Kossel

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Kossel

Release status: experimental

Kossel.jpg
Description
Delta robot 3D printer with extrusion frame.
License
Author
Contributors
Based-on
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CAD Models
External Link


Kossel is a parametric delta robot 3D printer, built in 2012 by Johann in Seattle, USA, based on his Rostock prototype.

It is named after Albrecht Kossel, German biochemist and pioneer in the study of genetics. He was awarded the Nobel Prize for Physiology or Medicine in 1910 for his work in determining the chemical composition of nucleic acids, the genetic substance of biological cells.

History

There are several similar printers in the Kossel family.

Legacy Kossel

  • Spectra Fishline instead of timing belt.
  • 623 bearings running directly on vertical OpenBeam, 6 bearings per carriage.
  • PG35L extruder directly on the end effector (moving platform).
  • This design is deprecated but the source files are still available.

OpenBeam Kossel Pro

  • Terence Tam's design for mass manufacturing.
  • Successfully funded on Kickstarter.
  • Stamped and injection molded parts instead of 3D printed.

Mini Kossel

  • This is Johann's latest and stable version.
  • The rest of this page describes the details of Mini Kossel.

Design Goals

  • Zero backlash.
  • Speed: 320 mm/s in all 3 directions.
  • Resolution: 100 steps/mm in all 3 directions.
  • Repeatability: better than 0.03 mm (30 micron)
  • Build volume: cylindrical, 170mm diameter, 240mm height.
  • Footprint: triangle, 300 mm width (240mm OpenBeam + printed corners).
  • Frame height: 600 mm.
  • Print surface: round glass, doesn't move.
  • Mass of end effector with hotend: less than 50 grams.
  • Simplicity: fewer than 200 parts.
  • Hardware cost: less than $600 USD.
  • Fully automatic print surface level calibration (autolevel).

Optionally scale down to a Traveling RepRap that fits within IATA hand luggage size limit (see transportation):

  • Frame height: 550 mm.
  • Footprint: triangle, 270 mm width, 250 mm across (210mm OpenBeam + printed corners).

Bill of Materials

Printed parts

This set of parts weighed in at 271g (without power supply brackets).

Recommended print settings:

  • Layer height = 0.2 to 0.3 mm (around 60% of your nozzle size)
  • Perimeters = 3
  • Top/bottom solid layers = 3
  • Infill density = 50%

Frame

Fasteners

  • 100x M3x8mm stainless steel screws (frame and most connections)
  • 100x M3 stainless steel nuts
  • 100x M3 nyloc nuts
  • 12x M3x25mm stainless steel screws (belt idlers and effector-rod attachments)
  • 6x M3x35mm stainless steel screws (tensioners)
  • 50x M3x6mm stainless steel screws (rail attachment to extrusions - 8mm is too long!)
  • 12x M3x16mm stainless steel screws (push rod attachment)
  • 6x M2.5x12mm screws (micro switches)
  • 3x M2.5x16mm (automatic bed leveling probe)
     note: The 100 counts are exact, not box qty. If you desire spares...

Linear motion

  • 3x 400mm hardened steel rail and carriages HIWIN MGN-12H
  • 3x 1164mm GT2 belt closed loop with 2mm pitch and 6mm width
  • 6x F623ZZ flanged bearings 3x10x4mm (or F684ZZ 4x9x4mm for printed parts before June 21st)
  • 3x GT2 pulley with 16 teeth and 2mm pitch
  • 3x Kysan NEMA17 stepper motor

Diagonal push rods

Bowden

Motor

  • 1x NEMA-17 motor with an integrated Planetary gearbox with a 5 2/11 :1 ratio.(http://robot-italy.com)
  • 1x Spur Gear, 22 Tooth, 12mm od, 8mm id - #S10T05M022S0508 from SDP-SI
  • 3x M3-0.5x25 Cap Screw
  • 3x M3 Washer

Idler

  • 1x 625 ball bearing (5x16x5)
  • 1x M5-0.8x20 Cap Screw
  • 1x M5 Washer
  • 1x M5-0.8 Hex Nut (Nylock optional)
  • 1x M3-0.5x16 Cap Screw
  • 1x M3 Washer
  • 1x M3-0.5 Hex Nut, Nylock

Endstops

Automatic bed leveling probe

Z-probe showing safety pin detail.
  • 1x Micro switch (same as for endstops above)
  • 1x Bondhus 1.5mm allen wrench
  • 1x Safety pin with 2.5mm loop
  • 2x Ball point pen spring
  • 1x Euro-style terminal block connector
  • 1x Heat shrink tubing ID=2mm

Electronics

Assembly instructions

Autolevel probe

Kossel mini build

X_MAX, Y_MAX, Z_MAX top endstops: NC (Normally Connected). M119 for these should show:

  • TRIGGERED when the carriage touches the endstop.
  • open during normal operation.

Z_MIN autolevel probe: NO (Normally Open). M119 for Z_MIN should show:

  • TRIGGERED when the autolevel probe is retracted (up).
  • open when the autolevel probe is deployed (down).
  • TRIGGERED when the autolevel probe touches the print surface.

Make sure that M119 does NOT show X_MIN or Y_MIN, if it does you must change them to -1 in Marlin/pins.h.

Viki LCD with Azteeg X3

References:

Connect Viki J2 to Azteeg EXP3 port like this:

  • +5V to +5V (red)
  • GND to GND (black)
  • SDA to SDA (blue)
  • SCL to SCL (green)
  • ENC_A to D22 (white)
  • ENC_B to D7 (yellow)

Connect Viki J3 to Azteeg ICSP port like this:

  • CS to CHIP SELECT (D53) (red)
  • BTN to D32 on EXP2 (optional) (black)
  • DI to MOSI (blue)
  • CLK to SCK (green)
  • DO to MISO (white)
  • CD to CARD DETECT (D49) (yellow)

CS (D53) and CD (D49) are directly next to the ICSP port, under the expansion shield.

BTN is for the pause/stop/resume LCD button (aka kill switch). We recommend not connecting it and using a power switch for emergency stop instead. If you do want to use it, it should be connected to the Arduino BTN_ENC pin. Otherwise set BTN_ENC to -1 if not used.

This uses the LiquidTWI2 library v1.2.3 or later. Copy the LiquidTWI2 directory into the Arduino libraries subdirectory (something like /Applications/Arduino.app/Contents/Resources/Java/libraries/LiquidTWI2, just next to the existing LiquidCrystal folder). If you end up with a directory named "LiquidTWI2-master" then remove the "-master" part.

If you get compile errors in Wire.h, try Arduino version 0023.

In Marlin/Configuration.h uncomment or adjust the following lines:

  • #define MOTHERBOARD 33 // Azteeg X3
  • #define SDSUPPORT true
  • #define LCD_I2C_VIKI

In Marlin/pins.h under MOTHERBOARD == 33 adjust the following lines:

  • #define SDSS 53
  • #define SDCARDDETECT 49
  • #define BTN_EN1 22
  • #define BTN_EN2 7
  • #define BTN_ENC 31

Disconnect solder jumper JP12 at bottom of Azteeg X3 to disable onboard SD slot and use pins for external SD reader (Viki LCD SD slot).

Links