Anet A8 single motor Z axis drive by osadchy

Last crawled date: 3 years ago

This is a way to sync the Z-axis drive using a single motor.
Printed parts:
plateL.stl - top left plate, the motor and idler are mounted here
plateR.stl - top right plate, essentially a mirror image of the left plate, but without the motor and pulley.
rod_plug.stl (print 2) - replaces the original guiding rod plugs on top plates
rod_holder.stl (print 2) - holds the guiding rods from below, since the motors aren't there anymore
tube_guard.stl (optional) - keeps my bowden tube from interfering with the timing belt
If you prefer the motor on the right, you can print mirror images of the plateL.stl and plateR.stl.
Hardware needed:
use the original 4 M3 screws and nuts to mount the top plates
976mm 488 teeth GT2 (6mm) closed belt (https://www.aliexpress.com/item/Hot-sales-GT2-timing-belt-976-2GT-6-length-976mm-width-6mm-teeth-488-for-3D/32299312364.html)
GT2 18 teeth pulley 5mm bore - mounted on the motor (https://www.aliexpress.com/item/3d-printer-2GT-GT2-Timing-Pulley-18-teeth-Alumium-Bore-5mm-for-GT2-Belt-Width-6mm/32835852375.html)
2x flange bearings 8mm bore (https://www.aliexpress.com/item/8mm-Bearing-Zinc-Alloy-Miniature-Bearing-Pedestal-KFL08-Flange-Pillow-Block-Bearing-diy-cnc-parts/32773248332.html)
2x GT2 36teeth timing pulleys with 8mm bore (https://www.aliexpress.com/item/3d-printer-pulley-aluminum-timing-pulley-2GT-36teeth-bore-5mm-6mm-6-35mm-8mm-10mm-pulley/32658350983.html)
1x idler pulley for GT2, 5mm bore - (https://www.aliexpress.com/item/Timing-Gear-Pulley-Without-tooth-Idle-Pulley-synchronous-Round-5mm-For-GT2-Belt-Width-6MM-Power/32761426168.html)
M8 rod, length 349mm - needed to stiffen the frame, because the frame is too flimsy to withstand the timing belt tension
4x M8 nuts and washers to fix the M8 rod
4x M5 25mm screws and nuts and washers - to fix the flange bearings
1x M5 40mm screw and 2x M5 nuts and a washer - to mount the pulley idler
2x M3 20mm screws and nuts for the top rod plugs
4x M3 15mm screws and nuts to mount the bottom rod holders
4x M3 12mm screws and washers for motor mounting
The mounting holes for the flange bearings are a bit oversized so you can keep the leadscrews and the guiding rods parallel. The way I did it:
Mount the flange bearing without tightening the mounting screws
fix the leadscrews in the bearings
bring the X-axis assembly (the one that rides on the leadscrews and rods) all the way up (maximal expected Z height)
ensure that the leadscrews are parallel to the guiding rods (I eyeballed it, by keeping the bottom of the leadscrews above the Z motor axes, which were yet unmounted at this stage).
tighten the flange bearing mounting screws
Don't forget to change the steps/mm parameter for the z axis (from the original 400 to 800)
Hope I included everything here. If you find anything missing, please comment and I'll answer/update.