Cura seems to be leaving a section of wall unprinted

[flyfishingdad 0]

I've been making cookie cutters and chasing my tail when it comes to a particular issue. At first I thought it was a calibration issue with the machine (ender 3) or some settings causing under extrusion. On the inside wall of the cutter there would always be a section in which the outside perimeter did not print. When reprinting after changing settings it would still be there, in the same spot, same issue. I am using Cura 3.6

[flyfishingdad 0]

Also, while waiting to have this post approved, I downloaded cura 4.0 beta and tried that, same problem occured. 

[gr5 2,005]

Did you look at this in layer view?  Always check in layer view before you print it.  If it's missing in layer view then it will be missing on the print.  Guaranteed.

 

Also look at the part in xray view.  If you see any red in this area then that's almost certainly the problem.  Post screenshots of the problem in layer view and normal view and xray view please and you should get lots of suggestions.

[flyfishingdad 0]

Nope it looks all good in the layer preview. Shows a nice solid red shell line being laid down. The total thickness of the cutter is only 1.2mm at that point so it lays down a middle line and an outer shell line on either side. First thing I did was check to see if for some reason it was skipping totally. It goes over it, according to the preview, but if it is doing the same thing with the hotend, then for some reason it's not extruding any filament when it passes over that spot.

[flyfishingdad 0]

So, something I noticed, when changing a couple settings. I tried optimizing printing order, it changed the way it printed it, and at first glance I thought, YES it worked, but upon a closer look, it simply moved the problem to another area. So, I looked at the the preview a little closer, and I noticed something. This new problem zone shares something in common with the previous problem zones. Both problem zones are right where the line starts. So for some reason, its starting to print there, but there is no filament coming out for the first 10 millimeters or so. I tried reducing retraction settings to 3mm, didn't fix it. (but it did bring back some stringing that my 5mm retraction settings eliminated) What could be the deal? There are other spots in the print where it starts a new line that DON'T have this problem, it is just one spot, and seems to happen on several of the cookie cutters I have printed.

[burtoogle 508]

Assuming that you are using the right amount of retraction, the most likely reason for this is that you are using combing and it is doing a long un-retracted travel before the bad zone. So set the max combing distance without retract value to something like 10 and will make the combing use retraction for the longer travels.

 

[flyfishingdad 0]

Xray looks good. Already tried changing distance before retract, so I turned off combing altogether. No luck there. Tried printing outside walls first, no luck. Ugh. Frustrating.