X,Y,Z overhead crane

I'm designing a small scale X,Y,Z overhead crane.

it is for moving objects to accurate locations in a 2X2X1 meter tank.

for the X and Y movement it will have a rail and a on it a cross rail.

for the z movement i have to make a lifting mechanism to move an object of around 1.5 kg up and down.

for all 3 movements i am going to use a stepper motor because of its accuracy and ability to hold postion.

for the lifting mechanism i've thought of a rack and pinion arrangement but it i think it will increase the weight a lot.

plz suggest a suitable lifting mechanism.

also suggest mechanism for x-y movement (rail and cross rail) using stepper motors.

 

watch here https://www.youtube.com/watch?v=6drMZqmyXQc for X and Y movement.

 

thank u nich

 

I and others replied in the other thread you started on this subject. Posting two separate threads just fragments the discussion.