Started with some VEX parts. Bought a linear motion kit and a 16-pack rack gear.
Screwed the green racks with the metal provided in the kit.
Screwed the bracket in the kit to green inner slider truck.
The two pieces easily slide onto each other.
Test comparison with blue prints by TatsuTetsu.
How a rack and pinion setup works
Add a motor for automatic movement.
Attached another bracket and motor on top.
Now for the blade. Vex 2-wire motor, Vex 1x25 metal bar, 2 screws, 2 nuts, 1 Vex lock plate.
Added Vex standoffs and a 10-tooth sprocket.
Added second metal bar.
Started second half of the blade. Vex 1x24 metal bar, 2 screws, 2 nuts, 1 metal shaft, 1 Vex 40-tooth sprocket.
Put it all together.
Attach to first half of blade with a metal shaft and shaft collars.
Add chain. This chain works just like a bike.
Added a gear train at base since previous attachment testing showed that the motor wasn't strong enough to hold the blade setup right off the shaft.
Test attachment with gear train.
Holds position well. Attached a base.
Left to do: