Originally Posted by turbostang  However, if you aren't using a counter balance but an air cylinder instead...you aren't moving the weight of the counterweight AND you are only moving a small amount of the weight of the knee.
I am more concerned with the rigidity of the quill when it hangs out 5". |
The effect of the counter weight is to support or keep the weight of the knee etc in equilibrium, the required force to move the supported weight at the accelerated rate is the job of the servo to overcome the inertia required, this would be similar/same to a horizontal X or Y axis inertia demands .
With a C.B. system, you can only set an estimated weight, as the load will alter according to the part load weight. Even in a system I have, which is a constant force counter-balanced air system.
I have never experienced a problem with the quill extension, these mills were originally designed for manual milling using the quill, so I assume they have been engineered to also suit the conditions demanded by CNC.
Al.