Here is the fixture that I use for straightening sections. I purchase hollow rope at the Hardware store and pull the solid core out and use the braid. You  can get rope in 1/8 to 1/2 " sizes. I buy a 250' coil of the three sizes  that I use. I have a 7' x 3' x 4' oven that I cure graphite in that I  use to cure my rods at 250 degrees for 20 minutes.