How to find the moment of an arm

[Matthew_H]

Thanks. We will get to work on the equations now.

[Denman]

not really
and its not stats, its mechanics....
if you can send me a diagram of how it works, i#m afraid i dont know what you mean by scissor lift.....

[ChrisH]

Originally Posted by Denman

not really
and its not stats, its mechanics....
if you can send me a diagram of how it works, i#m afraid i dont know what you mean by scissor lift.....

No, he really meant statics. Statics is the science of computing forces in things that are not accelerating. It is also useful if you are dealing with motion that is slow enough to be considered static. The essence of Statics is found in the basic equation: the sum of the forces = 0. When you design a bridge you use statics. When you design a slow moving arm, you use statics. When you design a fast moving arm (One where you get a significant amount of "whip") you use Dynamics.

Stats is usually short for Statistics, the science of making sense of large amounts of individually useless data.

BTW a scissors lift is a non-trivial statics problem.

[Greg Ross]

Matt,

Am I understanding correctly that you're planning on deploying your scissor lift other than vertically? In my experience, that's a bad idea. You might be able to ameliorate problems if you have some (extreme) precision machining capabilities. But even if you do, you might want to reconsider your design.

Consider that each joint in your mechanism will have some slop in it. This causes sag when the lift is deployed non-vertically. And each stage in your scissor mechanism compounds the sag. If you have very many stages, you will have a LOT of sagging going on out at the end of your arm.