Layer gaps and shell issues!

[Mils24]

Hi guys

I am new to the forum and this is my first post. I have spent the last few minutes searching through for others who have posted about the same thing but cant find anything so apologies if I have missed threads and Im duplicating with this one. Any links to other threads is greatly appreciated!

I am new to 3D printing and recently received a Kickstarter Delta printer kit. I have it up and running and my first few prints have been pretty good. However over the past week or so I have started getting A LOT of missed layers / holes and gaps in layers as seen below or attached (new to embedding/attaching images too, sorry)

I have tried searching around various websites and forums for help and I just cant seem to get an answer for this.

Background info:
Heavy duty wooden frame Delta construction
High quality IGUS slider rails on each tower (nylon slider in alloy rail)
Carbon tubes with bonded in rod end bearings.
Models sliced in Cura
Board - Arduino Due c/w RADDS
Firmware - Retetier 0.92 (i think - 0.91 at earliest)
Printed in PLA
Heated bed - 65
Hot End - 210
Print speed - 50mm/s
Travel Speed - 150mm/s
Flow 100%
Retraction enabled
Nozzle size - 0.5mm
Perimeters - 1.0mm (2)
Top and Bottom infill - 1.0mm (2)
Infil 25%

Ive also tried various different PLA suppliers and all the same result. Note - the material is all kept in click seal bags with silica sachets in a box in a bookcase beside a radiator so I doubt moisture ingress to the PLA is the problem. I also have taken one of the spools I have in its bag and put it in the 'hotpress/airing cupboard' for a few days to drive out any moisture which didn't solve the problem.

I don't think it is software or firmware related as I have not changed any settings and have had prints that have had perfect shells without any problems shown above.

I am pulling my hair out trying to solve this and absolutely ANY help is greatly welcomed!!

Many thanks in advance

[DBFIU]

Looks like your extruder is skipping or maybe pinchwheel is slipping. Do you know how to remedy these problems? I had the same problems and my prints were doing just what you showed. Show me a picture of your extruder.

You might need to figure out if something is causing your extruder to encounter a ton of extra resistance, I am assuming you have a bowden style extruder because you said you had a delta printer, make sure it is easy to pull filament through your bowden cable and it isnt snagging or binding up. That can cause what you are showing.

[Mils24]

Hi DBFIU

I will add a photo of the Extruder tomorrow night after work as it is now 12.05am with me and I am in bed.

From memory it is an Airtripper Bowden extruder BSB edition from Thingiverse.
There are two adjustable screws to provide more or less tension on the bearing that rolls on the filament and I have tried tightening them and loosening them but it hasn't made a difference.
Maybe some oil may help? (Obviously only on the bearing and not the mk8 extruder gear)

I will also check the boden tube but I don't think there is anything stuck in it.
I will do a full strip down tomorrow night to see.

Thanks

[LambdaFF]

Have you tried pushing filament by hand at the entrance of the bowden tube through the (hot) hot end ? If you can't do it by hand, friction is too high in the tube + hot end. If you can perhaps your extruder is not powerful enough or as DBFIU suggested the pinchwheel needs to be retensioned. What does your kickstarter kit seller says ?

[Mils24]

Hey guys

I have tried what you said and pushed the filament by hand along the boden tube and out the hot hotend with ease so I don't think there is any blockages in the boden tube.

I have also tightened up the screws on the extruder guide wheel and still the problem continues!

I really don't understand how this has just started happening as it was fine just over a week or so ago, any other points I should check?

Thanks