Tag Archives: Ashtar 3D Printer Series

3D Printer: IDEX for Ashtar K, M, D and C (2021/01)

Updates:

  • 2021/01/31: added comparison regarding Multiple Switching Extrusions (MSE)
  • 2021/01/18: added IDEX Features with Pros/Cons, Ashtar Series Genealogy, Comparison Dual Material approaches, and brief Hardware Requirements
  • 2021/01/15: first version with overview side-by-side

Mid of January 2021 (01/12 – 01/14) I added IDEX (Independent Dual Extrusion) option to 4 designs, all still in early draft stage – here as a summary side-by-side:

Ashtar K IDEX has been fairly easy, as I was using an improved “old” design of the X motor mount for the 2nd motor and 2nd belt, and since Ashtar M IDEX is using the same XZ frame, it was a matter of a few minutes to port that option as well.

Ashtar D IDEX with Classic XY belt routing was more tricky as there was little space left to add another motor, so I realized I need to utilize what’s there and take advantage of it – result is a very space saving solution, but it needs to be verified in real life first.

Ashtar C IDEX with Core XY with an additional X motor was easy, I just reused a slightly altered X motor/pulley mount of Ashtar D, so that was done fairly quickly as well, yet the challenge will be the firmware support, as currently (2021/01) only Duet RepRap firmware supports the CoreXYU as my design falls under.

Features of IDEX

Pros:

  • double printing: duplicate or mirror mode
    • double printing volume at same duration
  • two materials with different melting points
  • two colors (non-mixing) with
    • more reliable than dual nozzle setups, as inactive nozzle does not run over existing printed piece often
  • possibly different nozzle sizes
    • dedicated nozzle for infill vs outline

Cons:

  • slightly reduced build-volume in X-axis
  • added complexity

Comparison Dual/Multi Color/Material Extrusions

blue = relevant positive
red = relevant negative

Independent Dual Extrusions (IDEX)

  • complex setup
  • moderate cost
  • non-mixing
  • dual nozzles
  • dual heatblocks
  • dual heatsinks
  • normal retraction
  • no purge block 1)
  • no oozing over print
  • no inactive nozzle traveling
  • reliable 2)

★★★★★

Dual Hotends 2-in-2

  • simple setup
  • low cost
  • non-mixing
  • dual nozzles
  • dual heatblocks
  • dual heatsinks
  • normal retraction
  • no purge block
  • inactive nozzle oozing over prints
  • inactive nozzle travels over print
  • moderate reliability

★★★★★

Chimera 2-in-2

  • simple setup
  • clone: low cost
  • original: high cost
  • non-mixing
  • dual nozzles
  • dual heatblocks
  • single heatsink
  • normal retraction
  • no purge block
  • oozing of inactive material
  • inactive nozzle travels over print
  • moderate reliability

★★★★★

Cyclops 2-in-1

  • simple setup
  • clone: low cost
  • original: high cost
  • mixing
  • single nozzle
  • single heatblock
  • single heatsink
  • normal retraction
  • purge block required
  • no oozing of inactive material
  • clone: unreliable

★★★★ (clone)

Cyclops NF 2-in-1

  • simple setup
  • low cost
  • non-mixing
  • single nozzle
  • single heatblock
  • single heatsink
  • complex retraction
  • no oozing of inactive material
  • moderate reliability

★★★★★

Diamond Hotend 3-in-1

  • complex setup
  • clone: low cost
  • original: high cost
  • mixing
  • single nozzle
  • single heatblock
  • 3 heatsinks
  • tricky retraction
  • purge block required
  • no oozing of inactive material
  • moderate reliability

★★★★★

Multiple Switching Extrusions (MSE) 2-in-2, 3-in-3, 4-in-4

  • moderate complex setup
  • requires additional servo or motor
  • extendable 2, 3, or 4 colors/materials
  • low cost
  • non-mixing
  • multiple nozzles / heatblocks / heatsinks
  • normal retraction
  • no purge block 1)
  • no oozing of inactive material
  • no inactive nozzle touching print
  • reliable 2)

(rating comes later)

Y Splitter x-in-1

  • simple setup
  • extendable 2, 3, or 4 or more colors / materials
  • low cost
  • non-mixing
  • single nozzle
  • single heatblock
  • single heatsink
  • complex retraction
  • purge block required
  • no oozing of inactive material
  • moderate reliability

★★★★★

Footnotes

  1. in theory no purge block, but if ooze shields are shared among switching extrusions (more than 2 extrusions) there may be cross-contamination between colors/materials
  2. the printheads individually are proven to be reliable

Hints:

  • single heatblock = same print temperature
  • dual heatblock = different print temperatures possible
  • dual nozzle = different nozzle sizes possible

Hardware Requirements

  • 1x NEMA 17 42-45Nm with wire, extra stepper motor driver on motherboard
  • 100-110cm long 6mm wide GT2 belt
  • 1x pulley and 1x idler
  • 1x hotend (nozzle, heatblock, heat cartridge, heatbreak, heatsink), extra heating connector on motherboard

That’s it.