I made a mod for NVIDIA's VR Funhouse game that adds giant spiders. Apparently I'm an Unreal Engine developer now.
I've been trying to print a watch case using ShapeWays Steel material. It produces a great looking although heavy product. I've done 2 prints now and both were undersized. Initially I assumed this due to general incompetence at my end. However when I pulled the parts out and compared them with the CAD files and watch components its obvious that the printed parts have shrunk during the production process.
I checked on Shapeways and indeed if only I was better at reading I would have noticed this:
± 5% of any dimension (and one layer thickness of 0.1mm)
The bronze infiltration of each steel part makes this material less dimensionally accurate than other Shapeways materials. Shrinkage is more prevalent, especially on small holes and inner diameters. Accuracy and tolerance can vary greatly depending on the model, and are hard to predict because they are so geometry specific.
Metal that shrinks! Doh! 5% of 29mm is 1.45mm which is huge when considering the tolerances in play. The design needs to take this variability into account. For the movement I can just make the case diamater 1.5mm oversize and I'm good but for the crystal a 1.5mm gap is just too big. One solution would be to order the crystal (they come in many sizes and aren't expensive) after getting the print back.
Another solution would be to add a bezel that goes over the crystal holding it in.
The best solution would be to find a different material or production method.
Recently I found out a company is refinishing old pocket watches and making wrist watches out of them. Very cool stuff form the Vortic Watch Co.