Building a Roundhouse for the Hillside & Eastern
with Useful Hints for Modeling Roundhouses in General.

Some Background Information

The Atlas HO Roundhouse,
and the way they painted it.
The Atlas Model Railroad Co. Inc. of Hillside, New Jersey, has done a marvelous thing for those of us who use their turntables on our layouts: They have produced kits for roundhouses in N, HO and O scale that are tailor-made for use with their turntables. 

The Atlas Turntables
Before we get to the roundhouse, here are a few pertinent facts about the Atlas turntables.

Ironically, some of the features that make the Atlas turntable easy to use are part of the reason it is so often looked down upon by "serious" model railroaders.  Real turntables nearly always have pits with ring rails in the bottom, and steel girders under the track.  Real turntables are completely flexible in where they can stop and very seldom have the flat circular deck that is a necessary part of the Atlas model.  Still, the precise indexing and electrical features have induced some serious model railroaders to get one, if only to place under their pit floor to drive their realistic model turntables.

The N scale turntable is a scale 100 feet in diameter, and the O scale turntable is 96 scale feet in diameter, both respectable sizes.  Unfortunately, the HO turntable was designed to fit into track plans based on the 9-inch lengths of Atlas's popular Snap-Track®, and is thus only 9 inches in diameter, a scale 65' 4".  That length makes it suitable only for the shorter steam locomotive typical of the early 1900s and before, some small post-1910 steam switchers, and nearly all single unit Diesel locomotives. 

Note: When comparing a locomotive's wheelbase to the turntable's 65' length, don't forget to take into account the length added by the flanges on the wheels.  Some real railroads, the Union Pacific for example, turned locomotives that were slightly too long by jacking up axles until their flanges were clear of the rails.  Not much is to be gained this way, however, and it is a ticklish job in HO. 

(To see a page on the site illustrating another solution to the problem, click here and scroll about half-way down the page.) 

The Atlas Roundhouses
The Atlas Roundhouses are designed to be positioned right up against their turntables, with a fifteen degree angle between the stalls to match the "stops" of the turntable.

It appears, although I can only say for certain about the HO roundhouse,* that Atlas made their roundhouse's stalls long enough to take practically any locomotive that will fit on their turntable.

 Click below to see Atlas' descriptions of their roundhouses. 
#2843 N SCALE
#6904 O SCALE

* Atlas claims only an 8 inch stall length for their HO roundhouse, but I measure the distance between the inside of the door and the end of the track well as 9½ inches, and the coupler can extend past that.  Did I miss something here?

My Situation

The Hillside & Eastern's largest steamer is an ex-NP 2-6-2 built by ALCO's Brooks Locomotive Works in 1907.  With an Engine & Tender Wheel Base of 8 1/8 inches (59 scale feet) it can ride the Atlas turntable if positioned very carefully.  Even then, the footboards and couplers hang over the edge of the deck.

I model in HO, and the scale 65 foot turntable is not much of a hardship for my 1930s-era shortline, the Hillside & Eastern, because those older steam locomotives would have been all it could afford anyway. 

I need to work within a model railroad budget that is stretched in too many directions, so any given project must make use of materials on hand as much as possible, to save money for those which cannot be improvised.

A review of the Atlas HO Roundhouse kit said it could probably be assembled in about one evening's work.  I'm not going to argue with that, but in my case, I wanted to make a few changes.  Besides, lengthening the project is yet another way to get as much as possible out of a hobby dollar.

Desired Features in My Turntable/Roundhouse Area.
Here are a few of the "Givens and Druthers" that influenced decisions I made later.

The Required Changes
In order to implement the desired features, some changes would have to be made.

A Few Possible Improvements
With an eye toward ease of use, Atlas did a few things when designing their roundhouse floor that are not commonly found at most real roundhouses. 

Of these items, only the Bumper Problem is anything like a serious flaw.  The rest are cosmetic. 

I changed the Front Yard because it is so obvious to the eye and I thought it would be relatively easy to change. 

The interior, like most model kits, was never intended to be viewed.  If I hadn't stopped to research roundhouse interiors looking for bumpers, I'd probably be blissful in my ignorance.  But now, when I have to take the roundhouse roof off, as I undoubtedly will, I know it will bother me to see ties in there. 

For now, I will concentrate on the exterior, only doing interior work if it can be seen through the windows or from the stall doors. 

* The roundhouses I researched through 1940s photos include the IC and C&NW in Chicago, the AT&SF in San Bernardino CA and Shopton, IA, and the CRI&P in Blue Island IL.

How I Did It.
This is a work-in-progress, and is subject to revision without prior notice. 

