In response to the earlier CoreXY X carriage ( https://plus.google.com/117473262013510481637/posts/bubNqwatncW ), here’s how I have my independently adjustable belts.
The light blue plate clamps one end of the both belt.
The other ends slot into the side of the darker blue piece, which also holds an M3 nut to adjust the tension.
Rods are spaced 40mm apart and carriage is 40mm wide, using shorter LM8SUU bearings than the standard LM8UU.
The light blue screw heads sticking out front hold down the front half of the x carriage which mounts the direct drive extruder and hotend. Having this be 2 pieces means I can replace the entire extruder and x carriage without taking the x ends off which would require pretty much taking the entire moving XY structure out of the printer…
Curious why you went with 2x LM8SUU instead of one LM8LUU? The one-piece long bearing gets you more moment capacity (and thus stiffness) plus less reliance on carriage printing precision to prevent overconstraint binding.
I went with LM8SUU only because a single LM8LUU is over 40mm long.
45mm, yeah. Was that a major design constraint for you? The direct drive extruder is surely much larger than that…?
The extruder motor sticks off only about 2mm of either side, but this doesn’t limit the travel because it’s above the X ends. I had some 173mm rails as was trying to get as much travel as possible.
I like to see OnShape adopted more and more (at least it looks like it). I haven’t had the guts to cut the chord off DesignSpark Mechanical … which is way faster for me to design new things.
About the design I like the two piece carriage. Do you have a quick-change system for toolheads? I just now realize that with my whole printhead design (thing:1369402) I can’t quickly change for example a laser module instead of the extruders…
I don’t have a quick change mechanism and I don’t think I will design for different tools like a laser. I just tried to put all the screws you have to deal with in a place you can access them. To get the front off may be 9 screws total. 4 for extruder, 2 for hotend clamp, and 3 for front of x carriage.
