any one can find a scientific way to test knife quality?

[Cliff Stamp]

What's the major problem with establishing a set of standards for testing of knives similar to those of ASTM? ASTM standards are used extensively in my profession, architecture, to establish criteria for performance exclusive of design, ie, subjective requirements.

Nothing, in fact a large amount of such tests already exist in the form of standard materials data. These are tests like strength (tensile, compression, torsional, fatigue), impact (charpy, izod, torsional), wear (abrasive, adhesive), and corrosion (acid, salt spray), plus micro-graphs of the steel (at multiple RANDOM locations) to show the grain structure and level of carbide segregation. These tests are very definate and can all be done by INDEPENDENT sources so you are not depending on a maker/manufacturer doing a critical analysis on their own steel. Do you really want the carpenters who build your house to be able to inspect and pass their own work? Of course not, this would be so naive that everyone would immediately see the gross problems it would present.

Now with the basic materials properties defined you need to figure out how these actually translate to the knife in use. This is the current weak point because there is little done in this regard and often a lot of it is just based on assumptions which are often based on someone just selling something. If a steel tests really well in a certain measurement then all of a sudden that measurement is the critical one for knife performance. The problem that many have is waiting for some perfect set of tests. You don't sit in a lab and just think about how to collect data, you start doing it and refine the process through the experimentation. Your first results will be rather rough, you might even never publish them, but the growth is exponential, the more you learn the faster you will refine the work.

At a basic level I would just like to see more makers with definate measurements. Note only the type of grinds but the extent, what is the angle of the grinds, how thick is the edge. Where are the balance points, static and dynamic. Then of couse you add PUBLIC statements about thier knives versus specific benchmarks. As simple as "I compared my blade vs a 154CM blade heat treated by Paul Bos and the performance was increased by 15%". Now once this starts you can start to refine how the tests are performed, but you have to get the work started first. Without reference points there is no way to tell if the performance was impressive or not.

"I cut up a coffee can and the knife still easily carved wood. This is some impressive steel."

Really? You can in fact do that with a $10 machete. Ideally the reference points are the same for every maker. But get reference points used first and then worry about getting them the same. Kevin Cashen is leading a huge push to get makers to do this type of work. Manufacturers like Spyderco and Busse Combat have always done it. They each do different things, but will both be clear how they are determining performance when they develop their knives. There are custom makers with similar methods. Goddard and Wilson always use specific benchmarks and will tell you in great detail how they do the work so you can confirm/refute it.

If you ask Wilson for example about edge holding he doesn't say something like "The edge holding is excellent, I made 367 cuts on hemp before the edge was dull." That doesn't mean anything because there is no refernce and you don't know how the cutting was done. What Wilson will say is more like "A friend and I did some cutting and through an average of six rounds we found that there was a 20-30% increase in performance over ATS-34 in slicing 3/8" hemp. We stopped the cutting when the blades took more than 20 lbs to make a slice. The edges were all about 0.005" thick and sharpened on a coarse silicon carbide stone at about 15 degrees per side."

As a user you can be more demanding, stop taking the sparce materils data from maker/manufacturers and ask for the full spectrum of information not just the hand picked tests for which that steel excells. Whenever a maker/manufacturer starts promoting impressive performance then ask for definate benchmarks and reference points. Whenever there are claims of superior performance ask for the corrosponding weakness - it always exists. This will not make you very popular with the hypesters, but you will be very welcomed by the makers who are seeking performance.

-Cliff

 

[Gteckwreck]

The testing procedures are what I would be interested in seeing standardized.

I understand there are specific material tests for hardness, elasticity, etc. If we could standardize a series of cutting, chopping, penetration, etc., procedures, and do the tests under controlled conditions, while including the material testing that currently exists, we would be well on our way to a benchmark scientific standard. I think the Journeyman and Master Bladesmith tests are an example of what I'm talking about.

It would never answer the question of "which knife is best", because it would be pass/fail, but that's where subjectivity is, and will always be, important.

 

[Cliff Stamp]

I understand there are specific material tests for hardness, elasticity, etc. If we could standardize a series of cutting, chopping, penetration, etc., procedures, and do the tests under controlled conditions, while including the material testing that currently exists, we would be well on our way to a benchmark scientific standard.

Yes, this would be very nice indeed. I don't think it would be overly difficult, you are looking at basically shallow/deep cutting as well as dynamic issues for larger blades, see recent comments by possum on the latter. Again though you don't need to develop a uniform standard at once. For example to start off with it is easy to quantify sharpness on very light cord (meaning threads) and then perform a press cut and slice on 3/8" hemp. These give meaningful information on sharpness and shallow cutting ability.

I think the Journeyman and Master Bladesmith tests are an example of what I'm talking about.

Essentially, however the standard is quite low, Cashen has noted they can be passed by a blade prepared from mild steel.

-Cliff

 

[Ookpik]

Jewel or Junk? How can you tell? By Ookpik.


I am not going to tell you what knife to buy. That’s for you to decide. What you buy will depend on your intended use and your budget. There are so many choices. This seems to be the golden age of knives. Unfortunately, all knives are not created equal. No two knives are the same. If you examine two knives of the same make and model, there will be differences. These differences may affect the performance of the knife. This happens with production and custom knifes alike. When you are about to buy the knife you decide on, you must inspect it carefully to make sure you get a good one. Helping you with that inspection is the purpose of this article.

I advise against buying a knife sight unseen. If you order a knife, make sure you can return it if you don’t like it. I can only think of two manufactures that I would feel confident buying a knife from without inspecting it first. Those companies are Chris Reeve Knives and Microtech. Their knives are consistently almost perfect. Most other knives you look at will have some defects. Being able to spot these defects will help you decide between two knives of the same make and model. The price is the same, so you may as well pick the best example. All knives have defects. It’s up to you to decide if they are bad enough to stop you from buying the knife, or if you can live with them.

