Do all custom makers pre-test their blades?

[Happy Camper]

As an electrical engineer in the aerospace industry, I am used to rigorously testing every item produced before shipping.

It never occurred to me that bladesmiths might do the same until Terry told me he tests all his knives before putting the handles and guards on them.

Is this common among bladesmiths, or do most adhere to the industry standard of batch testing?

 

[Keith Montgomery]

I think that most if not all makers test their knives to make sure they work fine before they ship them. The problem with doing a thorough test on a blade is that when you are done you have destoyed the blade. There is no way that you could ever make any knives if you did that every time. Basic testing should be, and I'm sure is done to insure that knives being shipped do not have any obvious problems that would mean that the knife would have to be returned for repairs.


Edited to remove yet another typo.

 

[Wulf]

A thorough testing will usually result in the destruction of a blade. When a maker tries a new technique or modifies his approach to one part of the knifemaking process, he will often destroy the blade afterwards so he can measure the results. Makers like to see how far a blade will flex before it bends, or actually breaks, for example. Obviously, no maker can do this to each knife he makes, but if he tries using a new heat-treating technique, for example, he will want to run a few test blades just to see how they come out.

Oftentimes makers will also study warped or cracked blades to determine what went wrong. Just a few hours ago, I was visiting a local maker who gave me two composite damascus blades to break. I stuck them in a vice and pulled on them until they snapped in half. We then took the pieces over to his table and studied the grain structure through a loupe. It was quite an education to see how the high/low carbon damascus pattern looked in cross section after a differential heat treat. Though it seemed like an awful shame to do (even though the blades were already damaged), the value of the knowledge gained far outweighed the cost.

 

[george tichbourne]

Quality control is usually very high considering that MY name is on that blade when it goes out and it carries a lifetime guarantee.

Knifemakers like myself would not offer that lifetime guarantee (my lifetime of course) unless the knife will survive....the reason is simple we could not afford the damage to our reputations or pocketbook.

What does quality control involve?

Purchase of blade materials from a known source that will provide mill test reports if required.

Design within the limits of the chosen blade material.

Heat treat under controlled conditions.. If it is sent out will the heat treater provide charts?

All blades are tested by the heat treater to insure that specs are met. In most cases random sampling meets requirements.

Use of highest quality materials that the selling price and end use will support.

Final pre shipment inspection on all knives for fit, finish, and sharpness.

Packaging to prevent damage in shipment

Ongoing field testing to evaluate the product(my favorite part)

 

[Ed Fowler]

When the blade is first sharpened, I test for edge flex. Described in my book "Knife Talk". If the edge flexes right and left 7 times with no chip, I test for cut, using one lay out of a 1 1/8 inch hemp rope. These tests are preformed on every blade.
Destructive testing - on a representative sample or when ever a blade is suspect. Once you have a reliable steel, all from the same melt you can reduce the number of test blades. When I was using ball bearings, one blade from each ball bearing was sacraficed. Now about one out of 30.

 

[Jerry Hossom]

I think you will see different answers on this subject depending on how the knife is made. If a knife is forged, there are probably more opportinities for variability in the steel than a knife that is shaped from a single batch of high alloy steel and heat treated in a single batch. In the latter, ensuring that the batch is sound requires just a few simple stress tests with hard cutting on an edge that is ground excessively fine. I usually have one or two small knives in each batch that will allow me to do this. I can tell from cutting and torquing that edge if there is a problem. Heavier edges are not likely to be worse. My heat treater, Paul Bos, hardness tests each blade several times in the process to ensure the tempering is good and uniform. I see anywhere from 3 to 5 dimples from his tester in each blade. I don't need to repeat that, nor do I need to destroy blades once I'm satisfied with the process and each batch.

I agree with George that you don't put your name and a lifetime warrantee on a knife unless your certain it is right. Having been in the biomedical instrument business for a long time, there are big differences between a knife and a circuit board having hundreds of parts, each of which may be comprised of thousands or even millions of transistors. The opportunities for failure are much greater in the circuit board. That's why most are burnt in before being used. Still, I wouldn't mind a hunting trip for every hunter I make, just to be sure it can skin a deer like it should.

 

[Happy Camper]

I once bought a factory knife that failed on its first trip out. The 1/4" thick 1095 blade broke clean in half along its 10" blade on the fifth chop on a log. Had that knife been tested before shimpment (not likely with a cheap production knife), I woudln't have been left with nothing but a folding knife and a rock that day (still made a fire ).

Thanks for the replies; interesting range of testing protocol.

 

[Jerry Hossom]

That was most likely a tempering failure. The one thing that will probably always keep factory knives from realizing their full potential is that it isn't possible to temper a lot of blades at one time properly. It is just too critical a process. I suppose with a lot of very expensive equipment it might be, but not likely.

If you had etched that blade before using it, you likely would have seen the flaw. I etch all of my CPM-3V and A2 blades and most of my 154CM and S30V blade. Seeing a uniformly fine grain is reassuring. It also improves corrosion resistance.

 

[Happy Camper]

Interesting, Jerry. How do you like that S30V so far, by the way? I have been loosely following the S30V discussions and wondered what the latest is from your end.

 

[Jerry Hossom]

S30V is a great steel. I have to admit, my earlier ambivalence had more to do with working it than with its performance. It's tough stuff, and balances all the desireable features in a steel very nicely! When etched the grain is extremely fine, especially for a stainless, almost as smooth as CPM-3V but not quite. Gaucho ran an S30V blade through its paces awhile back and should be posting a review sometime.

 

[Happy Camper]

Well, it looks like Terry's ready to move on to mounting the guard and handle!

Hopefully if I feel too cowardly to use my knife, I can look at his pictures and realize the knife's already done it so I might as well go for it.

 

[Happy Camper]

Here he tests the rolled edge for sharpness on cigarette paper. This was actually before the chopping. After the 2X4 chopping, the blade still shaved, which was the green light to continue with the handle and guard.