I just ordered an Ultimaker 2, and I guess it will be a while before it arrives (I got two receipt emails; one said UM2 has 6-8 weeks lead time and the other said 8-10 weeks). Meanwhile:
My intended use is to make mechanical prototype parts in ABS. I have done this already with a Makerbot Replicator 1, so I have a feeling for what to expect, but I am hoping the new machine will do at least a little bit better.
What dimensional accuracy should I expect from parts? Say I print a rectangular bar with CAD dimensions 5 x 10 x 100 mm. How much different from 100.0 mm would I expect the actual length to be? If I print 10 of the same design on the same printer, how much variation might there be among the parts? Of course once I get the printer I can find the answer myself, but I'm just curious while I'm waiting.
I assume the dominant effect is the ABS shrinking and stress-relieving during cooling, which is dependent on geometry and % fill factor, resin composition, heater temperature, maybe even printhead speed (mm/sec) and other things. Are there any rules of thumb, or programs to calculate this? Or do users of consumer 3D printers generally not deal with tolerances?
Note: although a similar question appears in the FAQ
it only mentions the resolution of the printhead X-Y-Z movement. Resolution is not the same as accuracy, and printhead accuracy is not the same as finished part accuracy.