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JS Performance Test Knife
Absolutely Invaluable information! ANYONE planning on testing for JS needs to read/keep and eye on this thread!
THANK YOU MATT!
Work has been keeping me on my toes lately, but I hope to run #3 through the ringer sometime this weekend if all goes well. Here are a few pics I took the other night.
One thing I do after forging this steel to shape is to bring it to an "even" heat in the forge before letting it cool to room temp. Somewhere between 1650-1700 F. An inexpensive thermocouple and digital PID have taught me a lot. It's surprising how tight forge temp can be controlled by adjusting air flow, fuel, fuel pressure, etc.
One of these days I'll build a horizontal forge, but until then I remove the brick and run a 3" pipe through the windows to heat the blade to temps mentioned above. It heats the blade up evenly once everything comes back up to temp. It hadn't returned back up to full heat yet after installing the pipe in the pic below.
The drawing on my anvil is "fat" to allow some steel when grinding to final shape. I'm trying to use as few heats as possible to forge it close to the drawing. It's easy to get myself into trouble if I get too greedy. It's impressive how some guys can forge so close to final profile. I'll keep practicing.
Yes, I know that my anvil has freckles on it, I just work around them. 🙂
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Quick update....I decided to forge another performance knife (#4) and test two of them side by side. Both are currently just awaiting finish grinding and handles. Both knives have the same profile as #2.
The plan is for #3 is to replicate the overall geometry as tested on #2. The goal is to have it produce the same results.
#4 is going to be thin and light. An extreme distal taper in comparison, and skinny on the convex/edge. My prediction is that it'll cut the rope fine, but the 2x4's will be a challenge and will likely result in edge damage. In theory, it should bend easier, but........ I really don't know what to expect.
In the end, I just want to see how much can be asked of this steel before it starts "crying uncle" (using this shape/profile and HT recipe).
Hey Matt!
I just wanted to sincerely thank you for not only taking this journey, but for making the effort to offer/post all the great information. I REALLY hope that folks will find and read this! This is the kind of information that can take years to accumulate alone, and in the information you've posted to date, I see answers to most of the questions I get from folks who are prepping for their JS performance test. Good on ya!!
You bet Ed! It's forced personal accountability to stay focused on the task at hand by knowing there is a date set aside for the real test, and by sharing the experience on your forum. It's just too easy for my mind to race 100mph with different ideas and get sidetracked for too long.
A lot of visitors seemed to drop by the shop for a "quick chat" over the past few days which slowed down my progress. But.....both knives have handle epoxy curing as we speak. #4 has really piqued my interest for some reason.
It's going to drive me nuts, but I'll be out of the shop for two weeks attending to some business. I hope those folks that are following along don't think I've given up if I'm quiet until I return. I'm looking forward to sharing a review shortly!
Good morning!
I'm finally back home and ready to pick up where I left off.
Even though having to take a break from building knives over the past few weeks drove me absolutely nuts, I am truly grateful to have a good job to provide for my family.
I'll be testing the two knives soon that I left on the bench with micarta epoxied and clamped in place. I'm sure it's fully cured by now 🙂
Update! I've tested #3 and #4 and I have mixed feelings about the results.....
Knife #3 - Overall, it's a replica of #2. Cut rope nicely and chopped 2x4 with zero edge damage. Razor sharp afterwards when shaving hair. 90 degree bend with my dad spotting. Took it out of the vise to inspect after first bend. I could see a nick/crease from the vise jaws on the inside of the bend right where the blade was clamped into the jaws. I've never seen this before. This time I was using my newly mounted post/leg vise. I didn't think it would be much of an issue because the jaws are "smooth" and not "knurled" like my pipe vise. I've been putting brass inserts into the pipe vise before bending in the past. Didn't do with this vise.
Put #3 back into the same vise to proceed. I was able to bend it 2 more times to ninety degrees before it broke on what would have been the 4th overall bend. The grain structure looked good to me. I know it would've "passed", but I was discouraged because I stopped bending knife #2 after going 12 times back and forth to ninety degrees. #2 never broke. Still in one piece on my bench. Knives #1, #2, #3 all took a "set" at the exact same place after 1st bend. Same heat treat process and geometry, but #3 broke much easier!!!! 🙁
Knife #4 - I've been excited to test this knife not really knowing what I'd learn as it was thinner and noticeably lighter. If you look in previous posts, I expected edge damage from chopping wood and smooth sailing with everything else.
