How do I do that?
As briefly described in my previous post, I measured the backlash directly by taking pictures of the coupling. To be more specific:
-Remove the motor-gearbox assembly from the mount. Keeping half the coupling on the gearbox output shaft helps with the backlash measurement.?You should be able to rotate the output shaft with your fingers and feel the backlash.
-Take a pictures at each end of the backlash. I installed my camera on a tripod so I can easily align the images. The camera was facing the end of the shaft (or coupling half).
-In Photoshop, or other imaging software, measure the angle difference between the 2 images; this is the gearbox backlash. Convert the measured backlash to other units, for instance:
Backlash angle * 239.34 /? 360 deg = backlash in seconds at sidereal rate
-For the worm backlash, repeat the above taking pictures of the other coupling half on the worm which is still installed on the mount.
-If you believe there is backlash in the coupling itself, you could assemble the coupling, fix one end, and measure the backlash at the other end using the same approach.
Here is an example of the two pictures for the gearbox backlash, combined in a gif file:
Eric
