What Slic3r settings would correct this?

I'm printing this object and I'm getting some defects in the gcode that slic3r produces. At first I thought my printer was missing steps or not extruding plastic when it should, but the gcode shows the same defects my printer is printing. If you look at the files I've attached, you'll notice a small "ridge" near the bottom of one of the vent slots which looked to me like a missed step since the ridge is on both sides, but the gcode shows the ridge there at the same spot and it's only on the 2 fan vent slots and not the rest of the object. Also, you'll notice the walls aren't connected and there is a small gap. Another problem is that the width of the part isn't right. The STL file has the width of the top of the fan vents as 1mm, but I measure about 0.58 mm with my calipers. The comments in the gcode says Slic3r is using a 0.7 mm extrusion width. I'm using Slic3r v0.9.8 and my extrusion width is all set at 0 (auto) except first layer which is set to 200% (default settings). Overall, it's still a usable part but I'd like to know what is causing the defects.

Set the default extrusion width to the same value as the size of your nozzle.

You are getting a .58mm wall because the auto-calculated extrusion width is wrong. If it is auto-calculated to .7mm then the gcode will only make a single pass in a 1mm wall. If you have a .5mm nozzle, set the default extrusion to .5mm, and you will get two extruder passes in a 1mm wall. 1/.5=2 as 1/.7=1.4286. At a setting of .5mm with an actual of .58mm you will get a good overlap/bond between the two extruder passes the make the 1mm model wall.

Auto-calculated extrusion width has never worked for me. Manually set to your nozzle size, you will get much better print results overall.

Your print is probably tearing at the corners because you are only printing a single extruder wall at .7mm, and may be a little hot on your extruder temp.

You may have to recalibrate your extrusion multiplier a little as well with the manual extrusion width value.

Edited 1 time(s). Last edit at 03/31/2013 08:02PM by Dirty Steve.

I looked a bit closer at the STL file and the sketchup file and I realized that the fan vents differ in their thickness! They range from 0.7 to 1.0 mm. If I set slic3r extrusion width to 0.5, then the one side that's 1mm prints 2 layers, but the other sides only print one. So it seems I need to correct the model, calibrate my extrusion multiplier and set a width of 0.5 (my nozzle diameter). As far as my temp, I'm running at 185 degrees and I'm using PLA, should I try going lower?

Maybe just a few degrees lower temp, depending on your results with the .5mm extrusion width.

Try setting retraction at 1 or 2mm, 30mm/sec speed. That will clean up a lot of the blops and strings on the edges.