Re: [CAD_CAM_EDM_DRO] Servos

machinist24540 wrote:

>Hello,
>Has anyone homebrewed an upgrade/retrofit using servos on a BP BOSS
>or manual?
>

Yes, I put servos on a manual Bridgeport. I have position resolution of
.00005" on X and Y,
and position res of .0000025" (yes, 25 micro-inches) in Z, with a 10
TPI ballscrew. I'm
using 1000 cycle/rev encoders directly coupled to all leadscrews. The X
and Y screws are
5 TPI. I was lucky enough to grap a set of high-precision ground
ballscrews out of a PC
board drilling machine.

>I was wondering what would be involved.
>Would I see a big difference with the servos over staying with the
>steppers? (other than having a .001" step?)
>
>

The big difference is that you can get much faster rapid feeds at about
the same cost.
If you use a real servo system (as opposed to a step/direction input
servo driver) you
get continuous position readout at the CNC computer, you can also use it
as a DRO
in manual mode, and the computer can abort the operation if an axis is
lagging behind
for any reason (binding, crash, etc.) Servos can give much smoother
motion, especially
to the slow axis when making shallow angles or large arc moves.

But, it is more complicated, for sure.

Jon