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The Caboose Page

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After the successful completion of the Coal Gondola project, I wanted to continue to build on that experience, expanding the skills I learned in that process and learning new ones. The coal con was pretty much a one-piece model with added details; I felt that a multi-part model that needed to be assembled would be a good second effort. I thought about a boxcar, but felt I was up to something a little more challenging Ė I decided to model a caboose, which would be a greater challenge because of the windows and end platforms. A major goal for thismodel would be to develop casting techniques Iíd need to eventually build locomotive cabs and tenders.

Since there are no known drawings of a Housatonic RR caboose, I must improvise even more than I did with the coal gon. I wanted something that would reflect the era, the state of affairs on the railroad at the time (there were only 7 cabooses on the Housatonic in 1892), and something that would reflect a regional flavor. The prototype I selected was a Boston and Albany round roof bobber caboose, one that had no cupola, from around 1882.(See The American Railroad Freight Car by John White, p. 415.)The prototype had an unusual suspension for a bobber, which I thought briefly about trying to model.But in the end I chose to go with a standard bobber truck assembly from BC Models because I wanted this model to be similar to the B&A car, not exactly the same.

After ordering the trucks, I started looking through the Walthers catalog for parts Iíd need to build this model. There arenít many choices for caboose steps among the super-detail manufacturers, and I was getting depressed thinking about how I was going to build a mold anyway once I built-up a master model. It would be a complicated model, one I am not prepared to attack yet.While I sat thinking ďHow am I going to do this?Ē I was struck with inspiration Ė why do I need to scratchbuild and mold ALL the parts that go into this model? I am only planning a limited number of them (5-6) and if I could kitbash some of the more complicated elements, why not? The object is to build workable models to be used on the layout, not add complexity for its own sake. Thereíll be plenty of time for that later.

A quick search through my collection of turn of the century models soon turned up exactly what I needed Ė an MDC 34í old-timer combine. With just a little judicious cutting, the floor and end platforms can be removed, cut up and re-used in the kitbashed model. They donít exactly match the car in the photo but again the object isnít to make an exact copy of the B&A caboose.Since I had the one car on hand, I quickly whipped out my razor saw and performed surgery.  I didn't want the combines' bolsters, so cut off the ends just ahead of them.  I might use the bolsters for another project down the road.

So, a half-dozen old timer coaches are now on order, to be cut up for detail parts.  While I wait for the trucks and coaches to be delivered, I can get started on the plans for the rest of the car.  There is no dimensional drawing for the B&A caboose in the freight car book, so Iím going to use one from a New York Central bobber from around 1883 of very similar dimensions. (Same book, page 416-417.) Iíll use this car as an example to take dimensional data from, I just wonít include the cupola and Iíll center the windows. 

I got out the tools and started to lay out the car end first (right now I'm still waiting for the Trucks to arrive, I won't be able to do the sides until it gets here).  I got the dimensions from the scale drawing and laid them out carefully, then transferred the lines to the back of the scribed styrene.  After laying out all the lines, I carefully cut it out from the main sheet with a #11 hobby knife and straightedge.  A quick test fit against the end platform cut from the combine showed the part will fit well.

Looking closer at what supplies and detail parts I'll need, I thought briefly about building my own windows, then about using commercial castings.  There weren't any good windows in my collection or the Walthers catalog I liked, so I put that aside till later.  I saw right off the end doors from the Old Time combine happen to be just the right size for the caboose, and only took a few minutes to cut from the body of the car.  While I was at it, I noticed the end windows next to the door looked okay.  A few more swipes and they were separated too.  As it turns out, they were pretty darn close to the right size!  Some .040 x .020 strip styrene around the edges to frame the windows, and a big headache is solved cheap and easy.

The door got quarter-round strips glued next to it to represent the rounded door frame seen in the photo, as well as a header and footer.  This assembly then got glued into the car end, which more or less completed that part (I still need to locate and drill dimples for the body-mounted grab irons).  

