What size wire to use for 4-40 threading die
Personally I would not use the soldered on ends, it's a potential source of failure. The heat needed to obtain a good joint weekens the kwik link IMO. I purchased some 5-40, and 4-40 dies from Microfsteners. I use 1/8" welding rods, I have found the nickle alloy rods work better than the mild steel rods. You can purchase a handfull of 36" welding rods from a welding supply store for just afew bucks that will last almost forever.
Vince