3D Printing: 3D Printer Ashtar C: CoreXY Belt Routing

After some delay of parts, I finally was able to finalize the belt routing and configure the firmware for Ashtar C #1:

Belt Routing

belt-routing
CoreXY belt routing of Ashtar C

Early on I decided to separate belts of motors A and B in the Z axis, so they would not cross as such, and also hoped one axis of the carriage holding the X beam would allow some idlers to redirect the belts – to save space and keep frame dimension and build (or printable space) dimension close.

The Bowden tube and the wires of the hotend are preliminary arranged:

20190101_170842

Firmware

To configure the Marlin firmware turned out not that simple, as CoreXY has its own interdependencies of A & B motors: first X axis was reversed, whereas Y axis worked correctly, the INVERT_X_DIR setting on Configuration.h of Marlin did not help, it reversed the stepper motor direction, but not the actual X axis direction. After many attempts to use COREYX instead of COREXY I ended up

  • swap cables of A & B stepper motors
  • keep #define COREXY
  • #define INVERT_X_DIR = true and #define INVERT_Y_DIR = true

and X and Y direction worked correctly.

Preflight (no extrusion, just X & Y axis movement testing):

The stepper drivers still need some tuning, as I saw or rather heard a few missed steps at fast movement.

X & Y Endstops

The preliminary positions of the endstop are:

  • X endstop resides on the X beam left-hand side (USE_XMIN_PLUG)
  • Y endstop resides on the right-hand backside, (USE_YMAX_PLUG and HOME_DIR_Y 1)

Z Axis

I postponed the actual details of the Z axis, as my main concern of the design was to have a good CoreXY setup and then see how I would achieve the Z axis.

In order to use 625ZZ bearings I started to use them as idlers directly (after cleaning the grease off their surfaces) and also use them to increase contact surface when driving a closed belt which drives 3 or 4 threaded rods M6 x 500mm:

20190101_124138

Since the surface of the threaded rods is rough, I realized I need dedicated bearings to hold the rods at the bottom, otherwise the friction would wear on the mounts and increase its diameter. So, the Z axis isn’t finalized yet, but close.

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3D Printing: OpenSCAD Sketches #1

A few OpenSCAD sketches I’m currently work on, and later will publish as well:

Simple Compact Extruder

I used some aluminium MK8-based extruders but realized I required my own parametric extruder using 625ZZ bearing and I looked around and found Compact Bowden Extruder and adapted the overall design but coded it from scratch again:

sampleExtruder

It’s “right handed” by default, but filament can go both directions. The handle is pushed from “inward” with a spring, not so elegant, yet it saves space and filament does not have to go through the handle this way, which I prefer.

simple_compact_extruder() takes following parameters:

  • type:
    • "base": the base attached to the Nema 17 stepper motor
    • "handle": the push handle with the spring
    • "indicator": small indicate to put on the axis of the stepper motor
  • mount:
    • "none": (default) just attaches to Nema 17 stepper motor
    • "mount": simple mount (center)
    • "2020": extends flat (lower left version)
  • btd: Bowden tube diameter (default: 0mm), if 4mm is used, then Bowden tube can be inserted on both sides as guides for flexible filament close to the hobbed gear as shown below.

I use PC4-M6 push fit connector with PTFE tube 4mm OD / 2mm ID as guides, and began to use it right away on 3x printers for first tests:

Later I likely will integrate this design, once proven reliably working, with a Direct Drive Extruder design as well.

Dual E3D V6 Mount on 30mm X Carriage

My X carriage maintains 30mm horizontally distanced M3 mounts x 3 rows 20mm apart – the v_plate() (3 wheels) and h_plate() (4 wheels) as example:

and wanted a parametric dual E3D V6 hotend mount to print dual colors or materials for the Ashtar C #1:

Screenshot-from-2018-12-19-11-09-57-e1545214290923.png

dual_e3d_mount(): there are plenty parameters, but the most important ones:

  • type: "base" (left) or "clamp" for the clamp (right)
  • yoff: Y offset (when mounted the Z offset up), default: 0 (front one), 20 (middle and top)
  • nd: nozzle distance (Y-wise), default: 22 (most close possible), 35 (top one)

Example

First attempt to use it:

This design has been not yet printed but not yet in use, but soon as alternative to Chimera (dual hotends) or Cyclops (dual to one / mixing) hotends – two main issues:

  • part cooler needs to be narrow enough to sit aside of each other
  • part cooler should extend too much Y-wise too much, as the routing belt of the Ashtar C come into the way

The “Dual E3D V6 mount” was derived from preview designs as used for the Ashtar K:

The first one used two pairs of M3 screws, whereas the other more simple one requires in its base version just one pairs of M3 to mount the E3D V6 hotend and the mount itself to the X carriage; in case a slight Y offset is used, two pairs of M3 are required again.

