Tag Archives: IDEX

3D Printer: Multi Gantry Printer

by Rene K. Mueller · published December 9, 2024 Technology IDEX, IMEX, Multi Gantry, Parallel Printing

State: brain storming, early drafts

Y-XZ Gantries: Ashtar M MG-MIEX (Multi Gantry & Multiple Independent Extruders) [early draft]

Updates:

2022/12/22: adding Ashtar D (Classic XY) MG3 IDEX, comparing Y-XZ vs XY gantries in regards of inertia and slicing approaches thereof
2024/12/20: early idea to add tool changer as well
2024/12/16: adding more details with multiple extruders on same X gantry
2024/12/06: early ideas about single layer segmenting
2024/12/05: starting write-up

Introduction

While working on theoretical side of parallel 3D printing, I used the example of multi-gantry or Multi Gantry (MG) setup where a single bed is shared in Y – here a few rough sketches using Y-XZ gantries:

Multi Gantry with same order, Common Y rails

Y-XZ Gantry Approach

When having moving gantry implementing Y + XZ motion, there are several challenges, such as the Y- and the XZ motion system and making the thickness of each gantry as thin as possible to have as little “dead” or “unusable” space as it adds up and also limits the printable XY space.

Y motion system

We can share a single rail where each gantry rides hence Common Y rails, then they can’t change the order, in that case the belt routing becomes the main issue of concern – whereas when each gantry has its own rail hence Dedicated Y rails, and each gantry has a distinct height they can change the order (lift Z to the top and move over the lower one – hence each gantry has a different Z height, but with the filament and cabling the entanglement needs to be closely observed).

Single Rail, Multiple or Common Gantries

XZ motion system

We require to have two positioning axes to integrate here, the X and Z:

two independent motion systems (X axis = 1 motor, Z axis = 1 motor)
Core XZ system also using two motors, but having XZ motion combined

Jon Schone’s (ProperPrinting) 2 Gantry System: X & Z axes with each their own motor, sharing a single Y rail

Jon’s approach is clever to use CoreXZ and position both X/Z motors near the bed, so they don’t swing higher in Z, and only have the E motors ride on the X beam, yet, his setup is a single printhead on the X-beam.

XY Gantry Approach: Less Inertia

Classic XY (non-CoreXY) where X and Y motion is separated – like the Ashtar D – the moving gantry only has a X beam, where printhead and X motor resides – whereas with CoreXY only the printhead resides on the X beam, and XY motors are stationary/non-moving. As we separate in Y, we can use this Classic XY setup to add also multiple gantries, something like this:

Ashtar D MG3 IDEX [draft: Y motion not yet separated]

Comparison

Gantry KInematics	Moving Motors per GANTRY	Moving Motors in MG3 IDEX per Gantry	independeNt AXES per Gantry
Y-XZ	nX, Y, Z, nE	6 (2+1+1+2)	YZ
XY	nX, nE	4 (2 + 2)	Y

n-amount of printheads (IDEX: n=2) per gantry

The Y-XZ gantry setup has more moving parts, especially the heavier stepper motors, whereas XY gantry, as its name indicates, has the Z kinematics in common for all gantries and therefore only X motors moving – plus printhead (E) motors for both options.

So, if we aim to reduce the inertia like heavier stepper motors, we also lose that independence in the kinematics: with Classic XY gantries they all share the same Z height.

Slicing for Multi Gantry System

As I realized earlier, it makes no sense to statically segment Y-space for each gantry (e.g. Y-size/n) although it would make coding easier, but seamless printing would be impossible – in reality, we need slightly overlapping spaces to achieve zero space seams where the gantries print for the same piece, so we naturally choose flexible non-overlapping operations.

Layer Segmenting

Obviously one of the simple optimization is when we are looking at a single layer, and segment it area-wise to n-amount of gantries. For sake of consistency, a wall is assigned to a single gantry to have a seamless wall/perimeter.

