Hi everybody, this is the bottom side of a printed item,

3D Printing
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1

Hi everybody,
this is the bottom side of a printed item, as you can see, it appears as a ‘snake skin’, and that cause a bad removibg of the brim. I don’t know why it happens… I use a selfmade Kossel, glass heated bed, first layer 0.24, layer 0.2, 0.3 nozzle, 60 mm/sec, first layer goes at half speed. Thanks.

df21c7945975c92e0facb3dd24781b55.jpeg
df21c7945975c92e0facb3dd24781b55.jpeg4160×2336 3.3 MB

2

Absolutely nozzle too close to the bed.

3

I wonder if this is with every 3d model or just with that. Maybe the model was not 100% flat on the virtual surface before slicing.

4

I have noticed this effect with thicker initial layers and over-extrusion. Correcting the over-extrusion fixes it for me.

5

thanks all, @Neil_Darlow I don’t think about over extrusion, all work fine except this particular problem; @Tinkering_On_Steroid obviously the model is flat and gcode too; @Mark_Rehorst and @Ryan_Carlyle I use the ‘paper sheet method’ to calibrate Z axis, I always find the stronger point of contact, may be am I wrong? have I to use more space between paper and nozzle? the bed is calibrated very fine, I have the same ‘paper force’ under the nozzle in center and on three axis points (I have a deltabot)

6

It would be more helpful if the image had a mark from a marker or an arrow added digitally to show where the brim is.

7

it’s not necessary : you can recognize the brim easy, it’s the lighter red bord

8

I use a broken kitchen knife mounted in a pen tube. I bend the brim to a 90 degree or so angle, run the knife over it a few times and the edges come out slightly rounded off and smooth. That technique should work for you regardless of how stubborn your brim is.
By the way, what slicer?

9

You also had a color change behind the object, so it confused me.

10

@Dario_Marrini The “bacon” or “snakeskin” effect happens when the extrusion strands in the first layer become too wide. This makes the nozzle partially go back over previous strands, which means the freshly-extruded plastic gets squeezed out to the side. This creates the ripples you see. It’s a very common issue.

But why are your first layer strands too wide? Usually, it’s because the extruder is pushing too much plastic for the amount of space that is available. Possible reasons:

  • Your nozzle gap may be set too close, say if your piece of paper is thinner than your slicer expects you to use.
  • You may have a first-layer Z height offset set in your slicer that is included in gcode but not present when you manually level.
  • Your slicer settings may simply extrude more volume for the first layer to improve adhesion.
  • You may be over-extruding in general, but only notice it on the bottom layer.
  • If you level and THEN preheat, the bed may be expanding when it heats.
  • If you level and THEN add an adhesion layer like gluestick or hairspray or tape, your gap may be getting smaller after leveling.
  • Your print bed could be “crowned” or shaped like an upside-down bowl, and thus higher where you are printing than at the edges where you are leveling.
  • Since this is a delta, it could be your arm length is calibrated just a little bit off, and the nozzle is actually moving closer to the bed in the center than at the edges.

You can rule out the last two if you level at bed center AND next to each tower. Then focus on the slicer and setup possibilities.

11

I agree with what @Ryan_Carlyle ​ said. It seems you can rule out the last two based on your previous comment.

12

Try First layer at 0.15mm , 30mm speed .
I use always for the first layer half diam. of nozzle and works always fine for me , even for other diff. layer hights