 

I will update this post once the designs are published, after thorough testing in real life.

3D Printing: Ashtar K Printer: Electronics

Updates:

  • 2018/12/05: added MKS Gen L as alternative, for Ashtar C #1
  • 2018/11/25: added RAMPS 1.4 as alternative, for Ashtar K #2
  • 2018/08/28: initial version with CTC DIY I3 Kit

Sourcing Parts

The past months (2018/08) I began to use Aliexpress for ordering electronics – even prior going into 3d printing – and the past weeks my development cycles pretty much were depending on the 20-25 days delay until items arrived from China to Switzerland – and one develops some skill to anticipate what one would require as next – but some things only become known once you really tested parts thoroughly.

Anyway, the CTC DIY I3 Pro B (Geeetech DIY I3 Pro B clone) was still sold via Ebay (2018/08), at a price as low as EUR 80 incl. shipment, which is a true bargain.

Aliexpress (2018/08):

  • MKS Gen L mainboard (incl. drivers) with LCD (with dialer), 200×200 heatbed, end stops, cables: EUR 50
  • PSU 12V 240W: EUR 20
  • 5x Nema 17 45Nm stepper motors: EUR 35
  • Total: EUR 105 (without endstops and various cables to connect all together)

CTC DIY I3 Pro B Kit (2018/08):

  • Anet 1.0 mainboard, with 2 Lines LCD (4 buttons), 200×200 heatbed, end stop, cables, PSU 12V 240W, 5x Nema 17 45Nm stepper motors
  • Total EUR 80 (all cables included)

So I decided to get another CTC DIY to source the parts in one go, and likely upgrade later with individually sourced parts to have dual extruder motors (two color or material printing).

In 2018/11, when I started to build a second Ashtar K 38x30x33 #2 I checked Ebay with following prices:

Ebay (2018/11):

  • MKS Gen L: EUR 28
    • MKS Gen L mainboard: EUR 16
    • 5x A4988 drivers: EUR 6
    • RepRap Full Graphic LCD: EUR 11
  • RAMPS 1.4 with Arduino Mega, 5x A4988 drivers, Full Graphic LCD: EUR 28
  • 5x Nema 17 40-50Nm stepper motors with cables: EUR 26-35
  • PSU 12V 240W: EUR 20
  • Total EUR 74 – 83 (missing: endstops and various cables to connect all)

Burning Bootloader on Anet 1.0 Board

For now I use an “Anet V1.0” controller board (Atmel 1284P), as part of a “CTC DIY Kit” as mentioned, and it required some preparation:

  1. using Arduino Uno R3 (clone) and upload “Arduino ISP”
  2. attach Anet V1.0 board (detach all other cables) to Uno R3 bootloader-burning
  3. run “Burning Bootloader” with “Arduino as ISP” as writer
  4. downloading Marlin and edit main Configuration.h (not yet published) to match my specifications
  5. upload new firmware Marlin to “Anet V1.0” via USB upload

RAMPS 1.4 with RepRap Discount Full Graphic LCD

RAMPS 1.4 Schematic + PinoutFor the 2nd Ashtar K 3D Printer I used (2018/11) RAMPS 1.4 combo with Arduino Mega, which was easy to upload new firmware. RAMPS 1.4 is Open Hardware, the entire schematic and pinout is available or download diagram with pinout as one image (same as on the side) – but it’s also a hassle to plug correctly as the board plug descriptions are tiny or covered by parts so one has to consult documentation in details, and there many ways to do wrong (reverse or misalign plugs) and most of these can and do damage either the RAMPS 1.4 shield and/or the Arduino Mega beneath, including misaligning the endstops.

Endstops

  • using C and NC on the endstop and the board (power connector on the left) above the 2x Z motor connectors: XMIN, XMAX, YMIN, XMAX, ZMIN, XMAX, each:
    • top (Signal) -> C
    • middle (Ground) -> NC
    • bottom (5V) -> empty

while waiting for proper endstops to arrive, I salvaged microswitches from a faulty computer mouse to work as endstops

Marlin Firmware Changes

  • Configuration.h:
    • #define MOTHERBOARD BOARD_RAMPS_14_EFB
    • #define REPRAP_DISCOUNT_FULL_GRAPHIC_SMART_CONTROLLER
  • Configuration_adv.h:
    • commented out #define MENU_HOLLOW_FRAME so selected item is inversed
  • pin_RAMPS.h:
    • see #if ENABLED(REPRAP_DISCOUNT_SMART_CONTROLLER) and the following #if ENABLED(CR10_STOCKDISPLAY) after the #else check BTN_EN1 and BTN_EN2 and reverse the pins (31 <-> 33) so clockwise dialing goes down (and not up).

