Round 3 - Day 2 Heat Treat & Grind
The final edit of the show skips around a bit in round 3, they skip from day 1 to day 3 and it appears as if day 3 was my heat treat day. In reality, heat treat day was day 2. I began day 2 just like day 1, with a pre-day interview where we discussed what had happened the first day, what my plans were for day 2 (heat treat) and how apprehensive I was about getting through a heat treat with a blade intact. I spent time on the flight back from rounds 1 & 2 sketching out some ideas on how to forge certain elements of the sword and debating whether or not to heat treat before or after the grind. Initially, I'd planned on using a 'v-block' to forge the primary bevels and then clean them up at the grinder but by the end of day 1 I'd made my mind up to heat treat first, then grind the bevels in. I was just too nervous about spending all that valuable time getting the blade to a 90% finished shape before heat treat and then running out of time if something went wrong.
I started the heat treat process by bringing the blade up to heat slowly in a 2 inch tube inside the large 3 burner forge and doing a little gentle straightening.
Once the blade was at critical temperature, I took the blade out using two pair of tongs (holding the tang tightly and the blade loosely) and moved from the forge over to the 4 inch square-tube quench tank and quenched the blade in room temp 11-second commercial quench oil.
No pings indicating a crack occurred but I did come out of the quench with a very slight warp, around the middle of the blade. It skated a file and while I was happy about that I knew that the warp had to be addressed quickly. Before the quench I had setup an angle iron straightening jig in one of my post vises so that I would have a method to straighten fairly quickly. I'd tack-welded two long pieces of angle iron to the jaw faces to give me a longer surface area to press the blade together with. After a few tweaks I was able to get the blade fairly straight and it was now time to temper the blade. Some of the warp didn't come out until the grinding later on and I think the warp issues I dealt with didn't make the show because they were fairly easy to fix.
I'm sure every smith who goes into round 5 as a finalist does what they can to prepare in whatever amount of time they have before the film crew shows up. Research, shop prep and gathering materials are all a part of that pre-film work. A couple of nights before I began filming the 5 day build I did a lot of thinking about how to go about tempering the blade. I did not own a large heat treat oven and the one toaster oven I had for tempering smaller blades was obviously not up to the task of evenly heating a 32 inch blade for a specified time period. I talked this over with a few friends online and after some deliberation I decided to take Geoff Flato's advice and use several toaster ovens fashioned together rather than risk a flammable oil bath or to try and 'shoehorn' the sword into some other kind of oven. In the end, the triple toaster oven rig worked very well. Geoff mentioned that he'd seen a similar idea in use in Salem Straub's shop and we both agreed that the oil bath was just too risky of an idea. (See episode 8 from season 5 for a good example of why.) Besides, building the triple toaster oven rig took all of about an hour and was relatively inexpensive.
After straightening the blade I went straight into the triple tempering oven setup. I tempered the sword for three one hour cycles at 425 degrees, turning and moving the blade in and out of the three ovens every 15-20 minutes in order to compensate for the tubes connecting the ovens. While the blade was being tempered I began to cut out some wrought iron for the handle guard piece. I wound up making 2-3 attempts at finding the right size stock for it but eventually I settled on a piece and forged it into a rough 'submarine' shape and used a scrap off of this block for the clamshell guard. After forging these pieces of wrought iron into their basic starting shapes I put them aside.
When the tempering of the blade was complete I allowed the blade to cool until I could comfortably hold it without gloves and then I gently cooled it the rest of the way in water. I did a few light 'flex test' bends and felt that the temper was as good as I could get it with the equipment on hand. At this point I began the long and careful process of the first rough grind on the blade. I marked a center line down the length of the blade and used a 1-1/2 inch diameter rubber-coated small wheel to begin the grind of the two top bevels. I sat on a stool at the grinder, looking straight down on the small wheel and didn't move for hours.
I started grinding the blade from the tang/ricasso area and slowly worked my way down the length of the blade, grinding about 2-4 inch sections inches at a time with a free-hand hollow grind. The grinding took the rest of the day, it was the LONGEST grind session I'd ever done on a single blade. For the duration of the main grinding period I never let the blade get too hot before dunking it into a tall water tank. I never saw temper colors change on the blade which might indicate a possible ruined heat treat and I ran the belt grinder at a very low speed to avoid taking off too much material too quickly. This part of the build was very time consuming and required complete focus. I finished day 2 mentally drained but with the rough-forged forms for the handle guard and clamshell and a blade with all three bevels roughed in.
Next - Day 3 - Finicky Forging