Tag Archives: IDEX

3D Printing: Ashtar Series Printhead Options 2021/02

The past weeks (2021/02) I worked on various printhead designs, to summarize and provide an overview by mounting them on Ashtar K:

Also improved the display controller to simulate Marlin firmware and list heads and tool selection (MSE), coordinates (IDEX) or rotation angles (RTN & PAX).

So far all options are available for Ashtar C, D and M as well, but currently (2021/02) are just in draft and mostly untested.

RTN and PAX promise printable support-free overhangs, yet no public available slicing software exists to really take advantage of those two designs, as new algorithms of volume decomposition, sub-volume sequencing, collision detection are required and mostly debated in scientific papers as 2021/02 and only few companies, e.g. HAGE and VSHAPER, implemented new 5-axis 3D printing procedures, and DotXControl advertises a 5 Axis Slicer.

That’s it.

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

★★★★★

Tool Changer

  • complex setup
  • extendable to n-colors or materials
  • moderate cost
  • non-mixing
  • multiple nozzles / heatblocks / heatsinks
  • normal retraction
  • no oozing of inactive material
  • no inactive nozzle touching print
  • moderate reliability

(rating comes later)

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.

3D Printing: Ashtar C IDEX (Independent Dual Extrusion)

Status: just a draft

Updates:

  • 2021/01/14: quick start with a rough draft

Introduction

Well, after the IDEX option designs – still as drafts – worked for Ashtar K (Prusa i3), Ashtar M (Moving Gantry) and Ashtar D (Classic XY), I thought, why not also target Ashtar C (Core XY).

Ashtar D IDEX is definitely a narrow design, so I thought to reuse two parts of it for Ashtar C as well, and hopefully the A and B belts route around – and well, it seems mechanically to work out.

On the firmware part it seems this CoreXY plus additional X motor is called CoreXYU and supported by Duet RepRap firmware – but details need to be researched in more depth. On the first glance the “traditional” CoreXYU setup routes the U belt off the X beam and not place a motor on it as I do, but routes at the end of the frames so the motor is stationary – definitely something also to look at.

Draft

Gallery

Issues to Resolve

  • Firmware supporting CoreXY IDEX:
    • E1: X & Y provided through CoreXY by motors A & B
    • E2: X provided by X motor, Y provided by CoreXY where X=0 remains (both motors A & B have to operate to provide X=0 while Y is moved)
    • Duet RepRap firmware provides CoreXYU support, and it seems it would cover my use case here
    • Marlin firmware as of 2.x does not support CoreXYU yet
  • Moving the X motor – or U motor as in CoreXYU context – off the X beam and route a much longer belt and place the motor stationary like the motors A & B of CoreXY
  • Ooze prevention (same issue as with Ashtar D IDEX)

As I progress I will update this blog-post, and summarize also the developments in the Ashtar C project page.

References

  • CoreXYU: Dual Head for CoreXY, another more complex approach where 3rd motor is also stationary

That’s it.

3D Printing: Ashtar D IDEX (Independent Dual Extrusion)

Status: just a draft

Updates:

  • 2021/01/14: starting the draft, very experimental

Introduction

After just few hours working on IDEX option for Ashtar K and Ashtar M, I thought to try myself on doing IDEX on the very delicate Y carriage on Ashtar D – and after an hour roughly I realized, perhaps it is doable.

The main idea is to reuse the NEMA17 shaft as axis for the idler of the 2nd belt, and use 3mm diameter shaft with 5-10mm length as extension, and stabilize the extension in the idler itself likely the shaft seems long enough by itself – the most space saving option:

If possible, rotate entire X motor mount / carriage and mount it on the other X side.

Draft

I had to color the belts and V modules, as I otherwise get confused while fine-tuning the design within such narrow margins:

  • X1/E1 in green
  • X2/E2 in red

I just love symmetry!
I just love symmetry!

Gallery

Issues to Resolve

  • X motor-mount isn’t fully Y symmetric yet, it’s off by a few mm; needs some further fine-tuning until X2 motor-mount mounting holes align with V module, resolved
  • V module belt mount for X2 needs be adapted, as I can’t mirror it as that “back” mirrored is the “front” side where the printhead is mounted and occupied already, a new piece is required which mounts within the V module
    • dedicated piece ad_xcarriage_beltmount(idex=true) required
  • ooze prevention in rest position: some sort of metal sheet close by where the printhead’s nozzle can rest
  • mature Ashtar D design sufficiently beyond draft stage

As I progress I will update this blog-post, and update the Ashtar D project page as well.

That’s it.

3D Printer: Ashtar K IDEX (Independent Dual Extrusion)


Status
: just a draft

Updates:

  • 2021/01/19: improved 2nd X motor mount
  • 2021/01/15: removable/replaceable ooze prevention
  • 2021/01/14: Ashtar M (Moving Gantry – Draft) also with IDEX option now
  • 2021/01/13: ooze prevention at rest position added, mechanical conflict resolved
  • 2021/01/12: starting with a first draft, one mechanical conflict to be resolved

Introduction

I have been pondering on a dual independent X axis upgrade or option for a while, but the other designs of the Ashtar Series I wanted to do first (Ashtar D and Ashtar M) those matured by now (2021/01), so I decided to get back to IDEX upgrade for Ashtar K:

For now I like to keep single 2020 V slot alu extrusion for the X beam where the X carriage rides, and route the 2nd belt above for the 2nd X carriage – and this was a quick solution as earlier version of Ashtar K had the belt routed above the alu profile so I just reused the old pieces again.

“Above routed belt” option with its pieces are weaker and possibly need enforcement improved the strength, so it’s a fast start – just took me 2 hours – but needs definitely some fine-tuning. Alternatively the 2nd belt could be routed at the back of the X carriages, but fastening the 2nd X motor would be challenging.

For now I use the same code base of Ashtar K and introduce IDEX = true flag, and enhance a few existing pieces in parts.scad and optionally add those new pieces when rendering printer-ak.scad.

As I progress with this option or upgrade I update this blog-post.

Draft

Issues to Resolve

  • X carriage #1 belt mount conflicts mechanical with belt 2: redesign xcarriage_beltmount_2020 piece, make it shorted in Z or fasten it inside V module: resolved, shifted 2nd belt a bit Y off, and shorten xcarriage_beltmount_2020(idex=true) by 2mm.
  • “Above routed belt” pieces are weaker: enforcement required, resolved: piece strengthened (2021/01/19):
    • xcarriage_short_hmount_motor_2020 which is the base piece which routes the belt within the 2020, with idex=true option provides idler holder on top
    • X motor #2 is mounted on a x-mirrored version of xcarriage_hmount_motor(20,"left",idex=true) but definitely needs reinforcement, added ooze prevention in case of idex set
  • Nozzle drip prevention:
    • using a piece of sheet metal which the nozzle moves over when in rest position left or right, first attempt done (see below)
    • and/or use purge box with brush to clean nozzle after and before use
    • make extending “nose” detachable/replaceable as it’s expected to break or overheat otherwise entire X motors mount needs replacement, resolved
      • xcarriage_nose-idex-left and xcarriage_nose-idex-right with 10mm wide sheet metal insert
    • how dealing with long resting hot nozzle?
      • drop temperature by 5-10C in rest position, and heat up when in use again
      • heat creep possible weakening extending printed nose – heat insulation required attaching sheet metal

Gallery

Ashtar M IDEX

And since Ashtar M (Prusa i3 Moving Gantry – Draft) shares much of the Ashtar K design it took me a few mins to add the IDEX upgrade option as well:

References