MKS Gen L

20181205_135417

  • Configuration.h:
    • #define MOTHERBOARD BOARD_MKS_GEN_L

As far I can tell the end-stops take DuPont females and pin order is the same as with RAMPS 1.4, but orientation is crucial – otherwise the GND and VCC is shorted.

The plan is to use this board for Ashtar C #1.

 

I update this post as I go along.

3D Printing: Print3r 0.1.6 Release

Following major changes of 0.0.9 to 0.1.6 regarding Print3r (command line tool for 3d printing):

Multiple Slicers Support

Now print3r natively supports 4 different Open Source slicers:

  • Slic3r (slic3r)
  • Slic3r PE (Prusa Edition) (slic3r-pe)
  • CuraEngine Legacy (15.04) (cura-legacy)
  • CuraEngine (3.5.x) (cura)

which can be set with --slicer=<slicer> on the command line.

Slicer Independent Settings

Starting with 0.1.0 print3r provides a slicer-independent layer with a growing list of settings:

  • temperature
  • nozzle-diameter
  • filament-diameter
  • bed-temperature
  • etc.

Full list of settings you find at Print3r Github Wiki.

Slicer Specific Settings

Yet, if you must, you can still use slicer-specific settings to fine-tune settings according your print needs and printer capabilities.

Macros (other Profiles)

For often used settings like print quality, or filament settings, you can gather those settings and reference them in the command line like:

% print3r @filament/prusament @thin @hollow cube.scad

Quality Presets:

  • @coarse
  • @medium
  • @fine

Infill/Wall/Perimeter Presets:

  • @heavy
  • @light
  • @feather

OpenSCAD Integration

print3r already supported to print or slice .scad files,

% print3r print cube.scad

and now since 0.1.6 also following command line code integration is possible:

% print3r --scad print "cube(20)"
% print3r --scadlib=washer.scad --scad print "washer(5)"
% print3r --scadlib=parts.scad --scad "c_2020()" "edge_idler()"

Arbitrary Baudrate

Since 0.1.0 also arbitrary baudrate like 250000 (default of Marlin) is supported (Linux only, other platforms not yet), aside the common 115200.

Preview

As external Gcode viewer for preview command yagv is used, a very basic viewer – at a later time it might be replaced.

% print3r preview cube.scad

which converts, slices and preview the Gcode.

Extensive Documentation

Since the functionality of print3r is growing steadily, the requirement for proper documenation demanded its own Print3r Wiki where you find up-to-date information.

Download

https://github.com/Spiritdude/Print3r

3D Printing: Networked Printing with Print3r

Introduction

The moment you deal with more than one single 3d printer, but multiples – you want to access those with a single host: creating a cloud 3d printing facility.

After a few minutes researching the net for USB to network bridge, I realized the overhead to print via network is possible without Octoprint or some other solution, but simple ser2net and socat alone, thanks to this Github Issue by Marco E explaining his steps, so I reiterate his solution with some changes:

  • create USB to network bridge with ser2net per printer
  • create network to virtual serial per printer with socat on the host

Printers

Each printer you like to network has to have:

  • Linux OS (like Debian, Ubuntu or alike), e.g. Raspberry Pi or OrangePi or any kind of lowcost ARM-based board
  • USB connectivity where the 3d printer is wired
  • Wi-Fi (wireless) or Ethernet (wired) connectivity

Install

As next install ser2net serial to tcp bridge per printer:

% sudo apt install ser2net

Create a file named client.cfg, you may have to change the baudrate and/or the USB device:

3380:raw:600:/dev/ttyUSB0:115200 8DATABITS NONE 1STOPBIT -XONXOFF LOCAL -RTSCTS

Start ser2net on each printer:

% ser2net -c client.cfg

Host

As next prepare the host, where all the printers will be controlled from:

  • UNIX OS like Linux (Debian, Ubuntu, *BSD, macOS should work too)
  • Wi-Fi (wireless) or Ethernet (wired) connectivity
  • Print3r

Install

First make sure you have socat installed:

% sudo apt install socat

For each printer you are creating network back to (virtual) serial port – replace 192.168.0.16 with the IP of your printer(s):

% socat -d -d pty,raw,echo=0,b115200 tcp:192.168.0.16:3380
2018/10/07 10:08:16 socat[31821] N PTY is /dev/pts/29
2018/10/07 10:08:16 socat[31821] N opening connection to AF=2 192.168.0.16:3380
...

