A block of 6061 was squared up for the oil pan's workpiece. Some changes were made to the original pan design to accommodate the outer round bearings. When used with a .015" thick mounting gasket, the new pan will provide the additional 180 degrees of metal-to-metal contact needed to support each outer bearing.
The front and rear ends were machined using essentially the same operations used on the ends of the block. Again, 4-5-6 blocks were used to help stabilize the portion of the workpiece sticking above the vise, and a paper towel bib kept them free of the sticky coolant. After finishing its ends, the workpiece was repositioned so the pan's interior could be hogged out and its drafted walls finished. My modeling showed uncomfortably close clearances between the heads of the rod bolts and the inside corners of the pan, and so I added an array of clearance notches. Rather than use a magnetic drain plug, the floor of the pan was bored with a shallow hole for an epoxied magnet.
The pan's mounting holes were initially drilled undersize and tapped for screws that attached it to the fixture plate made earlier. When the machining was completed, the holes were opened up for the pan bolts.
With the workpiece attached to the fixture plate and its interior packed with modeling clay, the assembly was clamped in the vise for access to the pan's bottom surfaces. At first glance the pan looks fairly simple, but two of its three bottom surface aren't flat, and the sides have three degree draft angles. After being roughed in, the bottom was finished using a waterline operation and a long reach 3/8" ball end mill. The tool path steps were compiled for .0003" high scallops which blended into the surface after bead blasting.
After attaching the workpiece, the sides of the fixture plate should have been skimmed to insure the sides of the workpiece would be truly parallel to the jaws of the vise. I forgot to do this, and the pan's machined sides wound up diagonally offset from the already machined ends by .004" and had to be manually blended.
The full-size engine's oil pan was drawn steel and factory painted either black or Ford Blue. A similar shade of blue is available in Gun Kote that I'll likely use on some of the model's parts when their machining is completed. - Terry
