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12-21-2005, 06:55 PM | #1 |
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Proper voltage for hotwire?
I am wondering what everyone uses that has been cutting foam for a while in terms of voltage. I have a variable voltage supply that goes up to 15 volts and 35 amps. That is enough for about 2 feet of wire at the most, but I want to build a cutter with about 8 feet of wire. Would a variable supply up to 24 volts be sufficient?? I want to be able to control the heat so I can cut different ammounts of foam. If I go from cutting a full 8 feet and then try to cut something at around 2 feet I will have too much heat without adjusting it, right?
I would rather stick with a complete unit.. IE-not a variac and all that junk. Steve |
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12-21-2005, 07:51 PM | #2 |
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I am: Ken Currell
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The easiest way to vary the votage is with a variac but you will need an isolating transformer on the output side of the variac to prevent being electrocuted.
I have a 120 volt 15 amp variac and I am about to purchase a 40 volt 50 amp transformer for the output side. This setup is total overkill but that is what I have and the price was right. |
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12-21-2005, 07:57 PM | #3 |
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I am: Ken Currell
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I use several different bows with different lengths and thickness of wire.
With this setup I can use a wire that is bent to a shape and only a few inches long or 10 feet long if I want to. Each different length and thickness of wire requires a different amount of electricity to work properly. The easiest way is to do some test cuts until you get it just right. Even the different types of foam require changes te get the heat just right. |
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12-21-2005, 08:01 PM | #4 |
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I am: Ken Currell
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Sorry.
I forgot to mention that I never check the actual voltage. Some guys use a battery charger. You would have to get it right by adjusting the length and/or the diameter of the wire with that method. |
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12-21-2005, 08:07 PM | #5 |
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Steve,
Something is definitly wrong if you can only do about 2 feet with that many amps. My homebuilt one that I use to use was 24v 3 amps (Radio Shack) and I have cut up to 36" with it. 2 feet was fairly easy. The one I am using now is 28v 8 amps power supply with a dimmer in the line instead of varying the output. Ken, You are right, it is overkill but if the price is right then you have a deal. You can always turn it down but it is real hard to turn them up. John
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12-21-2005, 08:17 PM | #7 |
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I am: Ken Currell
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I will also use the variac to reduce the heat on a heat gun I bought after I rewire it so the fan runs properly.
I am sure I will find other uses for the variac. That makes it an even better buy. I got mine a a recycling/scap dealer. The transformer/welder at a pawn shop. |
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12-23-2005, 03:35 PM | #8 |
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I use a Variac with a transformer also. I use .020 piano wire on everything and have bows from 6 in. that screws to the front of my bench and is used like a coping saw, to a 4 footer, and find the voltage only varies between 7 and 12 volts at the most, for any length of wire. The cutter I use the most is a piece of plastic hot water pipe bent around in a bow. S hooks on one end so I can undo it when not being used, so it doesn't take a permanent bow. Looks like H but works the best of any of them, mostly because it weighs next to nothing. Cuts a 24 in. hunk of foam.
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01-02-2006, 08:05 PM | #9 | |||
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Re: Proper voltage for hotwire?
Quote:
If I had do it it over again, I'd use a 120/24V transfromer rated for 100VA and use one of those Leviton 600W dimmer switches on the primary side. See here: http://www.rcgroups.com/forums/showthread.php?t=287621 Quote:
Quote:
Brad
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Mine is not to reason why; I just wire them up to fry...I mean Fly! I don't suffer from insanity...I enjoy every minute of it!!! I never claimed to be the sharpest knife in the chandelier...... Brad Kacer MAAC # 29287 |
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