Drive Gear
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Drive Gear

Modelers often balk at bashing a drive by changing the number of driver pairs or the wheelbase spacing of the drivers because of fears that they won't be able to bash the moving parts including the side rods, piston rods, cylinders, and valve gear.  Often this fear is unfounded and was certainly so in this case.  

Side Rods

The major modification needed is to convert side rods designed for an 8 coupled loco to one needed for a six coupled locomotive.  This problem can be easily solved with a razor saw, file, epoxy and a piece of either K&S brass or Plastruct styrene rectangular tube.  In my case I had a K&S 1/32" x 1/16" rectangular tube.  It is almost the exact thickness and just slightly taller than the Aristo C-14 driver rods.

Use a razor saw to remove one of the middle beatings from one of the two side rods.  Keep the second rod intact for now.  Cut out the bearing with the raised nipple to carry the piston rod.  Then measure and cut two pieces of K&S rectangular tube that have lengths exactly the distance between the ends of the two bearings surrounding the piece that was removed.
The side rod shafts are too thick to fit inside the tube.  Use a file to reduce the thickness of the rod pieces until they slide snugly inside the rectangular tubes.  You will need to smooth the edges of the tube with a riffler file to allow the the shafts to slide in smoothly.

Test the length of the bashed rod against the other unmodified original.  You may need to file the shaft or the tube to get the lengths to match exactly and to get the holes to line up perfectly. 
Apply epoxy to the shafts and slide them into the tube.  Double check the length of the first rod against the unmodified original.  Once the glue has set on the first rod, repeat the same steps with the unmodified rod.  

Then use a razor saw to cut off the nipples that carry the piston rods flush with the shaft.  The two removed nipples are shown at the top of this photo.
Use epoxy or styrene glue to glue the nipples to the middle bearing.  Make sure the nipples are centered both vertically and horizontally between the bolts running through the middle bearing.
The side rods were painted with a Krylon Flat Black spray can. 

Cylinders

The Aristo cylinders lack the steam and drain cocks found on the prototype.

This shot shows the drain cocks (bottom of cylinders) and the steam cocks (protruding from side of valve area) that were fabricated from 3 mm Plastruct tube and 1.5 mm brass rod.  
The brass front and rear covers were removed or masked.  The cylinders were then painted with Krylon Flat Black.

Reassembly

With the individual drive train components bashed and painted, the remaining step was reassembly.  For the most part, this involved following the disassembly steps in reverse, with the exception of the cross head brace and side valve rods.  Of course, the side rods were screwed to one less set of drivers.

In this shot, the drive train is reassembled with the exception of the cross head brace and side valve rods.
In this shot, the drive train modifications are complete except for some mechanical tuning.
The wheel arrangement drive gear and chassis detailing is representative of a Baldwin 16D Mogul from 1876.
Here's the builders photo of the prototype.
 

The next step in the construction of this model is superstructure modifications.  The bulk of the superstructure will be built from scratch.

(c) 2007 Iron Horse 1:29