Gaps / Holes in Prints

All,

I see gaps/voids/holes in my prints. . Strangely, there are more gaps on one side of the print than the opposite side , and this happens even with some prints laid out 45° off axis. Also happens when 2x of the same model is printed at the same time - the same faces (often more than one) have gaps. Also, the gaps seem to follow a pattern, which makes me think this isn't a filament issue but something with the printer or controls.

I have a MendelMax 2.0 and have gone through most of the Reprap wiki calibration page. In the attached " " image, you can see a really nice 0.5mm cube test. The overhang test failed and I will have to tweak that later.

I've tried the following:

1. Increasing extrusion rate using M92 Ennn and M221 Snn (in separate trails) through Pronterface. This doesn't fix the issue - it just overfills the layers. You can somewhat see that the 20mm cube printed with high / extra material at the corners. The waviness of the cube went away after I installed Z carriage isolators.
2. Increasing temperature (this only makes the parts more brittle)
3. Adding a wiper to the filament (cotton scrap ziptied around the filament before the extruder)
4. Isolating the Z carriage (using Ohmeye's isolators). These helped with print quality. Now my gaps are straighter

I'm printing PLA at 180°C with a 60°C bed using "stock" settings - 30mm/s with 0.300mm layers and have the curved fan duct and spool holder installed.

Any tips would be appreciated!

Edited 1 time(s). Last edit at 08/18/2013 11:36PM by Filip.

Have you checked the tension on the extruder idler, and cleaned the teeth of the filament driver (hobbed bolt/gear, depending on your machine)?

If the teeth are partly clogged (due to too high or too low idler tension) it can slip at the same place, producing a pattern that repeats like that.

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-Nudel
Blog with RepRap Comic

Thanks for the help.

Actually I'm afraid to admit that my issue was way less complicated than I made it out to be.

In Slic3r, I had the external parameters setting set to 100, not 100%. The whole part would print at 30mm/s, until it would hit the perimeter where it would try and speed up to 100mm/s. The extruder couldn't keep up and gaps were the result. The printer would speed up for the infill anyway, and I printed almost half of the spool watching the printer speed up and slow down and never made the connection.

This issue drove me insane and I feel like a total idiot for skipping over the settings so quickly. Thanks for the help, I'll be sure to remember the gear teeth in case I see the gaps again.