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Recently I tooked a look at cheaper China 3D Printers and noticed they're all based on RepRap (mostly using Ramps for the electronics part) and the next day i saw a 2d Plotter based in the pi. Then I asked myself why the Pi isnt used in 3d printers.

Question: Why is the Arduino Mega/Due more used in 3D Printing than the RasPi? What are the Pro's and Con's for 3D Printing on the two systems?

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    Hard realtime is more difficult when you can't get the full specs for the main processor. – Ignacio Vazquez-Abrams Jul 8 '15 at 0:50
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A mutli-tasking operating system such as the Linux normally run on the pi is not particularly suited to doing hard real-time control such as coordinated pulse generation for multiple stepper motor axis trying to move as quickly as the rigidity and motor power will permit.

It is possible to use realtime extensions to the Linux kernel to get reasonable performance. And it is also possible to run something simpler than Linux on the pi.

However, it is also possible to use a far cheaper processor to get the actual G-code execution done (you don't really pay the Arduino cost premium when buying an ATmega on a dedicated board, so it's only a dollar or three more expensive than it "should be"). If one were to design printer electronics from scratch today, there are probably better choices, such as as ARM Cortex M0, M3 or M4 - but most of the printer designs came out of the same community where Arduino was a familiar choice, and there are probably more people willing to try to make small personal customizations to an Arduino codebase than there are willing to install the toolchain for a perhaps technically better, but less familiar solution. .

People do use Raspberry Pi's with 3d printers quite frequently though - they just use them for a different job: that of slicing and motion planning and potentially functioning as a network print server, which then drip-feeds the G code to the simpler (ATmega or whatever) based realtime executive. In effect, they use a pi as a cheap PC to host the ATmega-based printer, rather than dedicating an old PC to that job.

Ultimately, the rarely taken alternative of using a realtime Linux kernel extensions to control motion directly from a pi, vs the more common one of using an ATmega as a realtime motion delegate for the pi, are conceptually similar - it's just that in one case the realtime executive engine is a highest priority task on the main processor, and in the other it runs on a dedicated motion co-processor.

  • 3D printers are not all that run GCode. In fact they are rather late comers. Real time Linux and other real time solutions have been used quite successfully for a long time. People use Arduinos on cheap 3D printer because they are cheap, as is most software written for them. – user6569 Jul 9 '15 at 22:08

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