5 Cylinder radial aircraft engine

[xken]

George,

Great to see this engine started. How about some interim machining pictures to show us non machinists the set up and thought process involved?

Keep up the great job and I will be following this one.

Ken

[ScaleMotorcars]

Ill 2nd Kens post.

Man I really need a new lathe. I wouldn't dare attempt anything like this. The bed is so worn out I can move it a 1/4 up or sown and thats with it locked in place. NOT GOOD...

[hot ford coupe]

That's some serious machining right there.

[GeorgePapa]

Hi George,

I am really impressed (abd I am not an easy one ).

But anyway, it is not your first time you manage it.

George

[ScaleMotorcars]

Back in the late 1980's I was big into electric RC cars. I specifically remember the cover of one magazine having a Morton 5 radial mounted to a tether car. It was that car that got me into the vintage stuff.

I found these photos of Don Edmund's Morton powered car. I dont think its the same one since this one was built in the 90's and I remember the other car being original to the 1940s.

George, if your going to build the motor anyways why not build something to put it in. Just think of it as the ultimate motor stand.

Can you image the crowds at Glenmoor next year?

[gbritnell]

As per Ken's request I am posting some of the machining steps. Up first is the start of the project. Just a block of aluminum that was squared up and then set up in the 4 jaw chuck. The following operations were to drill and bore for the crank cavity. First the center drill, followed by several drills to get to size and finally the crank cavity was bored to the finished size.

[gbritnell]

The block was then turned around in the chuck and the initial reamed hole was indicated for true so that I could bore for the front bearing hole.

[gbritnell]

The block was moved from the lathe to the mill and mounted on a mandrel and clamped into the dividing head. The first step was to indicate the part so that it was running true. I have what's known as a set-true chuck on the dividing head. It has adjustable screws to allow perfect centering of the part. This tool would be used for doing the exact indexing for all the cylinder pads, bores and mounting holes. The dividing head was set at -0- and the flats were cut first. In the 3rd picture you will see a boss taking shape between two of the cylinders. This will be the oil return sump area. Between the other cylinders there will be a cut to remove the extra stock. After cutting the flats to the proper dimension I poked an end mill through the case as a pilot for the forthcoming boring bar.

[gbritnell]

At this point I cut the flats that would eventually be the top pads of the lifter bosses. I then drilled and reamed these holes at the proper angles. The next operation would be to install the boring bar, bore the holes for the cylinders and spotface the cylinder mounting surface. I wasn't quite sure how the intersection of the lifter bosses and the cylinder pads would be so that's why you see the extra stock left between the two areas.

[gbritnell]

The cylinder mounting holes were center drilled and drilled for 2-56 screws. The final operation that you see in this sequence is the drilling and milling for the oil sump cavity. There will be 2 pockets where the oil collects and then returned to the oil tank. There will be a cover plate over this area held on by two 1-72 screws.

[gbritnell]

The crankcase along with the fixture plate was removed from the dividing head and mounted vertically in the vise to drill the holes for the set screws which will keep the roller lifters from rotating. The first step was to indicate the fixture plug for center, then remount the crankcase in preparation for the drilling.

[gbritnell]

Here are 4 shots of the crankcase to this point.

[gbritnell]

The final machining operation is to remove the stock from around the lifter bosses and form the curve on the nose of the crankcase. The first thing needed was a step-off chart to create the nose curvature. With and Autocad program it's quite easy. You draw the radius of the desired curve, offset the radius of the cutter to be used and then plot the points on that curve. I then write the numbers down into a chart so that I can follow it at the mill. I blued up the area around the lifter holes and made up a template that would insert into the holes so that I could scribe the outline onto the crankcase. This would give me a guide for cutting.
The part mounted on the fixture was clamped back in the dividing head for this final machining operation.

[gbritnell]

The step-off process was started, working from the center upward. Each step was up so far and over so far and then the dividing head was rotated 360 degrees. Each step was repeated until I got to the lifter bosses. From there I had to continue the radius but work between each of the bosses, staying away from the line for the time being until the heavy stock was removed. Once the majority of the stock was cut I rotated the part so that the bosses were horizontal and then made qualifying cuts along the scribed lines.