For the rear bearing, I chose C63000 nickel aluminum bronze (known as QAL9-4 bronze here in China). This material has high strength because of the added nickel (needed for the thin mounting flange) and good wear resistance. The downside is this material is very “grabby” and tends to warp if you get it hot. Therefore, I’m going to machine it in two phases with a stress relieving operation in-between.
Here I’ve rough turned the aft face of the rear bearing leaving about 0.050″ on all surfaces to finish after stress relieving. I’ve turned the center boss to 23.5mm so that I can chuck it in a collet for the first part of the finishing operations.
The bore is also roughed out before the blank is parted off from the stock. Be careful of the parting operation as it can generate a lot of head and subsequently warp the part. Use a sharp tool and lots of coolant.
The part was then mounted on the arbor and the runout of the O.D. and the 0.062″ step previously turned on the backside was checked. Runout in both cases was less than 6µm.\
One final step before removing the part from the lathe was to lap the face of the bearing with some 800 grit wet-or-dry sandpaper backed by a ground steel parallel to insure a flat face and a good seal with the oilpump housing.
Before proceeding on to hole drilling, you should have completed the oil pump housing up to the point of drilling the gear shaft holes so that they can be align reamed in both the bearing and pump housing.
You should also consider completing the turning operations on the front bearing so that can be drilled in the same mill setup.
A simple drilling fixture for the bearing was made from a scrap of aluminum. The scrap was faced after clamping in the vise to be sure it was perpendicular to the mill spindle and a M10 hole was tapped near the center.
A 0.020″ recess was milled around the tapped hole to clear the boss on the backside of the bearing so that the majority of the bearing would be in contact with the tooling plate.
I had previously drilled the oil pump housing on this fixture so I’ve rotated all the hole positions 90° so that (hopefully) I will not hit a previously drilled hole in the tooling plate and knock my drill bit off-course.
Without removing the rear bearing from the fixture and loosing the location, the oil pump housing is attached. Here you can clearly see the extra #4 flat head screw on the bottom of the oil pump housing.
To put in the crankshaft oil passage 10° off the horizontal, I’m using a couple of #31 drills, in appropriate perimeter mounting holes drilled previously, resting on a parallel to lift the bearing boss clear of the front vise jaw.
I then indicated the center of the bearing, and offset the 0.170″ dimension from the face of the boss.
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