Bevel Gears from Andrew Johnston

Received these project photos in the inbox a few weeks back and just now getting around to posting them.  Andrew lives "across the pond" in England and is a model engineering enthusiast.  He cut out these bevel gears with his Tormach PCNC 1100.  From Andrew:

"The bevel gears are for use in the differentials of the two 4" scale traction engines I am building. I didn't agree with the drawings I have, so I designed my own gears in Alibre. CAM programming was done in Visualmill. The gears are 6DP, the pinions are about 2" OD and the gears 6" OD. The final gears are in cast iron, but I made prototypes in aluminum to test out the design and machining strategies.

The pinions use a roughing cut and a finishing cut, both using a 4mm three flute ball nose carbide cutter. The gears are roughed out with a 4mm cutter followed by a cleanup pass with a 3mm cutter and finally the finishing cut with a 2mm cutter. On the pinions I used the same cutting parameters for the cast iron as I used for the aluminum prototypes; 5000rpm and a feed of 400mm/min.

 By the way these gears are true bevel gears in that the tooth form scales uniformly as you move down the pitch cone. They are not the compromise that is normally used when the gears are machining using a horizontal mill and B&S involute gear cutters."

Thanks for sharing, Andrew!