Minitrains 0-4-0 Cab Modifications

Once the engine is disassembled it is time to make modifications to major components.  First, the cab.  It is a one piece styrene structure.  The tail light that is moulded into this part is rather silly, placed on the back of the bunker.  It will be replaced to a proper old time kerosene lantern.  The air vent at the top will be converted to a flip up opening.

0-4-0 Cab Before2


The side view highlights a significant number of changes.

  • The four round windows will be converted to square windows.
  • The bunker will be replaced with a taller and deeper bunker.  It will provide inside room for the DCC decoder.  Given that one of the responsibilities of the engine will be to haul oil cars to the kiln, it makes sense to model this engine as oil fired.
  • A side door will be added adjacent to the rear of the cab.  The door will have a shade above, a window in the top portion, and an arm rest.
  • The step will need to be repositioned and a more appropriate version scratch built.
  • Rivets will be removed from the cab portion and it will be converted to a wooden cab.

These changes will make the cab more representative of an American prototype.  Given that these changes will weaken the cab if all the cuts are done at the same time, the bunker will be removed and replaced before moving on to the doors.

0-4-0 Cab Before1

Squaring the Windows

The objective here is to change the shape but not the size of the windows as they need to work with both a taller bunker on the rear and the boiler on the front.  I tried two different techniques to square these round windows.  I won’t discuss the first technique as it didn’t work. Here are the windows in their original state.

0-4-0 Cab windows2


The technique that worked best for me is to get out my smallest square riffler file and start filing.  Once they were reasonably square, I used a sharp Exacto knife blade to finish them off.  In my case the windows don’t need to be perfect as they will be finished by bits of styrene to represent window casings.  These styrene pieces will make the window openings slightly smaller.  The photo also shows the tools I used.

0-4-0 Cab windows1

Remove Bunker

The next step was to remove the bunker to prepare for a larger deeper bunker.  I scored lines along the rivets ascending vertically from the bottom of the engine in the bunker area.  I used a trusted technique of dragging an exact knife backward.  I used a bit of rectangular brass tube to keep my score straight.  Ince i had deepened the score, I used a razor saw from the top of the bunker down to cut the top away from the cab.  At this point the razor saw is half way through the bunker.

0-4-0 Cab Bunker1JPG


I then used my Exacto knife to finish the cuts along the scores.  To ,my surprise, I ended up with three pieces.  On the left is the cab, less bunker.  Top right is the frame around the bunker.  Top bottom is the bunker.  That piece includes the two holes into which the screws holding the rear pilot are inserted.

0-4-0 Cab Bunker2

This means when I build the new pilot and bunker, I’ll need to consider how the pilot will be attached.

I got out my calipers.  You might recall that I intend to place the Digitrax DN136D DCC decoder inside the new bunker.  Its dimensions are 0.55” x 0.404” x 0.2”.  I first checked the width of the new opening.

0-4-0 Cab Bunker3JPG

If I lay the decoder on its side (the longest dimension at 0.55″), it should fit nicely.  I then checked the height of the opening.

0-4-0 Cab Bunker4JPG

The second longest dimension is 0.404″.  I don’t want the bunker to be that deep.  So the height of the opening needs to be increased.  So I got out my Exacto knife and scribed a line across the back that would increase height of the opening.  Once the scribe was deep enough I used the Exacto knife to cut vertically to the line.  A bit of a work with the file resulted in an opening that is 0.484″ tall.

0-4-0 Cab Bunker5JPG

Building the New Front and Rear Pilot

The old rear pilot was 0.25″ tall by 0.25″ deep by 0.75″ wide at the top.  It was tapered a bit making it narrower at the bottom.  The old front pilot was 0.25″ tall by 0.27″ deep by o.65″ wide at the top.  Like the rear pilot it was tapered making it narrow at the bottom.  The narrower width allowed the fronts of the cylinders to be seen.

I will make the rear pilot out of a 0.25″ by 0.25″ by 0.75″ solid wood piece (like the prototype) and machine it to hold the coupler.  

Building the new Oil Bunker

The oil bunker needs to be at least .20″ deep to accommodate the decoder without protruding into the cab, although there is some room behind the motor for a protrusion.  The old bunker was about 0.1″.  We don’t want the oil bunker protruding beyond the rear pilot (unsafe in a crash), so the bunker will be built 0.20″ deep on the outside, making it slightly less than 0.20″ inside.  Cab wall thickness is 0.04″, so the bunker will be fabricated from 0.04″ styrene.  If I create cover the joint between bunker and cab using a small strip of the same material, the opening will be narrowed to 0.56″.  I’ll wait until the decoder arrives to see whether this will work.


Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>