|Cylinders HM107 & HM108: The cylinders are
described in the
Engine Design III
page. The first step was to saw the really heavy iron bar
to the correct length for each cylinder ( the length of the bar
matches the width of the cylinder ~5.25" for the left cylinder
for the right cylinder. Photo shows the small band saw
doing the job slowly but seemingly with little effort.
|The next step was to saw slabs off the sides to
bring the shape closer to a rectangle.
|The next step was to use the lathe to square the
sides as shown on the right.
Cast iron is my favorite metal to machine --- it doesn't grab
the tools and leaves few burrs. However, it is really dirty.
The chips and dust must be vacuumed up frequently to minimize the
mess. (Also, I've learnt to not mention I'm machining
iron to the wife.)
|The next step was to saw off the four corners as
the first step in rounding the sides.
|This is the setup used to mill the corners round.
Note the spacers under the cylinder to lift it off the rotary table
so that the edge next to the table could be machined. The fist
cuts were taken by fixing the rotation and moving the milling table
left to right. Small cuts were taken ~ 0.05" .
This went really well and fairly quickly.
|Once the basic shape was achieve, the cuts were
taken while rotating the cylinder under the mill as shown on the
|After the milling was done the ends were smoothed on
the belt sander to get rid of the cutter marks.
That is the left cylinder shown in the photo. Both cylinders
made it to this point in one winter day that included three meals,
many snacks, some TV and a nap.
|The next day it was back to the lathe to bore the
cylinder holes. The 4-jaw chuck takes a few minutes
to set up with the dial indicator but works really well. The
holes were first drill using a sequence of drills up to 1.25; which
is the largest drill I have. Much really black dust and
a big pile of chips accumulated, but really nice holes.
|The photo at right shows the cylinder back on the
rotary table to mill the steam passages in the sides of the cylinder
holes. Note that the holes for the heads and observation
ports have been drilled and tapped. Also a slot has been
milled out for the exhaust manifold.
The woodruff cutter is cutting the recess for the exhaust from
the valve bushing.
|This is another view of cutting that exhaust
passage. These passages are made with cores in the prototype
cylinders so they are don't need to be very precise. This
operation turned out to be much easier than anticipated.
|This shows all the passages in the two cylinders.
|Another view of the steam passages in the cylinders.
The cylinders were bored and the passages machined on the second
|Exhaust Manifolds HM118 & HM119: The
manifolds are described in the
Engine Design IV
page. These were made on the same two days as the cylinders.
The manifolds were fabricated from
from 1 1/4" square aluminum bar stock in the the following
- Hole for exhaust output drilled
- Screw attachment holes drilled from bottom
- Recess in bottom milled out
- Excess sawed off top
- Flat part of top smoothed on mill.
- The rounded sides of the hump were made
using the mill as shown on the right
- The attachment holes counter bored for SHCS.
|This shows the finished manifolds.
If I was to do the manifolds again I'd probably use cast iron.
|Main Cylinder Bushings HM109 & Valve Bushing
HM113: The main cylinder bushing is described in
Engine Design III
and the Valve Bushing is described in
Engine Design IV.
The bushings are turned from 1.5" (valve) and 2.5" (main
cylinder) diameter cast iron rods. The end and the OD of the
bushing is turned on the end of the rod and then the bushing is
sawed off and the process repeated for the second bushing. The photo shows turning a valve bushing OD.
|The sawed end of the bushing is then turned to the
correct length. Next, the inside is drilled and then bored to the
correct ID. The photo shows boring a valve bushing.
|After all four bushings were finished to the correct
length, OD & ID, the 3 jaw chuck was moved from the lathe to the
rotary table on the mill.
This photo show milling the ports near
the end of a main cylinder bushing. The rotary table is used
to position the cylinder for the slot and the mill table is moved
left to make the cut.
Note that the cuts are made from the inside on the main
cylinder bushing. After the slots were milled, they were
widened on the outside using a rotary tool.
|The rotary table is positioned so that the axis is
horizontal to make the ports on the valve cylinder. The
exhaust ports are simple holes. The holes were first spotted
with a center drill and then a drill was used to make the hole as
shown in the photo.
|Groves for the main
passage ports were turned on the lathe. It is important to make these ports as accurate
as possible. These holes were drilled with the
center drill --- a drill that doesn't wander much. The holes
were then squared up with a file. The critical part it to make
the top and bottom of the holes line up with sides of the groove.
Even though the ports were drilled from the outside, there were
essentially no burrs on the inside.
|This shows the finished bushings.