Faulty head position reset (fix)

Problem: JohnNXT resets all the parts with limited movement at program startup. Many readers pointed out an issue about the neck mechanism: the neck would not properly reset, because the motor did not detect the stall correctly.

Solution: Jim Denson (Plainville, MA, USA) suggested this simple yet really effective modification to fix this neck reset problem. Just add a 1x3 Technic liftarm on the neck axle, between the base of the neck and the head. Thanks, Jim.

Click on the image at left to enlarge it.

Removable slave NXT (mod)

Problem: you may want to use the NXT bricks of JohnNXT without having to disassemble the robot completely. The master NXT is easy to take off, but the slave NXT is part of the base structure, and cannot be safely removed.

Solution: Massimiliano Valentini pointed out that is important to be able to easily reuse NXT bricks, and showed me his solution to the above problem. Building instructions to come...

Send me your hacks and mods about JohnNXT!

I will make them public here.