Re: [CAD_CAM_EDM_DRO] Why don't gantry systems "twist"

James Washer wrote:

>I've been looking at photos of gantry based routers, etc. and I cannot see why the gantry doesnt twist (i.e. varied travel on one side as opposed to the other).. Are they generally "ganged" using timing belts, or is there a motor on each side driving the gantry in lock step, etc?
>
>The designs generally don't look stiff enough to mechanicly resist twisting..
>
>

Large machines, like gantry bed mills, vertical boring mills, etc. use
"tandem" axes, where a pair of
servo drives are kept synchronized by the CNC control. These do not
have a stiff linkage between the
gantries, but a swivel bearing. This allows the machine to be slightly
out of alignment before
the axes are homed. After that, they should be in perfect alignment.

This prevents damage to the machine's structure if the two gantries do
ever get out of sync.

Jon