3rd Rail CoreXY (V2 )

thingiverse

After a long pause, I have finally gotten around to redesigning my previous machine(https://www.thingiverse.com/thing:3094320)—and correcting a number of previous design flaws. Where the first 3rd Rail was based on the 5Rail printer, this is a fully self-made design. The advantage is that now you get the full 310x310x400 print volume PLUS the ability to use a 5015 part cooler. Everything has been modeled in FreeCAD to ensure that belt paths are parallel. Z rails are set inside the cube frame, which is why the cooling fan issues cropped up in the first place. If you do not intend to enclose the machine and want a bulkier cooler, you'll want to flip the Z components outside the box (you may need longer L stock for the bed mount—I cut mine long ago to fit the inset layout.) *In theory* you should be okay using 16 tooth idlers and gears, but this was designed around 20 tooth geometry, so YMMV. If you're actually wanting to build this, I'd suggest grabbing the correct pulleys just to avoid marginally throwing the geometry off in the name of saving less than $10. I would suggest using nyloc nuts for the gantry bits, as they'll shake loose over time (especially if you insulate the chamber and run it hot). From my personal experience, you are fine printing this in ABS, so long as you do not take the chamber over ~45*C. After that, things may get droopy on you. If they part cooler droops, use the cropped fan shroud file (I am currently using this one, but if you're using the fan during prints, the other shrouds probably work better.) The part cooler is based on theD0ct0r's excellent design (https://www.thingiverse.com/thing:2769783). You can opt to use the Z stepper Mount.stl file if you want a sort of janky way to mount a single belted stepper for both screws. It never worked quite as nicely as I wanted (and was a HUGE pain to tension/assemble) so I went back to dual steppers (plus that let me make use of Marlin's G34 Auto Gantry Levelling). It is included for posterity or the adventurous.