Here's something I've been working on for several months, with some luck I can bring it to life this weekend when I finish the wiring.

The printer is a Core XY type and I included many ideas I had been mulling over for the past year or so:

-It is very compact, excluding the Smart Controller and extruder installation (that later I may place on top) the printer measures 35x35x34 centimeters, with a build volume of 26x22x15/16 (depending on heatbed arrangement); all printers I've seen with similar print volumes are much larger.
-The frame is built using of easily sourced and dirt cheap 19x19mm (3/4" sq.) aluminium tubing, I used a CNC router to drill the holes and trim the tubes to a precise length, all the rest of the structure is printed.
-I used linear rail bearings for the XY axes, very precise, smooth and again compact, in my opinion it's worth the extra price as compared to the usual rods used for this.
-The Z axis is made with three trapezoidal thread screws connected to a single motor with a belt, seems to work well but I need to test it under power. This arrangement allows the bed to be leveled by disengaging the belt and adjusting each individual screw, although I want to improve the "clutch" and move it to the front of the printer for easier access. Originally I was planning to use ballscrews, I tried the arrangement I had in mind but didn't work as well as I hoped.
-The Bowden extruder... I came up with a novel design, it's a bit of a secret for the moment.
-The Core XY belts don't cross at the front, there's a return pulley at each front corner with a tensioning arm, but I also want to improve the design of those with adjustment screws.
-The hotend holder is super light and compact, 3x4x10 cm only, I'd like to experiment with a water cooled hotend later on so I can make it much shorter.
-Compact power supply, 12V and 33A but almost half the size of the ones used normally.
-All the motors, controller and power supply are mounted at the back, so the wiring is kept very short.
-The heated bed will be built in several layers, a phenolic base plate, a layer of cork for insulation, the heating element, an aluminium plate on top and finally the removable glass print surface itself.
-Finally the print area can be enclosed easily, an acrylic divider (cut, not installed yet) will separate the print area from the electronics on the back, there's going to be side and front panels and a door and later on I'll experiment with making lightweight bellows (ie. aluminized mylar and Kapton) to seal the top, this will allow to keep a constant temperature during printing... or at least that's the theory.

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