Urthman Posted July 23, 2015 Share Posted July 23, 2015 Truck leaf spring. Forged down to about 1/4", normalized 3x, cut, and 'eyeball' ground.Fun experiment so far. Quote Link to comment Share on other sites More sharing options...
mitch4ging Posted July 23, 2015 Share Posted July 23, 2015 Looking good! Look forward to the finished product. Quote Link to comment Share on other sites More sharing options...
jmccustomknives Posted July 24, 2015 Share Posted July 24, 2015 Did you use a press, or hammer to thin your material? Quote Link to comment Share on other sites More sharing options...
Urthman Posted July 24, 2015 Author Share Posted July 24, 2015 Hammer! It felt a bit like work. But was good cardio, and more fun than running or sit-ups... Quote Link to comment Share on other sites More sharing options...
cliffrat Posted July 24, 2015 Share Posted July 24, 2015 Do you know what truck the spring came out of? Quote Link to comment Share on other sites More sharing options...
Urthman Posted July 24, 2015 Author Share Posted July 24, 2015 Not sure. My mechanic let me raid his metal pile- I'm guessing they came out of some Fleet/Work vehicle. The springs are about 4 feet long, and each leaf is about 3/4" thick at the widest point. Quote Link to comment Share on other sites More sharing options...
Urthman Posted July 25, 2015 Author Share Posted July 25, 2015 So I quenched my knife today, and a bunch of cut-off test pieces.The steel certainly hardened, because my test piece snapped immediately when I tried to bend it Next step will be tempering. I'm thinking of throwing the test pieces in my oven at different temperatures/times and see how they behave when done (sharpen/bend test). Then do the actual knife with whichever 'recipe' worked best.How's that sound to you folks who have actually done this before? Any other advice?Thanks all for input!-Jeremy Quote Link to comment Share on other sites More sharing options...
Urthman Posted July 25, 2015 Author Share Posted July 25, 2015 I tempered a scrap piece at 350 degrees for 2 hours. Once cooled, I was able to flex that piece a few degrees before it snapped. I'll try another round at 375 degrees and see what that does.This is like a high school science fair project, except more useful and more fun... Quote Link to comment Share on other sites More sharing options...
Urthman Posted July 26, 2015 Author Share Posted July 26, 2015 after another 2-hour bake at 375, I tested a couple more samples.Both snapped at a few degrees of bend. But it does take some muscle to get the steel bent to that point.Sanity check: Is this a dumb test for a knife? How much "should" a typical camp/outdoor knife flex before breaking?I see a lot of talk about this "90 degree flex test" for knives submitted for Journeyman testing. I get the feeling this is well beyond what I should be shooting for. Hm, I'm realizing that my sample pieces are not a true test of what the knife will do either. The samples were single-quenched. The knife was triple-quenched, with the last two quenches being edge-only. So one can assume the spine will be softer and more flexible.Sorry- I'm just sort of thinking out loud at this point... Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted July 26, 2015 Share Posted July 26, 2015 Are you using an oven thermometer to double check the actual temps at where you place the blade/test sample?What is appropriate depends a LOT on the end user; I like to do a whole blade temper a couple of times and then temper the back of the blade a bit further. On the other hand I've dug a firepit with a pattern welded blade before; when I saw the winces I pointed out that I had made the blade and so I couldn't do anything to it I couldn't fix---(even if the fix was welding up a new blade...) Quote Link to comment Share on other sites More sharing options...
Urthman Posted July 26, 2015 Author Share Posted July 26, 2015 Hi Thomas,Yep- I've got a temp probe that I set on the middle rack. That showed me that my oven swung about 30 degrees as it cycled on/off.Putting the probe in a steel pipe, I found the temp was much more regulated- within 3-4 degrees.Do you mind sharing your method of 'tempering the back of the blade a bit further'?I think I'll do the full-blade temper in the oven a couple times, but I like the idea of hitting the back of the blade as well for some extra insurance... Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted July 27, 2015 Share Posted July 27, 2015 Tempering tongs, using a torch (even propane) with the edge in a pan of water, thick slab of steel heated red hot that was a bit shorter than the blade so the tip can project off it and stay cooler. I've used them all to good effect. Great to hear that you measured the oven and figured a way to deal with swings. Oven knobs are notorious for being inaccurate. Quote Link to comment Share on other sites More sharing options...
