Getting started with the Raspberry Pi 3 OctoPrint Bundle

After upgrading to the low friction spool holder,
I just got myself the Raspberry Pi 3 OctoPrint Bundle from Watterott.
It shall be the center component of my Ultimate Filament sensor.

Since it doesn't come with any instructions, here is what you need to do:


Don't plug it in yet!
Insert the SD card into a regular computer and edit the file octopi-network.txt .

Then insert the 2 transparent elements into the 2 holes near the micro USB socket.
(Yes, there are 2 plugs for 4 holes and no instructions.)

Now insert the Raspberry Pi and then insert the SD card.
The contacts should face upwards.
(It is near impossible to the the cards out again.)

After switching it on, you can connect to it via http://octopi.local .


You can also access the raspberry via SSH
ssh pi@octopi.local
The default password is "raspberry.
The SD card is mounted as /boot
The OctoPrint config file is at "/home/pi/.octoprint/config.yaml"
You can restart the server via "sudo /etc/init.d/octoprint restart"

If your Wifi access point via
sudo sudo iwlist wlan0 scanning | grep ESSID
can't be seen by Linux, run
sudo raspi-config 
and select "5 internationalization options" -> "I4 select Wifi locale"
to enable the Raspberry to see all Wifi channels that are legal in your country.

The Raspian I got was very old. I had to provide Internet via Ethernet and do
sudo apt-get update
sudo apt-get dist-upgrade
then it was able to see Wifi networks on Channel 40 (5GHz) and 12+13 (2.4GHz).

GPIO fun 

While at the shell, you can have fun with the GPIO pins in Bash.
Sadly you can't set the pull-up resistors from the shell.
However my image came with WiringPi already installed.
It doesn't have a "--help" or a man page on the Pi itself, so here are the basics:
  • gpio readall
  • gpio mode (pin) in/out
  • gpio mode (pin) up/down/tri         (set pull up resistors)
  • gpio read (pin)
  • gpio write (pin) 0/1
  • gpio wfi (pin) rising/falling/both    (non-busy waiting for a state change)
  • (more)
  • (reading multiple gpios )
  • ...including timeout via read -t (seconds) || echo "timeout detected"  ...still in bash ;) 


Sorry, there is no hole for the Raspberry Pi camera. The best place to cut one is probably on the side (so you don't damage the cool logo), above the camera connector.

This longer cable (Reichelt) may be helpful.

Cura slicing

Luckily the Bundle comes with thje CuraEngine plugin preinstalled. So slicing it not much of a problem.You can imort your existing 15.x profiles (but not 2.1.1 profiles) in Settings->Plugins->CuraEngine->import profile.

BTW, there are "send to Octoprint" plugins for Cura on the desktop!

Ultimaker II setup

The Ultimaker series is not supported out of the box.

Settings->printer profile:

Profile  (UM2 extended)

  • Color: default
  • (X) Rectangular 
  • Origin: lower left
  • X: 223mm
  • Y: 223mm
  • Z: 315mm
  • (X) heated bed

Profile  (UM2 go)

  • Color: default
  • (X) Rectangular 
  • Origin: lower left
  • X: 120mm
  • Y: 120mm
  • Z: 115mm
  • (X) heated bed

Profile  (UM2)

  • Color: default
  • (X) Rectangular 
  • Origin: lower left
  • X: 223mm
  • Y: 223mm
  • Z: 205mm
  • (X) heated bed


After "after abort of a print job" enter:
;fans off
;extruder heater off
M104 S0
;heated bed heater off (if you have it)
M140 S0
;metric values
;absolute positioning
;move Z and X/Y to min endstops
G28 Z0 X0 Y0
;relative positioning
;retract the filament
G1 E-5 F300
;steppers off
;absolute positioning

Cura 15

in Cura set: GCode Type = RepRap (Marlin/Sprinter)
start.gcode (first line must be blank)

;Sliced at: {day} {date} {time}
;Basic settings: Layer height: {layer_height} Walls: {wall_thickness} Fill: {fill_density}
;Print time: {print_time}
;Filament used: {filament_amount}m {filament_weight}g
;Filament cost: {filament_cost}
;M190 S{print_bed_temperature} ;Uncomment to add your own bed temperature line
;M109 S{print_temperature} ;Uncomment to add your own temperature line
G21        ;metric values
G90        ;absolute positioning
M82        ;set extruder to absolute mode
M107       ;start with the fan off
G28 X0 Y0  ;move X/Y to min endstops
G28 Z0     ;move Z to min endstops
G0 X20 Y20 F{travel_speed} ;bring extruder to the front
G1 Z25.0 F{travel_speed} ;move the platform down 25mm
G92 E0                  ;zero the extruded length
G1 F200 E25              ;extrude 25mm of feed stock
G92 E0                  ;zero the extruded length again
G1 F{travel_speed}
;Put printing message on LCD screen
M117 Printing...
end.gcode (first line must be blank)
;End GCode
M107 ;fans off
M104 S0                     ;extruder heater off
M140 S0                     ;heated bed heater off (if you have it)
G21 ;metric values
G90 ;absolute positioning
G28 Z0 X0 Y0 ;move Z and  X/Y to min endstops
G91                                    ;relative positioning
G1 E-15 F300 ;retract the filament
M84                         ;steppers off
G90                         ;absolute positioning

