Clint,
I am flattered for the mention, and sure feel bad about your problem. If memory serves me correctly, when I was researching the JB Weld, I believe that it starts to break down at about 600 degrees Fahrenheit. U-m-m.. you're in Canada aren't you? I'll bet you guys use Celcius. That's what -- about 316 degrees Celcius?
Since you are going to re-heat treat, you should be able gradually bring the temp up until the JB Weld starts to break down, and tap the guard off. I've never had to do it, so I can't say with any certainty.
I can tell you however, how to avoid this in the future. Immediately after the final tempering, put an edge on the blade and test it. Test the daylights out of it. Once it passes the tests, then and only then move on to cleaning it up, etching, and assembling. I do this with every single knife I make.
At the risk of looking like a smartass, I'll show you some of the things I do.
Tempering Colors (1084)
For 1084, I use 400 degrees F. At this temperature I get dark straw. The bit of peacock (purple) at the edge and the tip is good. It will give a good tough edge. If you are using a kitchen oven, go out and buy an oven thermometer. Kitchen ovens are generally not very accurate. Some are off by 50 degrees F. or more, and many (most?) have spikes during the cycles. My kitchen oven when set for 380 degrees F. will actually hit 400 F. and spike to 410 F. If your oven was set for 450 F., it is possible that it actually went to 500 F, and then spiked even higher.
Rolling The Edge
As stated, I put an edge on the blade right after tempering. You can see the tempering colors here, as well as a hint of the temper line. I am slack belting a convex edge.
Checking For A Keen Edge
Hold and cut thin slices from a piece of paper to check the keeness of the edge. Magazine paper is okay. Newspaper is better.
If you really want to check for sharpness, try a cigarette paper. This is not easy, especially with a big knife.
Checking the Toughness of the Edge
On smaller knives like this hunter, I find a board with a good hard knot, and hack away at the knot.
On larger knives, I do the knot trick and chop the board in two a couple or three times.
Sometimes I'll also hack a limb off a tree, chop on a piece of landscaping timber, slice rope, etc., but every knife at least does the paper slicing and board hacking/chopping. When you are doing this, work the entire edge, not just one spot.
Testing the Tip
This is a step I only added in the last year months or so. I'll jam the tip into a board, a chuck of wood, etc. and then twist or pry chunks out.
Check the Edge for Shaving Sharpness
After all the tests have been performed, I make sure that the edge will still shave hair. Then I do a visual inspection of the edge. To do this, I go outside in good sunlight and hold the blade edge up. Rock the blade in the sunlight and watch the edge. Any soft spots wherethe edge flattened or rolled over will sparkle like a diamond.
I also do an inspection by feel. You can do this by lightly dragging the edge across the edge of a sheet of paper. I usually do it on the edge of my fingernail, which is not as safe. What you are feeling for is a catch in the movement. This would signify a small chip in the edge.
Here's the guidelines I use when "reading" the edge. If there is a flat spot, then the blade is drawn back too far. If there is a chip, the blade has not been drwan back enough. If the edge just has little crinkles in it, there is a good chance that I just have the edge too fine. For that problem I would go back beef up the edge by changing the convexity, and go through the tests again.
If all went well, THEN I move on to the cleaning up, hand-rubbed finish, etching, etc.
Hope this helps.
