Sunday, July 3, 2022

Modeling SP 32451 (Part 1) - Sunshine B-50-15 Resin Kit

Many years ago I picked up a Sunshine resin kit for SP's B-50-15 class.  The only model that they had in stock was for the original wood-sided version.  By the early 1950s many cars of the B-50-15/16 classes had been rebuilt with steel side sheathing starting in the 1936-1937 time frame and continuing through into the post-war years.

Sunshine SP B-50-15 roughly assembled, roof still loose to add weight.

Rapido has announced a injection molded kit for the B-50-15/16 classes and both wood and metal versions of the side sheathing.  So we won't always have to build-up resin models of this class once those are released.  I'm also working on a research post for the prototype information, which should help everyone selecting which versions to get in their Rapido car orders.

A Short History

The B-50-15 and -16 classes were built in large numbers between 1925 and 1928, totaling an amazing 4903 cars!  By 1950 less than 5% of the fleet was out of revenue service and by 1955 their numbers were starting to drop, but the classes remained in common service through 1960.

SP 14480-15979 (1500 cars) - Murphy Roof (1st 750 cars) Viking Roof (2nd 750 cars), T-Section trucks
ML&T 36210-36509 (300 cars) - Murphy Roof, Arch-bar trucks when built
ML&T 53060-53559 (500 cars) - Hutchins Roof, T-Section trucks
SP 20000-20499 (500 cars) - Hutchins Roof, T-Section trucks
SP 31560-32659 (1100 cars) - Viking Roof (1nd 600 cars), Hutchins Roof (2nd 500 cars), T-Section trucks
        Total 3900 cars

SP 37340-37839 (500 cars) - Viking Roof, T-Section trucks
SD&A 7000-7002 (3 cars) - Viking Roof, T-Section trucks
T&NO 53500-54059 (500 cars) - Viking Roof, T-Section trucks
        Total 1003 cars

The version of the car I have is Sunshine Kit #38.7, which has the notes "SP B-50-15 20000-499, 32160-659 Series Freight, Wood, Hutchins Roof, 1920-1950s."  Thankfully there's a great photo of SP 32451 in Thompson's SP Freight Cars Vol.4 on pg 223 showing the car in 1949, after it was upgraded with AB brakes in 1947 and still wood sheathed.

Shortly, I'll be posting a blog on Modeling B-50-Series (Part 4) - "Pre-depression" B-50-15/16 Class Boxcars, which will be a more complete history of the B-50-15/16 cars and their rebuilds into the 1940s and 1950s.  (I just want to get a few more model photos before I post a bunch of text with no pretty models or examples to see!)  So keep an eye out for that!

Building the Kit

The castings from Sunshine are very nice.  This blog post is mostly going to be photos of gray chunks of resin becoming the shape of a boxcar.  Enjoy!

Main body parts laid out for prep work.

I prepared the castings with a bit of light sanding with the pink sanding pad (shown in the photo above), which made quick work of roughing up the smooth mating surfaces of the resin castings.  ACC/CA "superglue" is used to assemble the resin parts, so having a good roughed surface for bonding is ideal.

There are also plenty of details included which I'm not showing in the photo above, such as the doors, running board, brake parts, etc.

Assembling the Main Body

Strips of styrene cut to fit in the corners of the car.

To aid in the construction, I pre-cut lengths of styrene to fit inside the corners of the sides and ends.

Styrene corner strip glued in place with ACC/CA glue.

I also marked the floor thickness and location with a mechanical pencil.

Styrene corner strips ACC'd in place.

  The styrene strips should also help locate the floor after the ends and sides are assembled.

A machinist's square is used to ensure the ends are square

I applied the ACC/CA to the ends of the car side and styrene strip, then placed the ends into the glue, checking that the tops of the ends and side are even.  The roof on this kit has a flat bottom, so ideally everything will meet properly if the tops are even.

Exterior view of the square at work while the end dries in place.

This assembly process worked well, allowing about 10-15 minutes for the ACC/CA to fully harden on the resin.

Both ends attached to one side.

In hindsight, it may have been better and easier to glue one end to each side, then assemble the two halves, than to drop the last side between the ends.

Additional styrene strips appled to ends to help bonding the roof and floor in place.

I considered if I wanted to glue in the floor permanently or the roof.  I decided the roof would be easy to align to the top exterior of the car, and the floor would be more helpful in ensuring the car was square when gluing the walls in place.

Floor and second wall glued in place.

The floor was somewhat challenging to glue in, but wasn't too bad as the endsills are flush with the bottom edge of the floor and the bottom of the poling pockets match up bottom of the sides very nicely.

View of assembled basic body.

The body is set set aside for 20-30 minutes, allowing the glue to dry and harden. 
SP 32451 interior with styrene strip corner reinforcement.

Two additional styrene strips are added in side the floor-side joint about 1/3 the length of the car.  This helps give some strength to the floor joints while I finish drilling and tapping the bolster holes for the truck screws.

Underframe Detailing

Bottom view of floor in place.

Underside of the floor is marked with A-End and B-End based on the dead-lever bracket to the right of the cross beams.  This is about the only orientation indicators on the floor as to which end is which.  Given the prototype car I'm modeling was upgraded with AB-Brakes in 1947, I'll be going with that version of the underbody details.

Marking and Drilling Grab Iron Holes

The model will need a number of grab irons installed.  I marked the locations roughly with my mechanical pencil.  However, the light gray resin is somewhat difficult to see the exact placement of where I'll want the holes.  I plan to drill them after the body is assembled and receives a quick shot of primer color.

Trucks & Couplers

As the Sunshine kits don't come with trucks, I'm swiping a set of Red Caboose T-Section trucks from one of my SP S-40-5/8 class stock cars for this kit.  Of course some cars were receiving replacement trucks of AAR U-Section design by the 1940+ era. 

Trucks installed with 2-56 screws.

I'm sure the new tooled Rapido T-Section trucks will be quite the hit with modelers, considering how many prototype cars should still have T-section trucks under them in the 1940-1955 era.

Couplers will come shortly, as I'll need to decide which coupler boxes to use on the model and drill mounting holes.  Weights will come shortly as well, as I can't seal up the roof until the car is weighted.

In Closing

The Sunshine B-50-15 kit is coming along very nicely.  Before priming the model, I'll need to wash it and apply the rest of the cast resin details, which will need to bond directly to the body.

SP 32451, B-50-15, Under construction sitting at Owenyo.

I also have one of the excellent one-piece body Westerfield resin B-50-15 Steel-sheathed "Overnight" versions to build, so that will be its own blog series.  It will be nice to have two of these very common single-sheath SP boxcars in service when the Jawbone Branch can start running trains.

Jason Hill

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