I am building a hotwire table. I'm using my tattoo power supply as a source. It's output is fine (3-15-V Dc).Even the clip cord reads the same . When I connect it to the table my voltage goes crazy! So the problem has to be in my table components. Is a "stove" Bolt necessary? Or will any bolt do?
Any bolt will do fine, but I agree the problem is not necessarily with your power supply.
So… let's see if I can keep this simple.
Any time a power supply is placed under an electrical load (your cutter) you will see a small voltage drop at any attached reader. This is a normal result of electrical resistance, current output, etc.
But your problem is MOST likely related to the maximum output amperage/wattage of your power supply. If the numbers are going all crazy once you hook up your supply, then I'd wager a guess you're "clipping" out the power supply as an over current protection. Or, if there is no OCP, then it could just be feeding back, overloading your power supply and it's shorting out.
Here is a document I have on OCP - Link
Relating all this back to your cutter.
Your cutter has a defined resistance, and when an electrical pressure (voltage) is placed on that circuit (cutter) it will generate a current (amperage). If your resistance is too low, and your voltage is too high, it will allow too much current to flow; and that flowing current may be higher than what your power supply can handle.
Your solution is to use a smaller gauge nichrome wire (which has a higher resistance) or include a resistor in your circuit. I have a tutorial video on making your own resistor out of aluminum wire.
Check out my Electrical Calculations Videos ( link ) which should be a really good walk through from beginning to end.