Well, I was wrong about this knife! It cut rope like a dream. I chopped the 2x4 two times with no edge damage. Inspected the edge with my #6 optivisor to be sure. Shaved hair easily. I then proceeded to chop the 2x4 again without sharpening. No edge damage. Chopped the rope again without sharpening and it was just as easy as the first time. Inspected with optivisor again. No edge damage! I was on cloud nine. The lighter weight didn't seem to hinder me at all chopping wood. I couldn't wait to see how well this lighter, skinnier, blade that just performed beyond my predictions and expectations showed out in the bend test....
I chose not to insert brass again so that both knives were tested the same. Wanted to see if it left a mark from the vise again after the first bend. But to my surprise, the damn thing snapped in half right when my dad told me to stop at the 90 degree point!!!!!! I was speechless. I'd have lost every dollar in my pocket if someone wanted to bet on that happening. The grain structure looked fine.
Do ya'll think I'm off base in suspecting that the vise setup is a major contributing factor in this? When inspecting all of the knives, I see that I have a less taper in the tangs on #3 and #4 then I did on #1 and #2. This was not intentional. I've tried my best to keep all other known variables the same with all of the blades. My mind has been running wild to be honest. I've been humbled. I'm a bit discouraged.
I'll fire up the forge tomorrow afternoon to begin #5 with curiosity and determination.
#5 has been forged, annealed, and rough ground. I'll run it through the HT process today and tomorrow. If all goes as planned, I'll test it this weekend and share the results and a picture or two. Wish me luck!
Here's something that may or may not be interesting to some of you.
I like to thermal cycle 3 times and cool to room temp in between each heat before I quench. Blade #5 was as straight as I could get it before first TC. Checked it before putting it back into the oven and it was still straight.
Checked it after TC #2 for straightness and it had a noticeable warp. Although I was annoyed, I proceeded.
Checked for straightness after cooling from TC#3 and it was as straight as it was when I started the process!
Heated it back up to temp and quenched. The blade survived and was straight.
I read a lot and understand what is likely taking place in the steel, but I'm not comfortable explaining it as there are experts out there that already have.
But....since I've seen this happen a few times now, I thought I'd share. If you see a warp during your TC process, keep going and see what happens.
Maybe its Voodoo, or maybe I go cross eyed on occasion who knows?! Anyways, take a look at your blades during the TC process, it's kind of cool what you see!
Knife #5 performed well. Info:
- Micarta, 1 copper pin, and 1/4" lanyard tubing
- All measurements on the knife are within ABS parameters
- 500 Grit satin finish
Performance:
- Rope - Clean cut with the "snip" sound I like to hear
- Chop - I put the 2x4 in a vise to chop. I like this better than resting it on my knee & ground. Feels like I can open up on it and strike the wood as hard as I want without fear of a glancing blow cutting me. About 12-15 strikes both times. No edge damage visually (optivisor) or on my thumbnail
- Shave - I'm running out of arm and lower leg hair lol
- Bend - I was really on edge going into the bend this time, but I'm happy with the results. 6 times. I left this one in one piece rather than bending until it broke. Used brass inserts on jaws of vise.
#5 final thoughts:
- I got a bad batch of 120 grit belts that were not cut straight or something. They wobble way too much to be usable for anything precise. Don't try to make them work near plunge. Use them for non important tasks. I'll likely use them for non knife related shop tasks.
- I'm learning to really appreciate the disc grinder and find myself leaving the 2x72 at a much lower grit
- It's worth removing any "hot spots" on your handle. I left one little spot on kinife#4 that I didn't think would make much difference. It didn't matter at all until I chopped a 2x4 a few times with it biting my hand. Felt like a shoe that was too small on a long hike. Screw that. It only takes seconds to adjust. #5 didn't bite me back when chopping.
- I'm miles away from being an expert on edge geometry, but I'm finding that you'll just "know" when the convex feels right and the edge is thin enough to leave the belt/disc and finish it up on the sharpening stone.
- What I mean is that: it's not too thin (to the point that you'll have to "back it up" a bit to get it thick enough to sharpen), not too thick (I dislike steep secondary bevels and they perform as bad as they look), sharp enough to cut you, but yet not sharp enough to be sharp.
- That sounds like I just shared useless information and the kind of answer that used to annoy me. Always seemed as if secrets were being kept when I got an answer like that. That is not my intent at all
- If someone wanted some starting thickness measurements, I have them to share, but honestly, you'll just know
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