Jump to content
Sign in to follow this  
Richard A. (Woody) Hanson

Cracked Blade

Recommended Posts

I mentor the Students at the South Dakota School of Mines and Technology Blacksmith Club.  Last week Zack came over to my house on Sunday along with a couple other guys to work on knives.  He finished the rough shaping of his blade on my belt sander and then we heat treated the blade.  After we tempered it, we noticed a crack.  The crack ran lengthwise down the center of the blade clear thru the blade and more than half way to the tang.  It almost looked like a forge weld came delaminated but this was a piece of leaf spring and as far as we know it had never been forge welded.  Any ideas on what would cause a crack like that?  I told him he could split it the rest of the way and make two very thin knives  :)   I told him to find someone at the school who could do a failure analysis but I would appreciate any advice any of you could give me. 

Share this post


Link to post
Share on other sites

Hello!!

I have seen this happen many times..and usually it is the result of a couple of things:  1: bad rolling at the mill...2: improper HT..usually not tempering quickly enough after hardening.. but usually it's a bad roll at the mill...sometimes a bit of slag gets in there and during the rolling.... it gets longer and longer as the bar is rolled out..and then it can just "pop" apart..

Hope this helps..

JPH

Share this post


Link to post
Share on other sites

Old leaf spring? Maybe a stress fracture from use that wasn't noticed until the stress of the quench.

BTW-welcome to the forums. We used to have some land up in Custer in The Hills. beautiful country. My blacksmith mentor used to live up there.

Edited by Joshua States

Share this post


Link to post
Share on other sites

Thanks Jim.  We went right from quench to the oven so I don't think it was the HT but who knows with Junk Yard Steel.  I also don't know what he did to it beforehand.  I do know he heat treated it once then decided he had more file work to do on the edge and he annealed it.  It probably suffered more than one cold hit too boot.

  • Like 1

Share this post


Link to post
Share on other sites

Joshua, it is beautiful country, I live right on the west edge of town so the hills start at my doorstep almost.  We are two blocks down the street from the Stave Kirke Chapel in the Hills and a mile from Canyon Lake.  Who was your mentor? 

Share this post


Link to post
Share on other sites
6 hours ago, Richard A. (Woody) Hanson said:

Joshua, it is beautiful country, I live right on the west edge of town so the hills start at my doorstep almost.  We are two blocks down the street from the Stave Kirke Chapel in the Hills and a mile from Canyon Lake.  Who was your mentor? 

A fellow named Paul Duval. He passed away in 2007 (or was it 2008?). Climbing accident in the Needles.

Share this post


Link to post
Share on other sites

First thing coming to mind is like Joshua said, could be residual fractures from the springs original life.

Type of crack though, reminds me of hearing that if you clay 1560 you can actually cause the edge to shear from the spine.. The crack your describing sounds more like that.. You didn't mention claying, so I assume you didn't, but how thick was the spine compared to the edge? What was the quenchant? If I had to guess, there was a significant difference in cooling speed between the edge and spine, most likely caused by either differences in thickness, or uneven heating (also probably caused by different thickness).

 

Share this post


Link to post
Share on other sites

I think the mystery has been solved.  I went to the school of mines blacksmith club this afternoon.  Zack had another blade he made from a different piece of leaf spring. The thing is about 10 inches long, blade, and 3 inches wide by 1/4 inch thick.   He edge quenched this one, in oil, then at about a black heat he water quenched the blade and it split from stem to stern right down the middle.  There were numerous stress cracks in the blade from hammering it when it was too cold.  I took the mess in my hands and broke the tang off with my fingers.  Lord love a Duck, in all my years I have never cracked a blade that bad.  I think I have had a couple that broke in half from a little stress crack but that thing was as  close to an explosion as you can get without having shrapnel involved.  The first blade he oil quenched at my place and I told him when it was cool to take it to the sink and scrub the oil off the blade with some fast orange hand cleaner. Evidently it wasn't cold when he did the scrub and the crack opened up after it was tempered.  Anyway thanks for the help.  I took a bunch of grinding machines, angle grinders and belt sander,  down there today and we dressed up the faces of the anvils and the hammers.  Then I painted the beater hammers, ones used for striking other tools like chisels and punches RED.  trying to teach them not to use good smithing hammers for beaters.  Now we are going to mark the weight on each anvil and mark the maximum weight of the hammer that should be used on them.  I have heard of a 50:1 ratio but I think a 40:1 will be ok.  The anvils there have been getting some serious abuse.   

Another kid has been forging a blade out of a farrier's rasp for 3 weeks now.  He quenched that in oil today and it didn't seem to get as hard as he wanted.  Who knows he may have had one of those made in Bangladesh case hardened wonders.  Anyway he decided to quench that in water.  Evidently it had some carbon in it because it cracked in more places than a squirrel stores nuts.  Tuesday I am giving that bunch a knife making class.  Lord help me  :)  

One young lady decided he wanted to make a war axe that her favorite super hero carries.  She had a piece of 2 inch square bar about 16 inches long.  She asked me for some advice.  I told her to cut it to about 12 inches, upset one end till the whole thing is about 1o inches.  That is the size she wanted, and then slit an eye in it and forge the blade.  She took off to the Mechanical lab and came back in a few minutes with the thing cut to 12 inches and said don't worry about the eye, I can machine that.  To say the least I was impressed.  Anyway several of the big guys helped her get the thing upset and they all started forging the cutting edge.  All I did was hold the metal on the anvil for them.  This will be interesting when it's done.  She is very determined.  I asked her where she got the steel and she said it was a piece of hot rolled that has  has been laying around the machine lab for years.  Evidently it is mild steel. 

Share this post


Link to post
Share on other sites

Well Woody, you have quite the job ahead of you. Good luck and have fun!

I thought I might share with you a photo that Paul gave to me for safe-keeping. It was one of his most favorite days in his life.

Paul & Francis Whitaker.jpg

Share this post


Link to post
Share on other sites

Great picture Joshua.  One of my treasured pictures is of Me, Junior Strassil and Cheryl, baby anvil. Taken in Jr.s  shop in Fall City, Nebraska a few years back.  Cheryl had a heart attack and they did an auction to raise money for her.  I donated a Damascus blade to the auction.  Then a while later I took an Oxygen Concentrator that my wife used before she passed away down to Junior so his wife could use it instead of relying on expensive bottled oxygen.  Jr. Cheryl and I got together in his shop to play in the fire for a while before I left for home. 

I see you are in New River, AZ do you know Rich Hale in Glendale by any chance.  He is a great guy and makes beautiful knives.  Look him up in you don't already know him.  My son lives in Prescott Valley, AZ and every time we go to AZ Jackie and I stop by to see Rich and spend some time with him.  He has taught me a lot.  

 

Share this post


Link to post
Share on other sites

So when I painted the beater hammers red, I got some red paint on my hand. Isaac said be sure you don't do anything illegal on your way home, you will be caught red handed. Then he said "what do you call a cracked blade?" I said I don't know, he said "A Zackto knife" I need to have a talk with that kid. :)

Share this post


Link to post
Share on other sites

The Saga of Zack's cracked blades continues.  There are none so blind as those who refuse to see and there are none so uninformed, a polite choice of words on my part, as those who refuse to ASK.  I went to the Blacksmith Club at the School of Mines yesterday and Zack showed me the new knife he is working on he said that it had some microscopic cracks running lengthwise on the spine of the blade.  He said he had researched it on the internet and he found that springs tend to crack like that from use.  That is true.  But this is the third blade he has cracked in much the same manner.  I asked him what he quenched this one in and he said oil.  I asked him what temperature he quenched it from.  he said it was bright yellow when I took it out of the forge and it was still orange when I got it to the oil.  "Houston we have a problem." The world is going to run out of leaf springs before Zack gets a knife made.  I told him to check the next one with a magnet and when it goes non magnetic quench it then.  Zack asked me if his blade was worth finishing since he had a couple weeks into it.  I took it and gave it a quick soak in ferric chloride.  Then rinsed the blade off with hot water and when it dried I carded the spine off with some fine sand paper.  It showed little micro cracks all over the spine.  I told him it was his knife but if it were mine I would junk it. 

The club has a tool that I have never seen before.  it is like a flatter but with a face about  8 or 9 inches square and over an inch thick.  It weighs around 10 pounds or so.  It is not designed to be struck with a hammer like a flatter.  Any ideas on what it is.  I thought it might have been used to flatten sheets of steel, get the warps out of them. 

There was an ad in Craig's list a guy in Hill City had some band saw blades to give away.  I went up there on Thursday.  Lord Love A Duck!  I got a whole pickup box full.  they are 1 1/4 inch wide and when broken and laid out, 13 feet long.  There was 66 of them.  I chopped them up into 1 foot pieces today to use them in pattern welded blades.  He showed me a box that one came in, they are double hard not bi-metal.  I told him I would make him a knife, he wants a drop point hunter with an antler handle.  I am not wild about antlers but he will get one. 

Share this post


Link to post
Share on other sites

Zack will learn. Sooner or later he will get it right.

I cannot say the name Rich Hale rings a bell, but then again I am terrible with names. I do know a lot of AZ smiths because I belong to AABA, but I cannot remember names for the life of me. A quick check of Rich Hale in Glendale on FB and I cannot say I know him.

Amazing score on that blade stock! Post some pics of that knife when you get working on it.

 

Share this post


Link to post
Share on other sites

Woody, that tool you're describing sounds like it's a large set hammer.  It's used to make sharp 90° bends in metal.

Doug

Share this post


Link to post
Share on other sites

Doug, I will take a picture of it next time I am at the College and post it.  Joshua, Rich is a member of the AZ knifemakers guild, he has made their guild blade several times.  That is a blade for each member and available only to members.  I don't think Rich is a member of the Arizona association, however he used to teach a farrier's class at Glendale Community College.  He is a retired Captain from the Glendale Fire Dept. 

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

×