Air bubbles in filament on exit from nozzle

Hi fellow mendelbots and Reprappers,

I am currently experiencing inconsistent extrusion from my rapidbot.
It seems as though air is being trapped somewhere and creating bubbles in the filament as it comes out the nozzle.
I have heard that moisture absorbtion can be a cause in pla but I tried the same reel of material in my orcabot and it works fine.

Here is a photo:



and Video Link:

Bubbly filament

Hope anyone can point me in the right direction for a solution.

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3D Printing never sleeps
MAGICMODEL

I had similar results from cheap filament. Some Chinese suppliers don't care too much about quality. I have some clear I bought that started to ooze from the nozzle all the way down at 130C and was like liquid at 180. Managed to print with it at 170, but it was a bit messy.

With filament, you get what you pay for. Was this cheap stuff?

Yep it was from China but its good stuff and I have been using it for months on my first printer orcabot from mendelparts and been getting really great results.

really strange problem you have there.
so the same filament works fine in another printer thus proving its not the filament. Have you tried a different filament in the rapidbot.

im really struggling to see how it could be the extruder. At no point is there a vacuum to draw in air to mix with the filament.
that only leaves the chance that air is being trapped in the tooth marks left in the fillament by the hobbed bolt and forced down into the extruder. Long shot and unlikely but if its not in the filament then the air has to come from somewhere.

good luck