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Quality Control?


Bruno
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Hello's,

 

Infrequent Poster here. I have some questions about quality control. Say for example I have a known steel that I can accurately harden and temper. Now with that steel I intend to make a bunch of Knives of Similar shape/design/purpose. Let's call them Camp Knives. So they all need to be tough, while balancing sharpness.

 

My question is how to best go about quality control or testing ? Say I want to give away or sell these knives. And I don't want to look like a n00bie when someone returns a broken, Poor Quality or unsafe Knife. So If I make a bunch of knives using a known steel within a controlled process, what is the best way to go about testing the knives?

 

Do I Torture test every knife I make or do I use the test pieces I make (which may be unpolished), as an adequate scale for determining how my finished knives would perform ?

 

For example, say I make Tester Camp knife that is unpolished and rough and probably without a handle, after heat treatment and temper, I test the knife. Let's say that I want the knife to bend and not break, while maintaining a sharp edge, so we would do an edge quench of the steel after good normalization, and then temper. If my steel reacted that way.

 

If I make my test knife, and all went well, and then stick it in a block of wood or vise and bend back and forth several times, then proceed to chop at some hard wood to test for edge retention, and all goes well with no break, chip or dullness of the edge, then one could think that quality of the blade is adequate?

 

So the real question, Is this test good enough for all the blades, or should every blade be tested to the same standards ?

 

If I thoroughly, test every blade, then I wonder if the possibility of micro fractures or unnecessary stress throughout the blade will occur.

If I make a brand new finished/polished blade, how far do I test it? I'm concerned that if I bend a brand new finished blade to 30 or more degrees and back several times, I'm diminishing the life of the blade. I realize that shouldn't be much of a concern to a well made blade and is probably out of scope for a camp knife, but I think that if well made automotive springs can break after repeated stress, then a knife made of thinner material can break easier after exerted to rough testing standards.

 

I want to make knives, though my resources are limited, and I don't want to unleash an inferior or unsafe knife, so much testing is required. Wondering how far I need to take every knife I make as far as testing goes without causing undue stress in the blade.

 

Any thoughts would be appreciated.

 

-Bruno

Edited by Bruno
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If your process is stable, controlled and based on a good understanding of heat treating, you could choose one *random* blade from each batch for testing.

As long as its siblings are treated the same way you may be fairly certain of the kind of quality you deliver.

 

Something you might want to consider: if you tell the owners of your knives they have an knife that won´t break, they may well put it to just such use that might break it anyway.

I guess what I am trying to say is that you can check for quality in different ways and you can strive for different types of quality.

 

The best knife might not be the one that cannot break.

 

It really depends on how the user understands the tool and his role in its performance. The way you design and test your knives will have an impact on this.

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Actually, as my knives are not very good (yet) and I don't have to worry too much about ruining them, I purposely broke the tip off my last knife. Stuck it in a tree, bent it to about 45 degrees (obtuse angle) before it snapped. That gave me a good insight as to how far it'll go, as well as a good peek at the crystal structure. Plus, it's just the last half-centimeter of the blade that broke off, so I can easily grind it back down to the point.

Trying to make each knife just a little better than the last

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Some destructive testing along the way will be necessary to test you heat treating process. Obviously you can't do that with every knife. You can do some chopping or shredding some fibrous rope with every knife that you make to test the edge holding ability. If you have the money to get a tester you can take hardness readings of just about all your knives. Most of the hardness testers must be used on an area with parallel sides so that will restrict your hardness testing.

 

What I do is try cutting some bailing wire or a thin brass rod by driving to blade through with a mallet. I also do a 2X4 chop with larger knives to make sure the edge holds up or shred some fibrous rope to test edge holding on smaller knives.

 

Doug

Edited by Doug Lester

HELP...I'm a twenty year old trapped in the body of an old man!!!

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I want to echo what Peter said. Make sure you bill your knives for what they are intended. For example, the man known as Nessmuk suggested that a knife intended for general use in a wilderness/camp setting should be very thin, very sharp, and have a belly to it.

 

He suggested that a hatchet should be taken along for chopping and hammering chores, and the knife for cutting/slicing/skinning, and a small two-blade folder for cutting rope, string, etc. That is a, "camp knife," of excellence. But it is not what most people mean when they say, "camp knife," or even what most people mean when they say, "Nessmuk," anymore. A large proportion (about 98% it seems) of those who claim to make Nessmuk knives have never read Woodcraft and Camping.

http://www.gutenberg.org/ebooks/34607

 

Use the old maxim of Form follows Function. Then, make very certain that the end users know what the intended functions are. The first quality control should be whether the knife is good at what it is intended. This is really a test of geometry. After that, test the heat treatment. Finally, but often quite important, is the appearance. Make sure the knife LOOKs like it should (appearance is part of Form and Function for collection blades).

 

Hope this helps.

kc

please visit my website http://www.professorsforge.com/

 

“Years ago I recognized my kinship with all living things, and I made up my mind that I was not one bit better than the meanest on the earth. I said then and I say now, that while there is a lower class, I am in it; while there is a criminal element, I am of it; while there is a soul in prison, I am not free.” E. V. Debs

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