What follows is an account of the joys and trials I encountered while building the Atlas HO roundhouse kit, their item 709.  I document this not because I think it is the best way, but as a record of what I did, in hopes that those who come after me may learn from my mistakes and find better ways.

Quick links to specific areas:
[Interior decorating] [ Floor ] [ Right Wall ] [ Back Wall ] [ Left Wall ] [ Roofs ]

The Office (Step 13)
I started with the kit's optional office, to gain experience and test materials and techniques before tackling the roundhouse.

The windows of the office are set quite deeply into the wall, to the point where the lack of brick detail around them becomes obvious.  It would be a nice touch to at least add the horizontal mortar lines.  The roundhouse windows don't have this problem.

There are two different part numbers for the steps: 20A and 20B.  I don't see any difference. 

Painting Considerations.
If the office is to be used, one of the roundhouse windows must be "bricked up" with the piece provided in the kit.  The office, then, clearly represents an addition made to an existing roundhouse. 

Modeling Mortar Lines Using the Wrong Kind of Paint.
I purchased Woodland Scenics' C1217 Concrete paint before I noticed it is for use on porous materials.  I tried it on plastic and found it did not stick very well.

That very property came to my rescue when it came time to highlight the mortar lines in the brick walls.  Prior to assembly, so they could be laid flat to dry, I painted the roundhouse walls with PollyScale Boxcar Red.  When they had dried thoroughly, I applied a thin coat of the Woodland Scenics Concrete paint, making sure to fill all the mortar lines.  After it dried, I wiped off the bricks with a slightly damp cloth and was rewarded with clean distinct mortar lines.

One way to emphasize that fact, almost like telling a story with colors, is to use different colors for the wall cap tiles and the brick and mortar.  I chose PollyScale Roof Red for the brick, PollyScale SCL Hopper Beige for the mortar, and Pactra Gloss Brown for the cap tiles.  I think the story would have been clearer if I had saved the darker Roof Red and Gloss Brown for the older structure, and used lighter colors for the addition, perhaps adding a little orange to the brown. 

Don't forget to paint the three brick pieces that go around the inside of the walls just above the roof. 

The door and windows in the office are recessed in from the brick surface of the wall.  This means the sides of the door and window area should be painted the color of the brick, and the lintel and sill areas should be painted to match the lintel and sill pieces.  The lintels and sills are a very good fit in the wall, but if there is still a visible crack between the sill and the wall piece, it can be filled with paint. 

I used a brush and Pactra flat white for the windows, but if I had it to do over, I would have used a spray gun or spray can for the windows to get uniform coverage.  Don't bother painting the outside edges of the door and windows; they don't show and must be free of paint to fit into the walls.

For the stairs and foundation, I didn't care for the grey color Atlas used to represent concrete, preferring something with a little more yellow in it.  Unlike the roundhouse floor, the outside edges of the foundation will be seen in the finished model.  I used PollyScale Aged Concrete.

When painting the foundation of the office, remember to paint the step at the bottom of the door.

Assembly Notes.
The office window sills lay flat as compared to the door and window lintels, which are upright.  They can be cemented in place before the windows are installed. 

The Window Panes
The kit contains a bag of pre-cut window pane material to go into the window openings before the frames.  I strongly suggest you keep the pieces in the bag until needed, as they are so transparent they can be very hard to find if misplaced or dropped. 
After making sure the window frame was clean enough to fit into the wall opening, I put the window glazing into the opening in the wall, then applied Testors Clear Parts Cement/Window Maker to the upper and lower edges of the frame before putting it into the opening.

Before starting final assembly, file off the raised round areas on the inside of the walls above the roof supports. 

Prior to cementing the roof in place, make sure it seats properly on the roof supports.  Otherwise, the brick pieces on the inside of the upper walls cannot be put into their proper position.

Knowing how fragile they can be, I left the over-the-door light fixture off until the office was almost finished.  When it came time to install it, I applied some damage-resistant techniques developed on my first model railroad. 

I tapered the square lug on the back of the fixture, drilled a #80 hole in the end of the lug, and glued in a short length of fine sewing thread.  This is run through the hole above the door, draped over a support inside the office (fashioned from a piece of sprue) and a small weight is attached to the loose end. 

When snagged by a passing arm, the fixture yields under pressure and does not break off.  When released, the thread pulls the fixture back against the outside wall of the office, and the lug squares it up. 

The Roundhouse Floor
The floor comes in two pieces, which must be cemented together.  Why Atlas made the floor for their three-stall roundhouse in two pieces instead of three I don't know.  I'm sure it makes life difficult for those who want a four or five stall roundhouse.

