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Discussion Starter · #1 ·
My Laguna 14SUV bandsaw is 220 volt with a garden variety push button magnetic motor starter. The machine comes with a foot brake, complete with a kill switch that interrupts the power to the magnetic coil in the switch, stopping the motor.

But there is no safety switch to keep from turning the machine on when the blade tension lever is in the un-tensioned position. If I forget to move the tension lever before starting the motor, the tire spins in the blade, then throws the blade into the throat plate. I want to install a limit switch in series with the brake switch so that the tension lever must be in the correct position to start the motor. That part is within my capabilities, but I can't find any information about how many amps the magnetic coil draws.

Question: Does anybody know what the typical amperage draw of the magnetic coil on a 220 volt motor starter is?? I'm not talking about the amperage draw of the motor itself, only the magnetic coil of the starter.
 

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Andy I can't answer your question but I may help you find the answer. Most every town of any size has an electric motor repair. That is who I would go to. The one in my town are very nice and want to help you out. They don't charge anything for little stuff like what you are wanting to know. The last time I was over there he again didn't want to charge me anything but I made him take $20 and told him to have nice lunch.
 

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Why not throw your question back to Laguna? Surely their Engineering Dept. can answer it, or make an alternate suggestion.
This issue may well have been brought up before with them. You could always just pull the plug...
 

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Discussion Starter · #4 ·
You could always just pull the plug...
You fail to understand . . . the purpose of the whole exercise is to protect myself from my own forgetfulness.
I finally got off my carcass and disassembled the saw enough to get to the brake switch. I'm surprised that it has 15 amp capacity. Now surely they aren't wasting 15 amps at 220 volts just to hold the magnetic switch closed. However, there are a plethora of 15 amp limit switches available at low prices, so I'll just buy one and sleep well at night.
 
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You could run power through a switch before it gets to the magnetic switch and then you don't have to worry about what it draws. Just use a switch that will carry the full load of the saw. Remember that you only have to switch one wire if you want. That might make it easier to find a switch. I would think you need a switch that is normally open and the lever would close it.
 
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A motor starter coil is going to draw hardly anything. If you are trying to size a limit switch with a large enough current rating, pretty much any generic mechanical limit switch would work.
If you don't like that answer, if you can provide more information/part number on the motor starter, we can be more specific.
Dave
 

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Discussion Starter · #8 ·
A motor starter coil is going to draw hardly anything. If you are trying to size a limit switch with a large enough current rating, pretty much any generic mechanical limit switch would work.
If you don't like that answer, if you can provide more information/part number on the motor starter, we can be more specific.
Dave
The motor starter is NHD brand model MS-15, made in China. It is nameplate rated for 3 HP motor on AC. However I couldn't find that specific model on the internet, nor even any data on current draw for the magnetic coil on any starter.

However, I have since uncovered the brake switch, which is rated for 15 amps. There are plenty of 15 amp limit switches available for under $10, so I'm set now.
 

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Hello!

Two different ways:

1) Install your switch to cut the main line then it should be a big powerfull rated switch like 15 amps 220 v

2) Install your switch to cut the foot brake switch coil line then the real minimal rating is small like 1 Amp , but 10 is usual and better.

Anyway, you can' t go wrong , install this, test it and it will work

3) the main safety switch is your brain.

Regards
Gerard
 

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David - Machinist in wood
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I've thought of the same thing, Andy, but fortunately I have yet to turn the saw on with the blade in the relaxed state. And, as others have said, I doubt the coil pulls much more than one amp, if that.

My routine with the saw is to open the top door, begin spinning the wheel by hand, then tension the blade. Only then do I turn it on, so it's probably my routine that has prevented me from turning it on in the relaxed state. And I'm OCD about 'my routines', just ask my wife... :nerd:

David
 

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I'd like to see what you come up with. I sometimes forget tensioning and the blade dismounts when I accidentally start the saw. (I'm old, that's my excuse.) I wonder if there might be some kind of magnetic or contact switch that would cut electrical power if the tension lever isn't engaged? Something simple and mechanical. This would be a great suggestion to pass along to Laguna, I'd hate to have my Resaw King blade come off the wheel and smack into the table...oh, nasty thought.
 

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Discussion Starter · #13 ·
Thanks for all the suggestions. I bought a 15 amp push-button momentary contact switch with cover. I'll wire it in series with the brake switch and mount it so the tension release handle pushes the button when the blade is tensioned.
 

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I have a 14" Grizzly BS and I put a foot long stick in a notch where the handle is that releases the tension. The piece of wood is about 1/4" thick, 3/4" wide and about a foot long. It helps me to see that the tension has been released from across the shop and reminds me to put tension the blade when I get ready to use it.
 

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I have had the same problem,forgetting to tension the blade before turning on the motor. To solve it I simply have a piece of paper covering the switch that says "tension blade". Since doing that have never had the problem again.
 

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Discussion Starter · #17 ·
There was a story making the rounds a few years ago about the days of the space race. The Americans found that their pens wouldn't write in zero gravity. They contracted with a pen manufacturer to build a pen with a pressurized ink cartridge that would write in zero gravity or upside down. The Russians used a pencil.

I'm an American.
 
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It's a true story. How much it cost was part of the story. I don't remember just how much the research cost but it was lots. My business partner bought one of the pens at a trade show he went to and it was an obscene amount of money for a pen at the time. And the joke was that the Russians spent something like a nickel.
 

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I like the sign. There are magnetic signs for fire places that say flue open on one edge and if you turn the sign upside down, the other edge says flue closed. It is nasty to start a fire if you have forgotten to open the flue and wastes energy to leave it open when not using the fireplace. Get a magnetic business card or something similar and mark it "tension on" and "tension off" When you release tension, invert the card. It is more durable than a paper or cardboard sign. P touch is great for lettering. I haven't messed up with the fireplace since I made the card. Cheaper than an interlock switch.

Sent from my SM-G900V using Tapatalk
 

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I use a small scrap of 3/4 thick wood. It says “tension blade” on it. When I untension the blade I stand the piece of wood up in the miter track.


In woodworking there is always more then one way to accomplish something.
 
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