Assembly of a Chinese 3D Delta Printer Kit

I got myself a Chinese 3D printer kit. It is a delta configuration build after the Reprap Kossel Mini . The Set included:

• Hardware (linear rails, belts, motors, screws feathers, print surface)
• Electronics (RAMPS 1.4, LC-display, SD-card, switches, cables)
• Extruder (direct bowden extruder)
• Hotend (E3D clone with heater cartridge and thermistor)
• Heated Bed PCB (for heating up the print surface)
• Free PLA filament

Contents of the two packages

Everything was shiped with DHL Express from Hong Kong and arrived 7 days after purchasing. Which is very nice for a package from china. Shipping was only 32$ extra. In Germay customs claimed another 68€ so in total 370€ which is not too bad for the two packages containing (hopefully) all of the parts needed for assembly.

Unpacking all the boxes leaves us with heaps of material. The threr cardboard boxes contain all of the parts. The tube contains the linear slides for the towers. The black beams are for the frame and the red PCB is the heater for the print surface. Included in the package were all the Allen keys needed for assembly. A lot of M3, M4 and M5 screws, nuts and various bits. An SD card with the necessary firmware and build instructions were included as well. All the mechanical connections are printed with PLA in a OK quality. The dimensions are met so I was no problem to put everything together.

All the assembly parts layed out on the table

With my comprehensive knowledge of simplified Chinese symbols, which is none, I could read some of the documentation. Luckily the internet is full of assembly instructions for the reprap Kossel mini.

After a few hours the mechanics where done and everything moves smoothly. After adjusting the delta values in the firmware, z height and probe offset for finding the true Z0 position it printed with the included PLA filament. The test cube was sliced with slic3r with a configuration I came up with. After a few layers the extruder stopped working and nothing was fed into the hotend anymore. After some fiddling around with the temperature and manually trying to push the filament through the hotend I dissembled the whole hotend part. It showed that the free filament sample had a huge part of 2mm diameter instead of 1.78, which i measured before configuring the slicer. Due to the large diamter the filament got stuck in the cold part of the hotend. Stupid thing but easyly fixable. Pushing with a small screwdriver from the nozzle side of the cold part released the stuck piece of filament.
Well the free sample found its way to the bin and a spool of light blue high quality PLA found its way to the extruder and out of it again. Tightening the hotend in a hot state will hopefully do the job.

The thing is running, litterally. A nice piece of hardware

If you are looking for a nice kit to build yourself a kossel mini 3D printer you can go for one of the cheap sets from china. But keep in mind, you are in for a steep learning curve. If you want to print 3D models and not fiddle around to much, buy something else.

Herbert Mk3: An der Wand

Das neue und offizielle Raspberry Pi Touchscreen mit DSI Anbindung und kapazitivem Touch ist endlich auch für mich lieferbar gewesen. Nachdem ich fast einen Monat darauf gewartet habe kann ich die Schaltzentrale für meine Wohnung jetzt endlich an den Nagel hängen...

Raspberry Pi 7" TFT Gehäuse: Modell

Mit einem eigenenen 3D-gedruckten Gehäuse hängt der Raspberry Pi 2 mit Display jetzt im Flur. Mit an Board ist ein BLE Dongle, zwei WLAN Sticks und ein 64GByte Massenspeicher. Auf dem System läuft ein Raspbian mit LXDE und Iceweasel Browser als Frontend und openhab, mogodb, mosquitto, HerbertScanner und HerbertNode im Backend.

Openhab mit mosquitto habe ich ja bereits in älteren Posts bereits erwähnt und mongodb als Datenbank ist auch keine Besonderheit. Die zwei interessanten Softwarekomponenten sind HerbertScanner und HerbertNode.

HerbertScanner ist eine Applikation, die mit dem BLED112 von BlueGiga kommuniziert und die Advertisement Pakete der BLE Buttons im Umkreis registriert. Ein Advertisement Paket im richtigen Format wird an mosquitto, also als MQTT Nachricht weitergeleitet. So werden Daten von BLE Endpunkten a die openhab Zentrale geleitet.
Die Konfiguration der BLE Geräte muss zur Zeit manuell durchgeführt werden. Dazu muss der MQTT Kanal '/Herbert/#' abonniert werden.  Dort werden alle Nachrichten abgeliefert. Neue Geräte erscheinen da dann auch und können mit der ID registriert werden.

HerbertNode ist eine Applikation, die für das Konfigurieren der WLAN Endpunkte eingesetzt wird. HerbertNode scannt die WLAN Netzwerke in der Umgebung und findet die Accesspunkte von ESP2866 Geräten. Diese starten, wenn sie keine Konfiguration besitzen, oder das konfigurierte Netzwerk nach 30 Sekunden nicht gefunden wurde in den Accesspoint Modus. Sobald HerbertNode eine ESP2866 SSID sieht, verbindet er sich mit dem AccessPoint und stellt eine HTTP Anfrage nach '/info'. Das Gerät gibt dann Informationen über sich im JSON-Format an HerbertNode weiter. HerbertNode hat eine Liste der verfügbaren Geräte im Umkreis. Vom Benutzer kann in dieser Liste das Gerät ausgewählt und dem Netzwerk hinzugefügt werden, dazu wird dem Gerät die SSID und der Zugangsschlüssel für das Herbert-WLAN übertragen.

Der Code wird im Laufe der nächsten Wochen noch verfeinert und stabilisiert. Es treten teilweise noch Fehler auf, die noch behoben werden müssen, bevor Herbert zum ersten mal veröffentlicht wird.

Converting a CC26xx Example Project Into Something Shareable

The example projects that are shipped with TI's BLE SDK are great. They show a huge variety of use cases for the BLE stack. The codes provided are great resources when it comes to information on how to build software for the CC26xx chip family. Doing so many examples leaves us with code that is used more often than once and so it is linked into the project. Basically every file that consists of some code is a virtual link to a file on the folder structure. That leaves us with the problem that sharing the project with an SVN or GIT server only gives us the few local files and none of the code that is important. Changing the code is possible but you have to remind yourself, that the files are not considered to have changed when submitting to a version control system. 

To conquer this issue we need to have some of the files we are going to change or that are not part of the SDK in a local version on our file system. Luckily we can just copy the files to a folder in the project of the workspace. This way the files are preserved and as a next step we delete the links to the files in the project explorer.

I moved the following files to local folders:

• simpleBLEPeripheral.c /.h
• board_key.c /.h
• simpleGATTprofile.c /.h
• main.c
• Board.c /.h
• appBLE.cfg

You now have to add the local folders to the include paths of your project so the files can be found during build. Especially the Board.h which contains the information on how the chip is integrated in the circuit. Remember to remove all the unnecessary folders from your include paths. If your project uses available files from the example projects (like profiles and utils) you can leave the links in you project. To share the project you can use Subclipse or Git. You will have to install the same version of the SDK if you want to compile the project we created.

You can read up on this instructions on how you can create your own GATT Profile.