Best Of Scratchbuild Project - CC&F Twin Trailer Flat Car

[Hyperion]

Hm, that might explain my problem with gluing brass/etch more than the brand of glue itself.

[GaryHinshaw]

Cool project Tim!  Something worthy of Gordon Odegard himself.  (I was just looking back through some '80s MRs and marveling at some of the projects he took on way back then.)

Keep us posted,
Gary

[BCR 570]

Before embarking on the actual build, here are some prototype photographs.  The first is an image of PGE 7102 at North Vancouver circa 1976:




The PGE cars were black with white stencilling.  This car is carrying a BCR flatdeck trailer and a BCR heater or reefer van trailer.


The second image illustrates a car repainted for the British Columbia Railway:




BCOL 7104 is BCR Dark Green and is carrying a flatdeck trailer and a reefer trailer.  Earlier repaints were BCR Light Green.


The cars had a length over the end sills of 85'-0" and a truck centre spacing of 62'-0".  Their construction includes two centre sills which are strapped together.  There are diaphragm plates at the centre of the car and at the lower end of each taper on the centre sills.  Located in between the bolster beams and diaphragms are a series of cross-ties with vertical stiffeners on the centre sill below.  The bolster beams, diaphragms and cross-ties all support the tread plate runways which are 30 inches wide.  The aprons (ramps) measure 48" x 30" and are both located at the 'A' end.  The cars rode on 70-Ton roller bearing trucks.

On with the build!


Tim

[sirenwerks]

Tim,

This project looks like a keeper. Document it well. I think it would make a great article (include drawings please).

[Leggy]

Let me guess, they'll be riding on BLMA bogies?

[BCR 570]

Yes - I hope to use BLMA 70-Ton trucks.

Centre Sills
The first parts to be prepared are the twin centre sills.  These are I-beams with a centre section 30" deep, end sections 16" deep, and tapered sections in between.  I estimated the top and bottom flanges to be about 12" or so wide.

The webs were cut from .020" x .188" strip styrene, and the top and bottom flanges were cut from .010" x .080" strip styrene.  From the end test section I learned that the Micro-Trains coupler would have to mount right up underneath the top flanges of the centre sills in order to sit at the right height.  This means that the centre sill webs would have to terminate behind the coupler boxes - a distance of 4'-6" from the end sills.

The photograph below illustrates the parts required for the construction of the centre sills, with one web attached to a top flange shown at the top:




The bottom flange pieces will be added at a later stage in construction (another lesson learned from the test sections).  The centre sill webs are marked with pencil to assist in locating the diaphragms, cross-ties and stiffeners which will be added.

There are two challenges in making these parts.  The first is to get a pair of centre sill top flanges and webs which match precisely in length.  The solution is to make several and select the ones which best match each other.  The second challenge is to attach the web to the top flange so that it is precisely in the centre and exactly perpendicular.  I accomplished this by using a long .030" shim positioned underneath the web during assembly.  In this way it is fairly easy to obtain a consistently centred and perpendicular I-beam.

The I-beams will be joined together at a later stage in construction.  Next up is manufacture of the diaphragms and bolster beams which will attach at right angles to the centre sills.


Tim

[BCR 570]

Diaphragm Plates
The next parts to be manufactured are the diaphragms.  Together with the bolster beams they provide the primary lateral support for the runways on top.  These cars had double diaphragms (flanges both sides) and were located at the centre of the car and at the lower end of the tapered section (total of six).

The diaphragms are perpendicular to the centre sill and butt up against the centre sill web inside the top and bottom flanges.  This means that the top and bottom flanges of the diaphragm must be offset by the distance from the centre sill web to the outside edge of the centre sill flanges.  In addition, the taper on the lower edge of the diaphragm plate must be offset by the same distance.

I cut the triangular plates from .010" x .188" strip styrene, and the top and bottom flanges from .010" x .060" strip styrene.  The offset for the flanges and the inside of the lower edge taper were marked using a .030" guide, and the outside end of the lower edge taper was marked with a .040" guide.  The flanges were glued to the plates using a .025" shim.

With these parts the challenge is to obtain consistent pairs of parts with flanges which are centred and perpendicular to the plate, and which are offset correctly at the inner end.  I made more than enough parts so that I can select the best ones and match them in pairs accordingly.

In addition to the pair of diaphraagm plates, an inner plate is required to go between the centre sills at these locations.  These provide the primary means of joining the two centre sills together.  I made these from .020" x .188" strip styrene cut to a width of 12".  The extra thickness will not be apparent inside the centre sill, and it will provide a stronger joint at these locations.

