 2020)

Jack,
White-neutral goes to L2?


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## Janderso (Aug 30, 2020)

Packard V8 said:


> Low voltage (115v) supply cord should have three wires; L1 hot (black), L2 neutral (white) and ground (green)  The green ground can go to one of the screws holding on the cover plate.
> 
> jack vines


That’s what I have. I just didn’t know where the white neutral went


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## newbydave (Aug 30, 2020)

Black to L-1 White to L-2


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## Janderso (Aug 30, 2020)

Thank you,
Ill give it a whirl this afternoon


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## aliva (Aug 30, 2020)

It should matter were the white goes. It's alternating current. But normally L 2 is white.


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## WCraig (Aug 30, 2020)

Janderso said:


> ... dual voltage 1.5hp Lessen motor ...  We are going for low voltage.


IANAE*

A 1.5 hp motor would require approximately 25 amps on a 120 volt circuit.  That means that you need heavy gauge wire in the wall to avoid overheating and the risk of fire.  To handle in the inrush of current on startup, the circuit should be oversized by at least 10% so that necessitates 30 amp wiring and circuit breaker.

What kind of motor starter is on the saw.  If it has overload heaters sized for 240 volts, they will also need to be changed.

You may want to consider installing a 240 circuit.

Craig
*I am not an electrician.


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## BGHansen (Aug 30, 2020)

FYI from Google (current draw for a 1.5 hp motor).  Might be some initial extra needed to get it going, think that is the starter capacitor's job.

Bruce


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## Bi11Hudson (Aug 30, 2020)

The diagram shown _should_ be enough. It is *very* direct. The line cord has two functional conductors. The third is a ground, attaching to any convenient metal part of the motor. As a rule, 120V circuits are set up where L1 is the hot, or black wire. L2 is the neutral, or white wire. The Ground, or green wire goes to the motor frame. The important issue is with the dual voltage connections. T2 and T8 connecting to Terminal [4]. T3 and T5 connecting to Terminal [2]. Terminal [3] is left open, no connection.

The diagram doesn't show rated current. Converting to 120V will effectively double the current. The line cord should be a minimum of AWG14, preferably AWG12 or larger. I personally like long line cords and usually make them out of half of an "industrial" 25 ft extension cord. A fairly inexpensive source for molded plugs. . . The AWG wire size is usually printed(heat stamped) at regular intervals along the cable jacket.

The circuit supplying the saw must also be capable of handling the high current. The saw was wired for 240 volts for a reason. They usually come pre-wired from the factory for 120 volts unless they are commercial grade. You may do well to stick with the 240 volt wiring. Depending on the location among other factors, "borrowing" a tap from a dryer or range plug may provide a temporary outlet.

If there is a starter or contactor on board, the overload "heaters" will need changing also. Stash the old ones in a plastic bag taped inside the starter enclosure so they can be found easily if needed. That low of HP motor likely doesn't  have any, but the previous owner may have put one on. If it is magnetic, the coil will need changing also.

.


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## Janderso (Aug 30, 2020)

I checked his wiring, hooked up neutral to L2, the motor won’t turn over. The blade jumps a bit but that’s it.
I have it in my truck.
Tomorrow I’ll ask you guys how to check the windings and start capacitor.
All I have is a Fluke T5-1000
Thank you
jeff


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## Janderso (Aug 30, 2020)

Bi11Hudson said:


> The diagram shown _should_ be enough for a twelve year old. It is *very* direct. The line cord has two functional conductors. The third is a ground, attaching to any convenient metal part of the motor. As a rule, 120V circuits are set up where L1 is the hot, or black wire. L2 is the neutral, or white wire. The Ground, or green wire goes to the motor frame. The important issue is with the dual voltage connections. T2 and T8 connecting to Terminal [4]. T3 and T5 connecting to Terminal [2]. Terminal [3] is left open, no connection.
> 
> The diagram doesn't show rated current. Converting to 120V will effectively double the current. The line cord should be a minimum of AWG14, preferably AWG12 or larger. I personally like long line cords and usually make them out of half of an "industrial" 25 ft extension cord. A fairly inexpensive source for molded plugs. . . The AWG wire size is usually printed(heat stamped) at regular intervals along the cable jacket.
> 
> ...


