challenger
Stainless
- Joined
- Mar 6, 2003
- Location
- Hampstead, NC-S.E. Coast
I have cobbled together a hot wire foam cutter. I use it to cut rigid insulating panels into "follower boards" which I use in some of my beehives during winter.
The cutter is made with 18" of 26 ga. Nichrome wire salvaged from a toaster or something-I forget exactly what appliance I got it from. I made a "bow" by heating and bending some 3/4" PVC pipe and I isolated the ends where the wire ends are and where the supply voltage goes to. The power supply I'm using is a regulated PS the is 24VDC/5A output. The problem I have is regulating the output so it doesn't make the wire too hot. Up until now I've been using a large 25 ohm rheostat which I paid a fair sum for a few years ago. This isn't the best way to control this circuit because I only need about 3 ohm added in series to the circuit to get the resistance proper for the right sire temperature. This uses a very small part of the rheostat which results in the rheostat getting pretty hot. Today I spent time adding another large 5 ohm resistor in parallel with the rheostat. This allowed me to put the wiper of the rheostat about 1/2 way which seems like something I can deal with. I found that I can control the wire temperature much better. My concern is is there is still a lot of heat coming from the rheostat and the resistor (an automotive ignition part).
Should this heat concern me? If not then I'll just make a metal box to put the resistors and PS into so there is no chance that parts will contact each other or contact me. I originally had the rheostat mounted to the bow and this got too hot for me to be happy with.
Thanks for any advice. I've looked far and wide for a better way to control the DC output but for a regulated DC output it seems like the adding of resistance is the only reliable way to do this. I don't want to buy another power supply so I need something that works with this one.
The cutter is made with 18" of 26 ga. Nichrome wire salvaged from a toaster or something-I forget exactly what appliance I got it from. I made a "bow" by heating and bending some 3/4" PVC pipe and I isolated the ends where the wire ends are and where the supply voltage goes to. The power supply I'm using is a regulated PS the is 24VDC/5A output. The problem I have is regulating the output so it doesn't make the wire too hot. Up until now I've been using a large 25 ohm rheostat which I paid a fair sum for a few years ago. This isn't the best way to control this circuit because I only need about 3 ohm added in series to the circuit to get the resistance proper for the right sire temperature. This uses a very small part of the rheostat which results in the rheostat getting pretty hot. Today I spent time adding another large 5 ohm resistor in parallel with the rheostat. This allowed me to put the wiper of the rheostat about 1/2 way which seems like something I can deal with. I found that I can control the wire temperature much better. My concern is is there is still a lot of heat coming from the rheostat and the resistor (an automotive ignition part).
Should this heat concern me? If not then I'll just make a metal box to put the resistors and PS into so there is no chance that parts will contact each other or contact me. I originally had the rheostat mounted to the bow and this got too hot for me to be happy with.
Thanks for any advice. I've looked far and wide for a better way to control the DC output but for a regulated DC output it seems like the adding of resistance is the only reliable way to do this. I don't want to buy another power supply so I need something that works with this one.