is not necessarily the right way or the wrong way to build a car. It’s
just my way and I hope to help you find ways of building your cars quickly.
If you’ve never built a car before this article will help you to get started.
While I do own a lathe and mill, the methods I will show
you here do not require the use of them. Some basic tools are all that are
required, a drill, a saw, a few files, etc. That said, if you want to make
your own trucks you will need a lathe. For the purposes of this article
I’m assuming the use of purchased trucks and couplers.
A welder is also an excellent tool to have. If you
don’t have the money to purchase one get together with a group of people from
your local club and buy one as a group. Set up your rules as to when it
can be used, etc and the cost becomes extremely affordable. I use a Hobart
135 MIG welder with a gas mixture of 75% Argon / 25% Carbon Dioxide. You
can use a flux-cored wire but the welds are not as clean.
Not interested in doing the welding? Cut all the
pieces and take them to a welder. The time to weld all the pieces together
is minimal compared to the time cutting and fitting. Many welders are
happy to see they don’t have to fit the pieces and can focus on “gluing” the
pieces together. This also helps to keep the cost down.
A Place To Start And Some Basic Math
click any image to enlarge
Not sure where to start? Head to your local
hobby shop and pick up an HO scale ruler and a car that you’d like to build.
Measure the dimensions on the car. In this case
our car is 50 scale feet long. Now comes the hard part. Multiply 50
by 1.5 and we get 75. That’s it! We now know that the car we are going to
build will be 75 inches long. Measure all your dimensions and do the math.
Now let’s say that you managed to find a set of
drawings with the actual dimensions of the car and they show 50’ 3”. Does
the math have to be confusing? Not a chance. We’ve already figured
out how long 50’ feet is. Now comes the easy part. We are working in
1/8th scale so every inch in 1:1 scale equals 1/8 of an inch in 1/8th scale.
So 3 inches equals 3/8ths of an inch. The total length of the car would be
Now that you have your dimensions, cut the basic parts
for the frame. I use a design that has worked well for Mountain Car
I start with a 1” x 2” thin wall box tube for the
backbone. Use your measurement from above and add two inches so that the
coupler pockets stick out beyond the ends of the car. The two cross
members above the trucks are also 1” x 2” box tube centered 8” from the end.
I recommend and use Mountain Car Co. trucks. As such I also add a 3” piece
of 1”x 2” tubing on each side of the backbone. These are what the frame
rides on. Note that some trucks such as Tom Bee trucks require an
additional 3/8” plate below that as well. Check with your trucks supplier
to see what they recommend for height. Depending on the length of your car
you will want to add one or more cross members made from 1” square tubing.
Next, use 1” angle iron for the perimeter of the frame.
Looking at the picture you will also see the bolts for
the couplers and the trucks. Measure 2” from each end of the backbone and
drill a 3/8” hole. These will be for your couplers. Now measure 8” from
each end of the backbone and drill a 3/8” hole. Next drill a 1/2” hole in
the upper side of the box tube only. These are for your trucks and the
larger upper hole is to recess the bolt head. I like to use a 3” long bolt
and drill a hole in the bolt for a hairpin lock. This setup facilitates
quick changes should a problem develop. If the hairpin lock did manage to
find its way out, the bolt is still fairly secure and won’t drop out on the
ground. I also round the corners off of the truck bolt head so that I can
keep the upper hole in the box tube as small as possible. Since I won’t be
putting any torque on the head (remember I’m using the hairpin lock) this
Let’s Build A Flat Car
Once the basic frame is built
almost any kind of car can be built from almost any material, a hopper made from
steel or a boxcar made from wood. In this clinic we will make a flat car
since these are so versatile and can be put together quickly. This is
your end piece (see photo). You will need to make two of these.
This is the side piece.
The photograph only shows half of it but it is one long piece that looks the
same at the other end. The metal bar lying on the side piece is for a
stirrup and you will see that later. You will need two side pieces as
The pieces for the sides were cut from 1/8” steel, 3”
wide and in this case 48 1/4” long. The extra 1/4” is to overlap the end
pieces. I used a band saw to cut the pieces to shape and then used a flap
wheel in an angle grinder to clean up the edges.
