Originally Posted by
joeavaerage
Hi,
I think you are making the part more complicated than it need be. If you used a thick solid plate, be it steel or aluminum would be by far and away the cheapest and
easiest solution. Flanges add manufacturing complexity.
Give us the details of the Z axis, namely the ballscrew diameter, ballscrew pitch, ballscrew length and then we can calculate the momentum equation which will likely show that the
increased mass of the solid plate is insignificant.
Just as an example: my new build mill has cast iron beds of 115kg each, but for the calculation I allowed the axis mass of 150kg. The ballcresws are 32mm diameter, 5mm pitch and 700mm long. The servo
has a first moment of inertia of 1.1 x 10-4 kg.m2. The momentum calculation shows that 80% of the momentum is in the rotating ballscrew alone, 12.5% in the armature of the servo
and the remaining 7.5% in the linear axis mass. So despite the axis weighing 150kg its still a minor contributor to the momentum. Thus if I decided to add a whole bunch of mass to the axis, say a trunnion table
and fifth axis, the extra mass is STILL a minor to modest contributor to the overall momentum.
Give us the details of the axis and we'll see just how important, or not, the mass is.
Craig