The first line reports the new virtual serial port, e.g. /dev/pts/29  or enforce a link of the new device:

% socat pty,raw,echo=0,b115200,link=/tmp/my-printer tcp:192.168.0.16:3380

you can reference /dev/pts/... or the link you defined with Print3r then:

% print3r --device=/tmp/my-printer --scale=2 --random-placement --fill-density=0 --perimeters=1 print xyzHollowCalibrationCube.scad
== Print3r 0.0.8 == https://github.com/Spiritdude/Print3r
print3r: conf: device /tmp/my-printer, bed 380x300mm, nozzle/d 0.5mm, layer/h 0.4mm, filament/d 1.75mm
print3r: scad to stl: done.
print3r: slice part to gcode: position 272,118, filament usage 2.38m, done.
print3r: print: 0h 03m elapsed, eta 0h 16m, 18.9% complete, z=0.60mm, layer #2, filament 0.42m

So you end up with something like this:

3d-printer-networking

So, that’s it, with ser2net on the printers, and socat on the host you have a rather simple and straight-forward cloud 3d printing facility.

I likely will extend Print3r to support networked printing with a simple all-in-one setup.

Update:

  • 2018/11/01: there is a slight drawback using ser2net: only takes common baudrates, but doesn’t support 250,000 which is the default baudrate for Marlin, 115,200 does work though. So, in case you plan to use ser2net reflash the firmware to use 115200 as baudrate.

3D Printing: Print3r (CLI)

example

Command Line Interface (CLI)

Although 3d parts need to be seen and visually so much is communicated, but Cura’s user interface feels conceptually skewed (“Prepare” vs “Monitor” tab) – and with the time I thought I want an ordinary command line interface to print parts quickly, easily multiply and random placement so the bed surface is more evenly used and not just the center – I have grown tired to move parts on the virtual bed.

So, I wrote print3r, a command line interface which utilizes Slic3r as backend. Its main features (Version 0.0.6):

  • command line interface, no GUI
  • UNIX platform (Linux, *BSD, macOS should work too)
  • print .scad (OpenSCAD), .stl, .obj, .amf and .3mf directly
    • it converts and slices depending on file format as needed
    • takes Slic3r command line arguments
    • multiply part
    • random placement
    • scale, rotate, translate or mirror (.scad or .stl only for now)
  • slice .stl, .obj, .amf and .3mf to .gcode
  • print gcode files
  • send gcode lines direct from command line arguments
  • send interactively gcode commands from the console
  • render .scad, .stl and .gcode to PNG for documentation purposes

Example

% print3r --printer=ashtar-k-30x30.ini --fill-density=0 --random-placement print Parts/cube.scad
== Print3r 0.0.3 == https://github.com/Spiritdude/Print3r
print3r: conf: device /dev/ttyUSB0, bed 300x300mm, nozzle/d 0.5mm, layer/h 0.4mm, filament/d 1.75mm
print3r: scad to stl: done.
print3r: slice parts to gcode: filament usage 79.67cm, done.
print3r: print: printing 0h 09m elapsed, eta 0h 00m, 100% complete (38494 of 38494), z=19.80mm, layer #50, filament 79.67cm

More information on the printer display: progress [%], eta and layer#:

20181005_170351

Result:

20180927_152946

and if you replace ‘print‘ with ‘render‘, like

print3r [...] --output=sample.png render Parts/cube.scad

cube-example

Download

Github.com: Spiritdude/Print3r

3D Printing: Ashtar K Printer: Printing #2

Upgrading X Motor Mount

Printing new X motor mount on CTC DIY I3, and replacing it on the new Ashtar K: CTC DIY I3 prints quite reliably – there is nothing to clean up – the piece I attach it right away:

Ashtar K lacked a proper print surface (before I received the black sticker surface), otherwise I would have printed the piece on itself.

Black Sticker as Bed Surface

The 400×400 black sticker arrived, and I cut it into 400x300mm and put it on the mirror – which worked well, and so far I can tell the surface is very very flat, much better than on alu heat bed.

bed-corner-detailCurrent bed setup (top to bottom):

  • 400x300mm black sticker (“frosted sticker”), apprx. 0.6mm thick
  • 400x300mm 3mm thick mirror
  • 210x210mm 12V alu heat bed
  • various cork patches under heat bed
  • 10mm light black foam material
  • 420x320mm 6mm plywood (white painted) as Y carriage
    • 4x printed corner mounts holding 3.7mm thick sticker/mirror combo
    • M3 x 35
    • M3 washer (below printed corner mount)
    • Spring (20mm long, ~10mm OD, 1mm wire)
    • M3 washer
    • printed knob (below plywood), 30mm OD, 8mm thick, M3 nut inserted

Now that I have a good print surface I finally printed pieces for itself.