Y Segmenting Single Layer for 4 gantries & nozzles (red, green, blue & yellow)

Infill areas are Y segmented
- each area (e.g. A1-A4) is the same to distribute work equally
Walls/perimeters are assigned to a single gantry
- if walls intersect each other in Y, those are printed sequentially not in parallel to avoid Y collision

The layer segmenting approach makes it rather easy so all nozzles have the same Z, thereby segmenting print jobs becomes easy as well.

Mixing Multi Gantry (MG) with IMEX (IDEX & ITEX etc)

We can also mix Multi Gantry (MG) with IDEX (Dual) or ITEX (Triple), or in general Independent Multi Extruders (IMEX), something like this:

Y-XZ Multi Gantry with IDEX: Independent Dual Extruders
per single XZ gantry

Layer Segmenting of Multi Gantry (4: red, green, blue, yellow) with IDEX (2) per Gantry

And like-wise segmenting layer areas in Y as before, and additionally segment in X for each printhead on Independent Multi Extruders (IMEX), in this example it’s IDEX (Dual).

As IMEX looks like scaling print parallelism further, one has to be aware of the spatial overhead for each printhead, e.g. a single printhead occupy ~40mm width in X, and similar in Y.

IDEX-MG3: Ashtar M vs Ashtar D

Early draft with more details based on Ashtar M (Y-XZ gantry), extended to MG, with Common Y rails with IDEX; and for comparison Ashtar D (XY gantry) with MG and IDEX:

Ashtar M MG3-MIEX2 [draft: Y motion system missing]

Challenges

1a) When doing a Y-XZ gantry IMEX2-MG3 (2 extruders/IDEX on each 3 gantry):
- X: 2*3 motors = 6 motors
- Y: 3 motors
- Z: 3 motors
- E: 2*3 = 6 motors
  we end up 6+3+3+6 = 18 motors to coordinate & control.
1b) for XY gantry approach:
- X: 2*3 = 6 motors
- Y: 3 motors
- Z: 1 motor (or more, but all synchronous)
- E: 2*3 = 6 motors
  we end up with 6+3+1+6 = 16 motors to coordinate & control.
2) Slim design of the gantry to reduce dead-space in Y.
3) Slim printhead design to reduce dead-space in X.
4) Slicer requires to coordinate 6 printheads (e.g. T0-T5) in non-colliding and efficient way.

Solutions

Slicer

A dedicated slicer is required which segments each layer into printable areas A₁ to A_n whereas n is the amount of gantries, and those areas might be further segmented by m-amount of printheads on the same gantry, so they share the same Y position but can have distinct X position but not switch order or collide.

As proposed above, a single printhead of a gantry is then assigned to print within the same Y-segment the walls/perimeters to have a clean wall, hence, the infills are distributed among all the printheads.

For segmenting entire sub-volume and not just layers, the Y-XZ would allow distinct Z, e.g. one gantry printing higher and another lower – the XY gantries share the same Z, therefore there only the layer segmenting is possible.

Firmware & Controller

The controller with its firmware we have a few options:

Duet3D/RRF: Multiple motion systems
- G-code Features
  - M400: wait for current moves to finish (when using T<n> with G1s together, applies to X, Y, Z, and also E)
  - M596 P<n> selects motion queue, prior each G0 or G1
  - M597: collision avoidance (at firmware level)
  - M598: sync up multiple motions (faster waits for the slower)
Klipper
Marlin
- one controller per gantry, orchestrating/sync between controller needed, hence a meta controller required (SBC)
  - using M400 to sync each controller by meta controller
- simple setup, reliable

To keep this in mind, the Y-XZ approach allows distinct Z for each gantry, whereas the XY approach all Z of the gantries are the same.

Adding Tool Changer (TC)

In order to support a tool changer, the printheads need to reach a common position in order to deposit and pick up tools. In case of a single/common Y-rail setup this seems at first sight challenging, only a dedicated tool change per gantry, at a particular a YZ position for example. The multi/dedicated Y-rail setup allows any gantry to reach a common region in YZ, and so any printhead could deposit and pickup a tool from the common toolset.

