Need Spring Selection Equations

[BrentD]

This is not directly tractor related, but I'm sure somebody might find the info useful at some tractor related application... I'm trying to design an articulating arm to mount a monitor to the wall by my recliner so I can sit and type in comfort. I need the arm to be able to bend horizontally at the point where it attaches to the wall, about halfway down the arm and at the end of the arm where the monitor attaches. I also need the arm to bend vertically with spring support along the last arm segment. I'm trying to figure out how to calculate what type of spring I will need to counterbalance the weight of the monitor and how to position it on the arm. I'm trying to decide whether to make the arm segments single beam or double-beam.

 

[Pooh_Bear]

It has been a long time since I did any calculations for springs,
but if I remember correctly the basic equation is F=ks,
Where F is the force applied by the spring based on the distance
it is stretched or compressed a distance s, and multiplied by
a spring constant of k. This formula is known as Hookes Law.

Other things to consider are maximum compression, where all the
coils are compressed to the point where they touch each other.

And maximum extension, where the spring is stretched to a point
where stretching it any further would deform the spring
causing it to not be able to return to its original state.

You need the force the spring is expected to exhibit,
and the distance of travel over which the spring will be stretched.
If you are swiveling an arm out away from a wall,
you will need the moment arm calculations at various points
in order to calculate expected forces on the spring.

Pooh Bear (aka Fluff For Brains)

 

[BrentD]

Yeah.. I found those same equations in my old physics books. Looking at the time needed to figure out everything I'd need to know, then looking at the cost of metal, I just decided it's cheaper to buy a monitor arm.