Hi. I have a minor troubleshooting problem for anyone able to answer, today.

3D Printing
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Hi. I have a minor troubleshooting problem for anyone able to answer, today. I’m a relative novice at 3D printing, I have some understanding of the technology, and I’ve been printing a few things, largely without issue, on my Replicator 2, but I have one minor problem that’s bothered me since I got it. When I’m printing a raft, at the back edge, when the print head changes direction to start coming forward again, the plastic doesn’t lay down nicely. It leads to a few loops sticking up. This isn’t a major issue as it’s on the edge of the raft, so it’s waste material anyway, but I’d still like to see why it’s happening.

I know the platform is level, I’ve spent a lot of time on getting that just right, so it’s not likely to be a levelling issue. My thinking is maybe the extrusion temperature is slightly too low for this filament. I’m using Bilby CNC’s PLA, which is supposed to melt between 190 C and 240 C, and my extrusion temperature is set to 230 C. I’m thinking if the temperature were set a little higher, the plastic wouldn’t get pulled up again as the printer changes direction.

Any help would be appreciated with this. Thanks. I’d upload a video to better explain it, but this only occurs to me after I see it on a print, and by then I’ve missed my opportunity to record it.

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If you’re absolutely positively sure that the nozzle-to-bed distance is consistent all the way around, and that you are extruding enough plastic to get a solid smoosh of the plastic into the bed, you might want to ensure that your Kapton is clean. Contamination from hand contact could make the bed no longer able to hold the plastic.

The other possibility is that at the extremes, the raft is taking acute angle turns, and that turn tugs on the plastic before it had a chance to set. Varying speed, temps, and nozzle elevation will affect this.

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It seems to only happen when printing the raft. The same angles on the actual model don’t cause an issue. I may have to try actually using kapton or painters tape, this whole time I’ve been printing straight onto the bed, because that’s what I saw in the Replicator 2 videos. I definitely have no problems with objects adhering to the platform, they can be quite tricky to safely remove when they’re done.

I actually have my suspicions the bed isn’t as flat as it could be. I printed a box that took up nearly the whole build surface, and there was a stringy region in the middle, on the lower layer. Nothing major, but noticable looking at the finish.