Hi everyone,
I bought a used Replicator 2 and have been using it for awhile to print various pieces for my job. I restored the settings to factory and am using MakerBot Desktop 3.9.2.1357, and I think all the parts are stock. Overall the accuracy of the printed part dimensions is really good, EXCEPT for the inside dimensions of hollow parts. See the attached picture of a test piece I’ve been printing to see what I mean by the inside dimensions. It doesn’t seem to matter the size, shape, or resolution I print at, the inside dimensions are always 0.025" (0.64mm) undersized. It really seems that the software is running the print head right along the cad line of the interior wall, instead of just beside it to account for the thickness of the extruded line of plastic. This is very consistent across all layers of a print. I’ve tried the stock settings, as well as messing around with custom settings (e.g. number of shells, fill density, etc), and this issue persists. So, am I missing something, and more importantly, is there something I can do to fix this? Any help will be greatly appreciated.
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What filament are you using? Many filaments shrink once they cool, I use a Rep 2X, and I have just learned to account for shrinkage in my models.
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1.75mm PLA, and tried various suppliers. The outside dimensions are within ±0.005 inches, so if it was shrinkage I’d expect they’d also be out by the 0.025" I’m seeing on the inside.
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Garyg
4
Hi
I’ve had things printed by various hubs over the past 3 years or so.
The anomaly you are noticing appears to be consistent with all of the FDM type printers I have used.
I usually do an offset to my drawings that gets me pretty close.
Inside dimensions I always offset 0.010 to 0.012 inches.
Outside dimensions I always offset by 0.003 inches.
When I do that, things come out very close to what I want.
I think you are correct in assuming that the print head runs right along the cad line.
It does this on the outside walls also, but I think the software somewhat offsets the line.
When it does the inside line, it still offsets as though it’s the outside line.
Maybe slicing software like Simplify 3D can account for this, but I’ve had things printed by people who use Simplify 3D and
the results are always similar.
…
I know this is not the answer you were looking for, but it is my experience.
I hope it helps you in some manner.
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Thank you Gary for your comments and feedback.
