AndreasL Dual z axis Smartrapcore ALU DjDemonD remix for 2020 with counterweight

thingiverse

This is my take on the AndreasL alternative dual Z axis for SmarTrapCore (http://www.thingiverse.com/thing:896556), remixed to fit the aluminum 2020 frame version. I've reoriented the axis so it sits front-to-back, not left-to-right, to prevent interference with the corexy gantry at the sides. So all parts labeled "R" are front and parts labeled "L" are back. Make sure your software's endstop settings and define_manual_x_home and define_manual_y_home settings match this configuration. To assemble the Z axis, follow these steps: attach the innermost front belt, then the back belt, and finally the front one. I found it helpful to place two objects of equal size under the bed plywood, rest the bed on them, and then attach the belts in that order. This avoids tilting the bed under unequal belt tension and makes adjusting the build plate level easier once assembled. When attaching the belts, ensure they are properly seated and not twisted. If you notice any issues with the belt path or tension, refer to the updated instructions below. UPDATED 04/02/17: To improve the belt path for the front descending belt, I've modified the Z-slides to include one belt clip in a slightly different position. This creates a straight belt path for the front descending belt, making the Z axis more accurate when the nozzle is near the bed. UPDATED: Top brackets now have added reinforcement and can be attached in exactly the same way as before. Much gratitude goes to AndreasL for the original design, which has performed admirably since I modified it and installed it. In May 2016, I swapped to a 16-tooth drive pulley with default settings of 100 steps/mm for a 1.8-degree stepper or 200 steps/mm for a 0.9-degree stepper. This provides slightly improved resolution but also adds some gearing to help the motor lift the axis. Also in May 2016, someone suggested adding a counterweight to reduce the harsh bump at the bottom of the Z axis descent. I designed a bearing holder to be mounted over the front lower bracket, which holds an M8 bolt, two large washers, and a 608zz bearing. A short run of belt cable is tied to the front-most belt and laid over the washer. You can add weight just less than your Z carriage/bed total assembly. I'm using a 500g weight for a 700g carriage, making it effectively 200g. In October 2016, I decided to do away with the Z probe and replace it with a Z endstop. I designed an add-on for the lower front Z axis bracket that holds a mechanical endstop module board. Super Glue or acetone weld the endstop bracket to the lower z axis front bracket, attach the endstop, bend the lever upwards slightly. To improve reproducibility when using the Z endstop, have something under the bed like landing gear or springs so that the bed stop just short of elastic tension from the endstop. When homing, the firmware will find the endstop trigger point without pressing it fully home. Another method is to have home Z (G28 Z) before home all in your start G-code. For more details on configuring the firmware and using this setup, refer to the link below: http://forums.reprap.org/read.php?344,703348 If you want to copy or edit these public files on Tinkercad, here are the links: https://tinkercad.com/things/hr1XKGkmAnA https://tinkercad.com/things/aeBVa3ZfJGA https://tinkercad.com/things/d5LJ8QEVrpP https://tinkercad.com/things/9UOXC4BadER https://tinkercad.com/things/iFL1oCg6VIM