"When Good knives Fail"

[MikePerrin]

Sorry guys, I couln't find the original thread.

Speaking in terms of production cutlery, any manufacturer will have failures. Ontario and Camillus are no different than others in that respect. I know Ontario had a few problems on the initial run of RTAKs which was corrected and they replaced problem blades promptly. That same scenerio could be repeated for any production maker, no exceptions.

I've used inexpensive, production blades, including the RTAK, a great deal in Central and South America and done a lot of work with them. I guess I'm lucky I didn't have the serious failures some have described on other threads. The RTAK performs very well for the rough bush work for which it was intended. Clearing campsites, cleaning out trees and grubbing in dirt, removing large roots, building structures (shelters), ...it's really good for rough chores and short enough to do some game cleaning also. I haven't done any lab testing, just years of bush work.

Admittedly if left to my own devices and choice I'll end up using Tramontina machetes every time though. There really is nothing that comes close to matching these machetes for the bush except another cheap machete (Imasca, Coronet, etc.) Ontario has also introduced an inexpensive, flexible machete along the Tramontina lines that works very well also.

In the end a guy really shouldn't be hingling his life on a blade to begin with. Yeah it's nice to think you have something reliable in your hand but anything can fail and will. If the man or woman doesn't have the wits and common sense to overcome equipment failure then perhaps he or she should limit their activities to within a couple of miles of the shopping mall.

Ya'll have a great forum . I truely enjoy reading it. Mike Perrin

 

[Roadrunner]

Good point about wits and common sense. I usually take any new blades out and give them a good workout anyway. I'm one of those people who turns into a little kid whenever I get a new toy, I just can't stop playing with it . So if it's going to break, it usually does it in a non-crucial situation so I have no worries taking it anywhere after that. Although I've never been to the Amazon either, but if I did I have a few blades that I would trust to go along for the ride.

 

[Cliff Stamp]

Probably in responce to this thread :

http://www.bladeforums.com/forums/showthread.php?s=&threadid=265390

-Cliff

 

[MikePerrin]

Yep.

 

[Turnkey]

Yesterday, I had to ship my Spyderco Dodo back to the Spyderco factory. The blade developed play and the lock eventually failed.

I can't tell you how disappointed I am with this, although Spyderco assured me they'd make it right, which I'm sure they'll do. I'm just irritated because I have to be without my knife, plus I have to pay to ship it back after I just paid to purchase it.

 

[Cliff Stamp]

Knowing how to work with less than optimal equipment, or even improvising from no equipment are very valuable skills. However so is knowing how to pick good equipment in the first place. Choosing a solid knife is no different than choosing a pair of boots. Yes you can make do with cheap boots which fall apart, however it is not like this is necessary, there are quality boots just like there are quality knives which have very high QC measures.

I use many types of blades, saws and other tools for such work as I want to be familiar with less than optimal tools. However when it comes to actually buying select ones which hopefully I can choose to have with me, I am going to buy the best ones I can as such situations are already difficult enough that I don't want to make it worse by working with a less than optimal blade or tool. It is hardly the case that options are not available.

-Cliff

 

[Minuteman]

Originally posted by Cliff Stamp
Knowing how to work with less than optimal equipment, or even improvising from no equipment are very valuable skills. However so is knowing how to pick good equipment in the first place. Choosing a solid knife is no different than choosing a pair of boots. Yes you can make do with cheap boots which fall apart, however it is not like this is necessary, there are quality boots just like there are quality knives which have very high QC measures.

-Cliff

Cliff, I think you have aptly summarized the premise upon which the original thread was started, and that is to answer the question: What can be done up front to mitigate knife failures in the field?

Of highest importance in this pursuit, I believe, is to select a blade geometry / steel / heat treatment combination that does not challenge the limits of the material properties in any way -- give yourself some margin. A simple way to accomplish this is to buy a softer blade (like a Tramontina machete) and be prepared to do a little extra sharpening. You buy reliability at the cost of edge holding ability. Unless you plan to be in a big hurry in a survival situation, this isn't really much of a loss.

Now if efficiency is more important than absolute reliability, then you must move closer to the limits of the material properties. People who need to get more work accomplished will usually take on additional risk to do so. If someone needed to clear five acres of scrub fir before dinner, they would probably prefer a higher performance blade.

Now if you want your cake and to eat it too -- high performance AND reliability -- then there is going to have to be some kind of testing involved. And the area I think is of critical importance in testing is to determine if there were any micro cracks in the blade when you purchased it. We talked about a number of ways to check for this: (1) cheap Radio Shack microscope along edge, (2) penetrant testing, (3) magnetic flux testing, (4) audio spectrographic analysis, or (5) use the knife under similar conditions for a while and see if it breaks.

It is nice that Swamp Rat does number (2) for you. I don't think we identified any other manufacturer that screened for cracks at 100%.

 

[Cliff Stamp]

Minuteman :

... select a blade geometry / steel / heat treatment combination that does not challenge the limits of the material properties in any way -- give yourself some margin.

Yes, that is a critical element. The problem is that knowing how to do this is difficult especially when considering the massive amount of conflicting opinions. Ask one maker about a steel for a specific task and you can find it highly recommended, ask another and they will say it is a horrible choice.

A simple way to accomplish this is to buy a softer blade (like a Tramontina machete) and be prepared to do a little extra sharpening. You buy reliability at the cost of edge holding ability. Unless you plan to be in a big hurry in a survival situation, this isn't really much of a loss.

