Pancake dies, as they are commonly known now, but which started out as RT Dies, were invented/presented by Roger Taylor in 1980. Skip to now, assuming knowledge of the difference between inexpensive pancake dies that are laser cut with the cut perpendicular to the die plate and are “loose fitting”, and self-made, or made -by-me dies, which are sawed out at a precise angle to give tight tolerance, I want to talk about a new development that started late in 2021.
After 35 years of using 0-1 tool steel, I poked around and found some 4130 alloy steel in the right thicknesses and decided to give it a try. 0-1 is a high carbon steel (.6% C) whereas 4130 is only .3% Carbon, an alloy not thought of or used for cutting dies, because the lower Carbon content means that it can’t be made as hard as the higher-Carbon steels. It’s considered a water quench steel, and is considerably less expensive than 0-1, and here’s the biggest reason: it’s a little bit softer, so it’s easier to saw. The numbers don’t indicate much of a difference, with annealed 4130 coming in at B85, and 0-1 at B85-95, but there’s always a range that the steels actually fall within, and it turns out that a seemingly small difference in number shows up as a more significant difference in real life, on average. My guess is 20-40% easier to saw, and with the number of dies that I saw, this is a huge difference.
The hardenability factor has some twists to it, but things start with the info stating that 0-1 can be hardened to RC62, and 4130 to RC 60, though an industrial heat treater said they wouldn’t harden a surface plate for a press harder than 51. Anyway, 4130 can be WATER quenched to maximum hardness, but pancake dies do NOT like being water quenched. The thermal shock is too great for such thin pieces, and so flatness and alignment pretty much go out the window, or at best, a high percentage of dies will either warp or shift out of alignment, or both. The only solution for me is to oil quench, though the industrial place said they would mar quench (molten salt). I don’t do that, or want to, so I tried the same oil I use for 0-1. No good. It doesn’t cool the 4130 fast enough to get very hard, so I tried a fast quench oil from McMaster Carr. Better, but not good. I did some learning and looking, and came upon a product called DASCO QUENCH LBA 15 , made by Quaker Houghton. Around $250 for 5 gallons. Not a typo. It works pretty well, but heat treating 4130 is still a very different animal than 0-1. It doesn’t get as hard as water quenching, or as hard as 0-1, but the details of that are for later.
After about a year struggling with sometimes horrific oxidation and difficult cleaning up of the resulting scale, then almost building a stainless steel reduction box for inside the kiln, I wound up at a very simple place, and a very much simplified process. Get the kiln very, very hot (1750-1800 F, whereas the stated quench temperature is around 1550-1600F) so that the dies heat up fast, and get them out quickly, quenching immediately, of course. Wipe, sand to remove any scale, and ultrasonic severely. You would cringe at some of the routines I tried, using pickle, and many more steps than what things boiled down to.
There’s the start, and there’s plenty more, which I’ll write about if there’s interest. If not, probably not any time soon.
Dar
