wildvortex Posted December 3, 2015 Share Posted December 3, 2015 I have a small sporting good store consigning a few knives for me which is great. I have only been smithing knives for about 9 months. My problem is that he wants to know knife strength. How do I test this without destroying the knife. All my knives are made from truck coil springs. Quote Link to comment Share on other sites More sharing options...
Charlotte Posted December 3, 2015 Share Posted December 3, 2015 Hmmm, Strength? That word has several different applications to objects made of steel. How does he mean strength? Strength in bending? In shock resistance? Hardness? Abrasion Resistance? If you haven't done destructive testing how can you make any statement about the suitability of your product? What steps have you take to ensure that the coil springs you used didn't have any internal flaws? ( One coil spring I came across had a cold shut through the length.) Used springs often have stress cracks that show up after forging the experts here have emphasized? ( I often think used springs came my way for a reason.) Btw how do you know for certain that the alloy you used was what you thought it was? How did decide how to heat treat? Just a cautionary group of questions. The professionals on this site have often remarked that it takes years to build a good reputation but only one bad result to break it. Quote Link to comment Share on other sites More sharing options...
Steve Sells Posted December 3, 2015 Share Posted December 3, 2015 Too cheap to buy good quality new stock, and risking used material is saving you less than $1 per blade, is that all your reputation is worth? Quote Link to comment Share on other sites More sharing options...
TacticallySharp Posted December 3, 2015 Share Posted December 3, 2015 I sell knives thru my local ACE Hardware. They are all of new steel, and I have destroyed several of them to see just how good they are. The most new steel has cost me including shipping on hunter size is $3. Better safe than sorry... Quote Link to comment Share on other sites More sharing options...
Worshipdrummer Posted December 3, 2015 Share Posted December 3, 2015 I love making knives out of coil/leaf springs that are bound for the scrap yard so I can sympathize with your choice to redeem them into a useful tool. However, I do not sell any of the knives I make from reclaimed springs for the same reasons as listed in multiple areas on this forum. I give the knives away to friends (telling them they may be great steel or not) or use them myself. Making a knife (correctly) requires a lot of work so if I was going to charge a price worthy of such work I would use known steel so the buyer (and you) can be assured of the steel quality and consistency. Again, there is nothing wrong with making a knife out of redeemed spring steel but I would not sell them, particularly at custom knife prices. Just my opinion; there are many here more learned than I. Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted December 3, 2015 Share Posted December 3, 2015 Probably wants to know the hardness as that is what is usually bandied about, You can buy your own Rockwell hardness tester, send them out for testing, or use a set of hardness testing files to get a general idea. If you do differential hardening or tempering the number will of course vary depending where it gets tested. Now for toughness you will need to do a charpy test---which destroys the test sample... Quote Link to comment Share on other sites More sharing options...
wildvortex Posted December 3, 2015 Author Share Posted December 3, 2015 19 minutes ago, ThomasPowers said: Probably wants to know the hardness as that is what is usually bandied about, You can buy your own Rockwell hardness tester, send them out for testing, or use a set of hardness testing files to get a general idea. If you do differential hardening or tempering the number will of course vary depending where it gets tested. Now for toughness you will need to do a charpy test---which destroys the test sample... Yes he has mentioned Rockwell strength. I started this as a hobby and only look for the knives to cover costs. The springs I get are from a truck modification shop. They are springs that were replaced as part of a lift. The price I sell them for does not even come close to custom prices. I want all my knives to be hand forged and to recycle steel. I don't call someone who buys a blank and puts a handle on it a "knife maker". Sorry to all those that do. It is just how I feel. While it is a custom knife all you did was dress a knife to me. At least with those who do stock removal are taking a piece of steel and shaping it into a knife. I do tell my customers that these are made from recycled steel and can have some flaws in the steel. Thanks for the help. I knew he had mentioned a specific type of testing but had forgotten what he has said. Where can I get Rockwell testing done and is it even worth it since it can very from blade to blade. Quote Link to comment Share on other sites More sharing options...
Steve Sells Posted December 3, 2015 Share Posted December 3, 2015 I love my testing files. its Rockwell hardness, not Rockwell strength, Hardness and strength are opposing attributes. and who said anything about kit knives? I said buy quality steel to start with not reuse garage for a knife. IF you read what has already been posted you would see many valid reasons why it s a bad idea, but you seem to have made up your mind already, so good luck, I wont waste either of our time any more. Keep your insurance paid up. Quote Link to comment Share on other sites More sharing options...
Worshipdrummer Posted December 3, 2015 Share Posted December 3, 2015 You may just want to look into a set of the testing files because like you said the steel composition from spring to spring will differ so one hardness test on one spring will not work to give consistent accurate information. There is a tool company named for a very large species of bear which has a set of the files for $40 on their site. There is also some very good info on this site about a general heat treat technique for spring steel. Sounds like you are up front with all involved in selling or purchasing your knives so I do not think there is more you can do. Also, just because someone buys tool/knife steel it does not mean they are not forging the blades themselves I know many who purchase drill rod and forge it into blades. I actually prefer to start with the round or rod shape when I forge a blade don't know why I just do. Quote Link to comment Share on other sites More sharing options...
TheoRockNazz Posted December 3, 2015 Share Posted December 3, 2015 Wild, as much as I love recycling, if these are to be sold and used you need to use quality metal. Steve is not kidding about keeping your insurance paid up - someone hurting themselves or another person with one of your blades could spell the end of your career before it even starts. It's also wise to form an LLC if you're selling blades, it can really save your hide. If you really like forging 5160 (spring steel), try 80CrV2; basically the upgraded version, but comes in easy-to-forge sizes Quote Link to comment Share on other sites More sharing options...
