Difference between revisions of "FFF Printer Tuning for Accuracy"
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=== Accounting for Extrusion Width=== | === Accounting for Extrusion Width=== | ||
Most slicers actually have a setting for extrusion width. Simply input your measured value. | Most slicers actually have a setting for extrusion width. Simply input your measured value. | ||
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| + | ==Perimeter Layer Ordering== | ||
| + | For tighter-tolerances, print the outermost perimeter first, followed by the inner perimeters. Doing so yields tighter tolerance features that printing innnermost-to-outermost. The reason why has to do with what's happening to the filament as it is being deposited. When printing any adjacent perimeters, imagine that the first perimeter wall is cooler and more solid than the second perimeter wall. As the second wall is printed with some slight overlap with the first, it is effectively "rolling" off of the original layer. The original layer is cooler, so it doesn't move as a result of the new layer overlapping it. The current perimeter being deposited, however, does shift slightly as it rolls off the prior perimeter. | ||
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| + | The most-obvious symptom of printing innermost-to-outermost is that parts will seem to be slightly too small no matter what settings you tweak. | ||
Revision as of 23:49, 22 September 2019
By accounting for a variety of factors that affect the accuracy of our printing process, we can dial in our 3D printers to get a fairly sufficient level of accuracy for functional, mechanical prototypes. Here's a breakdown of the factors to tune.
Contents
Extrusion Width
Even though nozzles come in fixed sizes, the resulting extruded line is almost always slightly thicker after it has been deposited onto the forming part. This happens for a variety of reasons. But the main reason is that each subsequent layer is squished onto the prior layer with some overlap to ensure that the two layers fuse. Accounting for this thickness is key to getting accurate feature sizes, especially for small holes.
Measuring Extrusion Width
We can measure extrusion width from a flat surface of a single-layer thick wall. To create such a test object, simply print a cube with an open top in vase mode. From here, measure the wall with a pair of calipers.
Accounting for Extrusion Width
Most slicers actually have a setting for extrusion width. Simply input your measured value.
Perimeter Layer Ordering
For tighter-tolerances, print the outermost perimeter first, followed by the inner perimeters. Doing so yields tighter tolerance features that printing innnermost-to-outermost. The reason why has to do with what's happening to the filament as it is being deposited. When printing any adjacent perimeters, imagine that the first perimeter wall is cooler and more solid than the second perimeter wall. As the second wall is printed with some slight overlap with the first, it is effectively "rolling" off of the original layer. The original layer is cooler, so it doesn't move as a result of the new layer overlapping it. The current perimeter being deposited, however, does shift slightly as it rolls off the prior perimeter.
The most-obvious symptom of printing innermost-to-outermost is that parts will seem to be slightly too small no matter what settings you tweak.
