Status of Octopi / OctoPrint on the i3 MK3?


I'm returning to 3D printing after an unwanted hiatus... the printer I had been using, a FlashForge 3D Creator Pro, suffered an accumulation of problems that required spending an increasing amount of time on fixes / maintenance and a diminishing portion of time on successful printing. I've just plunked down the cash for a Prusa i3 MK3 on the hope that it will be more reliable.

While waiting for my MK3 kit to arrive, I've started looking into running OctoPi as its controller. To my surprise, I've found a number of open questions about this general topic:

  • Some posts recommend the specially designed OctoPrint for MK3 image (; others recommend installing Raspbian Lite, OctoPi, and some special configuration for the MK3.

  • Some posts recommend running OctoPi/OctoPrint on an RPi Zero W connected via Einsy headers; others say that the Zero CPU is too limited. Some recommend a 3/3B/3B+, even though the Prusa printable case doesn't fit it and you might have to use USB; others say that USB control creates a performance bottleneck and loses some features, like the filament run-out sensor.

  • Some posts assert that using OctoPi, or indeed anything but the native software printing directly from an SD card, is likely to introduce problems. I guess I could use a FlashAir card to make life a little easier and send STLs over WiFi, but obviously, a lot of the advantages of OctoPi are gone.

Anyone care to weigh in?


Personally, I don't think the Raspberry Pi Zero (W) has enough cores to do the job justice. I would go for a Raspberry Pi 3B. Also, it seems like the guy who created the Prusa didn't understand the UART situation on the Pi computers. I remember posting on their forum about how you have to turn off Bluetooth and console use of the UART to allow the Prusa to work via soldered GPIO pins as they were doing. I'd say, just make things easier and don't use the Pi Zero.

Honestly, it's a small investment and in this scenario you're not soldering it to your printer. Fire it up and try it.


Don't use a Zero. Use a Pi3, make sure it has a good power supply. The only thing you lose is "power off recovery" by printing via Octoprint.

Use OctoPi proper, not the stale Prusa fork.

Who the eff recommends directly installing Lite and 'special configuration'?

I have a i3mk3 with a mmu2 printing away right now.


Very good. Just by instinct and past experience, I had started preparing a Raspberry Pi 3B+ with a typical configuration when I discovered the mess of conflicting opinions. Thanks for the feedback.

@tedder42: By "special configuration," I just meant a script that somebody put together to configure a basic OctoPi install for the MK3. I remember seeing one out there. Obviously there's a simpler configuration that just defines the OctoPi options for the MK3, which I'll plan to use.


yeah, NBD really. There's a nice bed level visualizer for the Prusa, otherwsie OctoPi is perfectly generic.

I use Slic3r PE because it's much better than generic Slic3r, but the Prusa fork of Octoprint isn't better- or needed.


Or an OctoPrint fork actually - it's an OctoPi fork really, and naming it "PrusaPrint" didn't really help with the overall confusion :smile:


I haven't built my Prusa Mk3 kit yet and want to buy the appropriate Pie before I do.

I don't care about slicing on the Pie. I am already in the routine of sorting that out on my pc.
The main things I want Octo for is to remote monitor the print job and to take time lapse video. I don't want to lose printer features that I just upgraded to have though.

Is the best option to get a 3B with external power supply and connect it through the GPIO with the ribbon cable? Or is it the slicing that the Zero is underpowered for, so putting the Zero right onto the printer the best option since I don't need to slice?

I'm sure there is a plain and simple answer to all this.


There is. Use an RPi3, especially if you want to use a webcam. If you want direct integration with the Einsy, wire up some connector to the GPIO pins. But even though Prusa Research recommends it, do not use a 0W. It is underpowered, it will cause you problems because just transmitting data over the wifi interface will cause slowdowns in your prints, and it is just not worth the hassle of dealing with it. There's a reason it is explicitly recommended against on the OctoPrint download page, even if people will tell you "it works totally great for them".


Many thanks for the response. Thats exactly what I needed.
Is there any particular RPi3 model? (A+, B+, etc)?
I'm inclined to get the biggest, most powerful but i've had trouble with incompatibility in the past (RasPlex won't run reliably on the 3B+).


Most people appear to be using a 3B with the 3B+ being the second most common one:

Note that ~6% are also using a Zero W even though it is recommended again. That's the "it works totally great for me" crowd - until it doesn't and they start opening tickets on Github or support topics here :wink: