K40 Motorized Bed

thingiverse

CHANGELOG:2023-10-13: Improved the “Stepper Support - Support” part to prevent nuts rotation2023-10-14: Reduced the global footprint and fixied various issues with the stepper support2024-01-09: Added some holes in the “Stepper Support - Tensioner” part to make assembly/disassembly easier + a new variant that can hold a long lever end-stop microswitch2024-01-17: Updated “Stepper Support - Tensioner - with microswitch support” part to make the microswitch seat a bit higher2024-02-08: Added the STEP filesI've been using for some time the really good motorized bed made by Jean-Philippe Civade but thought some things could be improved:the use of thin M5 threaded rods made the whole assembly a bit fragile and prone to seizing if they were not perfectly straight (which can end up being hard to source…). Also I found the pitch/lead being a bit low.it could be a bit wobbly due to the placement of the pulleys at each corner and to how the threaded rods were constrained by the beltthe stepper support felt a bit weakno built-in way to compensate for an uneven K40 floorI decided to look at other motorized beds but they either had some other weaknesses (eg.: the belt going inside of the danger zone) or required a lot of parts I didn't have on hand.So… I started working on a new one that fits my needs.It is made of:4x 100mm smooth rods to make sure the bed is going straight up without any wobbling4x 100mm T8 lead screws because sourcing straight ones is easy/cheap8x 608 bearings to constrain the lead screws with almost no friction4x optional F4-10M thrust ball bearings4x LM8UU linear bearings for the smooth rodsA 6mm GT2 belt (between 1250 and 1310mm. In my case a 1250mm one was perfect but that depends on the size of the final bed, I recommend buying an open one and closing it yourself using something like https://www.printables.com/model/417805-gt2-belt-jig-diy-closed-loop-belts)4x 8mm bore / 6mm width GT2 pulleys for the lead screws1x NEMA 17 stepper1x 5mm bore / 6mm width GT2 pulley for the stepper2x 5mm bore / 6mm width toothless pulleyssome 15x15mm / 1.5mm thickness squared steel tube (2x310mm + 2x280mm + 4x165mm, but I recommend measuring the available space before assembling the whole thing, depending on your K40 you may have to reduce the Y axis a bit - don't forget to take the space required by the stepper into account). You can use the following jig if you plan to cut it using a hack saw: https://www.printables.com/model/613718-15mm-square-tube-cutting-jigA steel expanded metal sheet (~360x260mm)4x M8 hex screws, washers and nuts that act as adjustable feet (or anchors if you want to)8x M3x16 round head screws for the lead screw nuts8x M3x35 hex socket cap screws + nuts to assemble the bottom corners4x M3x5 round head screws to hold the NEMA 17 stepper2x M3x50 screws + nuts for the tensionner (you can use shorter screws depending on how much you need to tighten your belt)2x M3x25 screws + nuts to attach the stepper support to the square tube2x M2x6 screws + nuts to attach the tensionner to the pulleys support