'TINY' another tiny engine but vertical and water cooled

[gbritnell]

 I make most of my heads from cast iron. The reason being I don't have to put valve guides and seats into the heads. My process for machining ports and seats has been well documented.
I center drill the hole, followed by drilling and reaming of the valve guide hole. I then drill the port undersize and finish it with an endmill. This leaves an nice sharp edge from which to cut the seat later on.
I modified the design of the head by adding a little more material to the valve guide holes on the top of the head. To accomplish this I left extra stock and then milled the head to the correct thickness leaving material around the guide hole. Using an annular cutter made from drill rod I cut the outer diameter of each of the bosses. As I stated my head also has the spark plug angle changed to keep the plug farther away from the valves and rocker post to limit the spark from possibly arcing to them.
 The remaining holes for the carb and muffler were then drilled and reamed.

[gbritnell]

 The cam/gear is made from steel. I wanted to use a minimum of brass on this engine so only used it as the second metal in combination with steel.
The rod was turned allowing enough material to cut the cam profile. It was then mounted in the dividing head and the profile stepped off. To cut the gear teeth I used a multi-toothed cutter that I had made for other projects. It's 48 DP and is made from drill rod and hardened.
The piece was parted off, filed smooth and polished.

[gbritnell]

When making very small parts I find it easier to machine them from either a piece of round stock or rectangular material depending on the shape. For the latch lever, governor weight arms and rocker arm I drew up the profile and then gave myself points of intersection using a .093 end mill. It was a matter of stepping around the profile to the numbers and then cutting the parts off with a small slitting saw.
The parts were then held in a small hand vise for filing and finishing.
The governor weights have an outside radius so I started with a small block of steel and mounted it in the lathe with the four jaw chuck. The radius was cut and then the block was transferred to the mill for drilling and finishing. These were then cut off with the slitting saw.

[gbritnell]

The flywheels were turned from a piece of 2.00 diameter 12L steel. The stock cleaned up to about 1.994 diameter. As stated I increased the diameter from 1.75 inches to 2.00 to get a little more mass.
The first side was turned and the center hole was drilled and bored (.187 diameter). Actually this was a pain job because the ball bearings that I ordered had an I.D. of .187 as opposed to .1875 (the decimal equivalent of 3/16 inch). This meant the crankshaft had to be .1865 and I couldn't use a reamer for the center hole on the flywheels. I have some very tiny  boring bars for the lathe but trying to cut and measure small holes like that are painstaking. With the first side done I cut the blank off and turned it around, indicated it true and cut the second side.
To machine the spokes I used an old aluminum fixture plate which I cut a recess into and 2 tapped holes for small clamps. The plate was mounted on my rotary table for all these operations.
The flywheel blanks were center drilled then drilled at each of the spoke corners. This was followed by cutting out the remaining material with a .187 four flute end mill. 

[gbritnell]

 Starting with a conical shaped 1/8 diameter carbide burr I broke the edges of each spoke. The small conical tip allowed me to get into the tangent point of the spoke and rim. I use a headband magnifier for this work to prevent the burr from running into the surrounding metal. To go this far and then gouge the part is frustrating to say the least. When using a small burr it's best to let it do the cutting. If you force it the burr will grab and take off. I use a Dremel grinder with a flex shaft for this work.
 After knocking all the edges off I went in with small files to clean up all the surfaces and fillets. The spokes were then polished with strips of emery cloth.
The gear side flywheel has a small boss turned on it to locate the governor weight bracket. The bracket is mounted with 0-80 flat head screws. The holes were countersunk deeper after the pictures were take so the screws are almost flush with the bracket.

[gbritnell]

 The valves are made from drill rod with the heads silver soldered on. They were then chucked in my small lathe using an ER 11 collet in a home-made set true holder. The heads of the valves were cut to size and the seats were cut at 45 degrees.
 The valve springs are made from stainless steel spring wire. The intake wire is .011 and the exhaust uses .016 wire. The rocker arm was machined like the other small parts but then it was mounted on a piece of round stock to cut circular bosses at each of the holes.
 The next pictures show the governor parts assembled. The tips of the arms and lockout lever have .05 radii on the ends to fit into the spool. The pushrod has a small bushing that can be adjusted with a small set screw to control the latching of the pushrod.

[Steamer5]

Hi George,
 I cant keep up on the  at the rate you are doing this!

A really nice write up & pictures & what's looking like a very nice addition to your family!

Cheers Kerrin

[Dave Otto]

Amazing work George!

It is nice to be able to follow along with another one of of your projects; thanks for sharing.

Dave

[Flyboy Jim]

Very nice looking. I really like the finish work you did on the flywheel. 

Jim

[fumopuc]

Hi George, very nice. Good to make some small things between big projects.

[Brian Rupnow]

George--Nice work, as always.---Brian

[kvom]

I really like the fixture block system for making the 1-piece crankshaft.  My next engine I want to do the same rather than make the built up version that gave me problems with the Westbury engine.

Am I correct in thinking that the same fixture could be used to make a crankshaft for a 2-cylinder engine by just rotating the stock 90 degrees for the second part?

[gbritnell]

Hi kvom,
Yes you can use a similar fixture for a multi-throw crankshaft.
I mill flats on the round stock to orient the throws.
The only other thing you have to do when making a multi-throw crankshaft is to make a support block for the outer end. This block will have a reamed hole to slide the crank into and a center drilled hole equal to the throw radius and supported by a live center.
Gbritnell

[steve-de24]

Thanks for another very interesting build log. Can I also give a late thank you for posting the drawings of your air cooled version (I missed them first time around). Am I right in thinking that you now use a lapped aluminum piston and, if so, have you any advice on how you do this? What material do you use for the lap and what sort of grit do you use? Thanks in advance.
Steve

[gbritnell]

Hi Steve,
You're correct, I am using a lapped aluminum piston. I hone the cylinder with a very fine grinding compound using my home made lap. I don't know what the grit is as the small container just says extra fine. When I'm through lapping the cylinder I use the slurry that has already been formed to do he piston.
I take a little bit of it and add some light oil to thin it out.
Gbritnell