Cutting Corners.
To put the roundhouse where I needed it to be to accommodate the Garden Track, I needed to remove a corner where it hit the basement wall.  Figuring how much to remove was not too difficult.  I used a three-piece cardboard template to get the exact shape and size.  Here is how I did it, step by step:

  1. I positioned the roundhouse floor against the turntable, but one "stop" further away from my basement wall than its desired final position.
  2. I cut the first piece of cardboard to fit snugly into the track well of the floor for the stall closest to the basement wall, making sure it was up against the end of the floor area.
  3. I laid the second piece of cardboard, about an inch wide, as an arm to extend from the first piece to a spot near the basement wall, close to where the roundhouse floor would hit the wall if it were in the right spot. I taped the second to the first piece.
  4. I then made a third piece of cardboard, one with one straight edge.  I held its straight edge against the basement wall, and taped it to the second piece.
  5. When all three pieces were securely taped together, I removed the cardboard template assembly from the track well close to the wall, and put it in the middle track well.
  6. I then marked the floor using the straight edge of the third piece of the cardboard template as a guide.  This minimum line showed me the part of the floor that must be removed, but not where the final cut would be.
  7. I looked over the roundhouse's side wall piece to find a structurally suitable place where the wall could be bent, making sure it was far enough from the corner to include all the area that needed to be removed.  That determined one end of the cut-off line.
  8. I used the roundhouse's back wall to measure the distance from the corner of the floor to the minimum line, using "bricks" as my unit of measure, rounded it up to the next whole number of bricks, and marked that as the other end of the cut-off line.
  9. I then scribed a line on the floor between those two points, and used that as a guide to cut off the corner of the floor.
I also had to file a notch in the side of the foundation, but that had to wait until I made the angle in the side wall.  Looking back on this, I'm not sure if the length of the side wall that will run along the cut-off line is correct.  We'll see. 

Positioning on the Table.
I decided to use #4 flathead woodscrews to fasten the roundhouse in place, counting on paint to help them blend in with the floor. 

The location of these screws is important, if they are to be accessible after the roundhouse is finished. 

After suitable screw-hole locations were selected, I drilled through the floor and plywood table with a 0.101" drill bit.  (A #4 screw is nominally 0.112" in diameter.)  I then enlarged the hole in the floor with a 0.125" drill bit and countersunk it for the flat head screws.  I then filled all the holes I'd drilled in the wrong places with Testors Contour Putty. 

To prevent the floor from buckling if the screws were over-tightened, I added pieces of styrene tube to the bottom of the floor around each hole.  I wound up re-attaching the tubes several times during the work on the floor.

Attaching the track.
Interestingly enough, there is no mention in the instructions for the roundhouse of installing track.  I guess we're expected to be smart enough to figure it out.  I think it is worth pointing out that the length of the area for the track is different from stall to stall.  When you cut pieces of track for the stalls, mark each piece so you know which stall it goes with.

Since I knew I would be assembling and disassembling the track and floor several times, I decided to use screws to attach the tracks to the bottom of the track wells.  The track wells are wider than the ties, but the gap for the track in the turntable base is a closer fit, which helps align the tracks with the turntable.  So don't fasten down the last few inches of track leading to the turntable.  The track will be held snugly in place by the turntable base, providing the rail alignment with the track on the turntable.

Please note that the center track well has a joint running down the middle, so putting the holes for the screws exactly in the center of the track might not be the best idea.  I lucked out.

After I cut each piece of track to length, I drilled holes for the screws through several ties and into the floor.  After this point, the tracks are not interchangeable parts, so be sure to do something to identify which piece is which.  I did it by drilling one of the holes decidedly off-center. 

Planning to Wire the Track.
The Atlas Roundhouse instructions said nothing about wiring the tracks, but it goes without saying that if you have a roundhouse full of locomotives there must be some provision in your track controls to kill the power to the tracks holding the locomotives you want to stay put.

To see a page about electrical connections to the Atlas Turntable, click here.
Ideally, a rotary switch would guarantee that one and only locomotive storage track would receive power.  The Garden Track counts as a storage track here, but the approach track(s) do not. 

Some rotary switches come with a movable stop to limit their rotation to however many positions you will be using.  If you use a rotary switch, be sure to include a position for "everything off." 

Actually Wiring the Track.
There are two small holes in the floor of each stall, apparently intended for feeder wires. 

I chose to solder stranded feeder wires to the outsides of the rails, then drill holes in the bottom of the track wells to route them under the floor.  To make the three track pieces easier to identify, I soldered the feeders for track 1 about 1 inch from the end, track 2 about 2 inches from the end, and so on.  I used black insulated wire to make them less obvious, and when the solder cooled, I painted the shiny areas flat black. 