MG MIEX Gantry Style	Toolset position
Y-XZ Common Y rails	ends of Y rail, unique Z positions per gantry
Y-XZ Dedicated Y rails	ends of Y rail, common or unique Z positions
XY	first & last gantry at ends of Y rail, Z fixed

XY gantry setup still can have a tool changer but only the most front gantry, and the most farthest gantry in regards of Y, the gantries in between – if more than total of 2 gantries used – cannot reach a toolset; unless the toolset itself moves close enough to hand over tools.

Commercial Collaboration

Currently I work on a MVP implementing the actual details (software & hardware), if you are interested in a commercial collaboration, contact me to discuss opportunities.

References

Parallel 3D Printing / Additive Manufacturing – Part 1
Jon Schone’s Multi Gantry Setup (YouTube)
Ashtar M (Y-XZ Gantry)
Ashtar D (XY Gantry)

Parallel 3D Printing / Additive Manufacturing – Part 1

by Rene K. Mueller · published December 9, 2024 Technology CM3P, Duplex3D, IDEX, IMEX, ITEX, MSLA, Parallel Printing, Rapid Liquid Printing, Xaar, Xolography

Updates:

2024/12/09: ready for publication
2024/12/04: completing first table on printheads & nozzles
2024/07/30: starting write up

Introduction

When depositing material through a nozzle, the variables to compose a workpiece depends on the amount of nozzles and their operational spaces – let’s lay out the different methods which gives us the foundation to tackle then parallel procedures in the next part in the series.

Printheads, Nozzles & Operational Space

	Printheads	Nozzles per Printhead	Nozzle Size [mm]	Layer Height [mm]	Material	Operational Space
Single nozzle FDM/FFF	1	1	0.1-1.0	0.1-0.6	Polymer (PLA, PETG, ABS)	100%
Dual nozzle FDM/FFF aka IDEX	2	1	0.1-1.0	0.1-0.6	Polymer (PLA, PETG, ABS)	2x 50%; horizontally separated
Duplex F2	2	1	0.1-1.0	0.1-0.6	Polymer (PLA, PETG, ABS)	2x 50%; vertical separated
CM3P Dual Conical	2	1	0.1-1.0	0.1-0.6	Polymer (PLA, PETG, ABS)	2x 50% of negative cone
Resin SLA (UV Laser)	1	1	0.150	0.050-0.150	Resins	100%
Resin MSLA (UV & LCD)	1	50M-100M	0.020-0.040	0.050-0.150	Resins	100%
Quantica NovoJet	1	96	0.050		Resins	100%
Stratasys J55 PolyJet	1	192^*)	0.2^*)	0.18	Resins	100%
Selective Laser Sintering/Melting	1+	1	0.1	0.05-0.10	Polymer or Metal Powder	100%

Stratasys J55: nozzles & nozzle size based on J850 specs, J55 details specs seem not publicized (2024/12)

Print Base

A print base is where the nozzle can extrude on. For the first layer, there is the print bed, after the first layer the workpiece or support structure can be build upon. One can alternatively use a stabilizing medium like silicon and extrude in such liquid medium which operates as bed or foundation like Rapid Liquid Printing (RLP) does:

The extruded material just has to stay where it was put, either a solid bed or a medium which prevents it to float out of position, or as traditionally printed on a print bed or base, very similar does Xolography where the solidified resin stays put as well.

Massive Parallel Nozzles Printhead

Resin printing with a printhead may have hundreds or even thousands of nozzles, yet, they share the same operational space, but due the parallel setup the print speed multiplies direct with the amount of parallel nozzles on the same printhead.

Xaar 128 printhead printing high viscous material

Massive Parallel Nozzles: MSLA

As mentioned above, we can also view Masked Stereolithography (MSLA) resin printing as a massive parallel nozzle setup, where each pixel is either an active or inactive nozzle depositing a voxel.

Separated vs Shared Operational Space

Disclosure: I have been contracted to work on the Duplex F2 software stack (2022-2024).

Let’s take a look at the Duplex F2 printer where space is separated vertically, or the CM3P dual conical printer where the cone space is separated horizontally, or the Multi Gantry 3D printer by Proper Printing (Jon Schone). We have two printheads which never collide due their separated operational space, the firmware is simple and path planning is simple, both heads pretty much can operate independently.

