In this video I show how I ended up mounting all the electronics for the Prusa i3 MK2 clone. As the frame wasn’t as solid as the original’s aluminium one I decided that it needed a brace, which provided the perfect location to mount the Arduino, RAMPS, Raspberry Pi and all supporting parts.
I also added a brace to the other side – which gives me room for electrical expansion!!!!
I mounted the whole thing to an office desk, I picked up for free, and even though all four corners of the Y axis are square and sit on the desk, there is a slight amount of hammering when printing.
To silence that I drew up and printed out some little securing clamps which just make sure they cannot move. You can click the image below to download the STL for these clamps. They should work on any printer using the same Y Axis design and the Prusa i3 MK2.
In the last video I noted I could’t work out how the Y limit switches fitted. In the course of investigating I noticed a bigger issue – the 3D Printed parts on all four corners of the Y Axis should have cutouts in the top to let the linear bearings partly slide “into” the corners….. mine didn’t.
Turns out that there is extra material in the prints that needs to be removed – revealing these cutouts!!! If you know you know – and I didn’t 🙂
I’d like to think this is an easy mistake to make – so worth mentioning here and in the video.
Sadly it means that the Y corners were also the wrong way around, so will have to take the Y Axis apart and make the corrections. Doh!
The good news is that it should fix the issue with the limit switch. Every cloud and all.
I decided to get on and cut the frame out first – made from two identical pieces of 12mm plywood glued and screwed together to maximise rigidity. ( I used 2x12mm as I had a sheet of 12mm lying around)
As I discuss in this video – I found the PDF template found on Thomas Sanladerer’s site a little bit tricky. It might be that its just lost quality due to scanning or something but the exact cut lines are hard to figure out as there is a double line around the edge and the hole marks are also slightly vague. On top of that I found it quite awkward to line up when printing on multiple sheets of A4.
So I made my own! Hopefully it helps out someone in the future looking to cut their own Prusa i3 frame.
As you can see, it is designed to be printed onto 6 A4 sheets – then each sheet should be cut along the green dotted lines. The edges these leave should be butted up against the red lines (not to be cut!!). Tape it all together and there you have it.
You will notice that this is slightly different to Tom’s – not in dimensions but in corner treatment. I have changed all internal corners into 5mm radius arcs. The idea being that you drill all these points with a 10mm drill before cutting out. This is much easier to do that trying to make accurate tight angles like the original.
One thing to note; I have only included the centre marks for the Z Axis top and bottom mounts. The rest are either for tie wrapping wires to or mounting the power supply/control boards. As none of that is critical, I left them out.
The other thing I might suggest is to only drill the two Z axis mount holes at the very bottom, then drill the rest using the actual 3D printed parts as a template. The reason being is that, with all the best will in the world, it is unlikely you will drill them all accurately from the template. As Tom found out.
My method was to drill the two bottom holes, use those to bolt in place the bottom Z axis mounts, then attach the smooth rods and top mounts and align everything up with a square. Mark the position of the rest of the holes through the 3D printed parts and then drill them.