2/11/2003, Machining the castings was started after I recovered from the
Cabin Fever trip.
The cylinder casting was faced top and bottom then set up on the
faceplate to bore for the cylinder liner as shown in the photo above. The
Base was then faced top and bottom and bolted to the cylinder. Two strips
of masking tape was applied to the faceplate and the Base was clamped down
firmly on the tape. This setup allows the cylinder to be removed from the
Base to inspect the two phase boring job.
The photo above shows the assembly being centered on the faceplate to
drill and bore the crankshaft tunnel.
The photo above shows the crankshaft tunnel boring operation. The boring tool is a short length of 1/2" Drill Rod with a 1/8" cross hole to hold a reground drill bit held in place with a setscrew. It is handy to be able to extend the drill bit.
The photo above shows boring the crankcase cavity out to the desired
dimensions. In this photo, the cylinder is unbolted from the base to
inspect the boring job. The crankcase cavity is cast into both the
Cylinder and Base but I preferred to bore it out a little larger.
The photo above shows the setup to drill, tap and bore the cam gear cavity. The boring bar is one flute of a reground two flute end mill with a 1/2" shank. A very sturdy boring bar that resists chatter !
2/20/2003
The crankshaft is turned from a length of 3/8" x 3/4" cold rolled
steel. The ends are laid out with a height gauge, center punched, center
drilled an placed between centers in the lathe. The center section is
turned to .251 with a modified cutoff blade, set in the tool holder so
that there is side rake on both sides. A right and left carriage stop is
used to prevent a mishap. The center section is brought to .250" using a
file and abrasive paper. A short length of 3/8 stock is soft soldered in
the gap to prevent bending the crank with pressure from the tailstock
center in the next operation.
One end of the crank is turned to .275. The crank is flipped around and
that end is turned to .275. The crank is flipped again and turned to
.252, flipped again and turned to .252.
The photo above shows the crank being lapped to .2501. In this case, a
1/2" square aluminum bar serves as a lap. Two additional laps are in the
background. After lapping, the crank is returned to the lathe.
The above photo shows the setup to cut the 20 degree taper and reduce
the end diameter for threading 10-32. The compound rest is set at 10
degrees and a left hand carriage stop is used. With the carriage up
against the stop, the compound is advanced to take successive cuts to
form the taper and reduce the end diameter.
The above photo shows the setup to cut the threads. The die is held in
the 3 jaw chuck with the spindle locked. The crank is supported with a
1/4" ID brass tube in the tailstock chuck. The crank is turned by hand
to cut the 10-32 threads.
(
The above photo shows the finished crankshaft with tapered and threaded
ends, ball bearings, gear and oil seals mounted, ready to "drop in" the
block. Although I personally like to taper mount the flywheel, I will
probably opt for a different flywheel mounting if the engine is offered
to the public as the taper is difficult to turn on larger lathes.
2/24/2003
The Cast Iron Cylinder Liner was turned and bored to .748" ID. A
Propane torch was used to heat the Block to about 400 degrees and the
liner was dropped in. A little persuasion was required to seat it
firmly in place. The liner was then lapped in place.
(
The above photo shows the lapping operation to remove all internal
tool marks and produce a perfectly round and parallel .750" bore.
The above photo is a closer look at the .747" OD cylinder lap. The
lengthwise slot is sawn with a radial saw blade, deep enough to leave
a thin "hinge" so that the two halves can be pushed apart with
an Socket Head bolt. A Cross slot is also sawn to ensure that the
Hinge section has uniform thickness from end to end. 300 grit, Clover
Leaf valve grinding compound is used with plenty of oil. The rotating
lap is moved in and out and the cylinder is occasionally reversed on
the lap. The lap speed is about 600 RPM . A messy job but necessary if
you want a good bore.
3/9/2003 The Cast Iron,
ring less piston was turned and lapped to fit the cylinder, a bit on
the snug side. A messy job but this ensures that the engine will
have excellent compression for the first 400 hours of operation. The
rod was machined and fitted with a Bronze split bearing. The photo
below shows the crank/rod/piston assembled, ready to drop in the
block.
The governor latch was made from Starret oil hardening flat bar
and both ends were hardened.
2/23/2003
The method of attaching the flywheel to the crankshaft has been
changed to feature a split type clamp hub that is pressed into the
flywheel. This allows removal and installing the flywheel with no
damage to the crank.
The governor weights and arms were machined and assembled as shown
in the photo below.
The next photo shows the governor weights and arms assembled on
the governor bracket and bolted to the flywheel .
An exploded view of the governor parts is shown below.
The governor latch was made from Starret oil hardening flat bar
and both ends were hardened. 
