NoName Triple-Z mod with Kelvin coupling and VenterMech anti Z wobble

thingiverse

User of the NoName CoreXY printer know that the four linear bars need to be aligned properly to not bind the linear bearings during Z movements.I always had issues with this causing bad Z artifacts and nothing helped so far.As the original NoName design intended bed screws for leveling and only had two Z spindles it could perform a Z-tilt at most but you still had to level the bed manually.To overcome all those restrictions and modernize this printer I designed a triple-Z mod with Kelvin coupling to get rid of the Z artifacts and implement auto bed leveling with three independent Z stepper motors.The new design depends on a new print bed that I found with the Zerog Hydra printer and uses 235 mm hole spacing.The bed itself measures 255x255x8 mm and can be sourced on AliExpress for example as a whole kit with heating mat and flexplate system.Coupling to the Z arms uses 12 mm balls with M4 threads that are used on the Kossel K800 printer.Screw length and aluminum spacer height depend on the overall distance to the used print head/nozzle and have to be determined later on.My design uses VenterMech Z-decouplers designed by Liam Venter and are not subject here and have to be obtained separately (refer to BOM for needed parts!): https://www.fastbikegear.co.nz/index.php?main_page=product_info&cPath=0&products_id=12371I tested a first version using MGN9H rails and carriages that worked fine so far but still showed Z artifacts so this new design is fully based on MGN12H and works flawlessly as the photo proves.The rails are 300 mm long.Furthermore TR8x4 spindles are used with a maximum length of 300 mm whereas the front ones might need to be cut to length accordingly.The linear rails are fixed with M3 hammer nuts, the motor mounts and wiggle woggle mounts with M4 ones for the 2020 type b nut 6 aluminum profiles being used for that printer.The spindles are loosely fixed on the top with the Wiggle Woggles from Liam Venter: https://www.thingiverse.com/thing:5063532Those fit into the respective mounts.Depending on the used print head you want to have the bed either centered or moved to the front.The bed mounts with "centered_bed" in their name are for the first option, the bed mounts without this are for the moved forward bed - applicable for my print head: https://www.thingiverse.com/thing:5811506Screw list:Wiggle Woggle mounts: 4 * M4x14/15Motor mounts: 10 M4x30 + 2 M4x8/10Stepper motors: 12 * M3x18Bed mounts: 6 * M3x10/12Bed arms: 8 M3x12/14 + 4 M3x16Lower drag chain mount: 2 * M3x8Drag chain: 5 M3x6 + 1 M3x14 (all countersunk screws)Wago clamp mount: 2 * M3x8other parts:round neodymium magnets 15x3: 2round neodymium magnet with hole 15x8x3: 1rigid (or flexible) couplings 5->8 mm: 3axial thrust bearings: F8-16M (8x16x5mm): 3stainless steel pins 3x20 mm: 2M3 threaded heat inserts: 15drag chain: 10x11mm open outside R18Please pay attention that you need to print the following part three times:z_motor_bearing_mount.stlAs the MGN12H carriages are wider than the 2020 aluminum profile you need to add 4 mm spacers between side panels and the aluminum profiles.Happy printing!