Originally Posted by vtdiy
What I need is the voltage and amperage measured that you use when you are cutting, and your hot wire length.
Here are some measurements I took from a bow that I've been using successfully for years:
Wire material: stainless steel, 0.016" diameter (see photo)
Power supply: transformer / dimmer type
Actual heated wire length: 34.2"
Voltage across heated length of wire: 19.1 VAC
Current: 2.62 amps
I adjust the current to get the best cutting action. Generally, this is just below the point where the wire starts to glow a dull red (as observed in a dark room).
I've found stainless steel to be much better than nichrome, and a fraction of the price. The 600' roll I bought (less than $20) will last me several dozen lifetimes. A bit thicker than the 0.016" I have would probably be better.
Just a note to those who may not be aware of it. The voltage and current from dimmer type controllers operating at anything less than full output cannot be accurately measured by most inexpensive, general-purpose multimeters. At the risk of oversimplifying, this is because these dimmers work by cutting off the electrical waveform part way through each cycle. Most multimeters cannot properly read the resulting "irregular" waveform, and the errors involved can be very significant. Accurate measurement needs a meter with what is called RMS capability (see photo). The measurements shown above were taken with a meter that has this.
Hope that helps. Good luck with your project.