Thank You, DannyT...

You are correct, I will still be dealing with step patterns, however, the thinner the layer the easier to post process the results and the more accurate in maintaining the cubic volume of the supplied file. My .STL files are provided within 4 decimal places of cubic volume. My best and most accurate results came from a ZCorp SLA epoxy hardened output, but, the output was too brittle for direct foundry molds. I continue to search for a study that provides accuracy results from 3D printers from high end to desktop printers. Warping continues to surface (pun intended) even from high end printers, when printing ABS. SLA is not a viable option. I've had SLA patterns warp in transit to the foundry. I have a prototype scheduled for delivery today from Shapeways that I am hoping will solve my problem to my satisfaction. The real proof of the pudding will be the cast weight in ductile iron from the provided split pattern.

Normally, I have to send two files representing the output as a split pattern for pattern plate mounting. I use dowel pin alignment for registration on the pattern plate, so, each split bottom has holes exactly placed to match a template held by the foundry. I add dowels to each split for alignment during finishing and then added and glued to match a 3/4" pattern plate. With the Shapeways printer, I was able to send both splits as a single file separated by including the dowels between splits. I was also able to create a thin shim that floats between the two splits. When I receive the output, I can cut the dowels in half and free the shim to be used by the foundry if additional weight is required to produce an output weighing 2 pounds 8 ounces when cast. This is an added bonus insuring that everything is printed at the same time and not susceptible to volume differences when splits are printed separately. At some point I will have to have the printing repeated so the foundry can cast two molds at one time creating a pair.

Sorry to be so long winded, but, it's accuracy that's paramount for my requirements. The thicker the step pattern the more difficult to determine what is needed to produce an accurate result. I paint all of my output with Acrylic Lacquer Primer and fill with a filler for follow up sanding to a smooth surface. The key...do I sand to the valleys or sand to the hill tops. Any method to improve accurate volume is my requirement. The preliminary discussion implied that 3MF might help.

Regards, Bob