'Hairy' surfaces when printing large areas

[pinthenet]

I have had an issue twice now when printing larger areas. I'm currently printing the Holes & Bosses calibration objects http://www.thingiverse.com/thing:231984 and I notice the effect already on layer 1 of the bosses object. I notice strings of filament left in most areas giving a 'hairy' appearance. I assume there's no retraction on these sections so I don't understand the cause. I am printing on a Velleman K8400 with Velleman PLA (blue) @185° and layer 0.2mm.

I had the issue once before with a large flat area, although this time it seems to be less extreme.

Any ideas? I found some references in the internet but nothing conclusive

John

[PinballGeorgio]

Speed and temperature are important. 185C is on the low site. Try 210 or 220C
Also check that your extruder is not moving over open area's, in S3D you can check avoid crossing open spaces...

[pinthenet]

It's difficult to take a photo - this is the best I could do, it's visible in the area on the left

[pinthenet]

sorry, missed you post, PinballGeorgio

Will try a higher temperature. I did wonder. It's not crossing any open spaces when it happens, maybe it's clearer from the image

[PinballGeorgio]

That looks like an under extrusion problem with speed to high.
Try to set the extrusion multiplier 10% higher, lower your printing speed.
Could also be an overextrusion problem, hard to see on the picture. You don't hear clicking sounds from the extruder stepper motor? Under extrusion could also be a problem of slipping filament or maybe a nozzle jam.
But playing with the extrusion multiplier and priinter speed settings should solve this