Re: [CAD_CAM_EDM_DRO] slave motor for geko 340???

Brent Fuchs wrote:

>I am building a gantry style machine to route wood with.
>2 of the axises have 2 screws each, I have decided to use
>a motor for each screw. Is my thinking correct? can I use
>two servo motors per geko 340 by connection one as a slave
>with no encoder, just connecting the armature???
>
>

no, absolutely not. Slight variations in the motors, friction, weight,
etc. will get
them out of sync very quickly (like less than a second). You need to have
a home switch on each portion of the axis. This is called a tandem axis
in CNC
parlance. It is frequently used on gantry-type machines like vertical
boring mills
and bed mills. You would need a separate Gecko servo drive and encoder
for each
motor. The gantry or axis will need to be constructed with links and
bearings so
the axes will not bind when slightly out of sync. You will have to add
some logic
between the CNC computer and the Gecko drives that stops the step pulses to
whichever motor reaches the home position first (when in search for home
mode).
This should allow both axes to be moved to home. Then this bit of logic
would
be switched to normal mode, and let all step pulses through to both
drives, and
they should stay in sync as long as they both stay enabled.

If you can't arrange the bearings and links to prevent binding when out
of sync,
then you will need to use one motor and belt drives to keep the two screws
synced.

Jon