A flathead V-8 engine

And I thought the bellhousing made a lot of chips! It was nothing like this next part. The oil pan.

I started with a large rectangular piece of 6061 aluminum. There is no easy way to rough it out and within the limits of my machine the following steps were the only ones I thought were feasible to get to where I wanted.

As with any part the first thing to do was to square up the stock. This was followed by center drilling and successive drilling with larger drills, first a .25 to serve as a pilot, next a .50, then a .625 and finally a .75.
The drills went to a safe depth for each level of the pan. I really didn't want to drill through a $50.00 piece of aluminum.

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Once the holes were drilled I used a couple of .50 dia. ball nosed mills. I used a short one to get most of the hogging done with the rigidity of the cutter. This was followed with the longest one I had to get down to the bottom of the lowest cavity. I had cutting dimensions to work to and stayed about .04 away from them, just in case.

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With the roughing out of the way it was time to start picking away at the internal radii. The hardest area was at the front of the pan where I had 3 surfaces coming together, the angular bottom, the angular sides and the side walls of the pan. Once all these shapes were cut close everything would need 2 degrees draft so all of the stepping would be repeated once again.

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The inside machining was finished so it was time to start on the outside. The first area which needed the most work was the front so I gave myself a layout line and bandsawed a big chunk of metal away. The piece was then clamped to an angle plate and with the angle set I cut to my layout line leaving a blob where the front radial shape was. Although I could have cut a little closer I didn't want to take a chance of undercutting anything. At this point it was no longer about money but the hours of drilling, roughing and step milling involved.

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Whew!!!! The front was done so the part was turned around to do the rear area. This had it's own set of issues due to the oil pump bulge. Once again after everything was roughed the mill head would have to be cocked over on 2 degrees to match all the outer surfaces to the inside shapes.

All of this 2 degree business wasn't really necessary but the full sized pan has draft on it and so will this one.

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The pan has 3 different depths. With the front and rear machined I carefully sawed the remaining two pieces from the bottom. The part was mounted to a fixture plate so I had some way to hold it. The bottom sets were milled, the radii stepped off and the side walls cut to 2 degrees. I then knocked down the large radii on the corners with a radiusing cutter getting as close to the angular surfaces as possible. This gave me a head start although there would still be a lot of material to remove to finish the radii.
I have some aggressive carbide burrs but was very careful not to undercut any of the features. One I got close it was all hand filing from that point.
I haven't decide whether I'm going to finish the inside. I have plenty of time for that.
gbritnell

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Here's a bit of information on the pan. Except for the very deepest pocket all of the other walls are .06 thick. The bottom is .110 because it needs threads for the drain plug.
As I have mentioned along the way, when making parts from bar stock the inside always needs to be done first. With most of the parts I'm making a fixture plate is also needed. At this point I have three, 2 of them serving double duty for other parts. It seems like a waste of material but some times there's no other way to hold a part for machining. Usually if a part has clearance holes for mounting screws I'll drill and tap them for mounting to the fixture plate and then go back and clearance drill them when I'm all finished machining the part.
gbritnell
 
It's time for an update on the engine. The plan is to make all of the big pieces which would represent the major castings and then go back and start making valves, sleeves, crankshaft etc.

I have just finished the water pump bodies. On a flathead engine there are two, one on each side of the front of the block. To get a water passage inside the pumps would have to be made in two pieces, the main outer part and a cover plate for the rear. The water pumps also have the front motor mounts cast into them so to replicate these I had to step the shape out on the backside of the main body to make the rib thick enough for strength.

I started with the back plates. These were roughed out, drilled and tapped then mounted on the rotary table to turn the boss and use the rotary table to cut all the angular edges. The tapped holes (2-56) are also for mounting to the fixture plate.

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The pump main body was next. As with the back covers the stock was cut to size leaving .02 for a safety margin. These are quite complex parts and would need multiple setups over the course of machining.

The eventual mounting holes were all tapped rather than drilled, this way they could be used for mounting to the fixture plate. The impeller shaft hole and the water inlet hole were also put in while the block was in the vise. The vise was then removed and the rotary table once again set up. The water cavity was lightly sketched onto the block and it was then indicated and clamped. You can see the offset motor mount rib sitting higher than the main surface.

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