Strange infill gaps Hi, I have a strange infill issue on large prints. For the first 4 layers or so, 100% infill looks good. However afterward, there are pretty large gaps in the infill (it looks like 95% for all intents and purposes), which means small holes in the end model as well as reduced part strength. Small parts however print just fine, with no gaps between the top infill lines. Hints at underextrusion, but the lines are still smooth and continuous, and there is no indication of filament grinding (I can usually hear it pretty well when it does grind). I tried a number of things: Increased the infill multiplier by over 20%, still gaps in later layers. Possibly smaller, but I can't tell easily. Tested the thickness of the problematic infill layer, it appears to be .20mm as it should be, so it's not z axis moving too much. Made sure z axis is moving correct amount of mm overall (calipers and calibration model, spot on) I can increase the extrusion multiplier further, but I'm worried at this point my bottom layers will turn out badly, it's already 1.1. My e steps are well-calibrated (recently too). Anyone experienced something like that or has any ideas? Thanks Prusa i3 rework Printing with natural PETG at 255 C https://reprap.org/forum/read.php?262,737175,737175#msg-737175 Sun, 09 Aug 2026 19:15:32 -0400 Phorum 5.2.23 https://reprap.org/forum/read.php?262,737175,738860#msg-738860 Re: Strange infill gaps https://reprap.org/forum/read.php?262,737175,738860#msg-738860
Now suspecting moisture in previous roll. Or just bad filament. At some point will dry the old filament and try again.]]> anvoice Printing Sat, 14 Jan 2017 21:14:51 -0500 https://reprap.org/forum/read.php?262,737175,737893#msg-737893 Re: Strange infill gaps https://reprap.org/forum/read.php?262,737175,737893#msg-737893 anvoice Printing Wed, 11 Jan 2017 23:02:12 -0500 https://reprap.org/forum/read.php?262,737175,737890#msg-737890 Re: Strange infill gaps https://reprap.org/forum/read.php?262,737175,737890#msg-737890
Quote

hard to see with clear filament so I usually went by touch to check for gaps

That brings back memories. When I started I assumed that the natural filaments would be the easiest to print with, so that's all I ordered. Then I discovered how hard it is to judge over or under extrusion with clear filament!]]> JamesK Printing Wed, 11 Jan 2017 22:02:27 -0500 https://reprap.org/forum/read.php?262,737175,737887#msg-737887 Re: Strange infill gaps https://reprap.org/forum/read.php?262,737175,737887#msg-737887
Unfortunately I don't have other colors to test at the moment, only 2 more rolls of natural eSun in the mail. I sincerely hope I can get this to print, as I prefer natural, and have already printed numerous good parts with PETG (mostly with the MatterHackers filament).

I'll report back if I manage to solve this problem for the eSun PETG or if the new rolls print better. In the meantime, still gladly taking suggestions.]]> anvoice Printing Wed, 11 Jan 2017 21:07:46 -0500 https://reprap.org/forum/read.php?262,737175,737769#msg-737769 Re: Strange infill gaps https://reprap.org/forum/read.php?262,737175,737769#msg-737769
With softer/lower temp filaments I've had problems later in a print where the filament was heating up as it passed by the hot stepper motor on the way in to the extruder which caused symptoms like you describe, with gradual under-extrusion developing. However, I haven't seen that with high temp filaments like PETG. (I solved the problem by using a piece of PTFE tube to insulate the filament from the motor for about 5 cm before entering into the direct drive extruder.)]]> JamesK Printing Wed, 11 Jan 2017 13:26:45 -0500 https://reprap.org/forum/read.php?262,737175,737537#msg-737537 Re: Strange infill gaps https://reprap.org/forum/read.php?262,737175,737537#msg-737537
I will next try different printing speeds and report how these turn out.

Biggest mystery though is that I've successfully printed this exact model before with a twin roll of eSun PETG, at the same exact settings. Problem seems to have started when I switched rolls, but no guarantee that that's the cause.

Edit: confirming gaps even at 10mm/s, as well as 30mm/s. Doesn't seem to get better with low speed (or higher speed).]]> anvoice Printing Tue, 10 Jan 2017 20:47:01 -0500 https://reprap.org/forum/read.php?262,737175,737255#msg-737255 Re: Strange infill gaps https://reprap.org/forum/read.php?262,737175,737255#msg-737255
This is a bizarre issue, are there no clues as to what might be causing it?

I've never tried honeycomb, does that print 100% infill? Can't imagine what that would look like. I can also try lowering my temps, but I seriously can't see a higher temp producing this problem.
Thanks.]]> anvoice Printing Tue, 10 Jan 2017 04:27:39 -0500 https://reprap.org/forum/read.php?262,737175,737220#msg-737220 Re: Strange infill gaps https://reprap.org/forum/read.php?262,737175,737220#msg-737220 Or try to use a different pattern for the infill. In my experience long straight lines are the worst, so try out Honeycomb or Hilbert curve for a change.

I had good results with 238°C and 30mm/s.]]> o_lampe Printing Tue, 10 Jan 2017 02:42:04 -0500 https://reprap.org/forum/read.php?262,737175,737175#msg-737175 Strange infill gaps https://reprap.org/forum/read.php?262,737175,737175#msg-737175 I have a strange infill issue on large prints. For the first 4 layers or so, 100% infill looks good. However afterward, there are pretty large gaps in the infill (it looks like 95% for all intents and purposes), which means small holes in the end model as well as reduced part strength. Small parts however print just fine, with no gaps between the top infill lines. Hints at underextrusion, but the lines are still smooth and continuous, and there is no indication of filament grinding (I can usually hear it pretty well when it does grind).

I tried a number of things:
Increased the infill multiplier by over 20%, still gaps in later layers. Possibly smaller, but I can't tell easily.
Tested the thickness of the problematic infill layer, it appears to be .20mm as it should be, so it's not z axis moving too much.
Made sure z axis is moving correct amount of mm overall (calipers and calibration model, spot on)

I can increase the extrusion multiplier further, but I'm worried at this point my bottom layers will turn out badly, it's already 1.1. My e steps are well-calibrated (recently too). Anyone experienced something like that or has any ideas?
Thanks

Prusa i3 rework
Printing with natural PETG at 255 C]]> anvoice Printing Mon, 09 Jan 2017 20:56:35 -0500