You want ideas for improvement Velleman, I will give them, but I will start by saying Im fairly disappointed in the Vertex. My previous printer was the K8200, and while it had its flaws, it has mostly been an enjoyable learning experience and is still being used regularly. I assumed Velleman had learned from it too when we ordered the vertex, but I was wrong. So here is a list of things I think are wrong with this printer.
- Hotend
The nozzles are proprietary, the price isnt bad, but you cant buy them from the places where you usually buy the rest of your stuff, like filament. And worse, there are no different sizes. .35mm size doesnt fit all, its unsuitable for compound filaments or translucent prints. The tiny nozzle and thus limited flow and layer height also makes that for rough prints, my K8200 is actually faster. A LOT faster even.
The print head design also isnt very convenient for maintenance. When a nozzle clogs, you can bet you cant easily remove the heatblock from the nozzle, and thus you have to remove everything, including temp sensor and associated wires. Then it gets worse, because you cant really remove the sensor while the nozzle is in the heatblock. I normally torch clogged nozzles, but now I cant because Id be torching the sensor. My hotend is currently in my kitchen oven at 180C hoping that will let me separate the nozzle from the block without damaging the sensor wire.
I also dont like the wire coming out at the bottom, just barely scraping over prints.
why did you not opt for an all metal hotend (like an E3D) with industry standard nozzles and no worries about peek melting and painless nozzle switching? This was probably by far the most popular and useful aftermarket upgrade to the K8200.
- cooling
When I saw the pictures with 2 fans I automatically assumed one fan to cool the hotend, one to cool the print. Makes sense no? Not so! Who thought it was a good idea to have both (very different) fans do 2 very different things simultaneously with a single control ? When printing PLA, I want a decent airflow, but then heating up takes forever. When bridging, I want to cool the print as much as I can, but then the nozzle with the underdimensioned heating element cools down way too much. When printing ABS at high temperature, I dont want my peek to melt, so I need reasonable cooling on the hotend, but I also dont want to warp the print by overcooling through those same fans. I cant choose! That alone makes printing ABS or high temp filaments almost impossible. It also confuses the heck out of slicers. Really, whoever designed this cooling, should be fired.
The tiny fan at the bottom also seems like an afterthought and hardly an efficient way to cool whatever its supposed to cool (PCB?). Why not a larger less noisy fan at least?
- Heated bed
Im sure Im not the first to say this, but really, no heated bed? Not even as an option? Build tak is not an alternative for it. It sticks perhaps too well to PLA, mine lasted all of one print with glass PLA (its still cemented to it, even after pulling off the build tak and bending it, putting it in the freezer, its there forever), and it doesnt stick nearly well enough for other materials, again making ABS pretty much impossible. The price is also exuberant considering it adds nothing over hairspray on a glass bed. Adding a heated bed is going to be a bit of a pain, changing Z sensors, PSU, etc because the printer isnt prepared for one. Upgrading the heat bed on the K8200 was perhaps the second most popular upgrade, and so for their next printer, Velleman decided we didnt need one at all 
Minor gripes
- extruders are painful (literally) to operate
- pulleys are too soft and/or grub screws to secure them, too small.
- Having to align 2 extruders to ~0.05mm essentially by cutting teflon tube to length is maybe not the best concept. Yeah you can just use force to screw the nozzle in or out a tiny bit more, but then it will either be too lose with the teflon not touching both sides, or it will be jammed so hard its even harder to ever clear a clogged nozzle.
- Enclosure that doesnt enclose. WHy not add a door and a bulged top so the printer is actually fully enclosed?
Of course, without heatbed, there is not much point anyway I guess.
In the end, for the price perhaps I expected too much, but I was hoping for a clear improvement over the K8200 with dual nozzle abilities. What I got was a printer that realistically can only print regular PLA, thats pretty good for fine prints, but slow for large/rough prints, a second nozzle that is all but unusable for dissoluble filament (my main motivation to buy this printer) and a lot of frustration. I had offered my K8200 for sale when I received the vertex, but I decided to keep it. Not sure Ill keep the vertex.
/end rant
