Extruder stepper intermittent, doesn't always return after retraction (Video)

Hi All,

I'm new to printing, and spent quite some time calibrating my Kossel Mini (running Marlin). However I've been having a lot of problems with what I believe I've narrowed down to the extruder retracting, but then sometimes not jumping forward to continue the next layer. When printing what seems like my 1000th calibration cube I'm still seeing layers where the filament does not immediately begin flowing out when it should at the start of a new layer. This leads to gaps which you can see in the attached photo. I've linked to a video that I took of the extruder running which shows exactly what I mean. If you watch carefully you can see the first two retractions that occur don't have a corresponding jump forward. The 3rd and subsequent retractions shown are normal and does have a corresponding jump forward. Sure enough, the print has two semi missing layers followed by perfect ones.

Video on YouTube

I've checked the G code that Slic3r produces and it looks correct to me, but just seems like the last line below is just occasionally being skipped:

G1 F2400.000 E8.32874
G92 E0
G1 Z12.400 F7800.000
G1 E2.80000 F2400.000 ;skipping this?


So I'm appealing to you good people - please, does anyone know what's going on here and how to fix it?

Many thanks in advance,

Rob

Try slowing the retraction speed down a little to see if it's skipping steps.

---

[3DKarma.com] - suppliers of quality, affordable 3D printer kits and filament for the UK market.

Thanks for your reply. I managed to get it sorted last night by giving the trimpot a 1/8 turn clockwise which has solved the problem.

Cheers
Rob