can anyone explain the cause of this??

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my extruder seems to be starving every 8 or 9 ish lines. then starts to be ok again for another 8-9 lines???

using a e3d etruder with 3mm ABS from 3dfilaprint. printing at 230c, 0.3 layer and 70mm/s speed. eveythings all calibrated, tell it to extrude 100mm filament and it feeds 100.2mm thru which seems good to me.

help anyone??

cheers mike

I believe that the common causes for this type of problem are unacceptable filament diameter variations (check with calipers at multiple places over several meters to ensure the filament diameter is stable) or possibly your filament spool binding up at one point in its rotation.....

Hi and thanks for the replies

just measured the filament and roundness and diameter along a 4-5 meter length seems to be 2.92 mm to 2.98. which as far as I can find seems to be good.

I've just printed an android figure, which cura reckons takes 4.7 meters on filament and although not as bad as in the image it still had missing/thin layers at least on the outside of the print.

it surely has to be something mechanical due to the regularity ?? doesn't it

I always measure the diameter and calibrate everywhere new roll via the thingiverse wall test. I've a new hotend, but the 1cm cube prints very well (but not the 1,5 variant)

The only other things that I can think of are bad or "dirty" filament or possibly the hotend momentarily damming up because the fan isn't running or there's something loose or scored inside.

I'll defer to someone with more experience with identifying print problems.....

Do you run a pipe from filament reel to extruder? If you don't then then loose filament can pull on the X carriage lifting it upwards. This causes every n layers to be too thick to lay properly.

Try unwinding enough of a coil of filament before printing and see if the issue goes away.

Also could be temperature swinging due to incorrect pid settings. At 70mm/s your extruder may only just maintain 230C. Monitor temperature over a print and see if it stays constant.

Try printing at say 30mm/s does the issue go away? Could be extruder gears binding every n rotations.

Quote
konwiddak
Do you run a pipe from filament reel to extruder? If you don't then then loose filament can pull on the X carriage lifting it upwards. This causes every n layers to be too thick to lay properly.

Try unwinding enough of a coil of filament before printing and see if the issue goes away.

Also could be temperature swinging due to incorrect pid settings. At 70mm/s your extruder may only just maintain 230C. Monitor temperature over a print and see if it stays constant.

Try printing at say 30mm/s does the issue go away? Could be extruder gears binding every n rotations.

i have it set as bowden with gregs wade extruder pulling the filament thru, with a filament pipe running from the feeder to the hot end. far as I can tell, No pull

I have slowed the printing down to 20mm/s and the quality is now constant but how to I get it faster. its all pretty well calibrated??

On the subject of temperature. I bought a non contact thermometer and testing the hot end at 200c it says its 177c. how do i know which figure is correct?, ive never set/changed anything in the marlin code for temp.

Thanks for the help all

mike

The same goes with the heated bed, repetier says 87.5c and the thermometer says 83c?

Verify your stepper driver for your extruder is not overheating.

It sounds like there is not enough filament to cover the area.
In Slic3r, if you're using it, go to 'Print Settings' then 'Advanced' and under 'Extrusion Width' increase the 'First layer' and 'Top solid infill' by 5% or 10%.