I'd like to start a thread here dedicated to providing "quasi" technical information regarding appropriate wire for foam cutting. There are several other wire threads but seem to lack in any discussions or info on comparisons of the physical properties of the various wire types available. We all want to use the best wire for our machines, but everyone seems to recommend a different wire or supplier.

To start off let me state what I believe the parameters for the ideal (best) wire are:

A - Resistance to breakage

B - Resistance to bending (bowing)

C - Uniform heating

D - Minimal current needs (high heat/current ratio)

E - Minimal stretching (elongation)

F - Modest tensioning force requirement

G - Availablity and reasonable cost

There seems to be two types of wire in use: Resistance and non-resistance (for lack of a better term) wires. Perhaps another appropriate terminology would be semi-conductor and conductor type.

Resistance wire (NiCr - Nickel/Chrome alloys) heats proportionately to the current (amperage) running through it and uses relatively low current. As most substances, it stretches (elongates) when heated and placed under tension. It is widely available in various gauges and alloy mixes.

The non-resistance wire that seems to be used by some here includes piano, guitar, leader, and other mostly steel alloy types. Correct me if I'm wrong but these require higher currents (dangerous and require more robust/expensive power supplies and VERY precise current control?), but offer an advantage over resistance wire in terms of higher strength, breakage resistance and minimal stretching.

I've always used NiCr wire for its availability and simple/low current requirements. It does seem prone to breakage however. In my mind, NiCr wire that rarely breaks would be ideal.

Feel free to post any corrections or additions to the preceeding
AND any wire technical specs/info or links to such info.

PLEASE NOTE: Please only post messages of technical or quasi-technical info regarding wire for foam cutting.

couldn't you just go to thicker nichrome wire instead of something that requires higher/dangerous currents?

I have had the most success by using Inconel 750X CU Alloy .0200 or .0140 in my foam cutting experience. It tensions very well and withstands very high heats. Using Inconel 750X is definately worth the price in the quality of the resulting cut foam parts. Please contact me for further information.

I look forward to seeing what comes up here. Its sort of hard to put a consistant label on all the different schools of thought since everyones machine is a different size. My 9 foot machine is going to require higher volts, amps etc. than some machine where the wire is 20 inches long.
The accumulative heat expansion of a material over a 20 inch lengh may be acceptable, while being an entirely impractical change on larger machines. Even the wire tension is going be hugely different between the different sized machines. Over the years, Ive found that the only thing I can use with a degree of reliability is the inconel .012-.014 It only epands about 1.5 inches over 105 inch lengh, and it can easily support the amount of tension that a wire that long needs. Ive been able to use the same wire sometimes for weeks, and sometimes ill break 3 a day. I believe the latter is due to small nicks in the wire or something, as all the other variable remain the same. If someone else is using something different on a large machine with good results, please let me know what it is.

Have you tried the Rene wire from skiKing link (url http://www.skykingrcproducts.com/accessories/foamcutterwire/renewire.html)
If so what do you think of it?