al5502 wrote:
Did somebody try to get rid of the feed screw all together
and replace it with a hydraulic cylinder?
At the first glance it may present several advantages:
no backlash, big force at low cost.
We go through this every 6 months or so. It looks neat at first glance, and if you
have lots of hydraulic gear around, might even be affordable. Proportional (Moog)
valves are REALLY expensive, like $3000 and up! The hydraulic pumps are expensive,
massively power-hungry, and LOUD! The hazards of a hydraulic leak at 3000 PSI
are very serious. You get oil injected under the skin, and it poisons you. A flexible
line blowing off can also be dangerous. If there is any air in the system, it tends to
go crazy with oscillation. The performance can be iffy, too, with jitter and stick-slip
friction.
I think if you add up all the parts costs, even surplus, you could go out and buy a complete
ballscrew retrofit and servo drives new!
Jon
