- Hodgson Part 077, Oil Pump Housing
- Hodgson Parts 079-083, Oil Pump Gears & Shafts
For the oil pump housing, I chose C63000 nickel aluminum bronze (known as QAL9-4 bronze here in China). This material has high strength because of the added nickel 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.
The bore is added next. Since I had previously turned the rear bearing, I matched this bore for a snug slip-fit over the bearing.
I’m leaving some extra stock here to finish grind both faces after stress-relieving.
Before proceeding on to hole drilling, you should have completed the rear bearing so that the gear shaft holes can be align reamed in both the pump housing and bearing.
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 oil pump housing 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.
This is all of the “standard” holes, other than the gear shaft holes, in the housing.
Now, I’ve added a whole bunch more. There are now 10 reamed 0.126″ holes and two larger holes. These will be used later to generate the profile of the oil pump. Here is the housing process sheet that explains the new additions.
Before any further work can be done to the housing, the gear shaft holes need to be align reamed with the rear bearing. Once all of the oil pump mounting holes have been tapped in the rear bearing, work can proceed on the oil pump housing.
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.
I pre-lapped one side of each gear on 1200 grit paper and placed the lapped side down against the shim stock in the bottom of the cavities. I then preceeded to lap the entire pump housing with the gears in place.
It appears that I got caught up in my work and forgot to photograph the oil passage milling. For this, first I plunged the three vertical passages with a 1/8″ ball-nose endmill and milled a short slot at the main bearing connection with the ball-nose cutter as well.
Next all of the horizontal connecting passages were cut with a 1/8″ flat end mill. Then with 1/8″ pins in holes “A” and “D” resting on the top of the vise jaws, I drilled the 1/8″ perimeter connecting holes for the suction and pressure ports.
Here I’ve got pins in both of the “C” holes to line up the sump oil passage for drilling. For right now, I’m going to stop with the 1/8″ drill – I’ll do the rest of the work on all of the ports after match drilling with the Crankcase ports.
For our last two surfaces, insert the pins in the holes marked “C” & “D”. For these surfaces, you’ll need to raise the housing up on parallels and remove the parallels and pins once the housing is clamped in place.
At this point, the housing is ready to be mounted in the Crankcase for match drilling the suction and pressure ports.
- Mount in crankcase and machine transfer pipe holes.
- Tap suction and pressure ports.
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(CAD drawings are in AutoCAD 2010 Format)