Knife Design – Do Ratios Matter?

Earlier today I read a thought-provoking article over at EveryDay Commentary about why knife design ratios matter. Tony, who is extremely thorough in his gear reviews, discussed why he will be adding a few new dimensional ratios in his upcoming knife, multi-tool, and LED flashlight reviews. I’m not exactly in agreement with his approach, and here’s why.

Good Design – a Combination of Science, Engineering, and Art

These days it’s not enough for knives and tools to just help complete a set of tasks. They must perform well, they must be durable, they must be comfortable to use, and they must look good (or at least not bad).

Tool design is a tricky thing. I won’t pretend to know all of the design considerations that go into designing a comfortable, high-performing, long-lasting, and aesthetically pleasing tool or accessory, but I know there are plenty. Since knives are more personal than your average hand and power tools, their designs require even more care.

Science, engineering, and art can sometimes be intertwined. Take the Golden Ratio, for example. Mathematicians can throw as many numbers and equations at you as they want, but at the end of the day why is the Golden Ratio aesthetically pleasing? It just is.

The Golden Ratio is about 1.62. Does this mean that furniture, tools, books, and other things with higher or lower dimensional ratios look bad? Not necessarily since there are many other objective and subjective factors that must be taken into consideration.

I asked Milwaukee product managers and the company president about the brands’ new M12 Fuel brushless drills and drivers and how many iterations the new handle design went through. It seems that the design process involved a lot of trial and error and subjective testing. From what I’ve seen, knives, at least the better ones, are designed in a similar manner where it’s done more by feel than by graph paper.

Dimensional Ratios

In his article, Tony discusses the reasons for including blade:handle and blade:weight ratios for folding knives.

Tony’s knife reviews – take his Sebenza review as an example – are based off a rating system where he breaks things down into terms of steel alloy selection, grind quality, blade shape, lock design and quality, overall design, fit and finish, retention, deployment, grip, and carry. Tony’s rating system is a smart way to approach reviews of similar products because it involves a mix of objective and subjective considerations.

I must say, I trust Tony’s reviews and enjoy his writings. His recent idea to measure and include blade length to weight ratios has the potential to be really helpful in knife reviews. Let’s say I’m looking for a compact gentleman’s knife that won’t weigh down my pocket. Being able to compare the blade:weight ratios for different knives he has reviewed would help me narrow my search and focus on those with the greatest ratio. The knives would of course also have to be sorted in terms of blade length to avoid confusion.

On the other hand, the blade length to handle length ratio is, in my opinion, unwise to use as a factor for comparison. As I mentioned in a reply to Tony’s post, such a ratio can be easily misconstrued. Just because favored knives have a ratio close to 0.70 does not necessarily mean other knives of similar ratio will be as good as those with lower ratios not as good.

Numbers can be misleading. This is not a rule, but something to remember, especially in regard to tools and knives.

Maybe blade/handle/weight ratios have huge contributions as to whether a knife feels good to use or not. Or maybe it’s all coincidental.

While some knife designers might use engineering modelling and simulation packages, the best seem to take more artistic approaches to their designs with goals of producing knives that just feel right. If there were dimensional sweet spots, wouldn’t we see more cookie-cutter designs?