OwlMtModels Mini-Kit Conversions for Accurail 40ft Boxcars

Time to upgrade my Accurail SP single-sheathed boxcar fleet

This post is to finally show the new conversion ends from OwlMtModels to make the basic Accurail 40ft Single Sheath USRA clones more like the SP B-50-8,10,11, and -13/14-class cars.  Accurail has offered these kits with either a 1920s "7-8" pressed steel end or a 4-vertical post wood-sheathed end.  Unfortunately, neither is right for SP's ~8000 single sheath boxcars of this rough design.

The stock wood ends of Accurail boxcars are nice, but the details on the ends aren't correct for the SP's boxcars.

Over the years I've built over 20 of the Accurail cars for my fleet during the late 1990s and early 2000s.  While resin models of these cars are available, I don't really want to build a new fleet of resin kits when I have so many Accurail cars already in my fleet.  Now that I'm building the Jawbone Branch layout, these converted Accurail cars will become the backbone of my SP wood-sheathed boxcar fleet.

The answer in the form of OwlMtModels' newly designed 3d printed ends.

The ends are 3d printed and include a large flange on the interior side to bond to the interior of the injection molded roof and sides of the Accurail body.

Multiple versions are in the works at OwlMtModels:

* OMM 4072 B-50-8/10/11 wood ends (with option for either plain end or lumber-door end.)

* OMM 4073 B-50-13/14 rebuilt steel Dreadnought Ends, vertical staff hand brake. (Almost all B-50-14s and many B-50-13s fitted during the 1930s.

* OMM 4074 B-50-13 As-built wood ends (with option for either plain end or lumber-door end.)

* OMM 4075 B-50-13/14 rebuilt steel Dreadnought Ends, with lower platform for power-brake refit.

In this post, I'm only working with pre-production samples of OMM 4073 and OMM 4074, which will be made available for sales at the SPH&TS 2024 Convention in Sparks, NV in mid-October.

The ends are designed to use Carmer cut bars, and so a pivot is provided for such, but not included.  Yarmouth Model Works makes several photo-etched Carmer levers, which should work on these parts.  Grab iron holes are printed into the ends, but probably have back-filled with resin before the processing was completed, so those will need to be drilled out.  The brake staff holes will probably need to be cleared too.  Then a suitable staff (wire) and wheel (probably Cal-Scale) will be installed.  The retaining valve has been printed in-place, but a 0.009" wire retainer pipe should be fitted on the Dreadnaught End version of these parts.  The wood ends have the retainer pipe printed-in-place.

Bonding flange which will allow the glue to form a tight grip between the body shell and the new ends.

Pre-assembly prep on the ends is minimal, but important none the less.  I carefully make a few light passes with my mill file to remove any remains of the support contact points from the bonding areas outside of the rib.  This will insure that the part fits smoothly against the end of the chopped Accurail car body.

Chopping the Body

Two long cuts are made in the ends of the body, just inboard of the sides.

The first step is to chop into the injection molded ends, along the inside edge of the sides.  Once the cuts are made, the end is popped out.  Note: I usually only do one end of the car at a time, this allows the other end to provide good rigidity and support to the sides and help keep everything square throughout the process.

I just bend the end of the car back and forth until it fatigues and breaks loose.

Step two is to trim back the sides to remove the original corner posts.  I did part of this with the razor saw in the past, as I got a little impatient on the second end (A-end), I went ahead and chomped through the last 1/16" of sides with my sprue-cutters.  I marked the parts to discard with a black Sharpie marker, stopping just at the edge of the wood boards.  It did require some careful alignment to be sure I wasn't going to bite too much off.  

Dry fitting the A-end for B-50-13/14 'as-built' wood end.

Side view of A-end after filing is complete on 1st prototype print.

In Step three, the last 0.015-0.025" of the sides are filed or sanded down to the ends of the wooden boards.  On the roof, the lateral 'running board' support should be as far back as I trim that section.  File everything smooth and even across the whole end.  I check the progress on keeping it square and even with a regular dry test fitting of the part.

Finished prep work sanding and filing car-end.

