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I'm a novice in 3D printing. I have a Lulzbot Kittaz 3D printer with a hexagonal hot end of 0.35 mm. I have printed a test subject, and while I was printing I encountered this extrusion problem. I'm using ABS with 230 °C hot end temperature and 85 °C bed temperature. What kind of problem is this and how should I rectify it?

I took this photo when the printer printed the first layer:

First layer of print

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It looks like you are not extruding at the correct rate. I would check your slicer settings for nozzle and filament size. Also check and calibrate for your filament diameter.

It looks like you could be getting better adhesion too. Lulzbot recommends a 110C bed temperature. That might help. (lulzbot.com/store/filament/abs under specifications)

These are some good resources to troubleshoot prints,

RepRap

All3DP

Simplify3D

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As Jmb2341 suggests, this over extrusion could be due to an excessive feed rate.

However, I would also like to add the possibility of your Z-height during the first layer being too close. For instance, if your first layer height is set to 0.4mm, but your print head actually moves as close as 0.2mm from the bed, there will be twice as much filament extruded than what it is actually room for below the nozzle. This, in turn, will appear like over extrusion, while the issue actually is your Z-leveling/height.

In general, unless you are using a raft, the amount of first layer over extrusion will often have to be balanced with the prints ability to stick to the bed. In other words, over extrusion during the first layer improves print stickiness, so that close bed leveling gives sticky prints but first layer over extrusion; while, distant bed leveling gives loose prints with more accurate first layer extrusion.

If you are wondering whether what you are seeing is over extrusion due to excessive feed rate or too close bed levelling, then you should try to inspect the extrusion of the top layer of some of your prints: If the top layer looks fine, your bed is leveled too close; however, if the top layer is over extruded as well, then your feed rate is too high.

Good luck!

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    $\begingroup$ You're right about the nozzle standoff. If it's a Z-height issue, then you'll see "over extrusion" throughout each layer. Unfortunately the photo doesn't tell us if that's the issue. However it is important to note that, if you can, specify the first layer (or few) to over extrude with ABS, you can reduce the chance of warping. The more surface area, the better with ABS. $\endgroup$ – tbm0115 Nov 1 '16 at 14:33
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Two things come to mind. First it is the first few layers. You could have the head Smashing into the print bed. Causing a massive build up of plastic the first few layers. And or you have over extrusion.

  1. Take a piece of paper. you want the distance from the head and the bed to be that width. Just enough friction to feel a light drag.

  2. After that verify that your first layer extrusion multiplier is under 1.5.

  3. Make sure you are extruding the correct amount. Take a ruler. Mark out 100mm. Have it extrude 100mm. Correct feed rates accordingly.

  4. Next check plastic diameter by taking the average over 10 samples over a meter of plastic. Enter accordingly.

  5. Then last you might have temp a bit high. Drop it a few degrees. Not a huge factor.

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