Something to be aware of: If you're upgrading an existing Hypercube to MGN rails on Y, you will need to either move the top rail down so it matches up with the new corner idler combo, and leave your existing motor and center extrusion in place, or move the motor and side extrusions up, which might mean getting longer rods and leadscrews if you've cut yours to an exact length.
This thing has lots of parts, so here's a quick instruction for narrowing down what you'll need to get this working.
XY joiners and caps come in 4 types, LM8UU/LM8LUU or LM10UU/LM10LUU for Y rods, or MGN9H or MGN12H for linear rails. new added XY joiners for MGN12H 20T idlers and F625ZZ bearings.
Corner bracket Idlers are for Y axis rails.
Top plates are sized either for MGN12H or MGN9H blocks.
Bottom plates are sized either for standard or volcano hotend lengths.
Rear plates are either blank (for sensorless TMC2130) or press-fit for a switch circuit board.
Front plates and clamps/fan ducts come in a variety of options. The fan ducts that say "with sensor mount holes" take any of the mounting arms listed, for 8,12,18mm round or BLTouch.
Important: The grey parts shown in the assembly photo above are from Ben Levi's excellent BLV Cube 3d printer. You can get them directly from his page. All the colored parts are available here.
Update Jan 22, 2020: Added parts for Gates and Mellow 20T 5mm bore idlers, XY joiners and Corner Idler brackets. Top plate for Direct mount BMG dual gear extruder aligned for V6 heatsink. It's compatible with both MGN12 carriers.
Update Jan 9, 2020: Added 2020 XY joiners for 20T idlers up to 11mm x 18mm for LM8UU, LM10UU.
Update Sept 18: Moved the endstop 1mm closer to the edge of the back plate after feedback that the switch wasn't connecting properly.
Update Aug 16: Added new bracket for BL Touch due to conflict with spaceship fan duct. Moves the BL Touch forward and down from the old bracket. Also expanded the screwholes to allow for some adjustment.
Update July 5: Was informed of a glaring error in my rear idler brackets - the screw hole was the wrong size for almost all of them. :( It's been fixed and uploaded replacement files.
Update June 9: Standardized the rear idler design, corrected some belt alignment issues, added XY joiner and rear bracket for 20T idlers.
Update May 1: Added XY Joiners and Carriage Top for MGN12C
Update Apr 27: Removed from "work in progress". There's enough people using the design successfully now.
Update Apr 15: added a remix of External XY Motor Mounts. These can be used inside the frame or outside if you need the extra Y travel for your printer. They also have a 5mm screw and nut hole for motor leveling, since the default motor bracket is known to flex under the tension of the belt.
Update Apr 10: I added XY joiners for MGN9H and MGN12H. The rails mount to the underside of the top extrusion. The existing motor mounts and idler mounts need to be moved up 20mm, and the Y rods removed. The MGN12H will stick outside the extrusions slightly, so keep that in mind if designing an enclosure. You can either use short 8mm long screws and fish them into the holes for the block, or use screws long enough to go right through, your choice. XY Joiner MGN9 needs 35mm m3 screws, MGN12 needs 30mm screws. Added 2020 corner bracket idlers for F623ZZ, F624ZZ and F625ZZ bearings. Added rail alignment jigs courtesy of Pumpal.
Update Apr 3: Added an extra hole to both rear plates and a new bottom for volcano hotends. This will move the fan and duct down the 8.5mm difference between the standard and volcano hotends. Also added a 3rd fan duct with longer arms. To determine which duct to use: Measure from the center of the bottom plate to the center of your heatsink nozzle. 20-27.5mm, use NF and Microswiss duct. 27.5-35mm, use V6 and Orion duct. 35-42.5mm, use 35-42.5 duct. I'll probably rename the others for distance instead of hotend at some point.
