FDM parts need to be produced within an accuracy of ±0.5 mm or 1% depending on which is greater. For example, in the case of a 40 mm cube, a 1% accuracy requirement would result in a max of 0.4 mm deviation. As this is below 0.5 mm, the 0.5 mm is leading and determines the maximum. A printed part of 40.2 x 39.7 x 39.6 mm would be acceptable as the deviations are within this 0.5 mm. Printing a cube that is 38.8 x 39.4 x 39.4 mm would not pass the dimensional accuracy requirements as the width deviates more than 1 mm.
Consistent Surfaces. The final print shouldn’t have any inconsistent surfaces. Retraction marks and a layer changing “seam” are acceptable. No delamination. The layers should be firmly attached, resulting in a print without gaps or cracks. Small details. Details larger than 0.8 mm in the model should be well discernible in the print.
All support material must be removed and brought down to a level where the surface is continuous. Small traces of support material are often unavoidable and acceptable.
These guidelines apply to all FDM orders on 3D Hubs and can only be deviated from when specifically discussed and agreed upon between Hub and Customer in the comments section on the order page.
If a customer raises a dispute, prints are reviewed against these quality guidelines. If the print doesn’t meet the guidelines, the customer will be fully refunded.
Appendix : Poor quality example
Printer does not extrude enough plastic, gaps between perimeters and infill
Printer extrudes too much plastic, prints looks very messy
Stringing or Oozing
Lots of strings and hairs left behind when moving between different sections of the print
Gaps in Top Layers
Holes or gaps in the top layers of the print
Small features become overheated and deformed
Curling or Rough Corners
Corners of the print tend to curl and deform after they are printed
Warping of large parts, particularly with high temperature materials such as ABS
Dimensional issues where the measured dimensions do not match the original design intent