Kozzy Posted December 3, 2015 Share Posted December 3, 2015 You'll need to ask him again what he actually wants the numbers on. He said "strength" implying tensile strength--something which really doesn't tell you much in a knife but might be used as a selling point with people who don't really understand what it is. Hardness testing probably won't give any usable information either--a good knife is a different hardness on the edge vs the spine vs the tang. There are pocket penetrators for hardness that aren't that expensive if you need to give a rockwell hardness number but again, it's mostly meaningless in a knife. Rather than go crazy trying to figure out what he wants, pin him down. You can then target your production to meet what he is seeking. And as others have said, you really do need to use certified materials rather than unknown scrap. By doing that you can make the tensile claim in a form that's useful as a sales pitch. "We make our knives from material that has a 70K PIS tensile strength" Remember and learn this lesson: In selling, PERCEPTION TRUMPS REALITY. You can give the buyer perceptions of strength and hardness (implied quality) with numerical values even though those don't really mean much in the grand scheme of a knife. The customers PERCEPTION of the knife will be better with numbers they don't really understand anyway. Quote Link to comment Share on other sites More sharing options...
wildvortex Posted December 3, 2015 Author Share Posted December 3, 2015 I don't mean that buying good steel to forge was not knife making. I guess I did the assume thing when speaking I assumed that the $3 steel for a knife was a refferal to buying blanks. I just have come across many custom "knife makers" at craft shows but when I ask about them I find they are blanks. Sorry Steve He did mean Rockwell even though he keeps saying strength. I remember him asking if i had them Rockwell tested the first time we spoke. So, what is the best carbon steel to buy for a knife? Quote Link to comment Share on other sites More sharing options...
Buzzkill Posted December 3, 2015 Share Posted December 3, 2015 Brace yourself. That last question may get you an avalanche of answers like, "What will the knife be used for? Is it going to be a slicer, chopper, skinner?" The answer may be different depending on the application. It will narrow down the selection somewhat if you ask which is the easiest high carbon steel to *forge and home heat treat* but even then you will probably get some differing opinions. Quote Link to comment Share on other sites More sharing options...
Steve Sells Posted December 3, 2015 Share Posted December 3, 2015 http://www.iforgeiron.com/topic/22426-new-knife-maker/ Quote Link to comment Share on other sites More sharing options...
TheoRockNazz Posted December 3, 2015 Share Posted December 3, 2015 Haha, Buzz that was the first thing that came to mind, I was actually kinda excited to respond, but you beat me to it... Quote Link to comment Share on other sites More sharing options...
wildvortex Posted December 3, 2015 Author Share Posted December 3, 2015 Thanks for the link Steve. Most of my knives have been utility, hunters and skinners, most are along that line. I have even done a commissioned crescent boline. I find that 5160 (probable coil spring)is workable but tough. It would be easier with something not as tough. Looking at specs 1095 looks pretty good. Any thoughts Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted December 3, 2015 Share Posted December 3, 2015 "Best" is a hot button for me as without the use case strictly defined there is no best! For a camp knife for rugged use and abuse I would prefer 5160 to 1095; if I was making a skinner for large game and only had those two alloys to chose from I would prefer the 1095. However, as mentioned, if I was selling them I would order new steel. Have you checked out Aldo the NJ Steel Baron's website? I personally know several professional bladesmiths who buy steel from him Quote Link to comment Share on other sites More sharing options...
Buzzkill Posted December 3, 2015 Share Posted December 3, 2015 Well there's a new bug I haven't seen before. I came back to read this thread and it reposted what I had written more than an hour ago. I swear there is a poltergeist in this software. Quote Link to comment Share on other sites More sharing options...
wildvortex Posted December 4, 2015 Author Share Posted December 4, 2015 Thomas thanks for the info. I have a local steel distributor here that I know can get me at least 1095. I understand the issues with stressed vs. New stock. I am going to look into new. The springs came to me cheap and yes Steve it is cheap. Hard to get into something on a disability paycheck. Drs. tell me not to lift over 20 lbs due to my back and I started going stir crazy. I am a gotta do something kind of person. Wife is willing to lift the heavier stuff for me when needed. So I figured making some knives could fill my te when I feel up to it and is along with my Maine upbringing. Kinda hoped that this hobby could someday get me off Disability. Didn't figure a startup cost. Forge, build a belt grinder, drill press. Ect. You all know the deal. Am just trying to get started. But that worries the wife and the more I spend without bringing in the more I get nagged by the Mrs. I read through the post again this evening. What the heck was I thinking! Don't know where the heck that rant came from. You all were trying to help and I go off on some tirant. Sorry guys! One one heck of a way to introduce myself to the community. Guess I can blame that one on meds and a bad morning. Had to redo 2 handles this morning because I found a crack in one and sanded into a void on some burl scales. Sorry again guys and thank you for your time it is much appreciated even though I didn't show it. Anyway this is the crescent boline I made Quote Link to comment Share on other sites More sharing options...
yahoo2 Posted December 4, 2015 Share Posted December 4, 2015 PERCEPTION TRUMPS REALITY that is good! I am hanging that one on the wall in the office as a sobering reminder Quote Link to comment Share on other sites More sharing options...
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