Since my new layout under construction will be quite large, I figured that I would need a large number of rolling stock, especially boxcars. My immediate thought was to copy the Micro Trains boxcars and populate my layout with them. As tempting as this was, I decided to try my hand at building a 3000 series boxcar that more closely resembled the prototype boxcars of the D&RGW. Numbering from 3000 to 3749, these boxcars differ greatly from the MT boxcars in a number of ways. They are a foot longer, a smidge wider, set down a little lower and have differences in the side door length. Here's an early comparison photo that illustrates the height difference. We won't even mention those ugly end doors on an MT boxcar, just so it doesn't give 'em the red face.
Differences aside, I built my patterns based on D&RGW 3705, which I photographed in 2000 at the Colorado Railroad Museum. I built it using Evergreen 2020 N-scale car siding. Starting with the flat sides and ends, I built the basic box shape and then added the roof. I started adding the flat strap iron corner bracing by sanding down .010x.020 until it was approximately .002 thick and then trimming it to width and length. Once applied to the car, I added carriage bolt head detail using pulled sprue sliced up into .003 thick pieces. These were applied using the tip of a new #11 x-acto blade. This is the finished shell, the photo sucks, but the shell turned out well. This shot shows the detail next to the side doors, and here is the 'A' end of the boxcar with my end door. I think it looks a wee bit better than the MT version, myself. Once finished with the shell, I added dimples with a no 80 bit to mark each grab iron location. This will save guessing and also eliminated the need for a drilling jig or template. I used the same techniques to build the sidedoor patterns. The underframe is made up of strip and sheet styrene and does have some woodgraining, but is basically just a simple pattern without much detail since it is mostly hidden.
With the pattern making out of the way, I built some simple open faced molds for the underframe, and another for the side doors, the needlebeam/queenposts and the aircylinder. The boxcar shell required a two piece mold, the plug/base mold and the top mold. The boxcar was initially placed in the mold box upside down and the top mold was poured. This was covered in mold release and then the plug/base was poured into the mold box. This was the cause of the air bubbles trapped in the original top mold which has since been repoured.
I tried out the initial rtv molds using a batch of alumilite resin with some color added. The first batch of parts didn't turn out much of a success. The sidedoors looked OK, but some of the carriage bolt heads trapped air. The entire length of the queenpost also trapped air, but since the masters were extra long, this really wasn't an issue. I have been 'picking' them when pouring in resin to prevent this. The aircylinder also trapped some air, but 'picking' solved this problem as well. The underframe came out pretty decent, for a first go, and I suspect this to be an easy to cast part. The main shell is altogether another story. The very first pull resulted in the air voids in the upper corners of the roof, and a general lack of the fine detail from casting. It's painfully obvious in the end photo. To correct some of these problems, I've changed my pouring techniques and drilled a main pouring sprue through the plug base allowing the air to vent through the long gates sticking out from the coupler box areas. I also drilled some vent holes to keep air from being trapped in the corners. One of the key things to help get better castings, is the heating of the mold to 200 degrees. This allows the resin to warm slightly when poured into the mold thereby reducing its viscosity and letting it flow into the details better. This simple change produced drastically better castings. This photo shows an assembled and painted boxcar from the side and from the end. You can see, I've got some usable castings from what I've done so far, but I'm not getting consistant enough results to cast out 750 usable pieces. I think pressure casting or vacuum casting will be needed to get consistant results. I'm not sure yet as to whether or not I'll invest in the needed equipment or if I'll have a casting shop do it, but I'll keep updating this page with my results as I get closer to making the initial 100 kits available. I'm working on finishing one model so I can post 'finished' pics on this page. Back to casting out boxcars!!!
I went ahead and invested in not only pressure casting, but vacuum casting as well. To make my vacuum rig, I started with a spun steel cylinder formerly used in high pressure welding gas service. These cylinders are manufactured to withinstand sustained pressures of over 2000 psig and hold up to repeated cycles from 29 inches of vacuum to full cylinder pressure. I cut the cylinder off at a height of 18" in a large industrial bandsaw. It was then drilled and tapped to accept a 1/4" pipe nipple to male flare. This mates to an HVAC hose and vacuum pump. A lid was fashioned from 1/2" thick clear polycarbonate. It works well, but I strongly recommend AGAINST fashioning your own pressure and vacuum vessels.
