Lines/ripples on layers

ToTo

My A5 lately prints visible lines on the xy surface, and it feels like ripples/ridges when running my finger over them (1st photo).  It's most obvious on the first layer (because of the black background, I guess).

Subsequent layers look less obvious (2nd photo), but the lines and rippling feel are the same...

The top (last) layer looks and feels really rough (3rd photo).  Sometimes it seems like lines are 'pushed' up by something (heat? air pockets? filament expands/contracts unevenly?)...

Has anyone had problem like this and know what causes it?

The z (side) surfaces are just fine.

Thanks!

Laser8302

looks a bit like over extrusion, or a bad nozzle. Try changing the nozzle and calibrating your E-steps per mm.

Samuel Pinches

Could be bed breathing? I agree - it could also be overextrusion.

ToTo

did a extruding test, and it seemed to over-extrude by ~ 6% (it extruded 106mm for a supposed 100mm extrusion). Is there a way to adjust to make it extrude correctly?  In the mean time, I tried to lower the extruding rate (to 95%), and it seems to help a bit, but the lines/ridges are still there (but less severe). 

One thing I noticed is that the top (outer) layer looks pretty dull/rough in appearance, though the layers underneath it seem to look shinier/better (I used a silk filament for these prints).  I already tried a new nozzle and the issue is still there.

Also, it seems like the lines are more visible for long nozzle movements.  For areas that nozzle moves ~ 30mm or less the lines are less and less visible or even disappeared.

Samuel Pinches

https://jgmakerforum.com/discussion/580/jgaurora-a5s-breathing-pulsing-bed

ToTo

yeah, I think the "breathing hotbed" issue makes sense, and that could be the cause of the issue I've been experiencing... (along with the over-extrusion).  Thanks everyone for your suggestions.

ToTo

I just observed the temperatures of the hotbed and hot end, and it looks like the hot end temperature fluctuates a lot, in a range of ~ +/- 3°C, every 10-15 sec or so.  The hotbed (set at 60°C) fluctuates just by -1°C (between 59 and 60°).  And I assume the readings shown on the printer's LCD is correct.  Could this temperature fluctuations be the main cause of my printer's problem?

Samuel Pinches

The fluctuations in temperature do not affect the severity of the bed breathing (if that is the problem you're experiencing). The breathing bed is almost instantaneous - the difference between ON and OFF are very significant. The problem is that the factory firmware uses "bang-bang" control of the bed heater.

By comparison, the custom firmware uses PID bed heating which should significantly reduce the severity of bed breathing.

ToTo

If the bed breathing happens only between on and off, and I normally wait ~ 15 min (after the printer is turned on) to start leveling the bed (i.e. the bed is leveled in its 'warped' position), then would bed breathing still be a problem?

Samuel Pinches

I think it still will be an issue, but I have not tested it. Best to try it and find out.