MODELING: NP 52′ Flat Car 1.0

 

Progress is being made on my latest project.   This is the start of a construction project to build a 1/48 scale model of a Northern Pacific fifty-two foot flat car.  The NP had a large number of this type of car with the following lot build dates and number:

 

In addition, the car was purchased for the Burlington, SP&S and Great Nothern.   Differences exist between the various Hill Lines in terms of hand brakes and lettering.

NOTES ON CONSTRUCTION

I have made some decisions on various aspects of the model construction.

  • Basic centersill and crossbears are made from .030″ styrene.  I have tried to use .020″ material but found that is not very rigid and have caused me problems in the past.
  • The centersill has been widened to increase the area for the car weight.  Flat cars are notorius for being light and having tracking problems in train service.  I noticed Jim King had done this for his 70-ton AAR flat car kit.
  • Rivets on the underframe will be Archer decal rivets.  The sidesill and endsills will have punched rivets.

CONSTRUCTION

I recommend you start with a copy of Railroad Model Craftsman November 2016 issue.  It has a decent scale drawing of this car.  I detected a few differences when compared to the blueprint obtained from the Northern Pacific Railway Historical Associations.  I suspected that the draftsman may have used a CB&Q or GN railroad drawing.  The RMC drawing is much easier to use given the way the railroad drawing shows only the “B” half of the car and added multiple footnotes on features used on the “A” end of the car.

CENTERSILL 

I started with a full sheet of .030″ styrene and squared all sides.  I marked key breakpoints for cutting out the shape of the two girders and baseplate  I also marked the location of the crossties and crossbearers along with the bolsters.  This will aid in the assembly of the various parts in the underframe.

My little aluminum blocks are helpful when squaring up the various parts while the solvent glue sets.  I use the blue tape on the rule to keep it from sliding on the slick plastic surface.

Once the girders are cut out, it is a good idea to cut the slots for the trainline, brake levers and branch pipe (right to left).  The block is to hold a Protocraft bushing for mounting the truck.   The block is .315″ wide.  It also served a good spacer for the girders.  Mark the stryene to make sure you get the correct orientation.

Here is one of my metal blocks holding the girder upright.  The blocks were salvaged from a scrap bin at my employer.  The blocks are square on all surfaces.   They were made as spacers for an electronics rack that went into a 637 Class submarine.  End of story on the liittle blocks.

I used a little fixture to aid in the glueing operation. Crude but effective at holding the strip at a 90-degree angle.

The next step is to fabricate and install the crossbearers on the frame.  They are cut from .030″ sheet with a .030″x.080″ strip at the base.   Add slots for trainline and brake rodding as appropriate.   The shape is defined by the drawings and it must fit between the centersill base and the sidesill channels. The car is 9’3″ across the sidesills.  The centersill base is 0.50″ wide and the sidesills are built up from .030″ with a .015″ thick riveted overlay.  The sidesill is 13″ high so I made a channel shape using .25″x.030″ strip for the full length of the sill.  I built up the height with a .020″x.100″ strip attached to the bottom the top edge.  A .020″x.060″ strip was added to the bottom to create the 13″ channel.   You may think that the wall thickness is excessive but remember the car will likely weight 14-16 ounces when completed.  You don’t want a lot of flex in the sidesill.

The body bolsters were cut from .020″ sheet with a .125″x.080″ spacer to create the form  Like the crossbearer, the sides of the bolster are drawn on the styrene and cut out with a fresh single-edged razor blade.

The bolster is installed on a 14″ by 37.5″ strip cut from .030″ styrene   The 37.5″ length was determined by the width of the centersill (24″) and the sidesill base (.100″ plus .015″ for side overlay.  These dimensions produced a frame width of 9’3″ per the drawing.

The next installment will finish up the underframe and add side and endsills.

Gene

 

 

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