Mounting the 400×300 bed (OSB 6mm, white painted) with 200×200 heat bed (which I hardly use, as I started to print on cold bed):

I currently use the white PU steel enhanced GT2 belts, and it produces hard edges, some ghosting, but more precise prints than the black rubber GT2 belts which just stretch too much – I have to research this more closely – about the type of reinforcement and the use with more heavy beds (Y carriage).

Just for the record regarding Y carriage (2018/09):

420×320 carriage:

  • 4mm plywood flexes, but has been quite flat – not recommended
  • 6mm plywood hardly flexes, but has been hard to buy truly flat – and so far my attempt to flatten it did not work well – not recommend unless it’s flat
  • 6mm OSB quite flat, does not flex much (3 or 4 sliders) – recommended

320×320 carriage (for 300×300 bed):

  • 4mm plywood works (3 sliders, 4 sliders recommended)
  • 6mm plywood works (3 sliders, 4 sliders possible if plywood is truly flat <0.2mm difference)
  • 6mm OSB quite flat, doesn’t flex (not yet tested)

Just to explain my thought or decision process for my setup:

  • the mirror should not be bend (of course)
  • the support structure should not be the edge mounts, but the foam in between
  • the carriage can be bent, but not flex
  • revelation: already bent means the springs with screws might extend the bent further with a flexing carriage, and not counter act – as the mirror should stay flat

so, even though the springs/screws and edge mount can adjust, the carriage should be fairly flat, and not flex at all – this way the edge mounts holding the glass/mirror only stabilize position. Main force to hold the glass/mirror, for my setup, is the foam in between. So, there is no “spring” induced vibration back/forth introduced, but the foam neutralizes such vibrations – and hardly adds weight/inertia.

Sliders & Belt Mount Positions

Top view with see-through (best mark “0,0” on both sides to keep reference).

bed-layouts

400×300 vs 300×300 Bed

Originally I focused on 300×300 bed at least, with some tweaking and narrow X carriage I was able to reach 380×300 printable bed, so it was suitable to use 400×300 plate as well.

It takes me about 5min to mount new bed, downgrade from 400×300 to 300×300:

Changes needed:

  • move Y endstop switch from left to Y carriage extrusion to the right side
  • Y stopper mounted on the bed needs to placed accordingly

With 300×300 bed the 0,0 is now plenty outside of the bed, with 400×300 the 0,0 is near the printed bed mount.

Setting Offsets for 300×300 bed

With 300×300 bed the 0,0 is now +32mm to right and +25mm deeper, hence the Gcode M206 is set like this:

M206 X-32 Y-25

H Plate/Module as X Carriage

The 3 wheels module riding on the 2020 alu extrusion I named “V plate” due the shape, the 4 wheels module “H plate” providing more stability or rigidity for use as X axis carriage, when the nozzle runs over slightly unclean extrusion and tilts upside. For the X carriage I choose a narrow (48mm wide hole-to-hole) version:

It’s the first/early version, the adjustment screws (M3x10) are very or too close to the bed for my taste, next version will use M3x8 and give more spacing. I like to keep the hotend close to the X carriage so not to waste Z space.

Additionally I made a new hotend mount so it would use another mounting holes than belt mount:

But now it’s harder to reach the hotend mount holes due the part cooler – oh well.

After few days, I noticed one wheel stopped to turn, no longer touching the alu extrusion – I guess the carriage slowly balanced itself and triangulized, no longer use the 4th wheel. I re-tighten the 4th wheel gently so it would roll again.

Z Couplers: To Wobble or Not To Wobble

As I posted before, I suspect the Z couplers to be the main source for Z wobbles, as the threaded rods may look and are cheap but they are mostly straight – the wobble actually is caused, after close observation, from the misalignment which happens when you screw the metal couplers on, in particular if you attached the lead screw or threaded rod with uneven surface – the thightening screws may or may not attach cleanly – and thereby push the Z rods out of the center of the Z stepper motor – when the Z thread holding the X axis is fixed, the resulting wobble is worse at low Z heights; and if you fasten the Z rods at the top, the wobble gets even worse.

couple-excentric

A simple remedy I found is to use printed couplers, two pieces which are screwed together with 4x M3 screws and nuts, a bit of an overkill, and a bit time consuming to fasten: incrementally tighten each screw over and over until all are tight – but I think it’s worth it: the two halves attach evenly and the PLA or ABS or whatever you printed the couplers, is soft enough so the threads of the Z rods carve themselves evenly into the coupler, and self center themselves this way – result is better centric attachment of the Z rods, not perfect but acceptable and better than poorly manufactured metal couplers.

couple-excentric2

As mentioned before, I switched from M8 to M6 for the Z axis the M6 provides 1mm movement per full turn, and is more flexible to even out out-of-center wobbles, better than the stiffer M8 threaded rod. If using couplers at all, and likely introduce out-of-center mounting, rather use a more flexible lead-screw or threaded rod than a stiffer one.