On the prototype photo you can see the cars' corners are thick, rounded posts with a bead along each edge before the regular siding.  I took the same .060 quarter-round strips I used on the car end, and I cut some .020 x .060 strips to go with them.  I touched a dab of cement between the strips to tack them in place, then massaged them with my fingers until the strip overhung the edge like you see in the photo.  I then flooded the joint with Tenax 7R and gently pressed the parts together.  3 more times, and a little sanding, and the corner posts were ready. I could have used .080 x .020 strips if I had them, or shimmed underneath the back edge with another slice of .020 strip, but eyeballing it worked out fine.

  D'oh!  Now click here to see why I couldn't use them. 

I should probably point out here that an invaluable tool I've been using on these projects is a sander with a movable block, and a fence to hold the part against.  It has made it possible to get flat edges and square corners that would be impossible with hand tools and loose sandpaper.  If you are thinking about taking on a project like this, get one immediately.  You will be very glad you did.  Mine is an odd brand I picked up at a train show, but Northwest Short Line (NWSL) sells one called the True Sander that you will love.

Rollin' Rollin' Rollin'

After a couple of weeks of waiting, the bobber caboose trucks came in. I have to say I was a little disappointed. They look nice, but all that came were a pair of side frames and a pair of 40Ē wheel sets. There is nothing to bridge the gap between the castings and hold them in gauge. I guess I was expecting too much, but for some reason it never occurred to me that Iíd just be getting side frames. I will have to use a wood or plastic rectangle to space them properly when the time comes to assemble the under-carriage. 


The bigger problem was the caboose trucks I ordered turned out to be longer than I expected. This one is my fault, the website noted the wheelbase (13í 6Ē), and I should have measured it before I ordered the parts Ė it just looked Ďrightí on the website. As it happens itís considerably longer that the prototypeís wheelbase, by about three feet. Bummer. If I want to model the car as it appears in the photo, Iíll have to cut up the castings and try to refit them, a big job. Or, I can return these and get the other type offered by BC models, which may be too small.

 I decided instead to increase the carís length by about three feet. I took a couple of photocopies of the NYC caboose drawings, cut them up and spliced them together, matching the axles of the truck with the drawing. It takes the car body from about 18í to 21í not including the end platforms, or about 14% longer. It doesnít really look like a Ďbobberí anymore, but more like a 4-wheel caboose. Oh well", I said, and went ahead with the plan.  

I started to work on the car side. I carefully measured the width and height of the car on the modified drawing, and cut a piece of scribed styrene to match. I scribed two lines along the length of the back where the top and bottom edges of the windows would be located. Then I centered the middle window opening and masked the vertical edges, and measured equal distances out from the center and marked the outer two window locations. A few careful swipes with a #11 blade and the window holes were opened up. Final fitting was done with a small flat file, and the windows were fitted and cemented in place. 

Next I drew a line along the edge on the back, 3-4 scale inches up from the bottom edge, and marked off the NBW (Nut-Bolt-Washer) locations on the bottom edge.  I got smarter this time and cut the NBWs off their sprues with part of the thin plastic leader attached, and pressed the leader through the dilled-out holes. then they were glued in place from behind. It went a helluva lot faster and came out better looking this time. 

Finally I took the new corner posts and glued them to the ends. They were intentionally made a little long, so I was able to trim them to the correct size after the glue dried. The side is now complete and ready to go into the mold box. 

Uh-Oh Again

About this time I heard from Bob Cook of BC Models, who makes the caboose trucks.  He'd read my earlier disappointed comments about the trucks here on the website, and the conversation with him led to my re-thinking the decision to change the size of the caboose.  Bob noted the truck has two toolbox faces on it each about 3 feet wide.  If one toolbox were to be cut out it would reduce the length by about the amount I'd added to the car side.  He offered that the appearance of the car was changed too radically by adding the 3 or so feet, and that I should reconsider shortening the truck to make the car look right again.  After considering his words I decided he was probably right.

