Tales of Woe!

[refinery mike]

I would not think that you would get acceptable results by threading CRS rods at 600 RPM with a simple die. l suspect that the rod is the problem. that is if the dies are good. Threading 1/4 28 thread should not be that hard. Do not expect to thread a .250 rod of CRS to get a 1/4 inch thread. My handbook says you can go all the way down to .238 for an acceptable thread. On brass you may start with .25 rod but CRS tends to squish up a little as well as cut. The effect is that the metal is wedging in the die and you are having to shear off the tops of the thread.
Threading a long thread in a die is less than optimal. It would be better to single point thread it close and finish the thread with a die. For some reason, no matter how carefully you start the thread. the thread gets out of wack with a die. the rod bends and the threads get twisted. Comercial rod is roll threaded. An interesting watch on Youtube is bolt making.
Putting a simple 1/4-28 thread on a steel rod should not be that hard. And remember if you wish once you have gotten a good start on the thread you can take it out of the lathe and thread it by hand in a vice if you wish to. Good luck. Mic the threaded rod you bough when it comes in,the threaded rod i buy is less than .250, I find it generaly to be a loose fit thread.