Yes, I think this is a bit of a dramatic drop though. You don't really need to go that soft. The main problem with many blades is that either the hardness is too high, or the steel really inherently brittle, which can give the impression that you can't get high performance without risking gross damage.

With use of quality very tough steels like L6, 1084, 5160, A8, hardened to 56-58 HRC, they are near impossible to break. You can literally smash them repeatidly with a hammer to no effect, except denting the face of the hammer. These blade steels will bend to large angles and spring back close to true.

Now if you want your cake and to eat it too -- high performance AND reliability -- then there is going to have to be some kind of testing involved.

Yes, the problem is that this is rarely done. It is also rare to have performance questions answered, what would happen to the blade if I did XXX, or are the performance claims made actually covered in the warrenty. Both of these aspects massively cut down on hype when they are held, and the blade quality is in general much higher.

As with any tool, or object you are going to depend upon, you would never wait until it had to be used to evaluate its functionality, that is a great way to put yourself in harms way. Always test out such products unless of course they are disposable (in which case buy more than one and test out a couple, and take spares).

The more important the knife the more important that testing be performed by the manufacturer, extensive R&D and random sampling during the run. If you get a paring knife that the heat treat was off, this is a lot different than if you are replying on an emergency tool.


-Cliff

 

[Minuteman]

Originally posted by Cliff Stamp
Minuteman :

Yes, I think this is a bit of a dramatic drop though. You don't really need to go that soft.

-Cliff

You're right Cliff, you don't need to go as soft as a Tramontina to dramatically improve reliability, but if you are going to use softness as a way to improve reliability you will definitely sacrifice edge holding -- considerably.

Wayne Goddard did a series of tests in one of his books where he made up several of the same knife -- same geometry, same steel, same heat treatment, except for varying the hardnesses from like 60 something down to maybe 50, as I recall. The hardnesses were all verified on a HRC tester.

He then subjected the knives to various tests of edge holding ability. To summarize his findings, if you want good edge holding you MUST be at 58 HRC or higher. Below that, even by a couple of points, edge holding fell off CONSIDERABLY. On the other hand, these knives were MUCH less likely to fail due to fracture.

This is the exact approach to survival knives that the US militiary has adopted for generations. If I'm not mistaken, the Kabars are specified for hardnesses in the mid fifties, not the high fifties. With 1095 steel, this makes a knife that will take a lot of abuse and can be made cheaply in large quantities. It is easily resharpened, so edge holding is not a major concern.

 

[Cliff Stamp]

Yes, when buying cheap you have to really over compensate for QC. If the heat treating variance is large, you have to shift the goal hardness down as that even with maximum variation you are still below the tolerance levels.

This discussion should basically go two different ways depending on the class of knives. With high end customs, if a maker was seeing +/- 3 HRC points, you would be leary of 58 HRC knives, as you are really looking at 55-61 HRC, however that kind of variance would make me stay away from them anyway.

-Cliff

 

[Minuteman]

Originally posted by MikePerrin
Admittedly if left to my own devices and choice I'll end up using Tramontina machetes every time though. There really is nothing that comes close to matching these machetes for the bush except another cheap machete (Imasca, Coronet, etc.)

Mike, I'm with you on the Tramontinas. I like them a lot more than any $10 knife deserves to be liked. Put one in my hand and I feel like a human bush hog.

 

[Minuteman]

Originally posted by Cliff Stamp
With high end customs, if a maker was seeing +/- 3 HRC points, you would be leary of 58 HRC knives, as you are really looking at 55-61 HRC, however that kind of variance would make me stay away from them anyway.
-Cliff

From Goddard's test results, +/- 3 HRC is way too big of a tolerance zone. 58, spot on, was just about right. 55 had low edge holding ability, but wouldn't break. 61 would stay sharp a very long time, but would snap right off.

58 +/- .5 HRC would be a more appropriate specification. As you said, as you move closer to the upper performance limit, the tolerances have to be tightened up (the principle behind statistical tolerancing methods).

 

[superc]

quote:Originally posted by storyville
Another obvious point, worth repeating, is to work and test the knife extensively in the backyard, or only 30' from the truck, so you have a good understanding of the knife's abilities in the unfortunate event that you slide into that freezing creek. The "emergency scenario" shouldn't be the first time one tests out the capabilities of a knife, or any gear...
Glen

This is true. I made that mistake once 30 years ago. Brought a new Case hunting knife and trustingly brought it as my main knife on a deep woods hunting trip for it's maiden trial. I still have the knife and if there was a way of attaching a .jpg pcture to this post I would show it. It was a pretty knife when new, good balance too. Good bread slicer. Long story short, the blade broke on a deer pelvic bone. 12 or more miles from anyone or anything. Deep snow (2 foot or more, drifts, wind, etc.). Had to finish with an ax and a Cub Scout pocket knife. Never again bought or trusted a Case.

 

[Minuteman]

Which, I guess, brings up yet another obvious point: Redundancy is a good means of achieving reliability. Or in other words -- carry more than one blade! This simple solution can even compensate for things like LOSING one of them (over the edge, into the water, etc.) let alone just breaking one.

In a similar situation many years ago, a friend of mine once finished up field dressing a deer with a set of nail trimmers! Even a Cub Scout knife would have been welcome in that case.