I should note at this stage I also am sure to clean the remains of the ends down to the inside shape of the body.  The new ends are designed to match the shape of the body's natural interior.  If I cut deeply into it, or make a chamfer around the end, it shouldn't be a problem.  However, I do like to keep the structure as clean as possible.  A few scratches or even rough sand paper marks could help with the bonding, but I don't want anything that will prevent the ribs on the new end from fitting down tightly when fitted.

Inside view of bonding flange with a bit of extra ACC flowed in after primary glue pass was made.

When satisfied that the dry fitting is good, as in the ends fit tightly against the body all the way around the joined edge with the Accurail body.  I remove the end and carefully put a small amount of thickened ACC/CA type glue along the inside corner of the end and the exterior side of the bonding rib.  I extend the glue application down the ends to the bottom, past the rib, where the end will still be in contact with the car-side.

I found often it is helpful at this point to have the frame of the car in-place inside the body.

Showing how I pivoted the end into place.  This is a little trickier with the larger flanged end.

The end is then slipped into place from above, allowing the notch in the end to wrap around the coupler box, but not bond to it.  In the past I've used a couple rubber bands to hold the end in place, however if any ACC/CA glue squeezes out, then it's very easy to end up with parts of a rubber band glued to the exterior of the car!  When I built this pre-production test conversion, I just held it with my fingers on the end, avoiding the sides of the end until the glue was cured.  This took only about two minutes before I could let go and it was well bonded.  (Production 3d prints have a checker pattern on the exterior of the flange, which should allow for an even stronger bond to form.

3d printed end and rubber bands to hold them in place while the glue dries.

Another option on the bonding process, is to use larger rubber bands (I used ones from larger broccoli bundles from the grocery store), and the carefully stretch these around the car body with the underframe in place.  I usually like to add a bit of shim to the car-side over the non-ladder area, so the rubber band can't get down against the joint where any ACC could come out, bonding the rubber band to the model!

In Closing

That pretty well wraps up the list of how to do the conversion of the basic Accurail car.  This should be applicable to even factory painted models.  Pre-painting the end should be possible, although I would avoid getting paint on the area which will be the bonding surfaces of the 3d print.  

Pacific Electric B-50-13 with B-50-13/14 Dreadnought End installed, before detailing.

A few details still need to be installed; wire grabs, roof walk end supports, and brake wheel/staff.  Also on most of my conversions, it's easier to just remove the plastic stirrup steps on the model.  I'll be replacing them with standard U-shape A-Line stirrups installed.  The PE car will be getting the 45ft radii curve brake rigging modification to match detail photos in a separate blog post.

T&NO B-50-13 with original Wood Ends.

New end reporting mark decals will be needed to finish the car after the conversion is complete.  Remember that the SP standard in the 1910s-1931 were to have the ends and roof painted black or have black car-cement (aka tar) applied.  After 1931 the SP started shifting to overall Freight Car Red, and Anthony Thompson suggests that the last black roof/end cars were so painted around 1942.  So paint your models accordingly.

Jason Hill

Related Articles:

Previous modeling posts on these classes, before these ends are available.

Modeling B-50-Series Boxcars (Part 3) - Plastic Options for B-50-8, -10, & -11 class cars

Plastic Options for B-50-12, B-50-13, B-50-14 class cars - Accurail & Tichy models

SP 24864 (Part 1) - Kitbashing B-50-10 from Accurail 40ft Boxcar - Not including these parts, I'm waiting for the earlier B-50-8/10/11 ends to be produced.

SP Jawbone Branch (Part 54) - Roadbed & Rough Scenery for Owenyo#3

Since my last post around the end of August, I've been continuing to make steady progress on Owenyo Module #3, which is the western most section of Owenyo. 

Mostly I've just been carefully pushing along the logical steps required to get each section done that won't block in or jump ahead of other steps, while keeping the maximum flexibility on the aspects that I still might want to have changes as I get to them.  The changes come in the exact positioning and height relative to the main line for the roadbed under where the transfer trestle will be going.

In this post, I'll get the blog caught up about half way to where the module is now as of the 18th of September, 2024.

I'll be going by construction dates in this post.

Aug 31, 2024

Looking Eastward and figuring where the Ballast-Deck Bridge will go.

