Enclosure heater by under-bed fan for BLV mgn cube

thingiverse

My build of BLV mgn cube has a large bed with an overpowered 800W heater. This mod is a fan which blows on the bed from below, using the excess heat to warm and circulate the air. I used a 4020 fan connected as a "heater" to the control board, which keeps the temperature in the enclosure constant. I can comfortably maintain 40C in the enclosure with a 60C bed, and 60C with a 100C bed. You need m3 screws to mount the fan (approximately fan height + 8mm), and 8mm m3 screws with t-nuts to mount the bracket to the bed frame. I attach a FreeCAD file for customization. I recommend to print this with some temperature resistant plastic (I used polycarbonate). No supports are needed. Since the mounting bracket is long, you may need to take into account how your plastics shrinks when cooled. BEWARE OF THERMAL EXPANSION. I found that parts of my cube expand unevenly. The worst is the X carriage, where a steel rail is bolted to an aluminum profile. These expand at different rates which causes the carriage to bend down. I changed the t-nuts on the X carriage from metal to plastic, and this seems to help, but more testing is needed.