Single wire foam cutter HOW TO MAKE ONE?
#1
Junior Member
Thread Starter
Join Date: May 2004
Location: Temecula,
CA
Posts: 16
Likes: 0
Received 0 Likes
on
0 Posts
Single wire foam cutter HOW TO MAKE ONE?
I have a simple wire cutter set up at home using a basic car battery charger, but I would like to have or make a home made hand held version of a single wire foam cutter, like the ones used for trains. My question: Can I use a simple power adapter from a small appliance or radio etc... to power a 4" or so single wire to cut slots or for trimming? I would need output information. Thanks
#3
Member
Join Date: Sep 2003
Location: Rothschild,
WI
Posts: 89
Likes: 0
Received 0 Likes
on
0 Posts
RE: Single wire foam cutter HOW TO MAKE ONE?
[link=http://1scom.net/~rv6_flyer/training/index.htm]Here[/link] is a tutorial on Hotwiring Foam Wings.
I made a power supply - works great - $30 high estimate.
I had to use a 4amp fuse - the 2amp kept blowing.
I think it'd be good to wire in a switch to "remove" one transformer from the circuit - for shorter bows.
But I know little to nothing about electricity - just an idea for an improvement...
I made a power supply - works great - $30 high estimate.
I had to use a 4amp fuse - the 2amp kept blowing.
I think it'd be good to wire in a switch to "remove" one transformer from the circuit - for shorter bows.
But I know little to nothing about electricity - just an idea for an improvement...
#4
Junior Member
Join Date: Jun 2004
Location: Silver Spring,
MD
Posts: 10
Likes: 0
Received 0 Likes
on
0 Posts
RE: Single wire foam cutter HOW TO MAKE ONE?
To size a power supply you have to use ohm's law:
I = E/R where I is current, E is voltage, R is resistance
On a wall adapter, voltage and current are written on the label. Voltage is always constant. The current listed is the max that the adapter can safely supply. The true current is determined by the load. You need to measure the resistance of the wire with a multimeter and calculate the current using ohm's law. Keep the current below the max, or you power supply will get very hot. Note it is possible for the voltage to be too low and the wire will not be hot enough. In this case you need a higher voltage supply.
4" is very short and will have a very low resistance. You don't need much voltage at all for this length. Try a flashlight battery (~1.5volts). Add a pot to adjust the resistance if it get too hot.
I = E/R where I is current, E is voltage, R is resistance
On a wall adapter, voltage and current are written on the label. Voltage is always constant. The current listed is the max that the adapter can safely supply. The true current is determined by the load. You need to measure the resistance of the wire with a multimeter and calculate the current using ohm's law. Keep the current below the max, or you power supply will get very hot. Note it is possible for the voltage to be too low and the wire will not be hot enough. In this case you need a higher voltage supply.
4" is very short and will have a very low resistance. You don't need much voltage at all for this length. Try a flashlight battery (~1.5volts). Add a pot to adjust the resistance if it get too hot.
#6
Join Date: Oct 2002
Location: Chilliwack, BC, CANADA
Posts: 12,425
Likes: 0
Received 22 Likes
on
19 Posts
RE: Single wire foam cutter HOW TO MAKE ONE?
It's not just the voltage. You need a supply that will also provide the current. Think of it as voltage being the water pressure in a pipe and the current is the gallons per minute that you can draw from it. To cut foam you need roughly 4 to 6 amps of flow through most of the wires I've seen used. A flashlight battery will not provide that much current in most cases and if it did the battery would run out in minutes. Similarly the wall wart supplies will not work either for the most part as they are usually limited to 1 amp or less. Mostly a lot less.
Oddly enough this is where a left over computer power supply can come to the rescue. Use the 5 volt side and it'll work like a champ. These supplies need a load on them or they do not run. The foam cutting wire will provide just the right amount of load. You may need a high current rheostat to adjust the heat of the wire. In this case you cannot use a lamp dimmer to control the supply so don't even think it. You can make your own rheostant from some 1/32 or .045 music wire. Put the music wire between two posts and use alligator leads or screw clamps to connect the power leads between the supply, the rheostat and the cutting wire. To lower your heat put the clips further apart on the rheostat wire. To raise it move them together. CAUTION! That rheostat wire is probably going to be just as hot as the cutting wire so be careful and put it where it won't do any damage.
Oddly enough this is where a left over computer power supply can come to the rescue. Use the 5 volt side and it'll work like a champ. These supplies need a load on them or they do not run. The foam cutting wire will provide just the right amount of load. You may need a high current rheostat to adjust the heat of the wire. In this case you cannot use a lamp dimmer to control the supply so don't even think it. You can make your own rheostant from some 1/32 or .045 music wire. Put the music wire between two posts and use alligator leads or screw clamps to connect the power leads between the supply, the rheostat and the cutting wire. To lower your heat put the clips further apart on the rheostat wire. To raise it move them together. CAUTION! That rheostat wire is probably going to be just as hot as the cutting wire so be careful and put it where it won't do any damage.