Chapter 6. K8200 or Reprap 3drag

Table of Contents

Z axis end stop switch
Z axis issue
Filament feeding issue
Temperature control issue
PT1000 instead NTC
Heated bed issue
Direct extruder
Double extruder

The 3drag printer,,, or Velleman 3D printer kit k8200 is a popular Open Source Printer Platform. Since it is an open project extensions projects as convert it to a CNC machine or add on a chocolate extruder exist

Figure 6.1. K8200


It uses the 3drag controller board following the "Arduino Mega 2560 oder Mega ADK" open source design.

A small incompatibility to the Arduino exists. An original Arduino resets each time a communication gets initiated due to the connection to the DTR signal. Since this would stop 3D printing, this line is cut on the 3Drag_controller and fed to a jumper that must be set when a new firmware gets uploaded.

The PC software reptier is recommended.

The Mega 2560 avr microcontroller uses the marlin firmware from The firmware must be configured for a particular printer (size of table, height, extruder nozzle, filament diameter, temperature sensors, ....). For a beginner it is best to download it from Velleman.

The controller board can be expanded with a user interface having a SDcard slot and a Text based LCD. This extension allows then to used the 3D printer autonomously

Figure 6.2. K8200 LCD

k8200 lcd

Filenames should be short to fit in the display. It prints directly from files containing G-code, those files have a *.gcode or *.g extension.

Buying the Velleman K8200 kit gives a very good cost performance ratio. However some skills mechanical, electronics, SW and finally be willing to spend a couple of days to adjust and fine tune it. The kit is not something for people that like to get something out of the box. However not have it out of the box, be open source and very well documented, the printer is a good platform that will not get obsolete quickly.

The mechanic is very well done some key components as are very robust and precise. Since everything is screwed together it looks not as an out of the box product. It requires some fine tuning until everything runs well. Things to take care are:

There are some weak points. Being positive, this helps to learn the basics in 3D printing. A complete assembled 3D printer might be easier to set up but when then some problems occur then limited documentation is around.


There are many issues known with this printer. Looking positive at it: This printer is used by many innovative and intelligent people that since it is open source steadily improve it. Considering those improvements it becomes an up to date trouble free printer platform. Platform, since it is never finished nor outdated. On the other hand buying a new one and then buying all the updates is not very interesting.

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