Update Apr 2: redesigned my usb-a 3.1 extension cable to carrier system to attach to this system using the 3 hole top blocks. https://www.thingiverse.com/thing:3270180
Update Mar 31 - Added a front plate with stock hypercube mounting holes, in case someone has a favorite design they want to bolt on to this system. Added the V6 clamp and fan duct for Precision Piezo Orion. This is untested Uses the V6 spaceship duct.
Update Mar 30 - Added a front plate and fan shroud for Microswiss hotend. This is untested. Uses the microswiss spaceship duct. Feedback on adjustments needed for fine tuning. Edited the duct for V6 and Piezo Orion. Created sensor mounts for BLtouch, and 8, 12, and 18mm round sensors that should work with all hotends and ducts. Added a top plate to support MGN9H.
Update Mar 27- Added a mount for Precision Piezo Orion. No fan duct for it yet, not sure how to connect it, to be honest. It moves the hotend another 4mm further forward, so that might mean the parts fan ducts will need adjustment.
Update Mar 24 - Altered the angle for the spaceship fan duct to blow slightly forward as well as downward so the streams of air don't impact directly at each other. Should exhaust the air out the front easier. Added benefit, it doesn't conflict with the BLTouch V6 clamp part from BLV. I've added in a modified V6 Clamp with 12mm sensor that clears the new duct. Added 2 additional mounting holes for the top of the carrier, 42mm center to center of the outside holes, and 21 mm from outside hole to middle hole, just in case you want to connect something additional to the top of the carrier.
Update Mar 23 - Added built-in supports for the fan opening on the Spaceship Duct. I was having trouble with post-processing supports appearing inside the duct. They remove easily with a pair of needlenose pliers. Also added a tool to assist getting the belts through the holes in the front and back plates. I recommend the belts be attached to the front plate first, and pulled so the end is right at the end of the clamp, so it doesn't affect the endstop. I added nut holes for the bottom plate, and altered the MK3 duct to allow the screws to be run through from the bottom of the duct into the plate, instead of top down. This allows the duct to be removed without disassembling the carrier.
Update Mar 21 - Added the plate and fan mount for the NF NC-01 cyclops 2in1out block, Also added mounting holes for the Hypercube 300 standard sensor holders to the V6 clamp/fan duct. If you use the original duct from BLV, this isn't necessary, as he has several different clamp/fan duct models for different sensors, but they conflict with the spaceship fan duct I've created, so I added these mounting holes as an alternative.
Update Mar 19 - Remixed Paul's Anet A8 Spaceship Fan Duct for the BLV carriage.
Update Mar 18 - Ben Levi's BLV MGN Cube X carriage is almost a perfect fit for this, so instead of reinventing the printer, I've just made a few minor modifications to his plates to add belt clamps. The rest of the parts can be found here: https://www.thingiverse.com/thing:3382718
As I make changes, I'll add them here as well. There's a few things I'd like to adjust, including the fan duct mounting method.
Update Mar 17 - increased the spacing around the bearings a little.
I'm starting a X axis linear rail conversion using a 2020 extrusion. This will be a "work in progress" for a while. The XY joiners I'm fairly happy with, though there may be some minor tweaks as I figure out the carrier.
This uses the twisted belt design of the HC300 and F623zz bearings, but I left room to put a small washer between the bearings so they don't rub the edge of the belt.
4 - 20-40mm m3 screws
For the bearings, and either just tighten them into the plastic, or drill out the hole and use a nyloc nut to secure it.
For the bearing covers.
8 - 10-12mm m3 screws
8 - 3mm nyloc nuts
You can use either the printed bearings, or ball bearings, as you choose.
2020 extrusion - If your rods are centered on the vertical 2020 extrusions, you should cut your 2020 to 41mm less than your Y rod center to center distance. If using HC300, that's 460 - 41 = 419mm. That gives 1mm of play to adjust the XY joiners in place.
Linear rail - cut to 81mm less than your Y rod center to center distance. For HC300, that's 460 - 81 = 379mm, again leaving 1mm of play. You can use tighter tolerances if you choose.
Printing: Spaceship Fan Duct and XY Joiner will need supports from bed only.