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Model Railroading > BN(SF) 40’ COIL CARe car (Part 1) - Intro


Date: 05/14/22 00:29
BN(SF) 40’ COIL CARe car (Part 1) - Intro
Author: tmotor

This is Part 1 of a series on the BN(SF) COIL CARe car project.
 
A unit Coil Train is an impressive sight.  Steel coils are some of the most dense loads on the rails.  A very heavy consist.  Throw-in some grades, and it will require lots of power.  When I saw one at Bakersfield (1999) I knew that I wanted to model it.  Each time a new coil car model was announced, I would see if it was a match.  And for 20 years, I have been disappointed.  It seemed like a pretty safe bet that it wouldn’t be offered (as RTR or a kit) in my lifetime.  if it was going to happen at all, it would need to be a DIY project.  My assumption was that I would use Evergreen I-beam strips, create some jigs, and punch-out 40 to 50 cars that were a reasonable facsimile, and call it good. 
 
With my modeling ability, I figured I would need a week of evenings (per car) to build the shell, mount the air brake equipment, then bend and mount bronze wire for plumbing, add some chain here and there, brackets, paint, decals, weathering. etc.  So, 50 cars?  Done in a year?   Yikes!  Consequently, this project was assigned a low priority.  Am I ever glad I waited.
 
High-Tech Scratch Building
For those that have been following my previous posts on 3D Printers, it is clear that another option now exists for us to create models that are not only as good as anything currently offered, but surpass them.  And it could not have come at a better time for me.  My eye sight isn’t what it used to be, and my eye-hand coordination is certainly past its peak performance.  By replacing my trusty X-Acto knife with CAD software, my modeling ability has been turbocharged.  I can zoom-in on a part and add details that could never be seen with the naked eye.  The number of details added is only limited by my time to add them.  If there is supposed to be a rivet there, it can be put there.  If there is a bend in the walkway sheet metal that forms a flange, no problem.
 
So now that there are a zillion dinky details, does that mean I need to add all of those parts individually to the model?  Nope.  The vast majority of the details can be printed in-place. 
 
Is There a Draft in Here?
But does that mean they will look like the cast-in details on the underframe of an Athearn Blue Box car?  Nope.  The 3D printer is free of the design limitations of injection molding, where the shape of the part needs to have “draft” (smooth, tapered sides) to allow the halves of the mold to pull-apart.  The reason that the Triple Valve on my Athearn Blue Box car looks like a lumpy Kleenex box, is because that is about the best that can be done; without having the mold be majorly complicated (and expensive).  For decades, the Triple Valve was accepted as being a “suggested detail” that was hidden underneath the car and didn’t require any more attention.  For those that were so inclined, the stock air brake details could be replaced with super-detail parts. Though modern tooling has elevated the detail on current models offered, they still require draft as part of the injection mold process.
 
For further info on Draft:
https://www.rapiddirect.com/blog/injection-molding-draft-angle/
 
3D printers don’t use molds.  It is possible to print parts with "undercut", such as a sphere, or a hollow part; or even a hollow sphere.  If it is rendered in the CAD geometry, the 3D printer can print it (assuming the part doesn’t exceed the printer’s resolution).  Instead of cutting dozens of parts from sprues, and assembling them as individual parts, let the 3D printer print the car with all of the super-detail components in-place. 
 
The Tortoise and the Hare
Granted, getting the very first part takes lots of CAD keyboard time, and then some fine-tuning on the 3D printer.  And, if it were a race for the first Coil Car model finished, the old-school Evergreen I-beam approach would win.  However, after the 3D printed part is dialed-in, the next car is just an overnight wait (vs. a week of work).  After some post processing, the car is ready for paint, weathering, and decals.  If the printer has the room to handle multiple cars, a fleet of cars can be printed in days; each with exactly the same level of detail and accuracy as the first car.  And… all fully assembled.  The level of accuracy and repeatability possible with a 3D printer is such a Game Changer!
 
But enough about the virtues of 3D printing, let’s talk about the COIL CARe car…
 
We CARe
BN took delivery of them from NSC (National Steel Car) in 1994 thru 1995.  They have a cushioned underframe, so the coupler shanks are longer than usual.  (They are designed to telescope to absorb the lateral G-forces.)  The concept is the coils will have a smoother ride.  They were marketed to customers as COIL CARe cars.  Hence the logo on the side with the lower case “e” pictured as reclining in a car.  (I dubbed it as the PacMan Logo, since that is what they suggest.  However, I doubt that is a common reference.)   
 
The coil loads are very heavy.  If they have a large diameter, only a few coils can be carried and not exceed the car’s weight capacity.  Though there might be plenty of physical room to add more coils, the load capacity is reached, so the car is “fully loaded”.  The 40’ length was designed to keep the car as short as possible, while still carrying the max payload.  However, it has a capacity for coils with diameters ranging from 40” to 80”.  If the coils have a small diameter, and are long, the car runs out of room and can’t hold any more coils.  The car will run significantly below (weight) capacity.   When BNSF ordered more COIL CARe cars, they wanted an extra 10’ to accommodate a wider range of loads.  No more of the 40’ version were ordered.  In fact, BN was the only railroad (to my knowledge) to order the 40’ version of the COIL CARe car from NSC.  (This will ensure that the NSC 40’ COIL CARe car will be kept off the radar of manufacturers looking for new models to offer.)
 
The road numbers as delivered from NSC are in the BN 686xxx range:
     BN 686027  thru
     BN 686863
Those are the lowest and highest road numbers for images I could find.  The road numbers may span the entire 686000 thru 686999 range, but I prefer to go from prototype photos. 
 
Conservatively, there were 836 COIL CARe 40’ cars built for the original BN order, delivered in bold Cascade Green.  (Though there could have been as many as 1000.)

Dave
 








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