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Jack of too many trades..
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Discussion Starter · #1 · (Edited)
I've been using a 1983 Jet (Asian) Contractor saw for about 9 years now. This week I had a chance to pick up a Rockwell Delta Cabinet Saw for a decent price, so I jumped on it. It's now sitting in my shop, waiting to be hooked up.

The Unisaw is 1973 model, great condition with a single phase, 2hp motor, but wired up for 220. We tested it for wobble and smooth running at the warehouse, so I know that it starts and runs ok.

Trouble is, I don't have 220 in my shop, and there's no room in my panel to upgrade right now, so I want to downgrade the setup for 110v.

I did the same for my old Jet via a small panel on the motor. Seems that it's usually just a matter of switching a couple wires. The diagram on the Unisaw motor shows pretty much the same thing

The issue is that this unisaw has some sort of gigantic breaker panel with a smaller sub-box that contains some sort of voltage transformer. These don't look original, and I'm not sure if the wiring setup can be configured to run at 110 - or if all this stuff is even necessary. This appears to be a very complex magnetic starter assembly. the brand Name is Arrow Hart of Hartford Connecticut. The push-button switch on the front is the same brand. My Jet is about 110x simpler than this.



The wires from the motor and the switch are in terrible shape. Hard and crumbly insulation. I put some shrink tube on for now, but it's beyond help. I will get a replacement cord tomorrow. Th wires in the rest of the main panel, and the smaller box with a transformer in it, are all nice and intact, so maybe I'll be safe with some new cords.

I have two questions:

1) Where are the wires for the motor voltage - inside the motor?

2) Is all this "stuff" necessary if i am going to run this saw at 110v? Should I keep this setup, or buy a modern/safer replacement setup?



One of the wires wasn't even hooked up to anything.


-edit-

Did I mention the sawdust? fine-fine dust inside of everything. breaker box, the connector box on the motor, the switch on the front.
 

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Looks like ya got a contactor or a motor starter there. Depending on the type of switch and how the motor is wired it is possible that it is necessary to have it. More info is needed to make that determination.
 

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What is the nameplate amperage? This will be doubled if you attempt to run on 120V.

The motor should state if it can be wired to run on 120V. I would be surprised. It likely needs a 30Amp circuit, if the motor can be run on 120V.

The picture you show may be the guts of a magnetic switch, common for the larger table saw motors.
 

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where's my table saw?
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I run a lot of motors on 220 V

Some are 3 HP with the contactor type magnetic switch and run on 20 AMP breakers. Others use just simple double pole, double throw switches on 20 AMP breakers. Those 220V motors draw about 8 AMPs, so a 20 amp 120 V setup would work.



If you can get inside the motor for a wiring diagram to show connections, line in and load, and rotation, that's all you'll need.Post a photo of the diagram if you find it OR go to OWWM or Vintage Machinery for a diagram of your motor. http://vintagemachinery.org/
 

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Looks like someone kludged up a starter; there is a 24v relay and a transformer. I can't really tell from your photos, but you might be better off ripping that stuff out no matter what you do.

2hp is normally about 2400w, so you would probably need to put in a 30a line to use it on 120v. (I am just guessing, and I can't read your motor plate) As long as you are putting in a line, it might as well be 240v.
 

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Jack of too many trades..
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Discussion Starter · #6 · (Edited)
This is a 2 HP motor. The plate pretty clearly says it can run on 115



The current Amperage of the dedicated line for my table saw is 20a

I agree that this stuff looks a bit sketchy. With all the dust and bad insulation, I'm surprised it didn't catch fire when we ran it at the warehouse.
Any recommendations on new "guts" for this starter setup?

--edit--

Also, what I know about this saw is that it came from a former High School woodshop.
 

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I've been using a 1983 Jet (Asian) Contractor saw for about 9 years now. This week I had a chance to pick up a Rockwell Delta Cabinet Saw for a decent price, so I jumped on it. It's now sitting in my shop, waiting to be hooked up.

The Unisaw is 1973 model, great condition with a single phase, 2hp motor, but wired up for 220. We tested it for wobble and smooth running at the warehouse, so I know that it starts and runs ok.

Trouble is, I don't have 220 in my shop, and there's no room in my panel to upgrade right now, so I want to downgrade the setup for 110v.

that wouldn't be my first choice.

I did the same for my old Jet via a small panel on the motor. Seems that it's usually just a matter of switching a couple wires. The diagram on the Unisaw motor shows pretty much the same thing

The issue is that this unisaw has some sort of gigantic breaker panel with a smaller sub-box that contains some sort of voltage transformer. These don't look original, and I'm not sure if the wiring setup can be configured to run at 110 - or if all this stuff is even necessary. This appears to be a very complex magnetic starter assembly. the brand Name is Arrow Hart of Hartford Connecticut. The push-button switch on the front is the same brand. My Jet is about 110x simpler than this.