3D Printing: Ashtar K Printer: Printing #1

It has been a few days (2018/09/04), since Ashtar K happen to be able to print, the heat bed still unfinished, some prints illustrated below are done with no leveling screws, the mirror just taped on the Y carriage – don’t laugh – later prints I had proper carriage and leveling screws included; a proper build surface I still wait for in the mail (400×400 black sticker to be cut in shape) – anyway, here some of the early prints:

40mm XYZ Calibration Cube

The original 20mm XYZ Calibration Cube is printed in 8 mins with 0.5mm nozzle at 0.4mm layer height, and so I thought, let’s print it 2x the size with 0.4mm layer height, merely 40 mins later this:

The quality is . . . impressive, this is just tuning a single day – mostly on the extrusion factor and print temperature – and this is what I hoped for: XYZ positioning almost flawless: there is slight ghosting on X axis (which could be resolved) shown on “Y”, and Y axis shown on the “X” which is fine, given the size of the bed and its weight and inertia this is OK.

I had to increase print temperature +20C from 200C to 220C for 80mm/s infill while printing with the 0.5mm nozzle, I otherwise would hear clicking from the extrusion stepper motor missing steps. I still use the classic E3D V6 (clone) heat block, not the Volcano heat block.

20mm Calibration Cube: Different Layer Heights

Printed with 0.5mm nozzle, left-to-right: 0.1mm, 0.2mm, 0.3mm and 0.4mm layer height, 60mm/s (80mm/s infill), 200C first layer, rest with 210C, pink glowing PLA by Sienoc.

20180831_070853

X Carriage: Sliders vs Wheels

While printing with slider carriage on the X axis, I noticed increased stuttering, and regardless if I thighten or loosen the grip, the stuttering remained, and slight horizontal tilt occured when changing direction on the X axis resulting in too narrow prints in X dimension.

20180827_093753
X carriage with white nylon wheels (23.mm OD / 7.3mm width)

So, I changed back to wheel-based carriage, first again 23/7.3 white nylon wheels (right photo), but when I printed “L” shape with 200mm length in X and Y and 1mm height in Z, I noticed slight Z sinus form as I saw before – while it rolled nicely, there was a wobble . . . and so I printed a new carriage which holds the black OpenRail Double V (clone) 24.4mm OD / 11mm width, and put it on the X carriage:

20180831_071941
X carriage with double V black wheels 24.4mm OD / 11mm width

A brief overview of the carriages riding on 2020 T slot (B-Type) alu extrusion:

carriages-selection

20180905_055421

Sliders: on the X axis it did not last, the stuttering was not avoidable; the issue is that the X carriage is one of the hardest axis of the Prusa i3 style geometry to handle: it isn’t just X directional rail, but also pressure on the Z with the weight of the print head, and running over overextruded filament – and it’s hard to pull the X carriage perfectly without the carriage have some vertical tilt as well – anyway, I still use the slider option on the Y carriage – and works fine so far.

White nylon 23/7.3mm wheel: rolls nicely, but gives wobble to the Z height when used on X carriage, apprx. 1mm, also doesn’t stay vertical upright, but tilts a bit with pressure – when the print head moves over overextruded print it doesn’t level it, but jumps over it. I currently use white nylon wheels on the Z carriage successfully.

Black double V delrin 24.4/11mm wheel

  • groove use: rolls very nicely, gives no wobble, and stays vertical. The next days and weeks will tell if the double V wheels do last on the T slot alu profiles – they are meant on proper V slot alu extrusions.
  • diagonal/edge use: rolls very nicely too, but surprisingly gives less tilt rigidity than groove use – the T slot 6 (B-Type) gives less surface at supposed 90deg edge, but is rather 85deg

Z Axis Linearity

As you may have read in the other post(s), I use M6 threaded rods, it’s flexible and rather aligns with the Z axis itself, whereas M8 is stiffer and misalignment – which by the way doesn’t come from the rod itself, but the mounting with the couplers – won’t impose on the X carriage – this is my own view and it happens to come true again with Ashtar K, after I changed my cheap CTC DIY I3 also to M6.

Now, the 1m long M6 threaded rod, enough for two Z axis each 500mm long, did just cost EUR 0.70, made in China but purchased locally in Germany, and the nylon wheel-based Z carriage happen to work perfectly so far – I expected some slight sinus wobble imposed by the nylon wheels as I encountered on the X carriage, but it seems when there is little force applied on the wheel the carriage works good enough.