So based on his ideas, I performed surgery on the truck sideframes and make the caboose the proper 18' size again.  But wait -- Erg!  I already built the car side and set everything up for a 21' length!  Grrr....  Got the tools out again.  I partially disassembled the caboose side by slicing off the corner posts very carefully, and them removed about 16" of wall from either end of the caboose side.  With the corner posts reattached the length of the car is now about 19 feet, within acceptable tolerances I'd say.  The windows aren't spaced as they are in the B&A picture (they had already been set before I shortened the side) but I think they will be acceptable too.  There is a slight chance I might do it over again at some point.

Over a week or so I got several suggestions from the Prototype Modelers' E-Group, as well as Mr. Cook on how to go about altering the metal side frame casting.  I considered them, decided on a course of action, and got my tools out. First, I used my center punch / scriber to scribe a pair of lines into the back of the metal side frame, representing the edges I wanted to keep once all the cutting was done. Then I cut the casting into three pieces with my jewelers saw, staying outside of the scribed lines. After cutting I placed each of the two 'keeper' castings onto the sanding block tool I use, and squared up each cut edge. I sanded each part to the scribed line, and when I was finished they mated really well and square. Turns out the finished truck is a skosh shorter than the NYC caboose truck (extra sanding?), but that will be OK. 

I then got out the epoxy glue and mixed some up. Nasty smell! I applied a thin bead of it to one face, and smeared it onto the other face by squeezing the parts together. I held them in place for about 5 minutes until the glue started to set, and gave them time to dry. I came back about an hour later, and boy does that epoxy work well! It made a very, very strong bond between the two halves, and I was able to start working the part right away. It's the first time I've used epoxy for model building, and based on this experience it won't be the last! 

I took a small strip of 400 grit wet/dry sandpaper and glued around the business end of a flat toothpick with a 45 degree bevel 'chisel' cut into it. I used this tool to carefully sand down the excess epoxy which was forced out of the joint. It worked very well, and I was able to do a really nice job smoothing the part line. I wasn't done though -- most of the advice I'd gotten suggested filling the seam with some sort of filler putty and sanding that to completely hide the joint. I got out my Squadron green putty and used a toothpick to apply the stuff to the seam. I also filled a depression on the truck beam that didn't look too hot. I let it dry for 30 minutes and then sanded again. Looks like this additional step really helped. I did not finish with finer grit sandpaper because I wanted a grainy, wooden appearance on the sanded areas. Finally I used my scriber to scratch in the board edges on the toolbox cover. 

I test-fit the wheelsets that came with the trucks at this time, and found to my dismay that one of the side frames' as-built axle cups was so deep the face of the wheel was rubbing the back of the side frame, and the axle point wasn't touching the back of the cup. I've always felt the needle points on an axle should be touching the center of the axle cups, so this wasn't acceptable. I decided as long as I had the putty out I would fill the as-built axle cups and worry about machining better ones later. This pretty much made up my mind that I'd have to go the full distance, making my own mold and casting the final side frames myself.  I asked Bob Cook for permission to copy his work as a part of my own efforts, he graciously allowed it as long as I do not sell any copies of the casting. 

The master pattern came out pretty good, I thought, and I got excited and set out to make the mold right away.  I embedded the side frame in a bed or clay, built a Lego mold box around it, painted on a thin coat of mold release and mixed up a batch of RTV.  I got ahead of myself and mixed up too much, so I didn't have time to paint the rubber into all the holes before pouring the whole slab.  I worked as much as I could with a toothpick as I was pouring it, as it turned out I think the final result was pretty good. 

After the pour, I decided to go ahead and make the mold for the car sides and ends since I had all my rubber materials out.  I glued the parts to a sheet of styrene and built a Lego mold box as I had with the side frame.  This time, I sealed the bottom edge with a bead of carpenters glue.  I also got smart and only mixed up a small batch of RTV rubber, and carefully poured and painted it onto the master model, careful to pick up every detail.  After that started to set up, I mixed up more RTV with some chunks of old mold material (saving money) and poured the rest of the mold.  

