Question? Why do all my prints end up measuring less then they should? I have to scale them up to 1.03 in order to get most of the dimensions to turn out. But then the holes end up being too small and slightly off in their positions. I must be missing a setting some where. Any suggestions?
There are a few causes of this:
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Slicer inaccuracy. I have found that slic3r produces slightly undersized dimensions of the order you describe. nophead has a technique for reducing perimeter flow rate to correct for dimensional Oversizing which slic3r has recently adopted.
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Shrinkage. The object shrinks from its intended dimensions as it cools. It is normally a small value and can be toleranced-out in your design.
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Representation of holes. Many CAD packages represent holes as polygons with the diameter measurement reflected in the vertices of the polygon not the flats. This leads to holes being undersized. Material stretching also affects hole size. Again, nophead has a solution in his Polyholes which create holes using polygons but dimension them across the flats. The number of vertices is also dynamically calculated based on hole diameter.
Google for these items and the results should direct you to nophead’s blog (http://hydraraptor.blogspot.co.uk) which describes his thinking on these effects.
I am new to 3d printing, and I am wrestling with this as well. @Neil_Darlow 's response was helpful. I have found that turning my model so that holes or areas with more precise measurement requirements are facing upward helps, since it eliminates drooping or support material issues. Given that, adding 1/32" to a hole seems to give me the space needed to accommodate a metal component.
8====D jerk off to it, it will work again
@Swiffty interesting concept