Bootstrapping a “Rostock” style RepRap 3D-Printer (Intro)

As a full-time engineer with a degree in “Mechatronics” I obviously had to trace the RepRap project. Working somewhat in advance development I even could persuade my superiors to commit to to a crowdfunding campaign just to see if such a machine was any good at all. After all fused filament fabrication (or fused deposition modeling, as Stratasys calls it) does not suffer from the short shelf-life (and high price) of the photopolymer used in Stereolithography. Or the price of selective laser sintering machnines.

And seeing how the open source philosophy drives the advances is just awesome.


But the aftermath of the “Sumpod Aluminium” indiegogo-campaign seemed to turn out complicated for the starter. And nothing happened for a long time. Out of frustration I read even more about the topic and posted a summary about it at (only direct link works as I explained here), followed by starting to build my own Replicating Rapid-prototyper mostly without printed parts.

To give you an idea of how long it took to finally get the Sumpod kit: I summarized in January 2013 and the parts arrived in February 2014 – about two years after the funding ended, if I am not completely mistaken.

First I took a closer look at the software toolchain.

Open Source CAD => STL-file
Open Source Slicer => G-code
Open Source Firmware controlling Open Source Hardware via G-code 🙂

There are long lists at and, but for generating a model I used OpenSCAD exclusively. Until I recently also tried Tinkercad. Other CAD packages were just too complicated for my casual usage. (And do I have a bit of expirience with Unigraphics and Inventor…)


Now I can say, that most of the models I printed were downloads. It’s just too easy to imagine how many others have already run into the problem you are just facing yourself and ask yeggi to search for an STL-file. 😉

To turn the 3D-model into G-code, so the controller of the fabber can steer this sort of glue gun to the proper positions, I quickly started to get comfortable with Cura (the 15.04-versions).


To get the list of commands to the machine (or to send direct commands for various reasons) I still use Printrun / Pronterface however.


The Sumpod uses the classic Arduino Mega with R.A.M.P.S. shield (1.4) to have a microcontroller translate the millimetres or centigrades coming from the PC via USB/UART-bridge to motor steps and power regulation to keep a certain A/D-converter value from the thermistor in regulation.


To get myself startet with minimal expense I choose a Sanguinololu, which integrates a lot of basic functions at less possible functionality – but having e.g. no SD-slot never has been a problem for me.


Both boards use 8bit Atmel controllers. If you plan on using some complicated mechanics (feeding the controller with a lot of trigonometric functions) they tend to be too feeble for rapid movements.

Many of these boards run the same firmware with just some modifications to a certain header file. (Just like all the mechanical parameters of a machine are written down in another header and the firmware algorithms always remain the same.) Marlin has always been fine for me, but meanwhile I have seen a lot of nice printers running Repetier.

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