Suddenly gaps on Z-Axis

Morning.

I am suddenly getting random gaps between layers. I'm using a Mendel90, all original, and tried two different brands of PLA with the exact same issue.
I'm printing at 195°, 60° bed temp. 0.3mm layer height, 50mm/s print speed, 40mm/s outside perimeter speed. This is happening at any infill amount.
I just got out some older items I printed and they don't seem to have this issue. Any ideas what could be causing this (see attachment)? That's an otherwise smooth side wall of a box.
The gaps are big enough to feel, I can even get a fingernail into some of them. It can't be bed calibration I think, otherwise they'd occur in the same spots, no?

Have you done a warm pull on your filament? I.E. changed the filament by setting your hotend to 80c and pulling the plug of filament out of the hotend to clear anything that might be causing an issue?

Tried that just now, didn't help. Still the same issue, and never at the same layer even with identical settings.

Have you looked through your gcode to see if it is in fact solid where it has gaps?

Yes. Those gaps are too small to actually be on purpose too, and will appear in randomly different spots even if I print the same gcode twice.

does the filament coming of the spool look ok its freely to move

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it might be the fillament is to saturated with moisture , do you have any other fillament to try with? , or cut out 100m of fillament put it in the oven at 50C for 1h mybe 2h and see if it improves with that part of the filament. i had simular isues but larger holes

Edited 1 time(s). Last edit at 04/29/2015 03:43PM by Darathy.

also check that it comes of the spool correctly slight pull can make it stop pushing filament through

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Check my rubbish blog for my prusa i3

up and running
[3dimetech.blogspot.co.uk]

I tried several different filaments and brands, and all filament is stored in airtight containers with moisture-binding pellets.
It worked flawlessly just some weeks ago in this exact setup.
I also replaced the wades block completely, since mine had several cracks.. unfortunately, it also made no difference.

Maybe your stepper motor is skipping steps randomly.
Is the tension on your stepper driver correct? Does the print improve if you increase your voltage slightly on the trimpod?

Regards,

Thomas

when the filament unwinds of the spool it can get trapped so it cause a pull effect that may cause issues

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Check my rubbish blog for my prusa i3

up and running
[3dimetech.blogspot.co.uk]