Have you ever wondered what to consider when developing knife handles? What's important? It's not that easy to answer.
For me, there are essentially four criteria . The knife handle must be ergonomic , meaning it fits comfortably in the hand. The handle must be aesthetically pleasing and fit seamlessly into the overall design of the knife. It must also be sturdy so that it can easily withstand the stresses of everyday use. Stability alone isn't enough, though; if the knife is too heavy, it's no fun to carry. Therefore, the handle must be as light as possible.
The two criteria of stability and lightness, in particular, are contradictory. Simply put, more material equals more stability. But that's only half the truth, because clever geometric design can circumvent this principle to a certain extent. This requires detailed insight into the stresses on the handle scales. This can be achieved using state-of-the-art engineering software . Therefore, the development of the Multiverse handle scales was carried out using the finite element method . These are simulations based on physics equations. It's like conducting a real test, only purely virtual on the computer. I use the open source software "FreeCAD" for this. A more detailed explanation can be found in my YouTube video : https://youtu.be/RRKT0VvgK0I
As a representative stress scenario, we simulated the handle scales being pressed together, as flexibility is a quality criterion. Who wants a knife that can be noticeably compressed? For this purpose , 100 N (equivalent to a weight of approximately 10 kg ) was applied to the middle, lower area of the handle scale. The calculated results are the stresses and deformations . I was able to determine directly how much the handle scales deformed, i.e., how far they bent inward.
No matter what material the handle is made of, it will always deform slightly. However, the deformation can be controlled by the choice of material and geometry. In the elastic range, deformation is mainly influenced by the modulus of elasticity . This is 210,000 MPa for steel , 110,000 MPa for titanium grade 5 (Ti6Al4V) , and 70,000 MPa for aluminum . The higher the modulus, the more difficult it is to deform the component. Strength properties such as yield strength and tensile strength are also important. Explaining these would go beyond the scope of this article, so a separate blog post may appear on the subject.
Now you know the basic calculation procedure. I used it to calculate different design variants. I started with a handle scale that wasn't milled on the inside. The maximum deformation here is 0.11 mm . The weight is high at 31.6 g . The detailed deformation distribution is shown in the next figure.
Next, a classic pattern commonly seen in the market was simulated. The milling machine's processing time is moderate, as the milling tool only has a few large geometries to process. The maximum deformation is 0.32 mm, with a handle scale weight of 23.0 g . I could have made it easy for myself by specifying this variant for series production. That would have saved time and been much easier for my OEM partner Reate . But I quickly realized that this wasn't the optimal compromise between stability and weight.
Therefore, other, different patterns known from aircraft construction were tested, as nowhere else is weight savings so important. Ultimately, the honeycomb structure proved superior. A significantly reduced deformation of 0.24 mm (-25%) was achieved while maintaining a nearly constant weight of 23.7 g . The deformations are quite small, but the comparison shows how the different milling patterns would react under greater forces and other loading conditions.
The honeycomb structure reduced the weight of the handle scale by 7.9 g. The 15.8 g saved on the entire knife can determine whether it's a pleasure to carry or perceived as a pocket weight.
The size of the individual honeycombs is subject to a further restriction: the corners must be machined with a standard milling tool radius. The final honeycomb pattern meets this criterion and extends to the area in front of the axle screw toward the blade, ensuring no lightweight construction potential is wasted. The contact surfaces of the blade bearings, as well as the fits and threads, were sufficiently recessed to avoid any potential weak points. As a result, the Multiverse is clad in handle scales that are refined down to the last detail, and whose level of sophistication is difficult to determine.
I'm sure you'll enjoy the Multiverse as much as I enjoyed developing it!
Best regards, David