Full Story on the catastrophic failure of Marbles 7"Trailmaker.

Cliff, There is no doubt that a thicker edge will take more abuse than a thinner edge, all else being equal...thats not in question.

The question is what went wrong with the blade in this post, and my guess is heat treat. Im making the assumption that the blade is ground like the other thousands of Marbles knives that see hard use year after year without fail.

Again, the best cutting knives ive ever used/seen had extremely thin edges, virtually no secondary bevel etc.. I dont know the exact angle of the edge. Some of the worst knives ive used had thick, cumbresom edges with a large secondary bevel. These same knives performed extremely well after re grinding the edge with NO edge damage etc........

I just dont agree that you cant absolutely tie a blades durability to the numbers you indicate. The things you CANT SEE OR MEASURE are much, much more important.

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"Never hit a man unless you must, but if you must, knock him down" Teddy Roosevelt.

www.lameyknives.com
 
Sporty:

<font face="Verdana, Arial" size="2">You mention these types of blades not being able to hold up under chopping knots?I was definitely chopping knotty 2X4's.</font>
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Chopping into knots is far more stressful than chopping into clear wood and you need a much stronger edge to be able to resist damage. However I don't think it could be just the grind in this case as you have severe deformation without fracture as well as chipping without deformation, both in the same blade, which doesn't make a lot of sense.

<font face="Verdana, Arial" size="2">Also, what about the blade on the BK&T Magnum Camp, I know it's not the same type of grind but it is still a very thin blade and it chops like the dickens.</font>
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The Magnum Camp is fairly thin behind the edge, I was quoted about 0.03", but I would bet that the edge bevel itself is fairly abtuse, about 22-26 degrees I would imagine. Correct me if I am wrong but I would assume this is much thicker than how the Marbles are ground.

In any case, given that the Magnum Camp is fairly light and neutral balanced, the edge will appear to be much stronger than it actually is because the impact energies that it sees are much lower than chopping blades usually see becuase of the low mass and neutral balance. That is to say, if you shifted the balance to say an inch infront of the blade, the edge could now start taking damage where it had not before.

Matt, yes, a blades durabilty (or anything else) is controlled by the properties of the steel and how well these are brought out by the heat treat. You obviously can't judge this by looking at the blade and/or taking a tape to it. The numbers I quoted are basically the best peforming blades I have seen (ie. the thinnest edges) that have the necessary durability levels and have to be used very carefully with the correct techniques.

-Cliff

[This message has been edited by Cliff Stamp (edited 01-10-2001).]
 
If this knife is of the 52100 steel and if they use high and low temprature salts for the heat treating, I might have a plausable solution to what happened.
Then again, maybe not.
If 52100 is taken from the high temp. pot and submerged in the low temp pot to harden, then removed for a short period of time (5 min. usually, about) and then returned to the low temp pot for the first tempering cycle. There is a possibility that the tip almost cooled enough to cycle the steel but the rest did not, which in effect, it is not tempered due to the steel not cooling enough between the dipping in the low temp pot.
This would cause the tip to be able to bend but the blade would still be too hard and would chip in such a manner.
I would definitely have to agree that it was the heat treat. I have had a blade chip in such a manner when testing after hardening and without using the tempering cycle. Even if you did chop a concrete block, the blade should not chip in the manner it did if it had been heat treated properly. Especially with the convex grind as it appears in the picture.

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Ray Kirk
http://www.tah-usa.net/raker
 
Ray :

<font face="Verdana, Arial" size="2">Even if you did chop a concrete block, the blade should not chip in the manner it did if it had been heat treated properly. Especially with the convex grind as it appears in the picture.</font>
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How should it behave then?

-Cliff
 
So...a new knife trailmaker arrived today from Marbles...no explanation of what went wrong but at least a new knife. The sheath is better on this one too. I haven't had time to test the new one so will let you all know as soon as I do. Thanks Marbles!
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- Sporty
 
It sure would be great if you went back to the same 2x4 and did some more chopping. Of course I'd look carefully for signs of hidden rocks or nails in the wood. If the 2x4 eats another blade I'd try splitting it up with a hatchet and see what the heck is embedded in that wood. Maybe someone hit it with some steel shot from a shotgun before the tree went to the mill.
 
I would do the reverse. Split the original 2x4 with a hatchet to look for imbeded material, and then test the new knife on a fresh piece of 2x4. There is no point in damaging another knife if the original damage has been caused by a hidden obstruction.
 
In the North East we use SPF (spruce, pine fir) 2x4's. They come kiln dried to 19% moisture content. The majority of these come through as spruce 2x4s. Spruce is a very soft and easily chopped wood.

In the South, many 2x4's are SYP (southern yellow pine) which comes kiln dried to the same 19%. It is a much harder wood when it is dry than is spruce.

2x4s are also commonly found in Douglas Fir and Hem Fir. Both of these woods also are much tougher than spruce.