While I put down what I expected to be the western yard switches several years ago, I've not actually wanted to place and glue the switch ties in place until I sort out the factors that need to work back onto Owenyo #2 Module from the #3 Module, including if I need to sand the top surfaces to be smooth.

SP 2850 with marks for options for Deck Bridge.

The foam was filled in with multiple pieces, including a couple of narrower strips patching over the front frame structure, cutting under the SP 2850 in the photo above.  The front edge MDF strip is actually nearly level with the roadbed, which is too high, so as I started Surforming down the foam, I ended up needing to use the saber-saw it down to form.

A somewhat southward-looking view of the mainline and trestle.

At this point, I cut out both proposed deck bridge down to the expected ground level... so I could evaluate both options against the prototype photos.  I decided that the eastern option would work best.

Looking westward out of Owenyo, and seeing how the trestle will align with the axis of the yard.

The middle yard track should align with about where the transition section of the trestle is to be located.

A lower view of the same.

As the paper elevation drawing is on the back side of the trestle, the transition section appears to be to the left of where it should be.  So this alignment of the trestle roadbed should work out about as well as the compression will allow.

The reverse angle of Owenyo Yard from the transition section of the dump trestle.

I layed in some loose bits of flex track to ponder the mainline route into the yard, just to mockup how this will look when it's done.

SP 2850 comparing the depth of the trestle-spur.

When I built the frame members into this module, I purposely made them level with each other and lower than needed to support the 1/4" MDF of the Trestle Spur roadbed.  This allows for shims to be put under the roadbed at this stage in the construction.

Last of my mock-up and playing with the static trains.

So now the questions become... How deep should the roadbed be placed?  How deep should the scenery foam make it appear... should the foam come above the mainline roadbed?  The selective compression to the shape of the spur, restricts how much space there is between the main and spur compared to the prototype acreage.

Time For Some Perspective

This process requires lots of viewing from various angles, visualizing how the foam will be fitted and formed.

In most of these photos, I'm checking the view-lines across the main track, down into the spur pit, the proportion of the trestle visible above the profile of the main track grade.

There's not much more to say about the following photos here, other than to show all the angles I evaluated these aspects from.

High angle view of whole area.

I even started pulling back and taking these photos from other angles, not usually viewed.

A view of the roughed in foam, glued in place.

I started gluing the foam in and used paper-towels on the lower staging yard to prevent any glue drips from fouling the tracks.  This worked about 99% of the time.  I did find one annoyingly stubborn drip that landed on one of the rails of the switch on the second track.  I eventually popped the glue off the rail and mostly cleared the tie with only minimal damage to the switch tie.

The tail of the spur roadbed does land against the rear frame structure.

My estimate of the depth of the trestle track pit should result in the floor of the GS gondolas being at about median ground level.  Unfortunately, the alignment of what I can place in this module is requiring the trestle to be a bit closer at the narrowest point, shifting it much farther east, compressed to the left than the prototype, and also having much more angle change of the main track on a much tighter radius than the prototype.  So all of this ends up being a compromise, and how much of the 'flavor' can I get to match photos.

Lower angle view.

Unfortunately at this point, I only have the early prototype 3d print of the Dump Trestle from late 2023.  I still need to do the updates to that drawing that I planned 9 months ago, but my hand injury prevented me from working on CAD drawings for many months.  So everything I'm doing here will be with the older test print.

Originally, I was hoping to have the spur level, but the main-track is still climbing on a 1.25% grade, so by the stub-end of the spur, it would be over 12-18" deeper than at the western end of the trestle.  I decided that because the trestle spur should be more level with the median land forms around it, I would have to put the trestle on a nearly 1% grade.  

Sept 1, 2024

As I'm a night-owl... the concept of a "new day" starting at midnight for the camera doesn't translate to my construction reality very well in telling this story, as many of these "next day" were actually just continuing past the clock hands being vertical.

Mounting the Foam

The rough foam placement along the front side of the roadbed.

I stopped at the front frame and the roadbed.  This left the last section between that and the spline sub-roadbed to fill in.  Around here I stopped, and came back the next evening after the glue had dried.

Nice to see it coming together.

Notice that I put down paper-towels to catch the Gorilla Glue drips from gluing in the foam to the spline sub-roadbed and front curved strip.

Clamping the main track roadbed sheet to the top of the sub-roadbed spline.

