Re: [CAD_CAM_EDM_DRO] Re: Higher performance systems

Mariss Freimanis wrote:

>Jon,
>
>The other thing being left out of the whole thing is Newton's
>contribution; the equal and opposite reaction thing. 400 lbs of
>reaction force appearing and disappearing on every acel/decel would
>get things rocking pretty good.
>
>

When I was building my own servo amps, I realized that an unstable
amp could be a real hazard, so I put the E-stop circuit together first.
While tuning my amps, I got a large scale oscillation that started the
machine
rocking at about 2 Hz. By the time I could get my hand on the button,
the machine was lifting its feet off the floor! This was the X axis of
the Bridgeport, and the head of the machine was swaying about 6" side
to side!

>Our pick-and-place machine gantry moves at about 4 ft/sec (2880 IPM)
>and I estimate the moving part weighs about 100 lbs. The machine
>itself weighs 3,000 lbs. We had to put anti-skid pads under its feet;
>otherwise it would start walking around the shop like a badly loaded
>washing machine.
>
>

Sure, there are machines that need to do this. I was thinking along the
lines
of a metal carving machine, as that was what he was talking about. A pick
and place machine has to move across a lot of empty space to get from the
parts supply to the far end of a PCB panel.

>It uses a toothed belt / pulley transmission and linear encoders. The
>belt is 3" wide to withstand the 1 or 2 HP the AC servo motor
>delivers to the load.
>
>

Wow! 3" wide belt!

Jon