Anet A2 dual Z single motor

thingiverse

I wanted dual Z screws with a single motor, and Supasorn's Tarantula solution was extremely simple and elegant. I remixed it to fit my Anet A2. The difference is that on the A2, the distance between the vertical frame and X bar is larger, so the motor mount and top mount had to be edited. I moved their position only 1mm further out on both, which was enough. I also edited the switch mount to match the switches used on the A2 and adjusted the switch position on the motor mount accordingly. I added a new holder for the X endstop switch because the original one didn't fit in the correct position anymore due to the second leadscrew. Supasorn's original lead screw nut holders should be used, and I included the files now for convenience; they haven't been changed from the original. All parts use M4 screws & T-nuts, except the motor mount, which uses M3 screws/nuts. All could easily be edited to use other sizes, but I left them as they were, since I had all sizes available. If you want to use Anet's original M5 screws/t-nuts, just print the parts with 100% infill and drill out the mounting holes with 5.0 or better yet, 5.5mm (to give you some alignment room) drill. Edit: Full screw list, as requested: * 10pcs of 412 CS + 4mm washers (2+2 for each upper mount to frame, 2+2 for nut mounts to X-bar, 2 for X-switch mount) * 8pcs of M312 BH + 3mm washers + locknuts for upper bearing mounts (2 per side) and nut to nut holder (2 per side) * 6pcs of M38 BH for fixing motor to motor holder (4) and Z switch riser (2) * 1pc 320 screw for Z height setting (I could get away with 10mm, but YMMV here, as I'm running a custom bed mount and glass on top of the bed) * 2pcs of M310 (M38 would also do) to fix motor mount to the frame * Original screws for X and Z switch mounts (28 or 210 CS, if lost/stolen/broken) * Original bearings For the second lead screw, you need to start with the top because that's how you tighten the belt. Fix the top so that the belt is reasonably tight (no need to go overboard), mark the position on the top frame. Fix the nut holder to the X bar so that the lead screw is vertical in X direction, and adjust the top bearing so that it's parallel to the frame in Y direction. To align the top and the nut holder perfectly, then remove the long leadscrew and use the original shorter one – lower the X-bar and screw it to the nut holder so that it's a bit lower than the top bearing. Loosen the nut mount screws and wiggle around until the top of the leadscrew points exactly at the top bearing hole. Tighten screws and repeat for the top mount – drop the leadscrew towards the nut through the bearing, but don't thread it in. Loosen the top mount and wiggle around (within the markings, don't move right-left, as this would affect belt tension!) until it's pointing straight at the nut. Tighten. Alignment should be good now. Fit the longer 400mm lead screw (I'm using 500 because that's what I had and I didn't want to cut it, but 400 is enough), pulleys and belt. You should be able to move the X-bar up and down quite easily and without any "tight spots" by turning the lead screws. Finally, to adjust the level of the X bar, bring it close to the top, loosen one of the pulleys and adjust ONE of the lead screws until the distance between the X bar and the top frame is the same on both sides. Assuming your frame is square, this should be then horizontal. Now relevel your bed and enjoy.