A few hours later I peeled the clay off the side frame mold and rebuilt the box to allow a second back mold to be poured.  Again I realized I screwed up, I should have embedded a couple of styrene cubes in the clay to leave depressions, which would become mold keys when the second mold was poured.  Lesson here, don't rush through steps!  I had to carve out a couple of crude keys with a hobby knife.  Another coat of mold release (got to or the rubber will bond to itself) and I poured the back part of the mold.  Once the two halves have been set up, I'll carve in channels to allow resin or metal to be poured in.  This will be my first pour-in mold, I'm looking forward to this.

Finally four hours went by and it was time to de-mold the car side and end mold.  It came of almost perfectly (one of the window mullions pulled off) and it is a great mold.  I immediately mixed up some resin and made a casting, I was very pleased with the results.  You can see the lanterns I decided to add at the last minute, a feature I copied from the NYC caboose.  I probably should have left them off but I felt it would save a little time later.

Not long after this the Truck mold was finished, so I pulled that out of the mold box.  It came out great!  I wanted to use this as a pour-in mold, so the first thing I did was cut in a gate and a vent.  The first pour was a disaster, it didn't completely fill the cavity and the vent clogged early.  I'll have to try more vents in more places.  In the meantime I used it as a two-part push mold and filled the first part, then slapped the back on and weighted it while the resin set up.  That worked pretty good!  In the image above you can see the original side frame, my modified side frame and the final casting of it.  

Update May 2005:

Itís been a long time since I updated this page, so I thought Iíd finally bring this project to a close.  I never completed this project, it stagnated and died on the vine over several years.  There were a number of reasons: 

First, a reasonably priced and readily available substitute became available in 2005 when Walthers brought out their 4-window wood caboose model.  I immediately saw that parts of it were very close in appearance to the Boston & Albany caboose in terms of window placement and style, roof style, and a number of other factors.  I got a one of these models and spent about 4-6 hours kitbashing it into a very nice and convincing model.  Itís not an exact match but it is more than close enough for my purposes.  Careful application of additional details will help make the appearance even closer.

Second, if you have read the web article on this site about the coal gondola you already know about some of the problems Iíve had with resin castings curling.  The pilot model, unfortunately, was not an exception.  The side walls took on a very nasty curve at the top where they were not supported after a while, and it really took the wind out of my sails for the project for a long time.  Had I been quicker to finish the model and braced it well, this might not have happened.  But itís too late now. 

Third, I ended up having a lot of trouble trying to get the bobber caboose truck castings to work.  It was very difficult to try and get them properly spaced and lined up; I spent hours working on this un-successfully.  In the end I used a fall-back plan and chopped the trucks out of an inexpensive Bachmann bobber caboose and grafted it onto the Walthers kitbash. This worked out pretty well.  Iíll do this again when I need to make more of these cabooses.

The project was not a complete failure in my mind Ė I enjoyed building the master models for this caboose as the article documents.  The work helped me build skills in model-making, kitbashing and molding and casting too.  Had the Walthers model never appeared I would eventually have built up several of these models and probably used the Bachmann caboose trucks. 

Part of the reason to cast this model was because I felt I was going to need a lot of them, from 6 to 12 models in all.  Though it takes about 3-4 hours to kitbash each one of these cabooses from the Walthers kit, the finished modelsí appearance and rugged construction compared to the resin-cast model is superior under operating (handling) conditions, and therefore IMO worth the extra time necessary.  Iíve ordered enough cars to build six of these cabooses, plus a different Walthers wood caboose to try another variant.

I will probably relent and build a couple of these cast models in time anyway, I have some stable wall castings we made after the pilot model and they could be assembled using the pilotís underframe and ends.  I know that eventually Iíll get annoyed at having spent so much time on this without any results.  Itíd be a good bet that someday there will be a couple of these models rolling around on the Housatonic RR.

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Use this link for good information on the casting process and quality resins and RTV's:

The Alumilite Home Page

This is a link to an excellent three-part tutorial on the casting process:

Dan Perez Studio's Moldmaking and Casting tutorial