Unusual Print Issue

I had an unusual print issue occur today that I hadn't seen before. The issue looks similar to banding, but it's only in the middle of my print height, not throughout. In the attached image "bad print", you'll see my first and second attempts at this particular part. On "PRINT 1", I noticed that in the Y direction (circled in black), the edges got very loose. Upon seeing this, I changed the design of the part from rounded edges to sharp corners to see if that would print any better. On "PRINT 2", you can see a slight improvement was made, but I believe it was just a coincidence. There was no noticeable issues in the X or Z direction.

Also attached is an image of the model that I'm trying to print for reference.

I'm using Skeinforge to slice and Nophead's PLA0.2 settings. I can also print objects of similar height, and they do not have this issue, which leads me to believe it's a slicing issue. Can anyone help me out with this one?

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BSBMX
.... which leads me to believe it's a slicing issue. Can anyone help me out with this one?

Have you looked, in software, at the GCode toolpath which Skeinforge has produced? I use Repetier host to "virtually" print and view how the hotend will move throughout the print job. You can select to look at individual layers, one by one or groups of layers as they build up in order to confirm (or otherwise) whether the hotend is doing what it is told to do.

Another approach would be to slice using a different slicer and see if you get the same result.

Alan

Hi,

Is your filament feed working freely? As the problem is transient I was wondering if your filament is catching and restricting head movement somehow. It looks mechanical to me rather than a slicer problem.

Regards,
Neil Darlow

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I try to write with consideration for all nationalities. Please let me know if something is unclear.
Printing with Mendel90 from fedora 25 using Cura, FreeCAD, MeshLab, OpenSCAD, Skeinforge and Slic3r tools.

The toolpath in Skeinforge shows nothing unusual, and the filament is feeding freely.

I was googling around looking for another slicer to use, and I came across MatterHacker's MatterControl software, which has Slic3r built into it. I have to say, even in its beta stages, this MatterControl program is pretty sweet. It had Mendel90 settings already programmed into it (though, I do need to fine-tune a few things). First print through this new software was this same piece that gave me troubles, and it printed without a hitch. So, I guess it's a slicing issue... if I can only figure out what setting in Skeinforge is causing the trouble.

Back to the MatterControl software--this program is impressive. I may just leave Skeinforge altogether. The program streamlines a lot of the process and is visually better than any other 3D printer program that I've seen. I may be late to the game on this one, but if you haven't checked out MatterControl yet, do yourself a favor and give it a try.

Odd because I have never known Skeinforge to get the outline wrong if the STL is manifold and if the tool path looks correct then the machine is not following the tool path. My best guess is an intermittently loose pulley that can slip between two positions.

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[www.hydraraptor.blogspot.com]

I celebrated too soon... I printed another copy and got even worse results (see attached image). Again, the X and Z directions are good, but something is going on in the Y direction. This is occurring when I use both Skeinforge and Slic3r.

Nophead, I checked on the Y motor aluminum gear, and it's tight and snug, definitely not slipping on the motor shaft. As the hotbed moves in the Y direction from both extremities, it looks smooth and consistent. However, if I turn the motors off and move the hotbed fast by hand, I can occasionally see the belt slip my one tooth. I have the belt very tight, so I don't think it's a looseness issue. Any idea what could be causing this?

It is simply that the belt is not tight enough. More recent kits ship with more flexible belt that doesn't need as much tension. PM me if you want an upgrade. The original belt does work though given enough tension.

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[www.hydraraptor.blogspot.com]