Urthman Posted July 27, 2015 Author Share Posted July 27, 2015 Thanks!!! Quote Link to comment Share on other sites More sharing options...
Urthman Posted August 5, 2015 Author Share Posted August 5, 2015 Spine draw using oxy-a torch and pan of water method.Maybe I could have gone a little closer to the edge, but I guess this looks about right... Quote Link to comment Share on other sites More sharing options...
Frosty Posted August 5, 2015 Share Posted August 5, 2015 You GUESS?Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
Urthman Posted August 5, 2015 Author Share Posted August 5, 2015 More like "I HOPE". This is uncharted territory for me... Quote Link to comment Share on other sites More sharing options...
Frosty Posted August 6, 2015 Share Posted August 6, 2015 All the more reason to spend time reading the knife making and heat treating sections here. Not to come across cross but blades aren't really the place for I guess unless you're making wall hangers and you've obviously put time and work into that one. There's no need to guess and gamble all the work you have invested when a few hours reading would give you a good grounding.I'm not a bladesmith guy but I can tell you the draw on the spine is about as wide as the full hard edge should be. As it stands right now if you achieved full hard in the hardening step your blade is dangerously brittle. Only the last say 1/2" or so of the edge should be in the pale straw range.I don't know how long it's been since you hardened your blade but without tempering there are stresses building and it may fail catastrophically just sitting there. At least pop it in a toaster oven set at 375-400f and give it an hour or two.Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
Urthman Posted August 6, 2015 Author Share Posted August 6, 2015 Oh believe me, I've spent many more hours reading about how to make a knife than I have actually working on this one. The tricky thing is, if you ask 10 different knife makers how they'd heat treat this knife, you'll get 10 different opinions. Condensing all the differing opinions into a decision on how to make *this* knife was not easy. I finally decided I had to stop reading and put all the advice into a knife and see how it turned out. This one has been triple quenched (1 full and two Edge) so theory says the spine should be "somewhat" soft to begin with. It was then tempered at 375 (twice, 2 hours each) and the spine drawn back for 'insurance'. The blade is stiff, but has some flex if I push it hard against a table top.I've also got 6 pieces of 'test blade' that I'm trying different tempers, spine draw methods, etc on so I can see how they stand up to destruction testing.Thanks for the feedback! Quote Link to comment Share on other sites More sharing options...
Frosty Posted August 6, 2015 Share Posted August 6, 2015 I've only ever made a couple knives and didn't heat treat either that way. Probably a good thing I don't make blades. Who's technique did you use? If you tried coming up with a technique after reading a bunch of opinions you're most likely really confused.Pick ONE master bladesmith who's shared their technique and stick to that method.I'll be quiet now and keep my non-bladesmith guy opinions where they belong. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
Urthman Posted August 6, 2015 Author Share Posted August 6, 2015 after some sanding... Quote Link to comment Share on other sites More sharing options...
Steve Sells Posted August 6, 2015 Share Posted August 6, 2015 First he hardened then gave one temper cycle to the full unit. Good. we should all agree at this point.Then he added some extra and decided to make spine even softer. This extra step of the spine is just that, extra and wont hurt as long as he didn't get too soft, or bleed into the cutting area. nice work Quote Link to comment Share on other sites More sharing options...
T.J.watts Posted August 6, 2015 Share Posted August 6, 2015 looking good Quote Link to comment Share on other sites More sharing options...
Urthman Posted August 6, 2015 Author Share Posted August 6, 2015 Thanks!I appreciate you chiming in Steve- helps to know I'm not too far off the beaten path.Gonna play with the handle today... Quote Link to comment Share on other sites More sharing options...
neg Posted August 6, 2015 Share Posted August 6, 2015 It looks great for even your tenth knife, let alone your first! I look forward to seeing it finished. Quote Link to comment Share on other sites More sharing options...
Urthman Posted August 7, 2015 Author Share Posted August 7, 2015 Handle attached and rough shaping started... Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.