Printing 330mm high 10mm diameter cylinder (with slider-based X carriage):

There was some slight extrusion inconsistencies, this is likely due the material, an broken vacuum seal of a newly purchased glowing pink PLA roll, actually, after watching the 2nd print closely, either GCode errors or USB transmission errors, as some segments of the circle (layer of a cylinder) is repeated for some unknown reason and so overextrusion occurs there (needs proper investigation)  – but the linearity is very good, and no Z wobble whatsoever.

Loopy Egg

60mm height “loopy egg”, printed with 0.5mm nozzle, 0.4mm layer height:

The “loopy egg” is a good benchmark for retraction settings, and stressing the extruder motor as the short segments making up the loops require a lot of push / pull on the filament. There was still some slight stringing, which I knew will happen, as the retraction is just set to 2mm at 35mm/s giving very good results. More prints will tell if I can stay with these retraction numbers.

Fighting Heat Creep

I currently use E3D V6 clones as hotends, one with 30mm “original” fan, and one with 40mm fan. And with the “original” smaller 30mm fan I experienced frequent clogging up within the hotend: some of the filament melted above the heat break and expanded and blocked any further extrusion – that happened now several times.

I tried to reduce the extrusion temperature but which caused decline of print quality. After trying to determine the root cause of the problem, I concluded that it was heat creep and insufficient cooling above the heat break, hence, the hotend fan, and I switched to 40mm fan – and the clogging disappeared, not quite yet . . . update follows.

20180831_071941
30mm Fan (front facing) with 5015 Fan Fang (top)
20180903_085124
40mm Fan (front facing) with 5015 Fan Fang (top)

Although both setups look very alike, I had to print out another fan fang which can contain 40mm fan.

Five Platonics

My favorite geometrical forms – aside the sphere – the sacred set:

Mirror as Bed

I’ve got 40cm x 30cm mirror which became my bed base, underneath with some tight springs some 6mm multilayered plywood, which was warped 2-3mm on the edge – but it didn’t matter (much). The mirror was the reference, and the Y carriage had to hold the mirror. That turned out to work very well: the mirror is truly flat, I leveled the bed once for tilting, after a week, I only had to tweak the Z endstop screw slightly, but I didn’t touch the screws mounting the mirrors to re-level the bed anymore.

So, using the mirror as bed worked well so far due the flatness – but the glass didn’t turn out to print good on it, the printed parts often detached before finishing the print, and ruin the print – so I used blue tape sheet as temporary solution until the black sticker arrives which I already use on the other 3d printer.

Reflection

As I designed Ashtar K with larger build volume, I choose 0.5mm nozzle at least, and the max 0.4mm layer really pays off in regards of print speed, while still maintain some details – I’m quite pleased so far.

3D Printing: Ashtar K: It’s Alive ;-)

Well, after merely 3 months (2018/06/06) when I started to code the first lines of OpenSCAD to develop a series of parametric Prusa i3-like designs, and few weeks ago decided to go with the “K” series with 2020 alu profiles: simple 11x 500mm beam T slot (B-Type) alu profiles – the 1st prototype happen to print the 20mm XYZ Calibration Cube as of 2018/08/27:

The bed is very temporarly fasten with tape, as I haven’t decided on the actual details of the bed mounting yet and leveling details – but I wanted to see how well the mechanics already works – and it performed quite well so far.

1st print came out mediocre, when I realized I had to tighten X and Y belts more, 2nd print came out much better; 0.5mm nozzle with 0.4mm layer height, merely printed in 8mins with 60mm/s print speed and 80mm/s 20% infill:

And just for the fun of it, 0.2mm layer height with 0.5mm nozzle, at 70mm/s:

Incredible quality: X and Y surface very good, some inconsistency at “X”, on the “Y” side some slight ghosting; but most surprising is the edges on the Z axis – I operate with a simple M6 threaded rod and M6 nut – that’s all – moving nylon wheel-based carriage up and down – sure, I require to print more tests, in particular larger prints to really see how well all axis print up to 300mm.

I had to use blue tape on the mirror otherwise PLA would not stick – eventually I will use the black sticker as I used for the CTC DIY printer which worked quite well.

Nylon Wheels vs Sliders

The past 2-3 weeks, while waiting the nylon wheels to arrive, I decided to check alternatives such as sliders with PTFE tubes – and this paid off: the nylon wheels 23.0mm OD with 7.3mm width sit quite nicely into the T slot (B-type) but when used in real life, like with X carriage, I had some sinus wobble in the vertical – apprx. 0.5mm to 1mm – way too much. So, I exchanged the wheel-based X carriage with the slider-based carriage, remounted the hotend with Bowden setup, and after 5mins the exchange was done:

Current setup:

  • X axis: slider-based carriage, holding on top and bottom side with 2 tightening screws
  • Y axis: simple sliders (just sitting on the groove)
  • Z axis: nylon wheel (23.0/7.3mm) based carriage

The next days and weeks I will review my options:

  • slider-based carriage with
    • 1 axis support or
    • 2 axis support
  • wheel-based carriage with
    • nylon wheels 23.0/7.3 and 23.0/7.0
    • double V wheels

both on T slot alu extrusion – I know ideally would be proper V slot alu extrusions, but I like to find out how good it works with the easily available T slot extrusions. Worst case is, I have to use on X and perhaps Z axis proper V slot alu extrusions, on the Y axis it seems the simple sliders (just a block) work fine.

0.5mm Nozzle

Since I deal with nearly 3x the bed surface compared to 200×200 I thought I have to use a bigger nozzle as well, as a bigger build volume would imply larger objects to be printed. The increase from 0.4mm to 0.5mm diameter also implies 1.5x or +50% more material being extruded and I still desire to print with 60mm/s average with 80mm/s infill – this means I have to test well the hotend performs with that speed and higher throughput of material.

Specifications

Current specifications of Ashtar K 3d printer:

  • 380 x 300 x 320 mm build volume (400 x 300 bed)
  • E3D V6 clone hotend
  • 0.5mm nozzle
  • Anet 1.0 controller board
  • 210 x 210mm 12V heatbed

TODO

  • bed mounting & leveling
  • 300×300 or 400×300 220V heatbed
  • proper print surface (likely black sticker 300×300 or 400×300)
  • improving cable management:
    • Y carriage and heatbed with proper cable chain
    • deciding on position of LCD display

3D Printing: Ashtar K Printer: Motor & Belts

Brief update of motors, belts, threaded rods and end stops mounted:

X Axis

I switched from slider based carriage to the nylon wheel (23.0mm OD, 7.3mm width) based carriage (X and Z axis), apprx. 120cm belt length.

 

Y Axis Belt

Apprx. 90cm belt length – with some considered cutting X + Y ~ 2m belt length.

This part was tricky – the parts are glued to bottom of the wooden carriage:

  1. mark the positions of the sliders (left: 65mm distance from top and bottom, left: center of top/bottom)
  2. glue 2x sliders on the left (where the Y motor is mounted)
  3. glue 1 slider on the right side
  4. put carriage on the rails, avoid any horizontal movement, push it slightly down (a slight snapping you sense from the sliders)
  5. let it rest (don’t touch or move it) for 30min – glue must dry
  6. move Y carriage gently forward & backward; if there is slight resistance then
    1. loosen all screws of the right 2020 beam so you can move it sideways
    2. then move carriage forward and backward and let the beam slightly find its new position
    3. when the carriage moves gently without resistance
    4. fasten the screws gently
    5. retest and if it’s still resitance, repeat procedure
    6. this is a bit tedious work, but worth it

This part is to do next (once I concluded those PTFE pipe chunk based sliders do their job well):

  1. drill holes and use Zip ties to fasten sliders
  2. glue Y carriage belt mount, let it dry
  3. mount GT2 belt to carriage belt mount
  4. fasten Y carriage belt mount with screws: drill holes from the bottom side

 

I will make some short videos of putting the carriage together and mounting it – it’s quite fast to attach and detach with those sliders (no screws to unfasten).

Z Axis

I extended the corner brackets so the Z stepper motors can be inserted, this weakens the part but saves quite a lot of space and hides the threaded rods nicely behind the 2020 Z beams. I might work on those brackets later to increase rigidity again.

Currently I use M6 threaded rods for the Z axis, one cycle gives 1mm height change.

X, Y, Z Motion & Homing

Flashing the Anet 1.0 board (which I currently use) with latest Marlin, this was required:

  • using Arduino Uno R3 (clone), installing Arduino ISP on it
  • cabling Uno R3 with Anet board (Uno powers Anet board with 5V, all stepper motors or power detached)
  • installing Bootloader (“Burning Bootloader”) with “Arduino as ISP” as writer
  • downloading latest Marlin, copying Anet Configuration.h and starting to change it

Finally, after hours fiddling around (bad install of Arduino failed to compile and/or upload anything to my Uno R3) the LCD display greeted with “Marlin 1.1.8” 🙂

Moving X, Y and Z axis briefly, 380 x 300 x 320 build volume with the current V carriage with 23mm OD, 7.3mm width nylon wheels – no extruder and no bed heating and leveling yet.