Upper Layers Separating

I printed out a test 40mm cube (I didn't let it finish all the way) and noticed that some of the layers had tiny gaps, some had major separation. Also, I selected a 3 layer shell which looks fine, but the outside layer in same cases seems to not have bonded to the 2 inner shell layers.

Which SF settings should I be playing with to fix a) the separation of layers, b) the shell layers not bonding?

SF has it printing at 210 C for base layers, 195 - 200 C thereafter. My heated bed is at 88 C.

Thanks for the expert advice!

Separating /warping layers:


Outside shell not bonding to inner shells:
[goo.gl]

Top view of shell not bonding. I nudged it out with a pin just to show:
[goo.gl]

Which version of SF are you using? If 40 and above, you decrease the Filament Packing Density Ratio. If before that, then increase the flow rate. If you measure the width of the filament, then you can calculate the ratio of this measurement to the expected width and apply that as the correction to those flow parameters.

If you think you have everything calibrated correctly, just increase the infill perimeter overlap by .05 at a time until you get it to stick.

Otherwise, observe the following:

I'm assuming you have the diameter and firmware extruder steps/mm set correctly.

To adjust SF:

To do it right, make/download a 1" cube.

Print said cube with line infill at an infill ratio of 1. The width over thickness should be 1.3-1.5 for the infill and perimeter. 1.3 spans gaps better, 1.5 makes stronger/faster parts.

Start printing cubes. You can stop the print after about the 5th layer to see what the inside looks like.

Increase the flow rate setting until the infill lines are meeting nearly perfectly. you don't want to mush them all together, nor have big gaps. Once the inside looks perfect, then increase the perimeter overlap by .05 until it sticks if it doesn't already.