First Knife total Failure for me.

J

jordan563

Joined
Sep 12, 2010
Messages
4
During this weekend I tryed to make a knife. I used a old truck leaf spring steel and forged a large bowie knife around 11 inch long and 1/4inch thick at the spine. I then heated the blade just above non magnetic and quench in diesel engine oil. The i tempered in the oven at 425 for 1 hour. Took it out a noticed a slight bend in the knife from quenching it, so i took it to the anvil and gave it a couple light hits with the 3lb hammer to try to straighten it somewhat.. The blade just broke right into.
What did i do wrong? Did i hit it to hard with the hammer? or did i not temper it high enough or long enough? Or was it from quenching it in the diesel engine oil? Help would be much appreciated.
 
If the steel was 5160 425 is a little low and one hour at temp is not enough time. Two 2 hour runs at 475 would be more like it.
That is if the steel is 5160 but hard to tell.

To test this put it back in the oven at 475 for the 2 hour soak and then see if it snaps when bent in a vise. There is always something to learn even from the broken stuff.

Keep at it, Fred
 
Jordan, do some homework first. What you used was probably 5160. If you quench it and harden it, and then do not temper it correctly, it will break when you hit it with a hammer every time.

Read some of the threads first. Use the forum to learn as much as you can and then try it again. The guys on this forum can help you with advice, but you need to do your homework first.
 
ATX said:
Jordan, do some homework first. What you used was probably 5160. If you quench it and harden it, and then do not temper it correctly, it will break when you hit it with a hammer every time.

Read some of the threads first. Use the forum to learn as much as you can and then try it again. The guys on this forum can help you with advice, but you need to do your homework first.
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Thanks for adding that. I agree there are some great stickies on this site. A lifetime of information.

Good post, Fred
 
Many problems here, but the first was not knowing what you were doing. It takes a bit of study and planning before making a knife...and a bowie is a big job to start on.

Filling out your profile would help,too.
 
bladsmth said:
Many problems here, but the first was not knowing what you were doing. It takes a bit of study and planning before making a knife...and a bowie is a big job to start on.

Filling out your profile would help,too.
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Ah yes, so much to learn and then there's where to start. At the beginning I guess. Oh well I digress.

Fred
 
Well, it's not a total failure. You now know what not to do, once you're finished, don't hit them with hammers. It's a big learning curve if you dont do some research first, you end up swearing a lot.
 
tattooedfreak said:
Well, it's not a total failure. You now know what not to do, once you're finished, don't hit them with hammers. It's a big learning curve if you dont do some research first, you end up swearing a lot.
Click to expand...

I've done my research and still swear alot:D
What does the grain look like in the break,is it a smooth grey or can you see crystal structure.Did you normalize before H/T or just go straight form forging to H/T.

Keep trying and read all you can
Stan
 
Jordan, one of the first knife blades I made, I hit it on the quenching tank just as I was putting it in the quenchant. The blade came out perfect, except for a small spur on the very tip of the knife blade from striking the tank. It was a full quench on a 5160 blade. I thought I could just tap the tip back in place without any damage also. I tapped it very lightly with a small hammer, ....and the tip broke off. So don't feel bad, just learn and try again. Now I strive to try and not make the same mistakes more than once.
 
Not a failure at all if you ask me. A learning experience maybe. I'm sure some of the greatest bladesmiths in the world started out this way.
 
Thanks alot for the help and support guys. I did normalize once before heat treating, and the grain at the break does not look smooth at all, it looks like a bunch of crystals.
 
If it looks like that then your normalizing didn't work,you have large grain structure from over heating,that could also have lead to the failure.
Its always a good idea to run 3 normalizing heats each cooler than the last,let the blade cool to room temp before the next cycle.
Stan
 
Does this make you feel any better?

knifewholeqe0.jpg


knifebrokewm7.jpg


kit0760rn6.jpg


That was one I quenched in water. It bent, so I hit it with a hammer trying to straighten it out before I tempered it...:D Live and learn...
 
EXCELLENT!

Here's the thing. Whatever went wrong, whatever classes you didn't take and whatever. you got up and did something. that's a good solid half of knifemaking, right there.

Next one, do the forging thing, then *normalize* 3 or 4 times. Go look that up, it's the thing to learn for this next time.

Temper longer.

Take a look at your blade, and see if there's a leetle bend. Probably will be. I'll be blunt, if it's something you can live with iin a "rough piece", then just live with it. balance it with final sanding some.

I've never straightened with a hammer, dunno why I would- but small pins in a vise works okay.
 
I second the normalize 3 times and the just over magnetic not being hot enough. Also, I use a lot of D2 which is not very forgiving as far as bending goes. What has worked for me on bowed blades is to temper one cycle then clamp it between 2 heavy bars of steel in such a way as it is straight, then temper again. If need be I will bow it a little past straight and retemper for another hour. There is a lot of difference in the slow easy pressure from a couple clamps and a couple clamps and hitting it with a hammer. Also, if you take it out of the quench after it has cooled to black for a little bit but, it is still hot, say 700f you can straighten it pretty easy with your GLOVED hands. Steel stays softer at that temp cooling from austensitic than it does at that temp getting hot. You have just started your journey of learning. As stated, don't think of it as a total failure, but as a learning experience. The next one will be better all the way around.
 
ib2v4u said:
I second the normalize 3 times and the just over magnetic not being hot enough. Also, I use a lot of D2 which is not very forgiving as far as bending goes. What has worked for me on bowed blades is to temper one cycle then clamp it between 2 heavy bars of steel in such a way as it is straight, then temper again. If need be I will bow it a little past straight and retemper for another hour. There is a lot of difference in the slow easy pressure from a couple clamps and a couple clamps and hitting it with a hammer. Also, if you take it out of the quench after it has cooled to black for a little bit but, it is still hot, say 700f you can straighten it pretty easy with your GLOVED hands. Steel stays softer at that temp cooling from austensitic than it does at that temp getting hot. You have just started your journey of learning. As stated, don't think of it as a total failure, but as a learning experience. The next one will be better all the way around.
Click to expand...

I've done both of these. Clamping a blade up for the oven I seem to do better running a second 2 hour cycle instead of 1 hour.

The interrupted quenching is golden for me. It's made a big difference, especially with the number of fairly large/thin blades I do. Search the forum for the term and you'll find some threads in here on the topic. At the same time, don't sweat it right away if you don't want to.

The only other real suggestion I have is to grab some 1075, 1080, or 1084. Those work very well with open forge heat treating and "random oil" quenching. (I prefer canola or safflower)
 
it isn't a failure, you learned something from it.

breaking a knife once in a while is just part of knife making.

learn to look at the grain structure every time you break a knife, this will also help.

I use to put broken knives on my wall in my shop, just to remind me, "don't do that again".

palmer.
 
Breaking a knife blade is not total failure so stop that. It was a disappointment and you learned something. Total failure is stopping your search for education and letting disappointment make you stop learning new things throughout your life. You never fail unless you quit. The flat out response to "I broke a knife blade" on this site is :"who ain't?" Did that help? Read, research, learn, figger it out for yourself, don't quit, anything worth learning is worth disappointment, education is a life long endeavor, I could go on. If that sounds like something that you heard from your daddy when you was a liddle kid maybe the ole boy was right and mebbe you should lissen to him. That said breaking a knife blade that you put your heart and soul into really DOES suck. You have the sympathy of everybody here except if you let something that small stop you. By the way, welcome to knifemaking and try not to do what you just more than two or three more times.
 
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