Heatbed design for mini kossels. Takes a 160mm kapton heater.
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README.md
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README.md

Mini-Kossel-Heatbed

Heatbed design for mini kossels. It is slightly elevated above the base extrusions in order to keep the motors underneath as cool as possible. For the same reason, there's a 3mm cork mat sandwiched between the heater and base aluminum plate. Quick and dirty steady-state thermal simulations have shown that the bottom alu plate will be about 60°C with a bed heated to 110°C.

Experiences after 18 months or so of operation

  • It works very well in general, heatup times are below 1 minute
  • 1 mm aluminum is on the lower end in terms of stiffness. If I redid this, I'd increase the metal to a least 2 mm

Features

  • Fits kossel mini
  • Solid construction using lasered 1mm aluminum sheets
  • thermal isolation towards the frame using ptfe tubing and PE washers for minimized heat loss and faster heatup times.
  • Cork isolation under the heater to protect motors underneath

Required materials

  • Cut alu_base, alu_fixture, alu_ring from 1 mm aluminum sheet
  • cork, circular, diameter around 180mm
  • kapton bed heater, 160mm diameter
  • 3 pieces of ptfe tubing 6mm od, ideally 3mm id, 6mm long
  • 3x M3x20 and nuts to fix the whole thing to your kossel, as well as three compression springs, approx. 6-9mm in height.
  • Your choice of build platform, i.e. boro, regular glass, carbon. Diameter 170 mm

Putting it all together

Check the exploded view and the pics to get a better idea.

  1. Align alu_fixture and alu_ring, mark the cutout of alu_ring on the fixture. It helps to stack alu_fixture and alu_ring using M6 screws in the holes while doing this.
  2. Glue your kapton heater on the marked alu_fixture
  3. Resolder the wires on the heater so that they point towards the heater's center. This way they'll go out nicely in the center hole of alu_base
  4. Prepare cork circle, cut out a hole big enough to get the cables of the heater and thermistor through
  5. Prepare the screws and ptfe-tubing (see pics for washer detail), put everything together.
  6. alu_fixture with glued-on kapton heater
  7. alu_ring
  8. cork circle
  9. alu_base
  10. Screw setup from top to bottom:
  11. M3 washer
  12. Plastic washer
  13. Into ptfe tube and through heatbed sandwich
  14. Plastic washer
  15. Spring
  16. Plastic washer
  17. Nut in extrusion