That's a perfect analogy actually. If you stand straight then there is only compression force on you hips and knees. You can do it for hours. If you squat then then you put torque on those joints. Try it. Stand straight and feel your thigh muscles. Then squat to where you thighs are close to horizontal. Feel your thighs again. They are suddenly very tight to counteract the torque you have created. Stay that way for thirty seconds and observe how your knees and back feel. Am I wrong?
In addition, if you squat fully so that the back of your thighs are resting on you calves (I'm glad that at my age I can still do this
), then you remove much of the torque and your thighs relax again. This principle is the reason for the "bottom block rest" feature in my design.
Interesting. So how does the drilled angled endpin relate to the above discussion?
I'm glad you like the squatting analogy. Your post made me consider that analogy further as a model to understand the bent endpin in the original post and the Lammax system I have.
I think there are five things to consider:
1) force, in the sense that physics defines it - potential energy, weight and leverage in this case
2) torque, in the physics definition - twisting force
3) how force and torque apply to a straight endpin
4) how the force and torque are different for a bent endpin
5) how our "squatting" model relates to a bent endpin
Let's start with #5. In the squat model, my torso represents the body of the bass. My hip sockets represent the endpin socket. My knees, ankles, and feet represent the different shafts of the endpin.
It's a pretty good model, except that I have two hip sockets - endpin sockets - instead of one.
With a straight endpin, that's similar to my standing with my legs straight out beneath me. There are two forces on the endpin, the weight of the bass and any torque you might incur if you spun your bass. Since most of us don't spin our basses, we can ignore any torque as very minimal. The simple linear force is mostly distributed equally to the round endpin socket, but if you lean your bass away from perpendicular to the floor, then I think there is a slight increase in force to the side of the endpin socket furthest from the floor, but because the socket is round, that's also minimal. Similar to if you stand with your legs straight below you and then lean one direction or another. For the most part, your torso just "rides" on the top of your leg bone, but your hip will experience some force from gravity.
In a bent endpin, like the one in the original post, and the Lammax, the model is mostly the same. The bass "rides" on top of the endpin, with a similar linear force for any lean from the perpendicular, but the torque force is much greater. That's why with the Lammax, you need to install a pin to keep the endpin from rotating in the socket. By analogy, a bent endpin is like starting to squat, but also twisting my torso away from parallel.
So, to address @Eric Hochberg 's question, if I haven't made any mistakes in my thinking, there's no additional force on the bass' endblock with an bent endpin like in the original post, than with a straight endpin, with the exception of the additional torque applied to the endpin socket. And so that's why I thought the statement that these kind of endpins put undue stress on the endblock was mistaken.
I think it's also worth noting that in Laborie's original angled endpin, by drilling the block, there's no additional torque at all, making it just like a straight endpin, at an angle, which is exactly what it is.
Guess I got more out of my physics class than I thought! Nerd out!