Oh, we have a problem.
This is an old house. He plugged it in yesterday and it ran then a fuse blew.
Yep, The light bulb screw in fuses are what blew.
Shoot.
No magnetic starter, just a 120v plug off the motor is how it came.
Would you please link or provide specs on the starter required?
I agree,, 220 gives the saw torque.


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## WCraig (Aug 30, 2020)

BGHansen said:


> FYI from Google (current draw for a 1.5 hp motor).  Might be some initial extra needed to get it going, think that is the starter capacitor's job.
> 
> Bruce
> 
> ...


The term "horsepower" has been badly abused over the years.  Sears used to sell woodworking routers that were rated at "3 HP" but required only 12 or 14 amps at 120 volts.  I believe they were measuring just before the motor stalled.

My older Unisaw has a 1.5 horsepower motor.  I mis-remembered the amp draw at 120 volts.  It is only 19.2 but that is still well above what a typical 15 amp household circuit can supply.  I run mine on 240 volts.




Craig


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## markba633csi (Aug 30, 2020)

Hi Jeff- yeah that's a pretty heavy current draw for a 120 volt household circuit.  Anything over 3/4 HP should be run on 240. 
Motors draw much more current when starting than running.  Blown fuse doesn't necessarily mean anything is wrong with the motor or house. 
-Mark


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## WCraig (Aug 30, 2020)

Janderso said:


> Oh, we have a problem.
> This is an old house. He plugged it in yesterday and it ran then a fuse blew.
> Yep, The light bulb screw in fuses are what blew.
> Shoot.
> ...


Please DON'T just screw in a bigger fuse.  That's a recipe to overheat the house wiring and cause a fire.

Use a motor rated starter sized for the amps the motor draws which depends on whether you go 120 or 240 volts.  Your choice of magnetic or manual.  Don't use a light switch--the contacts aren't designed to handle the current inrush and will eventually melt.  Likely in the On position.

AIUI, thermal overload (heaters) are not required for a motor that is always attended.  Thermal overload protection can help to prevent the motor from going up in smoke if overloaded.  Your choice.  Note, that many motors now have thermal protection built in:  the red reset button.  

All things being equal, the motor will perform exactly the same on 120 or 240 volts.  In practise, it is easier to do the wiring right with 240 volts and so you might have a little less voltage sag.  Doing it right with 120 volts means a circuit with heavy gauge wiring and an appropriate fuse or breaker. IOW, a new circuit.  If you have to run a new circuit, just supply it with 240 volts.

Craig


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## Janderso (Aug 31, 2020)

Hmm,
Thanks Craig. Good advice.


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## Janderso (Aug 31, 2020)

If this motor is toast I would want to replace it with a 220v.
The amp rating is basically cut in half.
What about those converters, basically an up transformer?
Would that do?
I was not thinking the old house could not support a table saw.
This motor draws a lot of amps.
Just looking for ideas.
Thanks


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## Bi11Hudson (Aug 31, 2020)

It seems there may be a couple of possibilities for what is wrong(?). If anything is. . .  In the first case, an "Edison" base fuse means the house probably has 15 amp plugs and likely only a few (3-4) circuits. Essentially, such an electric system eliminates the use of such a powerful saw. If used, it would need to be fed from a 30 amp circuit. The first thing to look for is a "penny" behind the fuse. That is almost guaranteed a fire. If the saw took the fuse there probably isn't one.

There are several possibilities to get that feed. An air conditioner, an electric dryer, or a range plug can provide 120 volts on a *temporary* basis. Simply take *one* of the 240 volt lines and the neutral for 120 volts. An appliance pigtail with one line insulated will serve for a temporary line adapter. A range is usually 50 amps, AC or dryer is usually 30.

For a starter, I found a couple at Grizzly. The links are listed below, but usually they can be found at Home Depot or Lowe's. I didn't want to get into a serious search, too distracting. . .









