The first pic that neck posted was the knife after it was profiled. This knife started as a piece of 5/16" X 2.5" X 13.5" bar of steel. I use layout fluid and scribe the outline of the knife out on the steel. I rough cut the profile out with a metal cutting bandsaw. The knife is then put on a 2"X72" belt grinder. This grinder has 2"X72" abrasive belt run by a 2HP variable speed motor. I start at 60 grit to get the final profile and finish with 220 grit at this stage. Ok now the knife is profiled to the outline that I want. And this particular blade weighs 2lbs 1oz. The next step is to mark and drill the holes for the pins which is pretty obvious how that happens.
Next is tapering the tang. I scribe center lines on the end of the tang at .040" apart, I then grind down to these lines. I hollow out the center of the tang with a 8" rubber wheel on the same grinder. It looks something like this.
This is to remove some of the metal out of the center of the handle to make the actual tapering easier and faster. Grinding the center out with the wheel is cheaper on belts also. After the center is removed I change to a flat platen. At this point I hold the blade with a magnet on the handle and grind with blade pointed down. I also take the tang from 60 grit thru 220 grit.
The blade stock started at 5/16" thick the end of the tang is at about .040" now. And the weight of the profile is reduced from 2lbs 1oz to 1lb 12oz. This removed about 5 oz off the total weight which doesnt sound like a lot until you consider that this weight was all removed from the handle and is unneccasary to begin with.
After the tang is tapered. It is time to grind the blade. I grind on a work rest now. The blade is marked with center lines at .025" apart, I start with 60 grit on the blade also. I start with the blade tilted at about a 45 degree angle and grind down to the center lines. I slowly work it down all the way to the spine for a full flat grind (FFG). I take the blade to 600 grit and then clean up the tang again. I take the tang to a worn out 600 grit. I also take the perimeter of the blade down to 400 grit using a 3/4" rubber wheel. The blade is now ready for heat treat.
The blade is then wrapped with .002" stainless steel heat treat foil. The foil is formed into an envelope to form an airtight barrier for the steel. With out this barrier the heat from the oven would burn the carbon out of the blade, rendering it useless. The recipe changes for each steel. CPM-M4 is an air hardening steel. Which means that you quench the steel in air not in oil or water. Some makers use a big fan to do their quench on air hardening steel. I use 1" thick aluminum plates. The plates act as heat sinks and absorb the heat out of the steel faster than moving air. They also act to help keep the blade from warping. The recipe I use for CPM-M4 is austenize at 1985 degrees farenheit, quench after a 30 minute hold at this temperature and temper twice for two hours each at 1000 degrees. This gives you a rockwell hardness of 61 on the C scale. Smaller blades will be harder with this same heat treat.
Here is a pic of the oven at about 1930 degrees Far.
WIP will continue with a pic of the blade after the heat treat, so stay tuned.