Wednesday, June 27, 2012


Another question emailed by a user, with my reply...

I found your video and info on NiChrome wire interesting.  I am working on a much longer run of NiChrome wire to burn through some tough fabric.  Are you available to discuss AC vs DC voltages?

No problem at all.

Long story short, when it comes to a resistance wire application (nichrome wire) it really doesn't matter. The fact of the matter is, NiChrome wire only requires an applied electrical pressure (voltage) and a current running through the circuit. Whether its a constant flow from direct current, or an alternating flow from alternating current it doesn't make any difference.

But as far as what your specific project requires, it really depends on the length of wire and the diameter you'll require - as you may be aware, both will impact the electrical requirements. 

AC power supplies are usually cheaper and have a higher voltage capability. Whereas DC power supplies are sometimes easier to come by.  I always warn users to be cautious of any power supply that outputs more than 45 volts, which is the threshold for penetrating dry human skin. Not many circuits require voltages this high, so why run the risk with a high output AC transformer? But both are perfectly acceptable options.

Jacob's Online has some good solid state step down AC transformers that are beefy and can handle quite the load. So if you intend on making your own supply, check out what he has stocked. I've personally made a power supply from his units, and it works great!

Otherwise check out the Benchtop Power Supply Section of the website which lists a few vendors that have great customer service and a variety of power supplies. I've referenced a few times, they have a great section on AC transformers

Hope that helps!


Thursday, June 21, 2012

Power Supplies & Wire

Here is another emailed question from a user regarding power supplies and type of wire. 

I was looking at your webpage regarding hot wire foam cutters. I tried making a cutter but it seems that I may have bought the wrong wire. I have a toy train transformer that cuts of in about 15 seconds after it heats the wire to cut. I bought fishing wire (stainless steel)... I am very frustrated with this and really want to make this work. I'm not interested in cutting foam but as I am in cutting PVC boards. 


I would recommend spending a little time and cruise through my website, it has all the information you desire. But I think the Introduction Page may answer alot of your questions.

There are a few things, stainless steel wire does not have published heating/electrical requirements so a lot of it's use is experimentation. NiChrome wire is preferred because we know how much electricity it takes to heat different lengths and gauges. That information is located here

It is unlikely that the train power supply will be effective for long term use. It wasn't designed to output the wattage (amperage (x) voltage) required to heat nichrome wire (or stainless steel wire) for extended periods of time or even short periods of time. Check out the power supply calculations page which will help explain why, and also provide you with ways of estimating your power supply requirements. 

The Introduction Page does have some general power supply information, but on the Materials Page there is a link to recommended power supplies for general small scale use. You may end up spending a bit to get a decent power supply, but it is worth alleviating the headache! On the Materials Page you'll also find a link to purchase NiChrome Wire, but I have always had superior customer service and recommend Jacobs-Online for nichrome wire. 


I know there wasn't a lot of content in this FAQ, but I just wanted to post so you can see the types of questions we receive. Also, I wanted to post the links to the website in case you too have similar questions. I always recommend people start out by reading through the introduction page for abridged notes to foam cutters.