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I've used Kanthal A1 before, and it works just fine.If you want a specific build or setup, i would go for nichrome because it has an easier readout of it's ohm/resistance per cm/inch etc. So it's easier to calculate how much power you should have running through the length of wire you use, depending on how hot you want it to get.I'm currently in the making of a high-end-diy hot wire cutter with variable power and I'm planning to use nichrome, but i might switch to titanium wire so it could be temperature controlled.
May I just say that the spring actually helps maintaining the stability of the wire, making it less flimsy. The wire expands and contracts when heating and cooling, so if you want to be able to have a more reliable straight wire to cut with, that doesn't bend AS much, put some springs on it :)I've seen another guy doing this with the spring: https://www.instructables.com/id/Plywood-Hot-Wire-...Oh BTW, I also wanted to add that your wire WILL hold, because if you're using force to push the object through, it doesn't get hot enough and/or you, well honestly, WE are too impatient ;)
It waa hard to get even but my girlfiend loves it!