The only point that I'm trying to make is that one man's 2x4 is not equal to another man's 2x4. Some woods used in common framing lumber are much harder than others, and ALL of them are much tougher when they reach a point of equilibrium (4% to 11% moisture content... depending where you live) than they are when you get them "kiln dried" from the lumber store.

A "dry" SYP or Fir 2x4 will bend a nail much easier than a "dry" Spruce 2x4. I'm sure the effect on a knife blade would be somewhat proportionate...

Michael

û

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He who has smelt the smoke is never free again...
 
Even on almost any hardwood though, I would expect several ordesr of magnitude less impact on a blade. It's not like it's chopping through case-hardened armor plate. It's a pity Marbles didn't confirm whether or not there was a heat-treat problem. I was curious.
 
So I got a e-note from Mike at Marble's about the knife...

> Thank you for your concern. it appears that your blade was never heat
> treated properly. we did discover a small batch of blades (less than 50)
> that somehow got thru the line in a semi-heat treated state. this was over
1
> 1/2 years ago. yours must have been from that batch. end of the mystery!!
> the only other way this can happen is if people try to cut bones or rocks.
> don't say nobody cuts rocks! we have had it happen. Mike Stewart @
Marble's.

So the mystery is solved...on to the testing of the new knife. Dude, C4 thanks for the 2X4 info, I would have thought 2X4's were sort of universal. The 2X4 was already examined for nails and bullets and none were found. Chop...chop...bye.

[This message has been edited by Sporty (edited 01-24-2001).]
 
Let's give Marble's a hand for looking into this and rectifying the problem. Yeah, another Marble's is definitely on my list.
 
Hi, sorry for the tardiness. But it was actually just last weekend that I finished my testing. If only I had every day just to test knives. Saw Fisk's article on home testing which inspired me a bit.

Here is the deal and it's just the plain truth and those of you that think me a Marbles hater will just have to continue to...ah whatever. First the good news...

It's a pretty knife, one of the few large high performance factory knives that looks good. India stag handles are top notch. It is something you would feel proud to hand down to your grandchild. It's not just a matte black tool-weapon. Oops I just insulted a bunch of people...hee hee...you know what they say about taste, it's personal. But in a practical sense it's old style looks give it a benign quality that won't raise eyebrows from others on the trail or in the camp. GRADE A+

Here is the deal, the knife chops 2X4's like butter. 1 min 15 sec per 2X4 on average. It is a great chopper, for a 7"er the big aluminum butt never lets it slip out of your hand even with gloves on. I used a 4 finger, sometimes 3 finger, with hand toward the back of the handle for more blade forward power, then with a wrist flick before impact. It never glances, always penetrates, and just has a great feel.

Check it out dudes, I cut down an 9" hardwood tree that was dead but not rotten, dried and frozen. It was as hard as a rock. I could not leave bite marks on it when I bit into it. The wood not the knife. Grrrr. I chopped it down as easy as with a hatchet. And it's pretty. Did I mention that. I mean I look good out there. GRADE A+

The aluminum butt, after much abuse has never loosened! A+

It ALSO is a pretty decent kitchen knife, cuts onions and tomatoes adequately. It's a great meat knife too, the edge is thin enough to do fine work. GRADE B

Then came the stabbing tests. FAIL! Man I don't know why they are grinding a tip like this on a 7" bowie. It's really crazy. The tips on this one and the one I had last that failed were ground out to a NEEDLE point, with no bevel at all. It is like a needle. Needle. THIN. I mean you could do surgery with this tip. Maybe that is their point, that they wanted it to be a meat knife. But it is weak for a backwoods utility knife. I just pressed the tip, 1/8" into a 2X4 and by pulling sideways with one finger about 10-15 degrees, bent the tip. I bent it back straight. Now I let the weight of my arm and the knife fall from shoulder to waist without added force, burying the extremely thin tip up to 1/4" in the 2X4 I pulled sideways with one finger 15 degrees and the tip snapped right off. 1/4" was missing.

This is extremely poor performance in my opinion. I have been testing a lot of thin bladed knives that pass this test but none, not even my German chef's knife are ground this thin at the tip. None have failed this test.

So I just ain't gonna send this knife back to the factory again. It's not their fault anyway, that's how they grind all their Trailmaker knives and I'm not gonna tell them any different. It's their choice and their customers seem happy. So I got out the old mill bastard and started to work...this is the first time I have ever done this. But after awhile I got a lot of enjoyment...and maybe opened a door into knife making...by creating what I felt to be the perfect tip for the knife.

I took a marker and drew out where how I wanted the tip to be and first just filed the bad way down the blade and the false edge down til I got the shape. Then moved the point to where it was meeting where the false edge and the cutting edge meet. Then I started building the bevel back to match the rest of the blade, but when I got to within 1/4" of the tip I steepened the bevel slightly. Then sanded, still have to buff. It doesn't change the look of the knife at all, the belly is a tiny bit rounder but I bet only I would notice. The thickness at the tip is similar to a Randall #14 and a Magnum Camp. It can withstand hard jerks to the side when sunk 1/4" into a 2X4. Which is all I ask.

