[johngalt47]

antiback lash rack. one idea for anti-back lash rack and pinion is to spring load a split pinion so that the gear teeth will seek both sides of the gear rack teeth. well I feel that since this is a rotaing item it is a hard idea to inplerment
i was think if we split the rack lets say 3/8" thick for the fixed rack (main rack) and a spring loaded rack right on top if if only 1/8" thick. making the total rack thickness 1/2"

[MattTheNoob]

Who is john galt?

Good idea, but I think it would make sense to make both parts of the rack the same thickness. The loading would be the same on each half. The spring needs to be stronger than any loading you are going to carry.

[johngalt47]

My thoughts were to have the fixed side thicker as it is the ultimate reference for the position anb have thin side used only for the anti-backlsh part of it. it will also allow the fixed side to have counterbored holes to sink the mounting hardware below flush to allow the spring loaded side to slide accross it. I wanted to keep the thickness at 1/2"

[AssassinXCV]

This way is completely opposite to yours, you could do something along the lines of how a vehicle's suspension works. pretend that the moving part (table of gantry) is the car, the gear is one of the wheels, and the rack is the road. If you picked up a car, the suspension would push the wheels away from the bottom of the car. By doing it this way, the gear would be pushed into the rack, the solution to anti-backlash problem.