Just building a pro 48x48 you bin the nylon nut and use a supplied thin washer. You then get 100% coverage on the rack you don't need to be making shims. The following is stated in the instructions. Your spindle may have the shaft installed in the spindle already, held in place with a plastic hex nut for protection during shipping. The plastic hex nut needs to be removed prior to installing the spindle.
The gantry is too heavy even for NEMA 34 size stepper motors. The gear reduction trades speed for power. In other words, it takes more revolutions of the stepper motor to move the gantry a given distance but it is able to move it.
@@buildbug3979 Thanks for your reply, actually I was asking if we can use reduction gear couple with their teeth touching directly instead of using belt.
If you use reduction gears the torque is increased, that's physical! Yes, you can use the stepper directly , but you won't have additional power, so you'll need a stepper powerful to do heavier work. Bottom line: it's more economical to use reduction gears than to buy super high-powered stepper's
The spring is there as a safety device. If your gantry is ever driven into the end stop of the axis (perhaps due to a software or configuration problem), the spring allows the pinon to move away from the rack and simply 'spin out' in place rather than continuing to transfer torque to the rack and the end stop. This makes a horrendous noise as you would expect as the pinion spins in place on the rack but its better than the alternative.
