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fabnavigator
(@fabnavigator)
Eminent Member
Tiny holes in printed walls

I recently posted about blemishes printing clear PETG. I switched to urban grey Prusament and now I clearly see that I have tiny holes in the walls. I'm using the standard PrusaSlicer settings for PETG and the MK3S. A google search found a similar image and they said the root cause was too much retraction. Is that it, or does someone know of other causes for these holes?

I'm using the standard Prusament PETG filament override settings of 1.4 mm retraction and 0.2 z-lift.

Posted : 11/01/2021 8:55 pm
bobstro
(@bobstro)
Illustrious Member
RE: Tiny holes in printed walls

If the issue is retraction, those holes should correspond to the z-seam created as the nozzle is moved from layer-to-layer.  Try changing Print Settings->Layers and perimeters->Advanced->Seam position to Aligned or Rear if it's not already. That will line up the seam transitions. The holes should line up then. 

From the picture, I'm not convinced that's what you're seeing. It looks like you're having a little under-extrusion overall. I'd try slowing down your external perimeter speed (I use 25mm/s) and maybe increasing heat slightly and see if that closes up those lines. Make sure your extrusion multiplier isn't too low.

My notes and disclaimers on 3D printing and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan...
Posted : 11/01/2021 9:51 pm
fabnavigator
(@fabnavigator)
Eminent Member
Topic starter answered:
RE: Tiny holes in printed walls

@bobstro

The holes do not line up with the layer changes. They are definitely random.

I like your thought about under-extrusion. I'm using the default setting so my external perimeter speed is already 25 mm/s. Extrusion multiplier is 1. I'm printing at 250 degrees.

Some additional information:

1. The model I printed with the holes has a wall thickness of 1.2 mm (three perimeters).

2. I normally print similar models with 1.6 mm walls (and they have never had holes).

3. I reprinted this model with 1.6 mm walls and there aren't any visible holes. I assume they are hidden behind the fourth perimeter.

I would like to fix this, because originally I was printing in clear filament, and a hole, even if it's hidden within the wall will be visible.

Sounds like a little more heat, slow down a little, and increase the extrusion multiplier a bit.

Thank you for your help.

Posted : 11/01/2021 11:51 pm
fabnavigator
(@fabnavigator)
Eminent Member
Topic starter answered:
RE: Tiny holes in printed walls

In regard to item 3. above, upon closer examination I see a small number of holes on the inside wall of the model.

Posted : 12/01/2021 5:20 pm
pavel.kolev7
(@pavel-kolev7)
New Member
RE: Tiny holes in printed walls

I’m having the same issue! Did you find a solution?

Posted : 07/12/2021 5:26 am
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