The end pieces were cut in the same fashion. The
cutout over the backbone was made by cutting many slots into the metal and then
using a die grinder the “tabs” were cut off. What tabs were left were then
gripped with a pair of pliers and bent back and forth until they broke off.
The edge was then filed smooth and the edges around the whole piece gone over
with the flap wheel to dress it.
I measured 3/4 of an inch for the depth of my plywood
and an 1/8th of an inch on the ends for the end pieces (photo).
I then clamped the piece in place (photo).
Here you can see the side piece welded in place (photo). Here is the end piece clamped and ready
for welding. I run a weld bead down the outside corner. Once it is
welded, I go back and clean up the weld with the flap wheel in the angle
The Devil Is In The Details
I don’t do rivets. Having said that, many people
do and there is nothing wrong with that. I use some simple methods for my
details and I tack weld them in place. While they may seem unusual at
first, an award won at the Train Mountain 2003 Triennial for “Best Diesel
Locomotive and Consist” says that they are at least believable.
For my stirrups I use a 1/8”
x 1/2” x 8” piece of stock. The marks are laid out at 1.5”, 1.5”, 2”,
1.5”, and 1.5” respectively. What you see is a 2” step, a 1.5” vertical
and a 1.5” twist on each end. I make four stirrups, one for each corner.
Start by placing your piece in a vise and using a square
to square it up to the vise head. Then using a hammer, bend the metal over
for the verticals at the marks (photo).
Next clamp one of the verticals in the vise at your
mark. “Choke down” on the piece about 3/8” with a pair of pliers and push
away from you ninety degrees. Turn the piece around in the vise with the
other vertical being clamped. Again come down 3/8” with your pliers, this
time pulling the pliers towards you ninety degrees. This will cause your
twists to rotate in opposite directions to each other. Weld these to the
inside of the side pieces at each end of the car (photo)
For stake pockets 1” channel
can be used. Layout a series of marks evenly spaced down the sides of your
car for stake pockets. Be sure to leave room at each end for the grab
irons. Apply a weld bead on each side of the stake pocket for a secure
For grab irons I use 1/8” brazing rod. Center
punch your locations. Using a #53 drill bit drill the holes and then
insert the grab iron. In this picture you can also see the stake pocket
and the stirrup in place (photo).
Point the welding gun at the center of the rod sticking
through the side and tap the trigger. The resulting button weld will hold
the grab irons in place very securely (photo).
This sample sheet shows some variations that are
possible. The two on the right have been button welded as above. The
two on the left have had the ends hammered flat on the anvil of my vise and the
holes drilled out. They are then riveted in place (photo).
The brake wheel plate is a 2”
x 3” piece of steel that the sides were also made from. It is shown here
with Precision Steel
Car’s brake wheel housing from their kit. Decide where you want to
place the plate and clamp it to the end piece. Tack weld it in place.
If need be, square it to the car. If you want a walkway under your brake
wheel you can use the expanded metal that you see behind the plate in the
picture. Weld two small angle brackets below the plate and tack a piece of
expanded metal to them.
What if you are building a car that has ribs? We
can handle that. I use 1/2” square tubing that is plug welded from the
Here is a rib clamped to a sample sheet (photo). I drill 3/8” holes in a row where the rib
will go. Make sure the rib is lined up over the holes (photo).
To plug weld the ribs, start
your weld up on the side of the hole. When you can see the edge of the
hole drop your weld down into it and follow the edge around the circle.
When all your plug welds are done, grind them flat with your flap wheel.
If you end up with divots in your weld, run a bead over them and grind the area
flat again. This will give you a surface that will require little to no
prep work for paint.
To show the strength of the weld I beat on the bottom
rib with a hammer. You can see the sheet metal beginning to fold before
the weld would break (photo).
Here you can see the ribs on
a gondola. The ribs have been plug welded and the sides are clamped in
place to be welded.
If you have small detail pieces, purchase a tube of
Loctite 330. It is a two part adhesive that once set creates an extremely strong
bond. You will probably destroy your part if you try to remove it.
All that is left for you to do is cut the plywood floor,
paint the car, and apply any decals that you want. In a very short time
and with basic tools you have created your own car.