Layering readily available styrene plastic is a useful method to model three dimensional surfaces in any scale of modeling railroading. The possibilities of this method are endless in the fabrication of structure walls, rolling stock components and in this particular case heavyweight passenger car siding.
A four layer version of this simple method was used to fabricate the replacement sides for the RPO cars needed on the Berkshire Line.
The Replacement Sides
The Branchline coach kit that was used as a core for the RPO's came with car sides that are approximately .075" in total thickness. The replacement sides will need to equal that thickness or be slightly less in order for the replacement sides to fit flush where they meet at the roof line and ends as the stock kit components were designed to do.
A total thickness of .070" was decided on for the replacement sides. The .005" discrepancy between the stock car side and replacement allows a leeway in the assembly process that could be shimmed out if necessary.
Readably available styrene in thicknesses of .010", .040" and .060" where used to build the RPO sides. Where ever possible out of the package stock width styrene strips that closest resembled the prototype dimensions in scale were used to ease and speed construction.
The base layer has a thickness of .010". This layer defines the width and height of the replacement sides. Because this is the foundation layer it is important to make it as square and dimensionally accurate as possible. Visibly, this layer will only represent the door panels and car corners when the sides are completed.
The RPO car corners have a radius, to simulate this radius a strip of .060" 1/4 round was glued vertically on top of the .010" base layer at each car corner to define the two ends of the replacement car sides. The .060" 1/4 round affixed on top of the .010" base layer are now equivalent to the finished thickness of .070".
In the photo below using a straight edge and square, the .060" 1/4 round has been glued at each car end. It is essential that this initial step be accurate and square as possible for a good fit to the car core at the ends and roof line in the end product.
The second layer has many individual parts, is the most difficult and time consuming layer to build. The door stiles, rails and mullions, window stiles and sashes will be outlined by this second layer. All pieces that make up the second layer will be .010" in thickness.
Because of the repetitive process of cutting same sized pieces for the doors and windows and also for the accurate and consistent placement of gluing these pieces onto the first layer, the use of several jigs will greatly speed this step and improve the overall end quality.
The second layer starts with the placement of the bottom door rails. In the photo below a styrene strip of .125" width is used as a jig to accurately locate and glue in place the bottom door rail at the correct height from the bottom of the car side. As a note, all the door rails are cut to a length longer than necessary with the extra length being covered up by the next layer. These rails are simply located right to left by working from a penciled centerline as below.
The next photo shows the two baggage doors and one postal apartment lower door rails glued in place. The initial use of a jig to locate these rails provides an accurate foundation to locate the remaining door parts.
Next photo shows the use of a custom sized .340" jig used to locate the center door rails referenced from the bottom door rail that is already glued in place.
The only purpose of the next photo is to demonstrate that the same .340" jig above can also used to set the stop on the "Chopper" that is used to uniformly cut all the door stile and mullion pieces of that size. Two of the door stiles of this size can be seen temporarily placed on the right door above.
To conclude the placement of the horizontal door pieces the top door rails are again located with a custom sized jig in the photo below. This time the jig is using the glued in place center door rail as a reference. Again, this .280" jig will be used the set the stop on the "Chopper" to cut the door stiles and mullions, this time the ones located between the center rail and top rail.
The below photo shows the placement of the first set of vertical door pieces (mullions). Working from the left using the .060" 1/4 round glued in place at the car end in the first layer as a reference point three different jigs are used to locate the first set of mullions.
The first jig from the left is cut to the height of the car side and .896" wide. The .896" dimension is the distance between the car end and door jamb of the first door. Being the correct size in height and width this first jig will later be used in layer three as a actual permanent piece of the car side.
The second jig in this stack (the one with the two black stripes) is a piece of .040' x .040" styrene strip, this represents the width of the .040" 1/4 round that will be used as a door jamb on the third layer.
The third jig in the stack is custom made width of .239", this is the distance from the door jamb to the first mullion and will be used to glue the first set of mullions in place.
The mullions are now glued in place and will be a reference point for the next set.
On these particular baggage doors there is a .200" space in between the mullions, there is the same .200" space between the mullions and the door stiles. In the photo below the .200" wide jigs are being used to set the second set of mullions. Note to make these .200" jigs they were cut off of one end of the .280" and .340" jigs to insure that they would be exactly the same dimension in height.
Below the .200" jigs were again used to set the door stiles in place and completes this baggage door. The pieces used for the door stiles are wider than necessary, this extra width provides a surface to glue the 1/4 round door jambs to when adding the next layer.
In the next photo, still working from the same car end additional jigs are stacked across the car side to build up the second baggage door. In this view the jigs added to the first two that were used to set up the first baggage door are from left to right,
(1) a jig equal to the width of the baggage door,
(2) another .040" x .040" strip for the door jamb,
(3) a second .896" wide piece again to be used with the third layer,
(4) one more .040" strip for the door jamb and
(5) the .239" jig used a second time to start the build up of the next door repeating the same procedure as the first.
Still working from the same car end additional jigs will be used across the width of the car side to build up the postal door and to outline window openings.
Below is a completed second layer of a car side. All three doors and windows have been outlined, again jigs were used to outline the window openings.
The areas on both sides and under all the doors have been filled in with a layer of .010" thick styrene. The only pieces critical here are under the doors, these strips are .100" in height and leave a .025" slot underneath the bottom door rail where a door sill will be added in the next layer. All these additional pieces will not be visible after the third layer is applied, their only purpose is provide a surface to glue the third layer to. The car side is now has an overall thickness of .020".
On third layer all pieces will be .040" thick. This thickness will give the doors and windows a prototypical inset from the outside car skin.
As mentioned before some of the jigs used in setting up the second layer are now are permanent pieces of the third layer. This includes the large pieces on both sides of the doors and between the center baggage door and windows. The remainder was filed in with pieces sized as needed.
Below is a closer shot of the pieces surrounding the center baggage door. The door sill will be placed in the slot under the bottom door rail and the jambs still need to be attached to both sides of the door in this photo.
The .020" thick door sill has been inserted into the provided slot and the .040" 1/4 round door jambs have been added to complete the door opening in this photo below.
The third layer is now complete and the side now has a total thickness of .060".
The fourth and final layer is a simple task of adding styrene strips for the letter board, the center reinforcement strip and the fish plates under the doors. These strips are all stock sized pieces, .100" for the fish plates, .080" center strip and .188" for the letter board. Additionally .040" pieces were added to the letter board over the doors and .100" over the windows. All the pieces on this layer are .010" thick.
The center strip was placed first. Again jigs were used to accurately space these strips from the bottom edge of the car side.
The letter board was placed next using the top edge of the car side as a reference point. Conversely the bottom edge of the car side was used as a reference point to attach the fish plates under the doors.
Next post will add some 3D rivet decals and finish up some odds and ends.