I have an object I am creating that should be a few inches wide. Before exporting from 3ds max I confirmed the size. But after I export both netfabb and shapeways tell me the model is less than 3mm wide. Is there a way to prevent this? I've never had this issue before with any other objects.

3ds max seems to always mess the scale up for me on export, all I do is make a note of what the largest dimension is supposed to be and then divide that number by what the largest dimension reads out as in netfabb and use that as a scale factor with the scale tool in netfabb.

It seems that 3DS Max has some display (or working) units and some internal (or actual) units.
Let us know If this solve your problem: it is at least the 3rd or 4th time someone complains about wrong export sizes with 3DS Max, so perhaps this has to be mentionned in the appropriate tutorial, if it is not already the case.

It works so long as I use mm as display units in max, when I change to cm display units its then out by a factor of 10, still its a lot easier to deal with knowing I can just scale by a factor of .1 in netfabb for all objects.