Kossel Mini build : Part 4

Recap :

Kossel Mini build : Part 0 – a brief explanation of intent and also sources where I got the parts

Kossel Mini build : Part 1 – assembled the top triangle frame, as it seemed like the simpler of the 4 main components

Kossel Mini build : Part 2 – assembled the diagonal rods by leveraging parts used on the bottom triangle base

Kossel Mini build : Part 3 – while building the effector, encountered some fitting issues on both the plastic and nylon screws.  A combination of dremel and tap and die were used to make things fit.  Also finished the auto level probe.

When the diagonal rods were complete, the 240mm extrusions were free(they are originally for the bottom base of the Kossel Mini).

I needed the following parts:

  1. 3 x bottom plastic pieces
  2. 49 x M3x8mm screw
  3. 33 x M3 nuts
  4. 6 x 240mm extrusions
  5. 3 x glass tabs
  6. 3 x stepper motors
  7. 3 x pulleys(with set screws installed)
  8. power resistor(from J-Head hotend kit)
  9. thermistor(from J-Head hotend kit)
  10. PTFE tubes for power resistor and thermistor

In addition, I also used the following:

  1. thermal paste
  2. kapton tape
  3. 40mm fan

The bottom assembly was quick(especially since having done the top assembly).

Install the pulleys to the shaft of the stepper motors

stepper motors with pulleys installed
stepper motors with pulleys installed


Putting that aside, put the screws and nuts on the bottom piece, each one takes 10 x M3x8mm screws with 10 x M3 nuts. Each piece had 2 extrusions attached, similar to how the top piece had one extrusion attached.

assembling the bottom piece 1
assembling the bottom piece 1
top and bottom done
top and bottom done

Mount the stepper motors with 4 x M3x8mm screws.  The angled grooves printed into the bottom piece helped in getting the hex allen wrench to tighten the screws.

bottom wrench in groove

To prepare the glass tabs, simply use 1 x M3x8mm screw with a M3 nut in the hole and slide the nut in the opening on the bottom plastic piece and leave them as is for now.

glass tabs installed


To finish the hotend, the resistor and thermistor must be installed.  Luckily, I have some leftover kapton tape from my Cupcake kit many years ago.

The “Chipset Thermal Package” kit also came with a thermal paste.  Using this video as reference, I wrapped it in kapton tape afterwards…

  1. to seal the thermal paste in, prevent dust/particles from contaminating it
  2. prevent it from leaking
  3. secure the resistor and the thermistor in place
  4. I had some kapton tape left around?

With these reasoning points, I applied some thermal paste in on the resistor and the hole in the hotend and inserted the thermal pasted coated resistor into the hole.

J-Head extruder

J-Head with resistor

For the thermistor, same treatment.

J-Head thermistor coated with thermal paste

J-Head resistor and thermistor installed


Note, the PTFE tubes have been installed at this point.

Using the Kapton tape, the resistor and the thermistor are secured into place.

J-Head kapton tape


I installed the hotend to the effector, first by attaching the hotend mount

hotend installed mount

Then onto the effector.

J-Head installed onto effector

Wires were soldered to the resistor,

J-Head resistor wires soldered


and also the thermistor (I didn’t take a photo of the thermistor wire with the heat shrink tube, but rest assured, the soldered joints are protected!)

J-Head thermistor wires soldered

Going back to the “Chipset Thermal Package” kit, the 40mm fan and 4 x M3x8mm screws are used to install the fan.

40mm fan


fan installed

I will stop here for now – the diagonal rods, hotend, and auto leveler are done, the frame needs to be completed and then the wiring can begin.  Also, the rails(ordered from aliexpress) are being shipped from China and it may introduce a delay in build progress of this printer.

See you next time!

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