RE: [CAD_CAM_EDM_DRO] Motorising a rotary table

Before I give any sort of advice, I'd like to ask a some of questions.

You already have an existing table with gear drive to which you are going to
adapt a servo motor. And you're wanting to know how to control an unknown
size and type of motor.

Question 1. Is the table just going to rotate without stopping at a
position? This can be driven without going to a servo.such as using a
stepper or even a DC motor with a controller and external sensor package.

Question 2. You have determined that the drive is a "zero backlash" type
drive, with the input shaft held stationary, the table can't be moved. If
the table moves, then the positioning error of the drive will never allow
you to achieve a accurate position. Your table position will always vary by
the amount of backlash and this condition will always get worse has the
drive wears. Weight of any fixtures attached to the table exacerbates the
problem and causes the drive to experience more wear quicker.

Question 3. You're wanting to drive the table to a given position and have
it stop accurately, as in an indexer? Camco/Ferguson provided a number of
work formulas to size this type of application.
http://www.camcoindex.com/Catalogs/Camco-NA-A-Engineering_051408.pdf.

R. Wink



From: CAD_CAM_EDM_DRO@yahoogroups.com
[mailto:CAD_CAM_EDM_DRO@yahoogroups.com] On Behalf Of michael_s@...
Sent: Tuesday, June 25, 2013 5:08 PM
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: [CAD_CAM_EDM_DRO] Motorising a rotary table





I have a 400mm rotary table that I wish to mechanise and understand that I
need to fit a servo motor to it. I would propose to mount the motor to the
input shaft after removing the handwheel .

Doing the mechanical is not a problem for me and even the wiring if I know
what to do. Please can anyone help me with information of what I need to buy
and how to wire things up. The handwheel to table ratio is 40:1 and I need
to be able to control the table rotation from zero to 5 rpm.

I envisage controlling the motor either from a switch or a foot pedal. It
would be handy if the motor could cause the table to rotate once and then
stop but this isn't vital.


Many thanks for any help that may be given.

Mike



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