> Next Wiring
< Previous Base rotator

2.2 Wrist rotator

The wrist-rotate motor block; note the rubber grommit at bottom left, and the small gap between the left edge of the block and the metalwork of the arm.
Unfortunately the design of the tiny servo motor used to rotate the wrist appears to have changed since the robot arm was designed. The version I received had wires coming sideways out of the back through a thick rubber grommit. This unfortunately prevents the insertion of the whole motor body through the hole in the front of the bracket.

My first solution was to simply mount the motor from the other side, and screw it on the inside of the bracket. This works up to a point, but then prevents the wrist movement (up-down, not rotate) from realizing its full range. This is particularly bothersome because it means you can’t have the grip horizontal when the arm is in a position which takes the grip close to the supporting surface.

In the end I got around the problem by carefully removing the back of the servo motor, and pulling the grommit away from the body. The dis-assembly can then be manipulated through the hole in the bracket, and carefully re-assembled once inside. The motor can then be screwed to the front of the bracket as per the instructions, and clearance is (just) enough for the wrist to see a full range (180 degrees) of movement.

> Next Wiring
< Previous Base rotator
Copyright © 2010, 2012 DM Bespoke Computer Solutions Ltd
All rights reserved