						Magnetic Switch, Single-Phase, 220V Only, 3 HP, 21-25A at Grizzly.com
					

These professional grade magnetic switches protect against thermal overload and automatically shut down if power is interrupted, so equipment won’t start when circuits are turned back on. Single-phase, 220V only. 3 HP, 21-25 amp.




					www.grizzly.com
				











						Single-Phase 110V 3 HP Mag Switch at Grizzly.com
					

<p>Professional-grade magnetic switches protect against thermal overload and automatically shut down if power is interrupted, so equipment won't start when circuits are turned back on. Single-Phase - 110V only. 3HP




					www.grizzly.com
				




They have bigger ones but 3 HP sounded like enough for your machine.

There is a device that is a little larger than a light switch that still fits a single gang box. It is(was??) from Square D. It may be available from W W Grainger. There is a heater sold for individual motor size that basically makes it a manual starter. It prevents automatic restarts. . . You'll need the "Full Load Amps"(FLA) for the motor.

Starting the motor you might try to spin the blade. Use a scrap of 2X4 and stand to the side so when the blade snatches it out of your hand you're not close to the saw.  That would confirm a start capacitor bad. Most likely there is an "open" wire somewhere when the voltage changes were being made.

Hope this helps. . .

.


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## Janderso (Aug 31, 2020)

Thank you Bill.
Plenty to think about.


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## Janderso (Aug 31, 2020)

Interesting. I took the motor to work. I runs fine. Needs bearings but it's pretty obvious the old house just doesn't have enough of a power supply to run this old 1.5HP motor at 20 max amps.
I  have a 3/4 hp motor. Prettty wimpy no?


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## pontiac428 (Aug 31, 2020)

For a table saw, I don't think 3/4 horse is wimpy.  1 hp might be better (what I have on my old Craftsman) as long as we ain't talking about a 14" blade here.  That Leeson motor should be a real nice unit if you can figure out how to send 220v to it and get the start circuit going.


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## Janderso (Aug 31, 2020)

Oh good, I'm glad to hear a 3/4 could run it. John York just set me up with a Rockwell 3/4 56 frame.
Considering the jury rigging we would have to do to get 220 in there, I think a clean 3/4 would be a better choice.
I'll take an old school 3/4 over today's 3/4 any day.


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## pontiac428 (Aug 31, 2020)

I think my Craftsman was originally spec'd for 3/4 horse, and the 1 HP China Central Freight motor was my Dad's "upgrade" (you know what they say about Chinese horses).  It was a while ago.  But if you have a line on a true 3/4 horse, I think you will be fine.  You'll probably stall the blade if you twist a sheet of plywood against it halfway through, but that's always the case.  




__





						What is True Horsepower of Taiwanese and Chinese Electric Motors?
					

The machines in my workshop include 3 Baldor motors, a Dewalt Motor on my old RAS, and three motors made in Taiwan or China.  The larger Baldor motors include NEMA Nominal Efficiency and Power Factor on the motor nameplate.  There is no such information on the Dewalt motor or the Taiwan or...



					sawmillcreek.org


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## Bi11Hudson (Aug 31, 2020)

Just a comment on newer motors vs "old school" motors. Power tools today, particularly Craftsman, are rated for max load amps, ie "_develops_ xxx HP". The same system being used by the Chinese. That rating is based on maximum current at rated voltage calculated in watts. 750 (m/l) watts equals 1.0 HP. It's actually 745 point_ something_ watts. When calculating loads, I usually use 750 watts. . . Easier to figure and a smidgen of wiggle room. Old school motors had power calculated based on torque. Which one is *more* correct is debatable. But knowing marketing editors and their shenanigans, I don't have much faith in the modern system. I have retrofitted Baldor motors to several of my machines. Tough and fully enclosed(TEFC) so swarf doesn't get into the electrics. I have a *1/3rd *HP on a Craftsman 12X36 that runs fine and takes anything I have thrown at it so far. Granted, I do small work as a rule. But the machine runs stable and never bogs down. Belts slip but it has never stalled.

.


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## Janderso (Sep 1, 2020)

Good old Baldor
That’s interesting about hp rating.


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