"It was announced today in the "HIGH MEADOW GAZETTE" that the HCNG took delivery of an
all metal tank car lettered "CONOCO" #7 to be used hauling diesel fuel up to High Meadow where
it will be transfer into tanker trucks and hauled north another 12 miles to the Paul Bunyan dam
building site. The car will enter service next week."
I had been looking at the plans for an "A" frame gallows turntable that I plan to build some day
in the future, in the Nov/Dec. 1989 issue of the Gazette when I saw this photo of the CONX #8
tank car modeled by Harry Brunk for his "Up Clear Creek" series. 
Oh yeah... The white lettering on the black car. it would be a great eye catcher. I sent off an email
to Stan Cedarleaf along with the photo and asked if he would make me a set. In checking in my
copy of C&Sng by Mallory Hope Ferrell, there wasn't a car numbered 7 on the C&S, so I decided to
use that number so there wouldn't be an conflict with other railroads. And after some tweaking,
Stan sent me the set.
The Bachmann car is almost a dead ringer for the CONX #8. It's only a foot longer and #8 didn't
have the cut outs in the frame above the trucks. At first glance it didn't look to be all that hard to
fill them in, but when I went to start working on the frame, having all the brake equipment glued
in place made it too fragile to work on so I left the cutouts in. The CONX tank cars on the C&S
were all different from each other any how, so who knows if there wasn't a car just like the
Bachmann car in CONOCO's roster. I had purchased a car lettered for UTLX in yellow printed on
the plastic tank. As I use Accucraft's 1:32 scale couplers on all my equipment, those Bachmann
couplers had to go, so there wasn't a whole lot to do to the frame.
After separating the tank from the frame, I used brake fluid to removed all the lettering from
the frame and tank. Next was filling in the cutouts at each end of the frame to fit the new smaller
coupler box's. After gluing in the filler pieces of .060 styrene and making final trimmings and
smoothing the ends, 
the new coupler box and coupler are mounted.
I thought I might be able to use the rivet heads from the underside of the frame for the rivet
heads needed to fill in the spaces along the bottom edge between the coupler box and the last
rivet, but they are 3/4 the size of the ones needed on the end. Now back when I modeled in
On2, I did a lot of part casting for my freight cars. Things like body bolsters, draft timbers,
etc., so the answer to my little problem is to make copies of the originals by make a mold of
the rivet heads and then cast new heads.
This has to be the smallest mold box I've ever made. To hold it in place while the mold cures
I had to lightly tack glue the box to the face of the end frame. This will easily clean up after
removing the mold box.
I use the Micro Mart 1 to 1 Rapid RTV system to make my molds. Two equal parts mixed
together and pour. Usually I mix up larger amounts to get a better ratio of equal amounts,
so to mix I just pour cup to cup to mix the parts together. By pouring the parts in a thin
stream high up on the inside of the other cup, less air bubbles are introduced. It's good
practice to let the RTV sit for about a minute or so after mixing to start letting any air to
gas out. Now when you are ready to pour the RTV, start in one corner of the mold box, which
is raised up a little, with a thin stream and let the RTV flow over the master part. Fill the mold
fence and to make castings of the part later, cover the top of the mold fence with a sheet of
styrene and when the mold cures, the bottom will be flat.
Now with this little mold box I used a round wood toothpick and dropped in one drop at a time
to make sure all of the rivet heads were covered without any bubbles. After filling the mold box to
the top of the box sides, I placed a small piece of .005 sheet on top and let it set up. In a few hours,
I popped out the mold. 
I use the CR 600 casting resin from Micro Mart. It has good working time and de mold time isn't
that long. Full cure is a few hours. I also discovered that small parts take longer to cure than a big
part. The resin in the cup completely cured before the small rivet heads did. The casting resin is a
1 to 1 formula also. They don't need to be exactly the same but as close as you can is best. When
mixing, do the same as you did for mixing the two mold parts together. Don't be in a hurry here.
5 or 6 pourings from one cup to another will do the trick. After mixing the resin, it will look a little
cloudy. Swirl the resin around in the cup one direction then the other. This cleans out the tiny
bubbles from mixing.
I used a piece of .020 brass wire to pick up a drop on the end of the wire and placing it in one of the
cavities. I got to the point where I could pick up enough resin to fill a cavity with a slight dish effect
on the back side. Made for easy gluing.
Next, I made and installed pipe extensions to replace the ones used by Bachmann for their angle cocks.
I had to relocate the angle cocks to fit better with the 1:32 couplers. I used .052 brass wire for the air
pipe to match the piping on the car and .033 brass wire to make the two u-bolts for attaching the air
pipes to the frame end.
The only thing needed to be done on the tank was to clean up a mold parting line that runs the length of
the tank and relocate the retaining valve from the side of the tank to the end of the tank near the brake
wheel. The bachmann valve didn't look like any retainer valve I've ever seen. So I used a Hartford Products
retainer valve to replace it.
Next is painting, decaling and finishing. See ya next time..
