Hi hoping there is someone out there who can advise me on a project that I would like to build. I want to build a storage unit for my n scale locomotives that can enter and exit from two different heights. So I want to load trains into the elevator from the lower area 533mm from the floor onto the elevator and be able to drive it up to the upper level 933mm from the floor. I would like to make the unit 4 lanes wide with a possibility of 9 different levels, I can reduce this to 8 levels if there is not the space to achieve the movement required. I initially was thinking of using a stepper motor to drive the unit up and down but I have been talking to people who have said this is not the best method for accuracy. The tracks at each level must line up exactly. I also dont really want the unit to be more than 150mm deep from front top back, and I envisage the length of the tracks inside the elevator to be between 1000mm and 1200mm long. Is there anyone out there that can help me with this build? Cheers Phil
There is truly no reason to worry about stepper accuracy. Theoretical resolution for a 1.8 degree (200 step) stepper used with a TR8x8 lead screw would be 8mm/200 steps per rotation = 0.04mm per step. If that's not sufficient alignment accuracy, using a TR8x2 screw would bring the full step resolution down to 0.01mm per step. Resolution can also be increased by using fractional steps but care needs to be exercised as fractional steps are lost with power off cycles and re-homing would be required with each power on cycle (but as re-homing is a good idea anyway with each power up that's kind of a non-point). Truly I would have such a system re-home every time it went to the lowest position such that it is persistently eliminating any errors. Other thoughts on increasing accuracy include using 0.9 degree (400 step) steppers or using closed loop steppers.
