I am having great results with my K8200 so far. But I find that it is usually best to babysit the printer for the first few layers to ensure that it is extruding cleanly.
What I have noticed is that the filament sometimes wants to curl around and stick to the outside of the nozzle, which causes a mess and can damage/destroy the print. This is a problem because the nozzle drips while pre-heating, and then when it homes the z-axis, it creates a blob of material on the tip. I usually have to reach in with pliers or a knife right before the print will begin to remove the leaked material.
I know I could use retraction to prevent the leaking during pre-heat. I am more interested in understanding why the filament curls as it leaves the extruder. If I raise the z-axis and extrude material into open space, I expect the drip to fall straight to the bed. But sometimes it will not do this, instead curling around.
Is this caused by material lodged inside the nozzle outlet? Or perhaps material burnt onto the outside of the nozzle? Any tips on how to prevent this would be greatly appreciated.
Once I get a clean, straight drip, I get much better prints.
This curling happens when the extruder nozzle height is above 1mm the heat bed.
Any 3D printer is not able to print in free air so the molten filament starts to curl.
General rule is: remove those curles at the beginning of the print, once the nozzle reaches zero height then the curling will stop.
Indeed retraction can avoid this.
I have this problem too when I print long / wide flat surfaces with ABS. It doesn’t do it all the time.
What I feel is happening, is the ABS is warping at the edges on a long / flat print. The extruder head then interferes with the surface that is already printed creating curling / burning. It looks like little charred balls of curled up filament.
The only solution I can find is to use methods to prevent curling and warping.
http://www.instructables.com/id/Prevent-3D-prints-from-warping-no-mess/
http://www.instructables.com/id/100-Warp-Free-MakerBot-3D-Printing/
The stock K8200 can not reach the bed temperature of above 100° needed for abs.
And if it does doubtfully, not for a long time.
If the heat bed has the right temperature, curling of the base layers will not happen.
Also, sorry but PCB heat beds are never real flat.
If the model is curling keep an eye on the distance of the nozzle to the heat bed.
A glass plate can solve this. This needs to be borosilicate glass.
Keep the velleman psu, but use a 24V 10Amp PSU for the heatbed.
Then the stock psu will have no problem with the rest of the printer.
Except when you change the stock extruder to one that reaches 300°C or above
that changes the rules again or very long waiting to reach that extruder temp.
Sure there are solutions but it seems better to fix the stock problems of the K8200.
The dripping in the preheating phase can be avoid by retracting the filament so that it not melts during preheat phase.