I got a Velleman K8200 3D printer kit for Christmas, and I just got it working today.
It took me about 28 hours of assembly to get working. 20 of those were following the online manual and the last 8 hours were fixing problems that cropped up.
Here's a Youtube video I recorded of it printing, and me pointing out a few things. Sorry that the quality of this video isn't high.
A few photos of the first thing I printed. 1 2 This casing was a large print - it took 4 hours to print. It was this printer's recommended "first print"; it's a box to house the controller board on the printer itself.
Anyway, I thought you might be interested in the problems I encountered after completing the assembly.
First, the Y axis motor wasn't moving the bed correctly. This took me a long time to diagnose. At first I thought it was a problem with the belt or the bearings, since the bed was a little hard to slide back and forth. But I lubricated it and the bed got a bit easier to slide, but the motor still had trouble pushing the bed. Then the belt fell off! I had apparently not attached it properly in the first place. So I fixed that, but it still wasn't working.
So I decided to dig in. I cut off the heatshrink and found a disconnected wire. Apparently I had failed to solder it properly, whoops! I resoldered and re-heat-shrunk all the connections. And it still wasn't working properly. Argh!
I removed the belt and put my finger on the motor gear. The motor itself was turning, but my finger could easily stop the gear... Oh. Duh. I tightened the screw which affixed the gear to the motor shaft, and it started working! Hooray!
The second problem was that the extruder would get "stuck". The extruder is the part that pushes the filament through the hot end -- it deposits the plastic. The extruder would work for a while and be happily pushing out plastic, and then it would sometimes get stuck and not be able to push the filament. If I used my fingers and turned the gear manually, it would often "unstick" and start working again. The extruder has a fancy adjustment bolt which lets you tighten and loosen its grip on the filament, so at first I thought this was the ticket and I spent a long time tweaking that bolt. But no dice.
I took apart the extruder. When I disconnected the stepper motor I noticed that even when there was no filament, the extruder wouldn't turn smoothly -- it would have "easy parts" and "hard parts" of its rotation. So the fix here was to loosen the main rotating bolt (the "hobbed bolt") that the gear was attached to. When I did that, the extruder turned a lot more smoothly, and on reassembly it had no problem pushing the plastic through.
But now when I printed, the plastic wasn't sticking properly to the bed. I adjusted the height of the bed endlessly, thinking it was a height problem, but it wasn't -- the bed was just not the proper material. I taped over it with blue painter's tape, as many people recommend on forums, and finally -- FINALLY -- I could print. Hooray!