Blob on perimeter start after Gap Fill

I have been tackling a issue for some days now, and i was able to pin point in what exact situation it occurs. Every time there is an extrusion for a Gap fill just before a perimeter start, i get a blob on the start of the perimeter that also translates most of the time to a unveven line of extrusion. I have tried this with SuperSlicer (2.4.58.5 and 2.5.59.0), tried with PrusaSlicer also. Im not completely sure if this is a problem with the Slicer, firmware or printer configuration. I think printer configuration might not be as i would have the same problem elsewhere. I found also that the line width was too big in some case and tried to reduce it, but it sill shows. Only thing that completely eliminates it is turning off gap fill. If that is off i get a seam that is very good and no blob. Tried with both normal Gap Fill and Arachne, in both cases the blob/ungly start layer is present.
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23 Replies
3DBoomer
3DBoomer2y ago
have you tuned pressure advance ?
genetic-orange
genetic-orange2y ago
Yes, on or off makes no difference Blob still forms
3DBoomer
3DBoomer2y ago
But have you tuned PA for this precise filament @this temp and speed ?
genetic-orange
genetic-orange2y ago
yes i did
genetic-orange
genetic-orange2y ago
genetic-orange
genetic-orange2y ago
this is the gcode for the benchy in black i also tried with latest prusaslicer on my mk2.5s, and same thing happens, not with the same amount of blob, smaller one, but still, its still there im starting to think this as something to do with the slicer, since superslicer is forked from prusaslicer
Yathani
Yathani2y ago
Arachne is causing more problems that it helps on SS .. try to work with the classic mod. Does this happen at the end/start of each line or only on gap filling? it could be your retraction speed where you might need to lower your deretraction speed
genetic-orange
genetic-orange2y ago
it happens on both arachne and classic. If the previous feature was a gap fill/arachne generated line, theni get this blob Its on start of each line after it does a gap fill. I think i tried 60 and 80, can try to go even lower. On the benchy at least, when the travel is longer, it seems to not impact as much as when its close, but then there are some that are very close but are not impacted as much also the only thing that really is common between them is gap fill before
Yathani
Yathani2y ago
Things I would try is to lower the temp of the print, ensure you have a minimum travel before retract set to 1.0mm a least or you could try different slicer like Orca slicer which has prepare profiles. I stopped using SS long time ago
adverse-sapphire
adverse-sapphire2y ago
@pmelim : Do you print extern perimeters first?
genetic-orange
genetic-orange2y ago
yes, but even if i dont, it can show a on the outside by buldging a bit but its more apparent when its external perimeter first
adverse-sapphire
adverse-sapphire2y ago
But if the external perimeter is printed after the internal, but before the infill, then the gap fill should not matter, should it?
genetic-orange
genetic-orange2y ago
depends on the part, for the benchy it prints the outside hull and then moves to the inside, ill do some screens
genetic-orange
genetic-orange2y ago
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genetic-orange
genetic-orange2y ago
does perimeters of the boat on the outside, then gapfill, then goes to the inside and does the perimeter and even if you have a part that doesnt have insland, lets say a hollow cube the gapfill will be the last thing it will print before layer change, and that will also be a problem
genetic-orange
genetic-orange2y ago
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adverse-sapphire
adverse-sapphire2y ago
Would you mind printing the XYZ calibration cube? https://www.thingiverse.com/thing:1278865 And after printing switch external first off
genetic-orange
genetic-orange2y ago
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genetic-orange
genetic-orange2y ago
forgot to adjust PA for this so only after some layers i was able to adjust different filament than the other ones
adverse-sapphire
adverse-sapphire2y ago
Ok, but why did you not put the seam at the edge? To make it comparable Since it it's quickly done: I would do it again
genetic-orange
genetic-orange2y ago
was a mistake, its placed on the rear and had to rotate the square with perimeter inside first, overall quality suffers, and i can see a buldge in the same layers that before had a blob, even tough they had incorrect PA one thing that iam now seing, is, i also tried the experimental feature from PS that allows to equalize pressure when going from from feature to feature, and gap fill does not adjust using that and in this last cube, the buldge happens on layers that dont have gap fill but do have solid infill with big layer lines i really tried my best to reduce volumetric flow on my test but maybe i was unable to somehow, and that really is what is causing the issue
adverse-sapphire
adverse-sapphire2y ago
@pmelim : Have you tried orcaslicer yet?
genetic-orange
genetic-orange2y ago
not yet, will try today or next few days, printer is busy printing parts for a client
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