I have trouble fixing the terrible seams I’m getting. I’ve followed Elli’s print tuning guide and calibrated extruder, tuned PA (it’s now 0.035) and extrusion multiplier.
I’ve tried adjusting both retraction length and speed, but it doesn’t seem to have much impact. I’m not using “wipe on retract” or “retract on layer change”, I only retract if travel distance is longer than 3mm. Retract is 0.3mm @35mm/s.
I’ve tried reducing PA smooth time too, but this also doesn’t seem to have a noticable impact.
I’ve tried reducing seam gap from the default 10% in Orca all the way down to 0%, but the bad seams persist.
I’ve tried with “wipe on loops” both disabled and enabled with no difference.
I’ve tried with both arachne and classic wall generator, no difference.
I’ve tried different wall orders, inner/outer, inner/outer/inner and outer/inner, all with the same bad seams.
Filament in the picture is matte PLA, it is without doubt dry and generally prints well aside from the seams. It’s stored vacuum sealed with silica, and I use a filament dryer to dry if I suspect wet filament.
I’m running out of ideas for where to tweak to get a decent result.
I have one just like that on my scrotum and was told it’s normal so I wouldn’t worry about it too much.
Randomize Z seam and make sure your flow/retraction settings are as good as you can get them.
Messing around with your nozzle temperature might help too: Keep in mind that the thermistor in the heat block might be off by a few degrees so if you can measure the temperature directly as a comparison, it can help you figure out how much it’s usually off by and adjust accordingly.
Randomised seams just spreads the issue out on the entire model surface, it looks even worse like that.
Randomize Z seam
There is never a situation where this is a good setting to have on.
Most probably PA. You should try adjusting it while printing using some g-code console. This way you get immediate feedback. What they often don’t tell you is that pressure advance is not something you can calibrate once and forget, it’s dependent on material, temperature, nozzle diameter and also a lot on feed rate and extrusion rate.
The need for PA and precise tuning is more pronounced the higher changes in extrusion rate you have eg, you print very fast or with wide or high layers.
Just play around with it a bit and I’m sure that you’ll find a better value after some layers.
There are even macros that try to remove the feed rate dependency by effectively replacing every g-code that adjusts feed-rate by a combination of the original g-code pre-ceded by an adjustment of PA. I haven’t tried them out yet though.
What’s weird is the differences of the effect between the layers. Is the every layer the same or is the path different for different layers? Maybe post some images of the inside of the model.
This is a good idea. I will further add that Klipper lets you dick with the linear/pressure advance parameters mid-print via GUI with its Fluidd interface. Other systems probably have similar capabilities.
A good test model for this might be a thin walled hollow cylinder with the Z seam facing the user (i.e. out the door or front of the machine) only 2 layers thick or so. That sounds like it ought to make the issue visible quickly, and with minimum of wasted time and filament on infill (not to mention ruined parts).
_ I’m not using … “retract on layer change”_
There’s your problem.
No, I’ve tried with that enabled as well, same issue. This isn’t before a layer change, it’s when it goes from extruding the walls to extruding the infill.
But even without infill this happens. It’s the end of the outer wall that doesn’t connect to the beginning of the outer wall and it’s not really fixed by reducing seam gap, so I’m not sure what’s actually causing it.
Disclaimer: I’m not into 3d printing. I’m just a wannabe with not enough time on my hands, so take this post with a bucket of salt. I have, on the other hand, worked a lot with automated machinery.
But if I were to make a guess, I would suspect some slack in either the X or Y direction, resulting in inaccuracy when the nozzle changes direction. This should in theory be less visible when the nozzle is not making sharp turns.
Are your belts tight? Any gears with poorly meshed teeth?
Also, are you able to turn the print (and the seam) 45 and 90 degrees? Do they show up just as ugly? If not, the issue is mechanically limited to one axis.