When using more than two printheads it is beneficial to share the operational space, yet assume 6 or 8 printheads, each printhead needs rods to keep the printhead and position and orient the nozzle(s), so overlapping operational space requires extreme well planned tool paths avoiding any collision of the printheads.

Regular Operation Space Separation

We can segment or separate the space evenly or according the reach of the printheads, and each separated space can be printed without colliding. Yet, in reality the printheads mounts limit that operational space into slightly smaller spaces, but ideally:

n_volumes = volume_total / volume_printhead

If the individual printhead volumes aren’t regular, then we end up with arbitrary amount of printheads to cover a given print volume:

volume_total = sum( volume_1..n )

In reality, we require (slightly) overlapping operation to get seamless operation, so the “regular operation space separation” is only theoretically, but not practically.

Overlapping Operational Spaces

When the printheads can reach each other operational space, they become overlapping and controlling tool path generation needs to take care no collision is occurring (same place at the same time).

The Static Non-Overlapping Operation has static defined operational spaces where the operators can function – it’s quite obvious such solution is impractical, as in real life there would be space which cannot be reached, a kind of blind seam not reachable by either operator.

The Flexible Non-Overlapping Operation is flexible defined operational spaces, in the illustration above those spaces are co-dependent.

The Static Overlapping Operation is when those operational spaces are overlapping, yet, prefixed or static operational spaces.

The Flexible Overlapping Operation is flexible operational spaces, yet due the nature of the setup these operators cannot occupy the same space at the same time which would result in physical collisions.

Now, the last part of the last sentence may sound obvious to even mention, but bear in mind you can have two projectors shining light into a resin bath, and expose and solidify a 3D model, then these two lights acting as operators indeed occupy the same space at the same time as part of their function. So, the operators functioning with light can occupy the same space at the same time, whereas solid operators, such as robotic arms, cannot.

Print Speed in Parallel Setups

total print speed [mm³/s] = n_printheads * n_nozzles * v_extrusion [mm³/s] * parallel_factor

whereas parallel_factor is 1.0 if printheads can print parallel, or is less if the operational space is overlapping and preventing printheads to operate parallel thereby.

~ * ~

“Parallel 3D Printing / Additive Manufacturing” Part 2 follows later (will be linked when published)

References

3D Printing: Ashtar Series Printhead Options 2021/02

by Rene K. Mueller · published February 10, 2021 Technology IDEX, MSE, PAX, RTN

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).

Independent Dual Extrusion (IDEX) with ooze shields in resting position
Multiple Switching Extrusion (MSE), Rotary Y(2) or Z(2-4), with ooze shields
Rotating Tilted Nozzle (RTN), 4 Axis printing
Penta Axis (PAX), 5 Axis printing

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)

by Rene K. Mueller · published January 15, 2021 Technology Ashtar 3D Printer Series, Dual Extrusion, IDEX, OpenSCAD

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

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
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)

by Rene K. Mueller · published January 14, 2021 Technology Ashtar C, Ashtar C 3D Printer, CoreXY, CoreXYU, IDEX, OpenSCAD

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

The A/B belts route around the new X motor mount (borrowed from Ashtar D design)

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)

by Rene K. Mueller · published January 14, 2021 Technology Ashtar D, Ashtar D 3D Printer, IDEX, OpenSCAD

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:

*Reusing NEMA 17 shaft as axis for idler*

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)

by Rene K. Mueller · published January 12, 2021 Technology Ashtar K, Ashtar K 3D Printer, IDEX, OpenSCAD

Status: verified design

Updates:

2021/07/30: design printed and mounted
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.

*2nd belt slight Y offset so X belt mount #1 doesn’t touch belt #2*

“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 5-10°C in rest position, and heat up when in use again
  - heat creep possible weakening extending printed nose – heat insulation required attaching sheet metal

Inside and Above 2020 belt routed X motor mount, w/ removable nose with ooze prevention

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

BCN3D Technology IDEX, some background info on IDEX
EnderIDEX Dual X-Axis Kit, simple upgrade for Ender 3, also with above routed belt
Rat Rig V-Cast IDEX, alu extrusion-based prefab kit