1

I’m setting up a new Ender 3 and I printed a pretty respectable Benchy with one weird flaw, Please look at the image, what is going on here? Cooling fan not putting out enough cooling? Too high a print temp? Or something else?

https://imgur.com/Fy3CfIC

Thanks
-Bob

2

Pretty typical issue for a Benchy and likely a cooling issue.
Since you don’t include any settings, materials or slicer hard to advise.

3

.12 layer height, I was trying Chep’s magic numbers for Ender 3, Prusa PLA and sliced on Slic3r. No cooling on first layer, 100% fan on layer 2 and beyond.

Incidentally I had a benchy I printed at .15 and it had the same raw spot in the same place but was about 1/3 the size.

Cheers
-Bob

4

Try a 0.2 layer. I find the thinner layers have more tendency to curl or otherwise have issue with heat when on an overhang.
Also you can try to point the bow more directly at the fan outlet.

Lower bed temps as much as possible and also extruder temp.

Sometimes using a raft with 1 or 2 layers that is a fair amount larger than the perimeter of the model can shield the lower overhangs of the model from bed heat a bit.