Originally Posted by
jeepsr4ever
The good news is they are completely adjustable for preload. The bad news is it takes some disassembly to get to the truck. You will need to remove the Y axis motor assembly by loosening the 2 3/16" stainless steel nuts and completely removing the Y axis assembly. Next you will need to locate the 4 socket head capscrews behind the rails and use a ball type allen wrench to remove them. Once removed the Z axis will be free and you will see the truck and Y axis adaptor plate. You can slide the truck all the way to the side of the gantry and remove the 1/4-20 socket head capscrew stop to allow the truck to slide off. There is one cam on the truck you will see where to loosed teh set screw and then loosen the precision bolt on the bear wheel. Once you loose the precision bolt on the bearing wheel turn it a little and tighten slightly. Then try your fit on the gantry rail. The truck should take quit a bit of force to get back on the rail. Use a rubber hammer or a plastic dead blow. Once you have a strong preload tighten the precision bolt and the setscrews on the other side and re-test. When your happy attach the Z axis assembly using the 4 long socket head capscrews (with your ball driver allen wrench) and then attach the Y axis assembly and using about 6lbs of force push the Y axis assembly into the gear rack and tighten the two 3/8 stainless nuts until the assembly is tight. To check for zero backlash turn the motor power on and try to move the Y axis assembly by hand back and forth. If you feel and movement back and forth under 5lbs you dont have the Y axis gear into the rack far enough.