The wires from the motor and the switch are in terrible shape. Hard and crumbly insulation. I put some shrink tube on for now, but it's beyond help. I will get a replacement cord tomorrow.

i replaced the wire from the magnetic starter (that's the "gigantic breaker panel with a smaller sub-box that contains some sort of voltage transformer) on a unisaw i refurbished last year. the magnetic starter shouldn't need to be touched and is a great safety feature ( when the saw loses power, it doesn't automatically restart when power is restored).

Th wires in the rest of the main panel, and the smaller box with a transformer in it, are all nice and intact, so maybe I'll be safe with some new cords.

I have two questions:

1) Where are the wires for the motor voltage - inside the motor?

yes

2) Is all this "stuff" necessary if i am going to run this saw at 110v? Should I keep this setup, or buy a modern/safer replacement setup?

you have a set up that is extremely reliable and safe right now.



One of the wires wasn't even hooked up to anything.

i had the same issue. HD didn't have any 10/3 SJ cord so i used 10/4 SJ cord and had one extra lead. not an issue.

-edit-

Did I mention the sawdust? fine-fine dust inside of everything. breaker box, the connector box on the motor, the switch on the front.
blow out the saw dust with compressed air. get a few tandem breakers for your panel to free up space in the electrical panel. adding a 20A 220v line is not a big deal at all, if one has a basic understanding of electrical wiring.

and looking ahead to dust collection for your new saw, see that little square plate beneath the magnetic starter on the saw's base? that makes a great dust collection port, as long as a floor is placed at the bottom of the saw's base (that's the wood slats sealed with foil tape). here's how i did it on the '72 unisaw i sold. with the OEM dust clean out door on the front of the saw and the fabricated motor cover, a 4" hose connected to the dust collection port did a remarkably good job of clearing dust from the saw cabinet.
 

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NEC says 125% of motor rated full load current, in this case 30 amp minimum, and #10 wire. Might better throw in a new sub panel, and run 240 volts as suggested above. Would also leave some room to expand for the next tool to come dragging in. :thumbsup:
 

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where's my table saw?
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Just me

But I would ditch that whole arrangement and use one of these:
http://www.grizzly.com/products/110-220V-Paddle-On-Off-Switch/H8243

I like the large safety paddles and use them on many of my stationary power tools. It is a double pole swicth and will break both the hot and neutral wires, not necessary for 120 V, but a good safety feature. I use them on my router tables running 120 V and my table saws running on 220 V. I replaced a magnetic type switch on an import bandsaw with one also, just as you are wanting to do.

I can't read the 115 V diagram in your photo, but I would simply follow that and use run the wires from the "line to switch" as shown. I like to use 12 ga stranded wire and solder the ends or use crimped on spade terminals. Use a little silicon grease to prevent oxidation of the copper. Black is hot, white is neutral and bare or green is ground to the frame and the green grounding conductor on the plug wire. :smile:
 

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Discussion Starter · #10 · (Edited)
But I would ditch that whole arrangement and use one of these:
http://www.grizzly.com/products/110-220V-Paddle-On-Off-Switch/H8243

I like the large safety paddles and use them on many of my stationary power tools. It is a double pole swicth and will break both the hot and neutral wires, not necessary for 120 V, but a good safety feature. I use them on my router tables running 120 V and my table saws running on 220 V. I replaced a magnetic type switch on an import bandsaw with one also, just as you are wanting to do.

I can't read the 115 V diagram in your photo, but I would simply follow that and use run the wires from the "line to switch" as shown. I like to use 12 ga stranded wire and solder the ends or use crimped on spade terminals. Use a little silicon grease to prevent oxidation of the copper. Black is hot, white is neutral and bare or green is ground to the frame and the green grounding conductor on the plug wire. :smile:
I've got a similar switch on my Jet. Are you suggesting that I can ditch the entire crazy-looking panel? My jet's wiring goes from the plug to the switch to the motor. That set up would be *highly* preferred here.

I plan to go 220, but my panel is full. Already have double-pole switches everywhere that can take them. I can do household wiring, but I'm not ready to install a sub-panel on my own.

--edit--

Also... where are the connectors depicted on the motor plate?
 

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where's my table saw?
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YUP, ditch the panel

I've got a similar switch on my Jet. Are you suggesting that I can ditch the entire crazy-looking panel? My jet goes from the plug to the switch to the motor. That would be *highly* preferred.

I plan to go 220, but my panel is full. Already have double-pole switches everywhere that can take them. I can do household wiring, but I'm not ready to install a sub-panel on my own.

--edit--

Also... where are the connectors depicted on the motor plate?
Last question first. See on the right side 115 diagram where it says "line to switch" those go to the switch. the wires from the plug go to the other side of the switch. SIMPLE. See where it says .."to reverse rotation above" interchange T5 and T8 if that's necessary.
 

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Jack of too many trades..
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Discussion Starter · #12 ·
looking ahead to dust collection for your new saw, see that little square plate beneath the magnetic starter on the saw's base? that makes a great dust collection port, as long as a floor is placed at the bottom of the saw's base (that's the wood slats sealed with foil tape). here's how i did it on the '72 unisaw i sold. with the OEM dust clean out door on the front of the saw and the fabricated motor cover, a 4" hose connected to the dust collection port did a remarkably good job of clearing dust from the saw cabinet.
Looks pretty nice. I've got a galvanized sheet metal cover for the engine side, with a dust-port built in. I doubt it worked very well, considering the dust that was inside of every nook and cranny in the saw. I'm planning to setup something better than a shop vac as soon as get things sorted on this saw.
 

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Discussion Starter · #13 ·
Last question first. See on the right side 115 diagram where it says "line to switch" those go to the switch. the wires from the plug go to the other side of the switch. SIMPLE. See where it says .."to reverse rotation above" interchange T5 and T8 if that's necessary.

Oh, I think get it now. I just change the wire-to-wire setup in the big square block on the motor itself.

The jet has a small terminal panel with spade and fork connectors in the side of the motor, I was looking for something like that here - guess it doesn't exist.

Thanks!

-edit-

this is the switch I put on my JTS-10

http://www.grizzly.com/products/110-220V-On-Off-Switch/H8238
 

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I agree with Warner: keep the relay control, it was added as a safety feature. In commercial applications machines must deenergize on power failure and stay off until manually restarted.

Regardless of how you get power to the saw you will need to run new wire. Either a 30-Amp @ 110-Volt, or a 15-Amp @ 220-Volt. The motors required amperage is listed on the name plate, and you should bump up by 15%, so at 110-Volts you will need 24 X 1.15=27.6-Amps, which means a 30-Amp circuit.

Since you are running new wire get a 220-Volt circuit installed.
 

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where's my table saw?
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commercial applications require a safety switch

The theory is, IF the power to the saw is lost due to a storm or other failure, the machine will NOT start up on it's own when the power is restored. This will prevent a piece in the machine from being thrown back or worse yet if the operator had decided to place their hands in the cutter path, they won't be injured. The chances of this happening are remote, and in a home shop all you have to do is turn the machine off...if you can find the switch in the dark.
Ideally your lighting circuit and the machine circuits are separate!
This would only be an issue if the whole shop lost power, it was night/dark and there was no available or backup lighting. I have no qualms about operating my machines without the magnetic switches although several in the shop have them. The paddle switch at hip level is all I need for an instant OFF. I often use mine that way instead of using my hand.

What you choose to do is up to you, but for a simplified solution, a manual switch will work.
 

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A 20 amp circuit won't fly for a motor drawing 24 amps nominally. If the current circuit wire is thick enough gauge, and your panel can handle the amp flow, there's a slim chance you could add a 30 amp breaker to the circuit, but I'd definitely consult an electrician first.

Best route....run 220v to it if at all possible. A 220v circuit will run at a much lower percentage of it's capacity....better situation, less voltage loss, less excess heat, quicker response.
 

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....Best route....run 220v to it if at all possible. A 220v circuit will run at a much lower percentage of it's capacity....better situation, less voltage loss, less excess heat, quicker response.
but not more power. that motor will only deliver 2 hp in either 110v or 220v configuration.
 

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If that motor nameplate doesn’t say TP or thermally protected anywhere on it you'll definitely need to keep that motor starter in place because it contains the thermal overload protection for the motor [Those two spring looking things in the middle of the motor starter]. If you rewire for 120V, you'll only need one in series with the hot conductor, but not the neutral. The transformer is the step down to reduce the line voltage to 24V for the starter's control circuit.
 

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Discussion Starter · #20 ·
Alrighty. You folks make a pretty convincing case.

I checked my breaker panel this AM and it looks like I've got x2 220V breakers already.

About 12 years ago, my father in-law (an electrician) installed a 30 amp 220v for us that services the 2nd floor (it splits into four 15a 110v breakers at a sub-box on the 2nd floor).

I also have a second 220v breaker. This one is 50a with 8 gauge wire and that used to service our old electric oven.

It looks like I can use this 220v position, (downgrade from 50a to 20A) and simply run my saw from this breaker location. I plan to eventually get some better-quality stationary tools, but for the moment, this saw is the only thing that needs 220v.

I'll replace the cord & switch wiring in the saw, but I'll keep the Unisaw wiring setup the same.
 
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