I know I am practically doing sacrilege, stepping on the graves of great men, in some people's eyes but the new tip and the whole knife has become the only knife I carry in the woods. Cuz now it's pretty and it works good. So am I a marbles hater? Or a lover...

-Sporty

PS- I love the sheath too, seems they are making them a bit stronger. Would like double snaps though. Will try to add some pics when I get the chance.


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The pen is mightier than the sword...but not as much fun!
 
While I can understand a knife with a really thin point like you describe not having a significant amount of prying strength in the tip, I don't think it is the expected behavior for it to take a perm set nor break under angles as low as you describe expecially since it is 5160.

Most blades that thin and long, even stainless ones, will allow the handle to deflect *much* further than 20 degrees. Interesting that it takes a perm. set and then breaks both at low angles, if it did one or the other you could guess a too low or too high a RC.

Concerning the chopping speed, the 1 min 15 sec, is a lot slower than the 45 sec time you noted for the Randal #14 and Magnum Camp. Any comments on the difference in performance?

Nice work.

<font face="Verdana, Arial" size="2">I could not leave bite marks on it when I bit into it.</font>
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Sounds like we are related.

-Cliff

 
Sorry it took so long to get back, I have indeed been busy. I will try to post pics of the sharpened tip version this week, promise.

Cliff said, "Concerning the chopping speed, the 1min 15 sec, is a lot slower than the 45 sec time you noted for the Randal #14 and Magnum Camp. Any comments on the difference in performance?"

I think this was just bad science, on the first tests I did I counted "one one thousand" and on the later I had someone timing me with a stopwatch. Duh.

About the tip bending and then breaking, I don't think it's a heat treat issue, it's more like you can BEND the fine tip of a needle or you can BREAK it in the middle. That's how it felt to me.

But as you told me Cliff I need to repeat my tests over a few times to and take breaks to account for variables and average them out.

My preliminary 2X4 (PA pine, times ar how long it takes to chop through, chopping full force, full strength) tests go like this...in no particular order...all knives were sharpened as good as I could get them with a file and a rock, some shaved hair, some like the sirupati, I couldn't get that sharp...


Marbles Trailmaker 7" Stag- 1min 15 sec (lno shock on the hand thanks to the big butt, deep penetration)


Becker/Fisk Magnum Camp Knife - 1 min 10 sec (some light hand shock, very good penetration)


CS Trailmaster - 1min 55 sec (very comfortable but not penetrating, some glancing blows, maybe need practice)


Randal Mod 14 7" - 1min 28 sec (no hand wear, limited penetration, some glancing blows)


CS Recon Tanto - 2min 33 sec (very comfortable, light weight limits penetration)


HI 15" Sirupati 1 min 55 sec (some hand shock, very limited penetration, BUT the force of it broke the 2X4 in half, 1/2 the way through. Part hammer, part knife, no toolbelt should be without)

The idea behind testing these particular knives is to test backpacking/camp knives that are roughly a pound and can do many camp chores from cutting food to chopping wood. Larger review with more in-depth tests to come..things may change as the average increases. Sigh, one of these weekends!:)

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The pen is mightier than the sword...but not as much fun!

[This message has been edited by Sporty (edited 03-27-2001).]

[This message has been edited by Sporty (edited 03-27-2001).]

[This message has been edited by Sporty (edited 03-27-2001).]
 
For once, may have something germane to bring up here. As it happens, am reading my way thru '97, '98, and '99 TK. In either March or May '98, there is a story about Marbles getting restarted in the knife business after 30 years or so out of it.

I don't remember which models, but Marbles had a few thousand blades -- which were always contracted out, not made by Marbles themselves -- that had been sitting gathering dust and rust for 30+ years. They cleaned up the blades, assembled some knives, and lo and behold, all, or virtually all, of them had failures much like yours, if not exactly. Something to do with rust getting into hairline fissures or something like that.

Anyhoo, am sure that Marbles will make good on it. As it happens, I just held my first ever Marble yesterday. Smaller one, 5" blade. What a great feeling knife. Instant confidence that sucker would do everything you asked of it, within limits of it's design. I also remember reading in article about Loveless -- he said flatly that Marbles knives were twice as good as any other production knives. Course, only an opinion, but kind of like "the elephant speaks."

Can't help but figure that maybe you got one of those decades old blades, that somehow hadn't sold or come to the surface before you bought it.

Good luck. Hope the replacement is everything you and Bob believe it will be.
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Asi es la vida

Bugs
 
<font face="Verdana, Arial" size="2">Originally posted by Sporty:
Marbles Trailmaker 7" Stag- 1min 15 sec (lno shock on the hand thanks to the big butt, deep penetration)
</font>
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That's just the way I like it.
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