Re: [CAD_CAM_EDM_DRO] Re: Doubling up servo's...

Why not just get the right sized servo for the job? It is not impossible to
get two servos to run in sync as the major CNC manufacturers do it all the
time but NOT using a single drive belt. They use them in sync to move two
tables or heads at the same time and it works quite well. However, they use one
drive for each motor, not one drive for both motors and they use one encoder
for each motor. It is up to the control and drives to make certain
everything syncs correctly. The OEM for whom I worked before going into business for
myself tried the single belt, single drive, two motor scenario and never did
get it to work because it was virtually impossible to properly tune the
drive so both motors were in perfect sync. Things like difference in wire
length, capacitance, resistance and other factors seem to make it very difficult to
get the two motors working in total sync using just the one drive. Also,
using one belt, ANY minor difference in motor speed, etc. would cause some
definite vibration problems as one motor would then be fighting the other. Using
two completely separate drive systems allow tuning each one so they do run
in sync and the feedback from the two encoders just helps in that respect.

If you do get it to work, you would be THE Guru. I assume the reason you
want to do it is that you have the motors but need more power than each one
provides for your application. Another design that has worked well when
needed to do this is using two motors with two completely separate ball screws or
rack and pinions for each motor and also a separate drive for each. Some of
the lower cost CNC routers use this system with good results.

Well, I didn't mean to ramble on but hope this helps out some.

Randy A.

I furnish technical support, repair, and other related services for your
industrial woodworking machinery. My background as Senior Service Engineer with
the SCM Group for nearly fifteen years with factory training, combines with
my extensive background in electronics, mechanics, pneumatics, electrical and
CNC machinery to offer you needed support for your machinery.



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