Next part to build was the extruder. This is the mechanical part that feeds the filament (plastic material) in to the extruder. It holds one motor and some gears. The tricky part here is to put a spring in that has quite some tension to it. And this also holds the last motor. It is very essential that everything runs smoothly again. The manual also talks about some bolts that need to be 'tight' and some that cannot me 'too tight'.
All very relative right. I thought as longs as it runs it must be OK. Then you have to attach it to the frame. I found out that this is not easy. You have to put some rings in between and they kept falling our every time I tried to screw it on. I think I did this 10 times over. But well. It is on now. This actually concludes most of the mechanical moving parts. Everything still runs fine so I'm quite happy so far.
Then you have to assemble the heated print bed. There are two tricky parts here. First of all you have to solder on a NTC on the backside. Not easy since it is a SMD component and it is very small. Luckily I did this before, but you need some skills and a good soldering iron for this. It is essential that you solder it as flat as possible or you will get into trouble later. Also the screws are actually to large. They stick out of the bed. Try to avoid that since the print head will only be 0.25 from the bed and the screws can be higher. You don't want to hit them since the software doesn't know the screws are there.
Then you finally get to install the mysterious part that you build the first. And suddenly you understand its purpose. It only holds the spool of filament later on. So the detailed description given about the measurements here make no sense at all since all the spools I've see so way are way smaller that this. But a well.. It fits :) I did have one spool laying around and of course it fitted easily. OK so far for the mechanical part. After this it will be electronics and lots of wiring.