Cura 2.1

The documentation should be here However that's not the whole picture incomplete.
You need an Ultimaker2extended, Ultimaker2Go or Ultimaker2 profile with the reprap g-code flavor to have start and end added to your gcode files including material temperatures, homing and shutdown. Like this one.
To avoid adding files to Cura itself (and keeping them after updating Cura),
you can put your .json files for a new machine definition here:
  • Cura 2.1 (Linux) ~/.local/share/cura/machines
  • Cura 2.2 (Linux) ~/.local/share/cura/definitions 
  • Cura 2.1 (OSX) ~/.cura/machines for 2.1 or ~/Library/Application Support/cura/definitions
  • Cura 2.1 (Windows) ~/AppData/Local/cura/machines
  • Cura 2.2 (Windows) ~/AppData/Local/cura/definitions for 2.2 
Due to bug #850, you need to copy the fdmprinter.json, Ultimaker2.json and other files you inherit from into the same directory.

You can also add additional materials (use the existing materials in Cura 2.1.2.app/Contents/Resources/cura/resources/profiles/materials as a reference) to
~/.cura/profiles/materials (OSX)
but be careful, the file structure is identical to the MATERIALS.txt that the firmware imports from an SD card but the property and section names inside are different. Strange design decision.

Ultimaker II attachment


It looks like self adhesive Velcro is the best option to attach the box to the back of your Ultimaker II.


Having a Raspberry Pi permanently connected to your printer, that has ample 5V and 12V, it is kind of silly to power it via a separate wall wart. So we should see about powering it from the Ultimaker.


g-code for "after pause"
G91 ;relative positioning
G1 E-25 F200 ;retract the filament before lifting the nozzle, to release some of the pressure
G1 Z20 F15000 ;move the platform down 20mm
G90 ;absolute positioning
G0 X20 Y20 ;bring extruder to the front
g-code for "resume after pause":
G91 ;relative positioning
G92 E0 ;zero the extruded length
G1 F200 E55 ;extrude 55mm of feed stock
G92 E0 ;zero the extruded length again
G1 Z-20 F15000 ;move the platform up 20mm again
G90  ;back to absolute positioning
G1 F600 ; set travel speed



Ultimaker II upgrade with Low Friction Spool-Holder

I'm currently upgrading my Ultimaker II with a "Low friction UM2 spoolholder" the YouMagine user IRobertI.

As I print a lot, I use huge and heavy Colorfabb 2.2Kg spools.
So when a spool is fresh and heavy, there is a lot of friction involved that the extruder needs to overcome.
My hope is to reduce this friction a great deal with this simple upgrade.

  • Print "608 mount" ith lots of infill, a large nozzle and thick layers. It needs to be strong.
  • M8x140 is plenty of length. It should have a hex head, so you only need 2 M8 nuts
  • You can use counter nuts (4 in total), so the nuts stay in place even with lots of vibration over a long time period
  • Use a bolt that has threads all the way (no smooth shaf and only threads at the tip)
  • Clean up the inside of "608 Core2 90mm" and "core 1", so a 608 bearing can be inserted into the far end
  • check the order of assembly:
  1. insert M8x100 hex headed bolt into "608 mount
  2. add M8 nut and 608 (skateboard) bearing, so "core 1" has a small air-gap wi "608 mount"
  3. add "core 1"
  4. add spacer
  5. add another 608 bearing and M8 nut (don't overrighten)
  6. add "608 Core2 90mm"
  7. add final "608 nut"


Panasonic YAGH for GH4 disassembly


I received a broken Panasonic YAGH unit for a GH4/GH4R camera.
The description was that it simply failed at some point and was dead. The original owner has a second YAGH in operation, so I'm ruling out handling error.

Since the Audio part also did not work, I can rule out any ground loop or static electricity issue with the SDI ports as the cause.
If the SDI ports  are broken, I'm still left with a good XLR audio preamp for my GH4. ;)

My educated guess is a burned protection diode/0 Ohm resistor/fuse in the power supply due to a power spike or ground loop.


This unit is all nuts and bolts.
Don't start this disassembly unless you have
  • a LOT of table space to lay out the bolts
  • a means to print photos you made of each board/side/layer to put the bolts on
  • I learned the hard way that putting the unit onto a photocopier does NOT produce good results
You have to remove all visible screws on all sides to remove the outher plastic hull.
Use the photos I made to get a good understanding of how the different parts inside connect to disassemble them later.
You can have to disconnect the board with the 2 XLR audio connectors to physically separate "Main" and "Power" board.
You have to disconnect the front panel "SW-Audio" board from the "Main" board to to physically separate the elements
You have to remove the lower board "Main" with the SDI connectors to remove the plastic on top of the "Power" board. 