I roughed the foam up a bit, shaping it down to the contour of the front curved MDF strip, however the strip was actually too high.

Watching as the Gorilla Glue expands and swells up between the curved front strip and the foam.

At this point I'm actually considering changing exactly what the position and angle of the trestle-spur will be.

...Midnight...

Foam roughed-in.

Since Part 53, I've been working on roughing out the pink-foam sub-scenery form and test fitting the roadbed strip to the top of the spline.  The edges of the roadbed have been sanded, so as to provide the rough shape of the roadbed.  

 The ballast-deck trestle provisions in the left side of this photo.

On "classical" layout constructions this would be done with the 'cork' roadbed strips.  However, on this layout the hand layed and spiked turnouts require a firmer roadbed than the spongy cork will provide.  I'm not too worried about sound or drumming of the layout top, as I'm familiar with layouts that used 1/4" pine spline strip laminated in-place roadbed, and there's no issues with sound.

The reverse angle showing the foam blended to shape with the Module #2 form.

Around this photo, I burrowed out the trestle from the sub-roadbed.

I couldn't get the saber-saw in the module to notch it for the trestle opening.  So I used the electric drill with about 3/16" bit to bore-out multiple holes, then broke out the sections of Masonite with pliers.  A rasp and mill-file was used to clean it out and get it properly shaped.  The earlier spacer blocks ended up landing at this location, so I didn't have to fill in any extra material between the Masonite spline strips.

The western end of the module in the roughed condition.

Sept 6, 2024

Owenyo #3 Roadbed glued and clamped, plus weights

I threw the kitchen sink in when I was gluing down the roadbed top sheet.  I didn't have enough clamps, so I grabbed anything else "heavy" around the shop to help hold it down and in place.

Right end of the module with roadbed glued and clamped, plus weights

The glue bottle and middle bar-clamp is where I have some issues below... but when I was bonding it and setting up the clamps, I didn't know that those sections were slightly twisting.  At a certain point with any of these construction projects is a informed bet that the step will pay off, but there's always the chance that something won't be as good as expected.  I believe that the mitigation of these risks is to have anything that can "go wrong" be in a limited nature.  Keep that "something" to be an issue that is "easy" to fix later.  Try to prevent anything catastrophic from happening. - No fire, no boom!

Fixing Cross-Grade Level?

After I bonded the roadbed to the spline sub-roadbed, I went through and checked the cross-level of the roadbed.  Finding a section that was subtly twisted by about 1/16" out of cross-level.  I don't want any super elevation, as this curve is only about 60-70 car lengths from the end of the branch, no one's going to be going "fast" through this curve.

In fact, this out-of-cross-level is actually a reverse-super-elevation!  So that definitely needs to be fixed.  I eventually fix this with an electric hand-sander.  I'm using the large level to do this, a 6 or 9" hand-level would be easier, but it works.

This point I'm showing how I was checking the 1.25% grade with a level, and a set point and height block, in this case a 1/4" block.  The grade ends up being pretty consistent.

On to Mocking Up Spur

In the previous photos, I was using shims of between 1/4" and 3/16" under the spur roadbed.

At this point, I removed the trestle spur to start working out the height shimming.

Notice that at this point the trestle spur and trestle mock-up are rising.  They're in the same X,Y position, but are just being shimmed up vertically.

Mocking everything up in place again.

In Closing

I'll leave it here for now.  This is only catching up about half-way to where the layout is now.  For now I'll show a sneak-peek of how the module looks today on Sept 17, 2024.

Photo from 2024-09-15, after installing the Trestle Spur, which I'll cover in detail in Part 55.

I've also made the decision that I will not be getting the Owenyo section of the layout operational for the SPH&TS Convention in Sparks this year.  Between my hand injury putting me out of commission to be able to work on the layout for more than six months of the last year, and other commitments in the next month.  I'd rather not rush the construction to get a "short term gain", but compromise on the long term goal of getting the layout built in the best way I can build it.

Jason Hill

Related Articles:

Jawbone Branch Layout Build Index - See all postings in this series from this linked page.

SP Jawbone Branch (Part 53) - Curved Spline Sub-Roadbed for Owenyo#3 - Previous post in the series