|Most of the parts were
machined on my CNC vertical machining center (KITAMURA Mycenter 1) and CNC Lathe
(Graziano SAG12) with simple jobs handled by the Bridgeport and drill press.
The machining center has a rotary forth axles that allow parts to be machined on
multiple surfaces with one setup. For example all the smoke box holes were
drilled in one setup (200 holes) and the cylinder block will be totally machined
Fixtures were made when required to hold or drill parts so that accuracy
could be maintained. Some fixtures were relatively simple while others
complex. Fabricated metal parts were sawed and bent on the press brake while
sheet metal parts were punched on the CNC turret punch and then bent and welded
as required. All parts were made from the geometry files created in the
Cad system (Pro/Engineer) along with the NC tool paths, which were down loaded
to the machine controls. All programs and fixtures were saved for future
The author and the CNC vertical machining center KITAMURA
CNC lathe Graziano SAG12
|Patterns were made of
aluminum or wood. Most were mounted on match plates although some of the
larger ones were loose. Most of the castings were made in gray or ductile iron
although a few were done in aluminum. I started out by making the parts for the
frame. I considered several methods of making the frame, one method is to
build it up out of bar stock or a second cut it out of steel plate or bar.
I rejected the first because it would be difficult to make it like the
prototype and decided to cut it out of ¾ steel plate. There is several
ways to do this and I have used them all. The popular processes include flame
cutting (including plasma and laser) then machining or to machine it out of the
| I decided to use a
process called water jet cutting. In water jet cutting an abrasive is mixed into
a very high pressure water jet (50,000 psi) and the jet is slowly moved along
the path to be cut. The abrasive cuts its way through the material leaving
a very fine accurate cut. Tolerances of .002 or .003 can be maintained. In
fact the cuts are so accurate that no milling was required on the frame rails.
The cost is higher than flame cutting but the time saved in milling all of the
surfaces more than makes up for the additional cost.
Because of the design being available on the computer all I had to do was
email the frame geometry to my vendor and he cut the frame right from that
geometry. The only machining required was drilling holes. They were done
on my CNC vertical machining center. Total machine time for a ready to assemble
frame rail was about 15 minutes. Figure 1 shows the frame rails ready to
Holes being drilled in the frame using the KITAMURA Mycenter 1
The drivers were cast in ductile iron and
turned on the CNC lathe. When I make wheels I start by facing the backside
and boring the center hole to size. I then turn the wheel around and face
the front side. Finally the wheel is placed on a mandrel and the outside
profiled. Once the drivers were turned they were placed on a pin on the
machining center table and the crankpin hole drilled and reamed in the correct
position. A broaching fixture was made that located the keyway in the main bore
relative to the crankpin.
|The axles were next. They were
turned on the CNC lathe and then a fixture was used to mill the axle and
eccentric keyways. How I usually do this is take a piece of square stock
and bore a hole thru to accept the axle diameter. A couple setscrews hold the
axle in position. The keyways are milled on one end then the fixture is
rotated 90 degrees and the keyways milled on the other end. I decided to
key the eccentrics to the axle as the prototype does. This eliminates the
chances of an eccentric slipping and aids in setting up the gear correctly. Ball
bearings were used on all axles including the front truck
|Next up was the front truck.
Again the frame was water jet cut as was the swing links and equalizing bars.
Casting were used for the center pivot journal boxes and wheels. Machining was
Main springs and equalization was the next components
tackled. Rockers were water jet cut, hangers were bent up out of 3/16 x ¾
steel. The spring leaves were cut and punched from .050 x ¾ 1095
hardened spring steel. The locomotive was sprung like the prototype
and is fully equalized.
Front pilot truck, frame, spring rigging, drivers are being
Boilers are being built by Ridge Locomotive
Works (Marty Knox) and are a true wagon top design with a steel shell and copper
tubes. Calculations show them to be a well-proportioned design and should
be good steamers with a very large steam space.
As the locomotive was proceeding work began on the tender. The tender
frame was fabricated out of channel and bar stock and bolted together just like
the prototype. A wood deck was added to complete the frame. The
tender trucks were constructed in line with the prototype. The only
exception is that I use ball bearings in place of the half brasses and
wedges that were prototype practice. The tender tank was supplied by
Locoparts and included all of the parts to construct the tank. The tank is
riveted together. Locoparts also supplied the hand pump, valves and other tank
Work is now under way on machining the cylinders and valve gear parts with
the goal of being able to test fire the locomotive by summer 2004. A future
article will report on the first tests of the locomotive and how things worked
Frame, drivers, pilot, cab, boiler and smokebox come together.