5 Cylinder radial (winter's project)

[gbritnell]

I worked on the outer crankcase cover today. I started with a block of aluminum, squared it up leaving a little stock on all faces. I laid out the center and then chucked it in the 4 jaw chuck on the lathe. The part was center drilled, drilled and bored.

 

[gbritnell]

The part was then turned around and mounted on the previously made mandrel. This necessitated cutting the step down from 1.625 to 1.562. The location step and bearing flange were cut and a nice fillet was put on the bearing flange for strength.
The part was then removed from the mandrel and mounted in the vise on the mill. I didn't document the hole drilling but the next step was to cut a .75 dia. x .125 deep recess for the distributor drive gear clearance. I used a .75 end mill and once to depth moved it out of the pocket to cut the bottom surface flat.

 

[gbritnell]

The next step was to do a rough layout on the face of the part just to give me a road map of where my cuts were going to be. The part was then mounted on the mandrel and put into the chuck on the dividing head.
This cover has the chamber for the intake tubes so the first cuts I made were to qualify these surfaces. In the course of cutting them I had to be aware of the mounting bosses and the oil return boss on the bottom.

 

[gbritnell]

While I had the part set up for the milling operations I plunged through with an end mill to serve as a pilot for the drilling operation. These holes are for the intake tubes.

 

[gbritnell]

While cutting all of the bosses and features on this and other parts I like to work to actual dimensions so everything is calculated from a surface or center point and then the table is moved the required amount, plus or minus the radius of the cutter being used.
With all the jogging and stepping required you certainly have to pay attention to where you're at.
The next 2 pictures show the mounting bosses as they were roughed from previous steps. I then made a step off chart to create the radius on the corners.
You can see in the first picture the oil return boss has already been stepped off and the mounting boss is next.
The second picture show the latter with the corner radius completed.

 

[gbritnell]

Finally all the machining on this part is complete with only a couple of small dimples here and there from not paying close enough attention. Tomorrow the benching will be completed and 2 of the parts will be finished.
George

 

[agmachado]

Hi George,

Very nice work!!!

:bow:

I will be here for next steps!!!

Thanks,

Alexandre

 

[Blogwitch]

George,

I love the way you manage to get those perfectly rounded and blended parts to come together. It really is the work of a true artisan.

I am not into mathematics any more to guide my cutters as you do, I have lost a few too many brain cells now due to medications, so I can only rough cut the profile and finish off by hand, with the help of a Dremel, they don't come out too bad.

It truly is wonderful watching you work, and it shows that if you take your time and work things out for each stage, even us mere mortals have some chance of success.


John

 

[CMS]

Such a marvel to witness a square block of aluminum remolded in such a way. :bow:

 

[kvom]

You're not wasting any time. Following along with interest. Thanks for sharing.

 

[cfellows]

I sure do admire your work, George. The way you finesse those shapes out of a block of metal is a joy to behold.

Chuck

 

[Ramon]

As a newbie here George just like to say your work and your conveyance of it for other's benefit is inspirational.

I've read it through twice now and no doubt will do so again - keep it coming.

Regards - Ramon

 

[steamer]

As a newbie here George just like to say your work and your conveyance of it for other's benefit is inspirational.



I might add, the more experienced of the group learn alot from George Too! :bow: :bow:

Yes George...do keep it coming!

Dave

 

[gbritnell]

Rather than finish this cover I decided to make the outer cover and bench them both at the same time.
I started with the usual block of aluminum, 6061 and squared it up. This cover would need an 1.562 dia. x .031 step to locate into the inner crankcase housing. I layed out a center, gave it a light centering tap and mounted it in the 4 jaw chuck. With my wiggler and indicator I got it running true and cut the boss.
From the lathe it went to the mill and got the oil pump, distributor drive and mounting holes put in. The part was then turned over and the spot faces for the gear clearance were put in with a small boring bar.
With this operation complete I blued up the piece and laid out the shapes for the oil pump, carb and distributor bosses.
I just roughed the material off, staying about .05 away from all the layout lines. All of these bosses are different heights so I cut the perimeter shapes before qualifying the heights. There is also a small fillet around all the shapes so staying away during the roughing process leaves me stock to cut the fillets.

 

[gbritnell]

With everything roughed I drilled the oil feed holes. It was necessary to put these in before cutting the oil pump pocket because they are close to the side wall of the pump cavity.
At this stage I needed another mounting fixture so I scrounged through my miscellaneous stock boxes, aluminum, steel, it didn't matter what material it was just that I could use it without having to chop into a new piece of stock. I found what originally was a starter adapter for one of my engines and it fit the bill nicely. A quick truing up in the lathe and a counterbore for the 1.562 boss and it was transferred to the mill to get the mounting holes put in.
I needed to be able to locate the fixture square as I moved it from the mill vise to the dividing head so when I was putting the mounting holes in I cut a flat on one side.
The first operation was to finish up the oil pump boss and pump cavity so I clamped the fixture between 2 v-blocks and indicated to find the center. That being completed I screwed the cover plate to the fixture and put 2 brass posts into the existing shaft holes so I could line them up perfectly. A couple of passes of the indicator and the fixture was tightened down.

 

[gbritnell]

After rereading my last post you might ask how, if after finding the center of the fixture how could I then rotate it to align the dowel pins? You can see from the photo that I have a stop rod coming in from the right side of the vise so once center was found I could loosen the vise, rotate the fixture and reclamp without losing my centers. In this next picture you can see the oil pump boss is finished. From here I kept rotating the fixture to machine the other features. Most everyone has seen the pictures that I have posted showing how I step off shapes with the sine/cosine method. As I have mentioned in the past sometimes it's just easier to do it this way rather than pull everything off the mill table to set up the rotary table, and then remount and indicate when finished.
I have learned to group operations when using this mill/drill machine so I don't have to do a lot of set up and tear down.
From the mill vise the part and fixture went back to the dividing head to get the perimeter radius cut.

 

[gbritnell]

The final operations were to step off the radii on the sides and bottom of the distributor housing. I originally had planned on putting a ball end on the boss but when the part took shape I realized that there wouldn't be much of a ball because of the way the carburetor boss intersected it. When I start benching these pieces I'll just put an nice radius on the boss and blend it into the other shapes.

 

[gbritnell]

The final 3 pictures show all the crankcase pieces screwed together, main crankcase, inner housing and outer cover. Tomorrow the hand work begins.
George

 

[gbritnell]

The crankcase components are finished. They were screwed together for their portrait.
I have 28 hours in the 3 parts. I think I'll tackle the next hardest parts, the cylinder heads. They will be made from 7075 aluminum. I will need to make a hand crank for my 6 inch lathe so that I can thread up against the top of the combustion chamber, likewise for the top of the cylinder.
George

 

[gbritnell]

Here's the final 3 pictures of the finished crankcase assembly.
George