Another post for Fred:
It is a good idea not to just get a die for that thread size, but also a few taps. Victor doesn't have them, but they are on
ebay. When I make screws, I often find myself tapping a section of aluminum rod to act as holders for the screws I've made.
There are lots of ways to slot a screw, but perhaps the cheapest and fastest way to do it, is to use the cutoff wheel of
a Dremel tool. You may have to build a jig to keep the angle right. And for what it is worth, I can't work on stuff without
a set of optivisors.