The photograph below illustrates the parts required for the diaphragm plates, with a completed pair at the top:




Next up will be various parts which make up the bolsters.


Tim

[Ed Kapuscinski]

Tim, did you think of making a jig for cutting those parts?

[BCR 570]

Tim, did you think of making a jig for cutting those parts?

Ed:  Good idea!  No I did not, although the use of cutting guides effectively did the same work for me.  I was pleased with the consistency of the parts I made.  Part of this exercise is to improve my scratchbuilding skills, so the practice is useful.

Tim

[SkipGear]

Tim,
 I hope you have a NWSL Chopper for this project.

[BCR 570]

Yes I do - it and the True Sander are being put to good use.

Tim

[BCR 570]

Bolster Parts
The bolsters are one area where a few departures may have to be made from prototypical dimensions and shapes in order to meet model requirements.  The bolsters will be built to accommodate the new 70-Ton trucks from BLMA Models (part #9025).

The end test section was used to work out the requirements for the trucks.  One important lesson I learned with the test section was that the model truck fouled the taper of the centre sills slightly when rotating.  I solved this by shortening the taper and inserting one scale foot of 16" depth between the end of the taper and the bolster hub.

The following photograph illustrates the various parts which will make up the bolster:




Top Row:  bolster top plates and bolster crown plate
2nd Row:  bolster beams and centre block
3rd Row:  bolster stiffeners and centre bearing plate
4th Row:  bolster bottom plates and bolster hub

Most of these parts will be added to the car later, but I elected to make them all in one sitting.  Note that the top plates are shorter than the bolster beams; as with the diaphragm plates, the top plates must be offset to allow the bolster beams to fit inside the centre sills.  The bottom plates are longer because they will extend out underneath the side sills.

All are made from strip styrene except for the bolster hubs which are from 1/8" tubing.  The bottom end of the hub was tapped for a #2-56 mounting screw.  During construction of the end test section I also learned that the inside diameter of the bolster hole on the BLMA truck is slightly smaller than the Micro-Trains trucks.  Consequently the 1/8" styrene tube, which passes easily through the hole in a Micro-Trains truck, has to be reduced in outside diameter to pass through the BLMA truck.  This was more difficult to accomplish than you might think; all of the other parts were fairly simple to produce.

The next parts to be made will be the running plates or runways which essentially comprise the decks for these cars.


Tim

[BCR 570]

Running Plates
These are the runways on which the trailer wheels roll when loaded aboard the flat car.  They were 30" wide and the surface was steel tread plate.  The running plates sit atop the bolster beams, diaphragms and cross-ties and stop six inches short of the end sills, so they need to be cut 84'-0" long.

I used .010" x .188" strip styrene which conveniently is 30" wide in N Scale.  For the tread plate surface I will use the etched tread plate material available from BLMA Models (part #250) which very conveniently includes 30" wide strips (thank you Craig!).  Unfortunately the strips are only 41' long so three sections will be required to complete each running plate.

Here are the component parts for the running plates:




Well enough of this parts manufacturing nonsense - it is time to start assembling a model!  The next stage will be to attach the bolster beams and diaphragms to the centre sills and add the running plates.


Tim

[DKS]

This is a great project, Tim, and you're doing exceptional work.

Recommend this topic be moved to Weathering, Detailing, and Scratchbuilding, and made Sticky for the time being. This is a worthwhile thread.

[BCR 570]

Yikes - I have never had a thread moved before.  Hopefully people will still be able to find it.  Not sure what 'sticky' means . . . unless you are talking about what happens to the styrene when I use too much glue.

David - Thank you for the encouragement.  I always enjoy seeing your work.


Assembly Begins
After a week of manufacturing parts, I am now able to begin assembly.  The bolster beams and diaphragms butt onto the centre sill and their top plates are level with the top plate of the centre sill.  This means that this stage of the assembly can be done effectively upside down on a flat surface.

I braced the centre sill upside down against an angle block with a .030" shim in behind.  I then glued the bolster beams and diaphragms to the centre sill using a set square to ensure a perpendicular joint.

The following photograph illustrates the centre sills with bolster beams and diaphragms attached.  The lower pair are upside down; the upper pair are resting on their inboard side:




The next step will be to attach the running plates.  This photograph shows a pair of centre sill/bolster/diaphragm assemblies with the running plates positioned beside them:




It is also time to begin manufacturing the cross ties and centre sill stiffeners, as there a lot of them (36 per car).


Tim