Aparently you can reconnect things in a way to run the YAGH without any case and easily reachable contacts. Just the upper side of "Main" and lower side of "POWER" are blocked because they mate to each other.

What surprised me was, that the unit actually contains an micro-HDMI to HDMI cable and a full sized HDMI socket inside!
My guess is that this is to easily replace a broken cable but then again...you need to completely disasembly EVERYTHING to reach that cable.

Power supply


The unit accepts XLR power with
  • 12V applied on Pin 4 and 
  • GND on pin 1. 
  • Pin 2+3 are not connected
  • Rated for 11-17V (1.4A at 12V) -> 16.8V D-Tap  power is fine but very near the top limit

Setup: I'm testing the unit with a DTap to XLR power adapter cable.
I could also use a lab power supply but attaching it would be difficult as the cables are very well insulated and leave no place where I could attach clamps.

Lessons learned: aparently you CAN insert a chinese D-Tap plug THE WRONG WAY without any resistance.

Found the problem? The Power board is not supplying power to any of the other board. The fuses are intact and there are no obviously burned capacitors or diodes that I could easily replace.

 SDI out


  • 1080p24/25/30 -> the same 1.5G SDI signal on all 4 outputs
  • 1080p50/60 -> the same 3G SDI signal on output 1 and 2
  • UHD at 24/2530fps or DCI 4K at 24fps ->4 FullHD segments as 1.5G SDI signals on each port
Conclusion: I can test the SDI ports using my Atomos Samurai Blade or shogun that both only have a single SDI input.

Audio board 

XLR inputs arrive in a small board "CJBB84417" with only passive componente.
They are then routed into the board "VJBB0F44" with 4 low noise amplifiers labeled "8202 304 JRC".
It also houses the Pogo pins to the large connector on the camera and a large connector to the main board.
My guess is, that this does all the audio pre-amp and hands these over to the camera.
It should also provide the volume level to the main board for display and get level information from the input board via the main board somehow.
All the other pins should just be routed through from the main board to the camera.
I fuether guess that if I supply this board with power and connect it to the GH4, it may work on it's own (with a fixed level value).
If the amplifiers are similar to the NJM8202, they should have a 15V power supply.



Ultimaker II filament sensor and remote control using Raspberry Pi

The Plan

This is still an idea, growing in my head. I don't know if or when I'll build it.

I want to attach a Raspberry Pi 3 to my Ultimaker II extended.
Obviously with Wifi and USB it will have
  • a camera, watching the print
  • a GPIO pin an Octoprint API call telling the Ultimaker to pause the print (via a tiny firmware modification)
I will replace the small, plastic filament idler pulley on the back of the maching (opposite to the extruder drive mechanism) and replace it with a ball bearing and 2 sensors
  • a trivial 2 bit rotary encoder to meassure the speed and amount of the filament and auto-pause if no filament is transported anymore
  • a load cell with a Hx711 module to tell how much pulling force is applied and auto-pause on no force = filament empty and too much force = something blocks the filament from moving
The too much force - part means it will also detect obstacles that would otherwise lead to underextrusion because filament is still being transported but way less then there should be.
  • a second load cell in the modified "Low friction UM2 spoolholder" will meassure the weight of the spool and thus tell me how much filament is left.
  • the modification is a 12-20cm arm with the load cell attached


  1. DONE: Raspberry Pi with Octoprint installed
  2. DONE: Designed parts for first prototype (using only Encoder and Dummy-Load Cells)
  3. DONE: Rotary Encoder arrived
  4. DONE: Pinout specified
  5. DONE: Waiting for load cells and Hx711 from China
  6. DONE: Test rotary encoder from Raspberry PI command line
  7. DONE: Test Octoprint API from Raspberry PI command line
  8. DONE:  Convert rotary encoder values to binary positions, movements, direction and speed
  9. DONE:  Wrote a simple filament monitor script that detects stalls and reverse movement and pauses the print via the Octoprint API
  10. DONE: Test Hx711 and load cell on Raspberry PI using Python
  11. DONE: The current "pause" in the Octoprint API is dangerous for scripts. It can resume if issued twice. ->fixed in Octoprint update
  12. DONE: solder the final cables and mount things on my UM2extended
  13. DONE:  designed modified "608 mount" to weight the remaining filament.
  14. DONE:  meassuring the weight of the remaining filament works! 
  15. DONE:  Write the final software including monitoring pulling force and spool-scale
  16. TODO: Write an assembly instruction including setting up the software.


Testing rotary encoder
Testing load cell for extruder pulling force

The software

I'm using a Raspberry Pi running Octoprint as the central controller.
The original plan was to use the Octoprint API.
For the final software (Here on GitHub) I decided to write an OctoPrint plugin.
I can not only detect if filament is supposed to move at the moment and issue a pause command without hacking the firmware and dual-using one of the homing switches as an E-Stop.
I can also display information (such as remaining filament) in the OctoPrint web interface
and offer my meassurements as new values in the OctoPrint API.

The parts

New method (using Octoprint API)
Old method (using GPIO signal to pause the printer):