Odd printing artifact? (Page 1 of 2)

ok, to start with, IF things are properly calibrated, you should not ever 'need' to use infill overlap to correct an issue like this.
that setting is nothing more than a bandaid (and a poor one at that) for improper calibration.

next, depending on the slicer you are using (Slic3r is my preference), you should be able to adjust the extrusion width of the infill and/or perimeters to take care of filling in small areas more completely.

What layer height are you running? .3mm, .2mm, .1mm? That can make a big difference. (One of my work-arounds for similar problems)

Also, try rotating your print in your design program, like 45 or 22.5 degrees. Will change the angle that the fills go in. (Just make sure to save that oddly rotated file under a different name)

Just brainstorming. I don't know why it's doing that to ya... 

The layer thickness is .06mm.

I guess I need to find out how the slicer works as far as what it decides to drop vs include?  Is there some kind of gcode viewer that would read gcode and display clearly the extrudes?

I think most slicers will allow you to view layer by layer after slicing is complete, if that's what you mean. You can preview the extrusion paths and moves.

Well do keep in mind that when you design for printing walls are composed of perimeters. So the width of your wall has to divide evenly by the thickness of your perimeter which is .48 with a .4 nozzle.

To make it easier on yourself, I would not convert to inches unless you just have to. Leave everything in metric since the printers and the gcode where built around the metric system. It just makes sizing things much easier. You also have to keep in mid that there is not imperial equivalent for every metric measurement so some material is lost or gained through conversion.

I tell my customers my system is based on the metric system so if then need something printed and are supplying the design then they need to have done all the conversion to metric if the design was originally in inches. It just makes the math easier and things like perimeter versus wall thickness are easier to figure out.

If possible I would make your wall thickness 2.4mm that divides evenly with .48. You could also change your nozzle to a different size if the math works better that way as well. If your heat block supports discreet nozzles.

The .48 is the correct wall thickness for a .4 nozzle it is the standard thickness created by the slicer such as Simplify3D unless you select different or override it.

I adjusted the part dimensions, and the split between the shell layers went away.  I have printed many of these parts, and the odd gappy kind of looks like under extruding only started happening recently.  Possibly when I put a new roll of filament on the machine.  Odd, it's the same color, same vendor, Monoprice black ABS.  Although, the spool changed - the originals were wider, and didn't fit on the holder, so one of the first parts I printed was an extension..

I adjusted the filament flow setting up a little - now the rafts look a little over extruded, parts still about the same.  I just started a run with slower printing speed settings - Reduced them from default by about 20-25%

Checked the E steps, and measured the length VS commanded length.  E steps was 415, corrected to 417 to get exactly to 10mm for 10mm.  Made no significant difference in the print quality.

Ok, I seem to have confused a couple of things.

The setup I used to measure the length of filament was to clamp a machinist's scale to the frame, with the filament running parallel to it's edge.  In a straight line down to the extruder, so no bending to throw errors into the measurement.  A small tape flag stuck on the filament.  I could read a distance error in the .010-.020" range.  Much better than trying to use a tape measure or some other hand held method.  I understand that running 100mm would divide the error another 10x. 

The filament measures .067" to .0675"  Mostly .067".
1.75mm-.06889"  so it is slightly under.

In the IIIP Cura, there is a Filament  section, with a setting for diameter [set for 1.75], and another for flow, in %, set for 100%.

I wasn't sure if you meant to print 1 shell thickness or 1 nozzle width? - Anyway, I made a model and printed it to use as a dimension test - 

I ran a print of the part in the picture -
1.00" x 1.00"  x .094488 wall thickness x .200 high.
The corners are radiused so the wall thickness is the same all the way around.

It measures 1.00" x 1.00" x .095" wall  x .204" high.

2.4mm [=.094488] is the shell thickness setting in Cura.   The Layer height is .06mm

There are no gaps or weird places in this part, like there are in the others that have very short extrude & travel movements.

The sides look really good - in fact, the little weird "marks" near the corner look a lot worse in the picture than they are.  The other sides are clean.

I also ran some other parts in between posts, and they came out as well as any others of them I have made, if not better.  But they don't have those little short extrude and move areas.  Those seem to be where this printer is having trouble.

Could the retraction distance being too long cause trouble there?

in cura you set the shell thickness in mm   so I would assume you would plug in the .48 mm in the structure section