Team Eventorizon: Build Diary

[overkill]

The only problem with using pre-hardened steel like Hardox is machining it like the broken disk; you can waterjet the profile but cutting the tapered tooth and the thin spokes would be difficult. Waterjetting a thinner disk is easy enough, but you will have lower KE for the same weight.

Comparing H13 and S7 steel, the S7 has the impact resistance needed in a KE weapon and the trick to getting the most out of it is to NOT harden it to the max. The US guys harden to RC 50 to 54 and that gives it even more toughness. Another critical thing is to use a heat treater who is familiar with the steel - I made a part in S7 and had a local shop do the heat treating. It came back super brittle and I am pretty sure they didn't anneal it properly, if at all.

[MikeNCR]

The US guys harden to RC 50 to 54 and that gives it even more toughness.

To add to that bit, on my old bar spinner Moros I had a 3" x 3/8" x 28" S7 bar spun by a short mag through a 2:1 right angle box. Besides a bit of mushrooming at the tip, I never had a problem with the bar failing.

A few videos: