Ed, while they specified and paid for the finest materials, evidence suggests they did not get them...
http://www.nytimes.com/1998/01/27/s...tanic-disaster.html?sec=&spon=&pagewanted=all
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Another question for knife makers
- Thread starter Ed Fowler
- Start date
http://www.nytimes.com/1998/01/27/s...tanic-disaster.html?sec=&spon=&pagewanted=all
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Kgd: While I listen carefully to those who test my knives in the field, I do not rely on their reports, I want to know through my own experience and try to develop experiments that predict what blades may face in extreme conditions.
My method of testing for cold temp performance was as follows:
1) I tested a blade that was heat treated in my usual manner, did 10 edge flexes and the edge did not chip. I ground out the portion of the blade that had been stressed by the edge flexes and resharpened the blade.
2) I placed the blade outside of my shop in -30 below temp over night then went outside and tested it for edge flex. Minor chipping on the 4th edge flex. Again I ground out the chips and sharpened the blade and tempered again 15 f. hotter.
3) I set the blade outside again over night and tested for chip the next morning - 10 edge flexes and no chip. Then I put it in my vice and flexed it to 90 degrees, it did not crack. I did not try multiple 90 degree flexes as the blade warmed up on the first flex.
I feel fairly confident that this was a valid test. I was not using a torque wrench at that time so had no index for strength other than it was very strong and required a piece of pipe over the tang to accomplish the 90 degrees.
x39 - that may very well be the case, like I said any disaster results in a lot of theories and pointing of fingers as to the cause. Like the scuttle fish, those who may have been guilty have a way blackening the water so that they become invisible. I do not mean to dispute any of them, just try to learn all I can from what I read.
I feel time is well spent on prevention.
My method of testing for cold temp performance was as follows:
1) I tested a blade that was heat treated in my usual manner, did 10 edge flexes and the edge did not chip. I ground out the portion of the blade that had been stressed by the edge flexes and resharpened the blade.
2) I placed the blade outside of my shop in -30 below temp over night then went outside and tested it for edge flex. Minor chipping on the 4th edge flex. Again I ground out the chips and sharpened the blade and tempered again 15 f. hotter.
3) I set the blade outside again over night and tested for chip the next morning - 10 edge flexes and no chip. Then I put it in my vice and flexed it to 90 degrees, it did not crack. I did not try multiple 90 degree flexes as the blade warmed up on the first flex.
I feel fairly confident that this was a valid test. I was not using a torque wrench at that time so had no index for strength other than it was very strong and required a piece of pipe over the tang to accomplish the 90 degrees.
x39 - that may very well be the case, like I said any disaster results in a lot of theories and pointing of fingers as to the cause. Like the scuttle fish, those who may have been guilty have a way blackening the water so that they become invisible. I do not mean to dispute any of them, just try to learn all I can from what I read.
I feel time is well spent on prevention.
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Interesting, I like how you used the same blade which survived the warm test first and re-tested it under cold conditions. Also interesting to your ability to iterate the HT according to the performance on the edge chip. Very good methodology. As a scientist, I appreciate your approach.
Thanks, I learned something!
Thanks, I learned something!
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- Jan 6, 2005
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- 9,680
Ed... are you using the brass rod test for edge flex? I am always looking for new ways to test my own work. Like I've said before... As a maker, if you're not failing, you're not growing.
Rick
Rick
I agree. The problem is, the more variables one is presented with, the more difficult it is to mitigate the outcome in a generally satisfactory manner.
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Kgd: thank you sir!
Magnussen: my brass rod test is accomplished on a smooth sharpening steel. I stroke the blade under pressure from ricasso to tip full length with enough pressure to perceptively deflect the edge.
Just for grins, the sharpening steel is Rc 62 but a 60 Rc blade will scratch it, actually shave flakes off of it. I used the brass rod for years then asked why (?) and went to the steel and it lasts a lot longer. I could not see the value of using a softer metal for flexing the rod.
Magnussen: my brass rod test is accomplished on a smooth sharpening steel. I stroke the blade under pressure from ricasso to tip full length with enough pressure to perceptively deflect the edge.
Just for grins, the sharpening steel is Rc 62 but a 60 Rc blade will scratch it, actually shave flakes off of it. I used the brass rod for years then asked why (?) and went to the steel and it lasts a lot longer. I could not see the value of using a softer metal for flexing the rod.
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- Jul 12, 2008
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- 1,397
I don't have much to say but very much interested in this thread
as winter mountaineering is one of my favorite outdoor activity.
I've broke an ice-ax due to low temperature.
It worked fine in -10c but the tip went off in -20c.
The ice gains hardness and strength while steel gets brittle.
as winter mountaineering is one of my favorite outdoor activity.
I've broke an ice-ax due to low temperature.
It worked fine in -10c but the tip went off in -20c.
The ice gains hardness and strength while steel gets brittle.
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- Nov 7, 2004
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This particular knife was fashioned from an old bayonet for Amundsen by Martin Ronne, and wound up being instrumental in saving Amundsen's life after a forced landing in the arctic. Interesting story at www.ronneantarcticexplorers.com/Martin_Ronne.htm
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Good information gentlemen!
It is interesting to see what appears to be a round hole in the tang where the handle broke.
A round hole in a blade or tang is a stress raiser. This can be partially compensated for by heat treatment, but a round hole many times is a source of failure and best to be avoided.
It is interesting to see what appears to be a round hole in the tang where the handle broke.
A round hole in a blade or tang is a stress raiser. This can be partially compensated for by heat treatment, but a round hole many times is a source of failure and best to be avoided.
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Post expired.
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Thank you, Mr. Fowler. Great honour to have such a response.
I've had no blade trouble due to cold so far but have something to talk about the handle.
That is to say, the handle must be made to be used with glove or mitten.
Most important is I think it's size, winter handle must be longer than summer time handle.
To be added, lesser exposed metal maybe better.
Thanks, Dannyboy Leather for sharing a great story of great explorer.
I've had no blade trouble due to cold so far but have something to talk about the handle.
That is to say, the handle must be made to be used with glove or mitten.
Most important is I think it's size, winter handle must be longer than summer time handle.
To be added, lesser exposed metal maybe better.
Thanks, Dannyboy Leather for sharing a great story of great explorer.
My pleasure, glad you enjoyed it.