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I'm facing a weird problem I cannot understand why it happens. Most of my objects have a large planar base so I don't have any adhesion issue. I'm using a PLA Silk gold filament from eSun (filament dryer is on while printing) and a Dremel 3D45 printer.

This is the bottom (first layer) of an object printed directly on the (glass) bed:

enter image description here enter image description here

Then I tried another object (very similar) using a raft. The raft itself is almost perfect:

enter image description here

But, again, the first layer of the actual object (only 0,1 mm air gap from the raft) has the same problems of the first one:

enter image description here

The most relevant settings I'm using in Cura are:

  • layer height: 0.2 mm
  • initial layer height: 0.3 mm
  • top/bottom line width: 0.4 mm
  • initial layer line width: 100%
  • top/bottom thickness: 0.8 mm
  • nozzle temperature: 205 °C
  • nozzle temperature initial layer: 210 °C
  • bed temperature: 60 °C
  • bed temperature initial layer: 65 °C
  • print speed: 50 mm/s
  • print speed initial layer: 25 mm/s
  • cooling: 100%
  • initial fan speed: 0%
  • regular fan speed at height: 0.3 mm

I enabled the auto-calibration before each print.

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Based on the scarring and the appearance of the printed holes, it looks as if the nozzle to bed distance is not good, it is probably too large (could be too close as well, if you consider the scarring where the nozzle might have picked up already deposited material). The bed is also quite hot, for PLA you could drop this to 50 °C

Note that an initial layer height of 0.3 mm is also quite large, it causes a lot of material to be deposited while there might be too much/too little room for the amount. Printing on glass should give you a shiny mirror glaze finish (unless the glass is textured); the images don't express that feature from printing on glass build platforms.

A raft generally shouldn't be necessary for PLA (but some exceptions may apply), but certainly not for large planar based prints with a decent amount of surface area in contact with the bed. It is hard to get a nice surface on top of a raft/support structure.

Rafts generally print very well as there is extra space in between the deposited lines, and there usually is some over-extrusion.

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  • $\begingroup$ Rafting here was just an experiment. I'm going to play with the initial layer height but I have some issues to find the best nozzle gap. The Dremel procedure is long and (to me) seems not so reliable. By the way under 50 °C the PLA does not stick to the bed (even with the purple glue) and the manufacturer suggests bed temperature up to 60 °C (comments on Amazon says this as well). $\endgroup$
    – Mark
    Sep 30, 2022 at 6:15
  • $\begingroup$ I got a very shiny finish on the bottom raising the initial layer flow to 105%. But the down side was it detached easily from the second layer! $\endgroup$
    – Mark
    Sep 30, 2022 at 6:17
  • $\begingroup$ This hints more to an incorrect nozzle to bed distance. You shouldn't change flow of the first layer, normally there are already modifiers at play for the first layer. $\endgroup$
    – 0scar
    Sep 30, 2022 at 9:46
  • $\begingroup$ Ok. Do you suggest to change the nozzle gap + or - 0.1 mm, try to print and see what happens? $\endgroup$
    – Mark
    Sep 30, 2022 at 12:47
  • $\begingroup$ You can easily redefine the height by editing the G-code file, see How to set the Z home offset or this answer. $\endgroup$
    – 0scar
    Sep 30, 2022 at 20:17

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