With the vacuum rig up and running, I started putting together the pressure setup. I had ordered this before building the vacuum tank, so I figured I'd give it a go. The system consists of a 2HP 4 gallon air compressor, a 5 gallon air reserve tank, and a 2-1/2 gallon pressure paint pot. The paint pot was modified by adding a 1/4 turn ball valve to dump the pressure once the resin is set, and also a ball valve in between the air reserve tank and the inlet of the paint pot. This allows me to build pressure in both the compressor's tank and the reserve tank, open the ball valve inlet to fill the paint pot up to the desired pressure, shut the inlet valve, let the resin set, then vent the pressure from the pot to remove the mold, all without wasting large volumes of air. The minimal waste and the 9 gallons of air at pressure allow me to cycle through alot of castings without having the compressor running continually.
I ran several runs of the boxcar in the original molds at various pressures. This was all well and good until I ran a batch of brown alumilite cranked up at 60 psi. This showed the shortcomings of the original molds made with Alumilite's 'Quick-Set' RTV. The quickset RTV is a good product, but I had poured this RTV without vacuuming it and apparantly, some tiny air bubbles were trapped just on the outside of the boxcar side wall. Under the 60 psi of air pressure, these imploded and resin was forced into the resulting cavity thereby ruining the mold. After a call to Alumilite and another thirty bucks, I had a jar of Dow Corning HSII on the way to the house. I've poured the new mold and am waiting for the entire thing to cure out before pulling both halves off of the master. I vacuumed the rtv this time, so, hopefully no more air bubbles. The HSII is much more flexible and tear resistant than the quick set rtv, so it should yield many more castings before it wears out.
The first mold from the HSII has proven this material as my choice for all future work. It is extremely flexible and tear resistant, so demolding is quite easy. A new mold was also made for the underframe and detail castings. I started prepainting the molds before casting and this seems to yield excellent results. The car body now comes out with a base coat of Floquil Boxcar Red. I'm going to prepaint the mold plug with Floquil Foundation for all of the production shells so that the interior won't need to be painted by the customer. Just another time saver for the assembler. The new molds shed some light on a couple of shortcomings on the underframe and detail castings. The underframe needs some sort of reinforcement between the far outside timber and the cylindrical bolster to strengthen this area and aid the flow of resin. This can be easily added and a new mold poured. The doors, needlebeams and the air cylinder need to be repositioned to help vent air from the mold when casting.This won't be so easy, as these pieces are bonded to a piece of sheet styrene with MEK. It might come down to making new door masters......more damned rivets.
The new masters would only compliment the etched detail sets for this kit. I decided to have a detail set of parts etched for two reasons; one, bending grabs by hand is a real bitch and two, I want you guys to feel like you're getting your money's worth when you buy a kit from me. I received the first sheet of 'test etchings' right after returning home from the 2002 Narrow Gauge Convention in Rhode Island. I was very happy with the quality and overall appearance, but a little bit disappointed with some details. (There goes a $180 photoetch plate!!) First off, I had given some bad info to the company that did the artwork. Second, the brake wheel centers didn't etch through and third, I had thought of several items that I wanted to change and/or add in. After working out these changes, the second set of artwork was sent to me. The bad info had been corrected, this being the width of the stirrup steps and the number of each size grab iron to include on the etch, the brake wheel is now being done as a 'half etch' to get the centers to etch all of the way through and the new items were added in........progress. So what are you going to get with your boxcar kit? Well.....the etch will include three sizes of grab irons, drill jigs, stirrup steps, brakewheels, a nice roofwalk etch with fold down braces, truss rod etches for those that don't want to use the 'E Z Line' and off all things, a set of cut levers for the car ends. Gotta work those scale coupler somehow!
Well, the new etchings finally showed up. They look great and will sharpen up the boxcars when compared to a Micro-Trains boxcar. I've included a comparison photo illustrating both the old etch and the new etch(labeled). This also shows you just what details will come with these boxcar kits..... so get your order in, but be patient, I'm about 50 orders behind!! Back to work on the wood roof master and boxcar orders!!!
