Our Approach to Testing
A note about our testing: We use real-world scenarios to compare the relative performance between multi tools. Laboratory testing is great, but multi tools are not used in controlled environments. Each multi tool has its own set of design features and we want to predict how it will perform when we carry it everyday.
Knife blades are sharpened to manufacturer specs and then tested. We want to know how much use we will get out of the blades before they need sharpening. It doesn’t matter if one tool has a longer blade than another, has a different shape or grind angle, and they are made from different steels. The question to answer is Which tool do I want to carry?
Our tests are designed to minimize variables and be repeatable, using practical scenarios that can be measured for quantified results. We describe them as semi-scientific.
Testing Knife Blades
For knife edges, there are three performance characteristics we want to know: how well the knife cuts initially (sharpness), how long the knife cuts effectively (edge retention), and how much work we can do with the knife until it needs sharpening (cut length).
For example, when we tested the Gerber Dime vs the Leatherman Squirt PS4 we found that on initial cuts the Dime went through 15 sheets of paper and Squirt PS4 was cutting 20 sheets. For the same amount of work, the Squirt PS4 gives 33% better results initially.
As the blade wears you can see the performance drop off for each, until they reach 50% of their starting result (what we consider dull). The Dime was dull after 300 passes when it was only cutting 7 sheets, the Squirt was dull after 400 passes.
Sharpness and edge retention are technical results, but what we really want to know is how much cutting gets done before the knife is dull. Our second chart shows that the Dime was able to cut 2175 feet of paper before it was dull, the Squirt nearly doubled that result at 4000 feet cut.
This is why we do real-world field testing and measure the results. Even though the Squirt was only 33% sharper, the Squirt has better blade steel and more usable edge. The Squirt stays sharper longer and you can do double the amount of work. The advantage would be even bigger if you continued using the Squirt until it was down to 7 pages per pass.
Straight Edge Knife Blade Testing
We finally found a way to use junk mail! Seriously though, the most common use for multi tool knife blades is to cut cardboard. Whether we are breaking down boxes or opening packaging we rely on a good knife. Cardboard is known for quickly dulling knives and the same clay additives are in magazine and catalog paper.
To compare the real world performance from two multi tools we sharpen both blades to manufacturer specs and then cut paper until the blade is dull (50% of its initial cutting effectiveness).
The test procedure is straightforward:
- The same paper is used for both blades we are comparing, we alternate the blades to minimize any variation.
- We drew the knife across the pages, starting from the spine and moving to the opposite edge
- We ‘calibrate’ our hand using a utility knife to make sure our passes are reaching the same cut depth and then we use the same pressure throughout the test
- We adjust the blade angle in our hand to continuously use the sharpest section of blade, just as you do in everyday use
- We end the test when the blades reach 50% of their starting cut effectiveness (i.e. if the blade initially cut 20 sheets of paper we stop when it is only cutting 10 sheets of paper per pass)
Serrated Edge Knife Blade Testing
Serrated edge knives are made for cutting rope, straps, belts, twine, fabric and other textured materials. A serrated edge is between a saw and a knife, the serrated teeth catch and rip the material as the blade goes back and forth.
To test serrated blades we looked at how they get used day to day life and decided to test with jute twine. A key factor when cutting twine is how many strokes it takes to cut the twine. For both convenience and safety, we want the twine cut on the first try. With more attempts come frustration, more force, and less carefulness. For combo blades we test the straight edge first then the serrated portion. The twine may also make contact with the straight edge, but since it is already dull any cutting is negligible.
Knife Blade Tip Strength Testing
The most common damage to knife blades are broken tips. Usually the root cause is we are prying with the blade instead of cutting, but reality is that most people don’t do everything right most of the time.
We are developing our tip strength test where we will measure how much force is required to break off the blade tip. That’s right, we are doing destructive testing!
Measuring Knife Blades
A Note on Knife Blade Length: For practical reasons I measure and report the straight-line length of the sharpened edge because it represents what the user experiences when using the blade. Most manufacturers report the AKTI measurement which includes the unsharpened ricasso.
The American Knife & Tool Institute (AKTI) recommends measuring from the tip to the forward-most aspect of the hilt or handle, but law enforcement agencies are not compelled to apply this method. The legal definition varies by locality and is not standardized, although they typically concern the stabbing depth of the knife.
For my own personal decision process to stay within legal requirements, I lay a string from the handle to the tip and follow all the curves in the blade, then measure the length of the string. Then I add 10% to the number for measurement error and use that blade length to compare to legal requirements.
Testing Needlenose Pliers Grip
Needlenose pliers see two main use cases: grabbing/pulling small objects and manipulating/twisting wires. So we test them both.
Testing Regular Pliers Grip
Regular pliers main job is to grab round objects – usually nuts and bolt heads. We measure how much torque we can apply with multi tool pliers.
Testing Pliers Jaw Strength
Coming soon – how much does it take to break your favorite multi tool pliers?
Testing Pliers Twisting Strength
Coming soon – how much torsion can multi tool pliers withstand?