I will talk about folding knives first. The modern folding knife looks simple, but it has many parts that must fit properly if the knife is to perform as intended. This is true for liner lock, lock back, and other designs.

Fit and finish – Everything should look good and fit well. There should be a good surface polish and finish. There should be no unintended gaps between parts. All edges should be smooth. None of the screws should have damaged heads. There should be no loose parts. This includes all screws, the scales, the pocket clip, and the thumb lugs.

Blade edge – The blade should be sharp enough to shave hair from your arm. The edge should be sharpened at the proper angle for your intended use. The sharpened surface on one side of the blade should be the same size and angle as the sharpened surface on the other side of the blade. A chisel grind blade will only be sharpened on one side. There should be no nicks or rough spots on the edge. The point should be sharp, not broken or damaged.

Blade grind – The blade should have an even grind. Both sides of the blade should look the same. The grind edges (lines) on one side of the blade should line up with the grind edges on the other side of the blade. On a chisel grind blade, the two sides of the blade will look different. One side will have grind lines. The other side will be flat. The blade should not be bent or warped.

Smoothness of opening – The blade should open smoothly. The pivot shouldn’t be too tight or too loose. Don’t count on being able to adjust the pivot tension when you get home. If the pivot is out of adjustment it can hide other defects.

Blade centering – The blade should be centered between the liners when the knife is closed. The blade should not contact the liners. Loose pivot tension can allow a liner lock to push the blade off center.

Blade position when closed – The edge of the blade should not contact the back spacer. That will dull or dent the edge. The tip of the blade should not be outside of the handle and be exposed when the knife is closed.

Blade closed detent – The ball detent on the liner lock should hold the blade fully closed. There should be no opening movement of the blade without the detent starting to disengage. The detent should be strong enough to hold the blade shut when you carry the knife, but not so strong as to prevent easy opening. Excessive pivot tension can mask position and strength defects in the detent.

Pivot washers – I prefer bronze pivot washers, but they are harder to use. The bearing surfaces on the inside of the liners must be parallel. If they aren’t, the pivot can’t be adjusted properly. The pivot will be too tight or the blade will have side play. Teflon washers are more forgiving of imprecision. They are softer and have a little give, making up for misalignment. If done right, bronze washers are better. When locked open, the blade will feel more solid. Watch out for damaged or deformed Teflon washers.

Blade play – The blade should have no up and down or side to side play when the knife is open and locked. There should be no side to side play when the knife is partially open or open all the way, with the lock held released. Excessive pivot tension can mask potential side to side play.

Liner lock – The liner lock should fully engage the blade-locking surface when the knife is gently opened. It should sit on the left side of the locking surface so there is room for wear. It should snap into place and feel secure. If the blade is flicked open, the liner lock should be in the same position as when the blade is opened gently. If the blade stop surfaces (stop pin and back of blade, or thumb lugs and edges of bolsters) aren’t aligned properly, there will be some give as the blade is opened forcefully. The blade will over-travel and spring back slightly. The liner lock will travel farther than when the blade was opened gently. The liner lock will then be hard to release because it is under pressure. This will also happen when you apply force to the handle during hard cutting.

Lock back – The lock back spring should be strong enough to lock the blade securely and prevent accidental release. The spring shouldn’t be so strong that the knife is difficult to close. The lock back should be flush with the back of the knife and should be in the same position whether the knife is open or closed. The cam action of the lock on the blade should pull the blade closed about the last 20 degrees and hold it closed.

Lock strength – The only way to really know the strength of the lock is by testing. Unfortunately, most tests are destructive. You could put the knife in a vice and measure the force it takes to close the blade. That would destroy the knife. You would have to test a few examples of the knife to see how much they vary. That would give you a good idea of how strong the average knife of that make and model is. You wouldn’t know the exact strength of the knife you are considering, but you would have a good idea. Spyderco does this test with their knives, but they generally don’t publish the results. You could gently try to close the knife by hand with out releasing the lock. You would have to be careful not to apply too much force and damage the knife. You would also have to be careful not to get cut if the knife slips or closes. You wouldn’t know the ultimate strength of the lock, but you would have some confidence in it’s strength. The merchant in the store will probably not like you testing a knife in this way.

Lock reliability – The spine whack test. Basically, you hold the open knife by the handle between your thumb and finger. You tap the back of the blade against a soft surface to see if the blade will close. You can use the palm of your hand or a soft piece of wood. You should perform this test with the knife horizontal. Rotate the knife, edge up, edge down, edge right, edge left, and test in each position. This test is different than the lock strength because of vibration and other dynamic factors. Some liner locks will be strong when tested statically, but will close easily when tested dynamically with the spine whack test. The spine whack should be done carefully so as not to damage the knife. You should also be careful not to cut yourself. Once again, the merchant won’t like this kind of testing. I don’t approve of lock testing because it may damage the knife. If you intend to use the knife for a tactical purpose, strength and reliability lock testing may be justified.

Fixed blade knives – Fixed blade knives are simple. What you see is what you get. Check for fit and finish, blade edge, and blade grind. Make sure the handle isn’t loose. Check the sheath to make sure the knife fits and is retained properly. A good sheath is important.

I guess that’s about it. Am I too fussy? Probably. Have I bought knives that I know have defects? Yes. Almost all knives will have some defects. Almost all knives will be good enough to perform their intended functions. Are they good enough for you? That’s for you to decide.