I ground the grease channels in the 2.5″ pins yesterday. See the following videos.
I ended up doing one spiral, with a 2″ pitch, and 5 channels running along the length of the pin and rotating slightly. Grease can typically travel about 1/2″ to 3/4″ away from the channels, depending on the clearance between the pin and the bushing. This pattern would distribute it to all except the very centers of the squares, but since the linkages and upper arm will be rotating around the pins, the rotation will cover the rest of the squares.
The channels are the width of the blade of the die grinder, and about 1/16 deep. I may need to make them deeper, as they may clog being this shallow. I’m asking my grandfather today and I’ll update tomorrow.
Update: Grandad said they’ll work. 2/14/12
I also purchased and began machining the bushings. More on that later, I’m heading to the shop.