After drilling the holes through the floor, I turned the floor over and drilled holes through the webs that help strengthen the floor so the wires can be routed to meet the wires from my track selector switch.

I used the largest hole-saw I had (2 1/8 inches) to make an opening in the table below the roundhouse for the wiring to pass through.  On the edge of the hole, below the table, I mounted a home-made socket with the wires from my track selector switch.  The ends of the wires from the tracks are soldered to 1/32" brass rods, which fit in the holes in the socket like the plugs on an old-fashioned telephone switchboard.

Finishing the Floor in the Track Well Areas.
To implement solid paving outside the rails would require adding removable strips roughly ¼" wide between the rails and the track well walls.  Making these removable is a work in progress.

An inspection pit between the rails would require cutting a rectangular hole in the bottom of the track well, cutting the ties that would cross the inspection pits, and regaging the track. 

Solid paving between the rails could be done with ½" wide pieces (actually up to 0.564" wide) fastened securely to prevent derailments. 

The Front Yard.
I decided the point at which I wanted the concrete floor to end would be about 9 scale inches in front of the front wall, or about 1/8" from the door hinge holes. 

On the two concrete areas adjacent to the side walls I scribed lines at a 90° angle to the side walls.  For the other two areas, I scribed lines at a 75° angle to the side walls.  (90° - 15°)  I darkened the scribed lines so they would be easy to see later on. 

The first cut I made was the one parallel to the floor about 1/16" above the bottom of the track well.  Thinking it would be a good way to maintain the proper depth of the cut, I clamped the blade of a hacksaw about 7/16" above my drill press table, and ran the floor back and forth on the table while holding it against the saw blade.  There has got to be an easier way to do that.  After getting the cut started, I switched to a hand-held hack-saw blade for the rest of the cut, stopping just short of the scribed lines.  I then cut down from the top of the floor piece, parallel to the scribed lines, into the end of the long cut, and dressed the ends of the floor with a file. 

All during the preparation, I was wondering what to use to cover the gaping triangular holes that were going to appear between the track wells.  As soon as I saw the shape of the pieces I removed, I had my answer.  The four pieces removed have the same exact angles as the holes they covered, and can be trimmed to fit and cemented in from the underside of the floor piece.  This surface will be covered with cinders later on.

I covered the holes in the ends of the floor where it meets the front yard with 0.020" styrene sheet, trimmed the excess flush with my rail nippers, filled with Testors Contour Putty, and rounded the corners. 

In hindsight, I think putting wax paper between the floor piece and the drill press table might have eased the friction, but I'm not sure how the wax would affect the paintability of the floor.

The Bumpers.
To prevent damage to equipment, the bumpers must catch the knuckle of the coupler, which is centered roughly ½ inch above the floor, and not the gladhand.  To hold my largest locomotive, the bumpers must sit back 3/8 of an inch from the end of the track.  It can't be so ridged that it could damage the coupler, but it should move no more than 3/8 of an inch, so the gladhand doesn't hit the wall.  In keeping with the fact that roundhouses have no bumpers, I'll have to come up with three bumpers that don't look like a bumpers. 

The spring for Bumper #1
The stout fellow, showing the slots in the floor that allow him some give.  I promised to repaint his trousers after this is all over. The underside of the floor, showing the plastic plate that keeps the man upright, and the copper bar that keeps it from sagging.
Bumper #1
Selecting a rather stout fellow from my collection of Airfix® OO scale polyethylene civilians, I carefully drilled a 0.028" diameter hole up through each of his legs.  I then fashioned a spring from 0.025 music wire.  Don't try to cut music wire with ordinary wire cutters, it will damage them.  To cut music wire, use the corner of a grinding wheel to grind it part way through, then flex the weakened spot until it breaks, and dress the ends to remove sharp edges. 

The spring is mounted below the roundhouse floor, and the ends go through a plastic block that keeps them upright, through the slits in the floor and are inserted into the holes in the legs of the man. 

The Inspection Pits.
Because of the length restriction of the turntable, most if not all the locomotives that use the roundhouse would require visits to a track with an inspection pit.  The Diesels would require pits because their traction motors are located on their trucks, and the steamers because most of the locomotives this size were equipped with inside valve gear.

I chose not to cut inspection pits into the floor of the track areas, but to just simulate them with flat black paint.

If I had cut pits into the floor, I would have removed the part of the track ties that cross the pits.  I then would have bowed the pit area rails slightly and cemented shims to the sides of the track area to push them back into gage.

Painting the Floor Assembly.
I painted the bottom and sides of the track areas Grimy Black.  I used a wash of Grimy Black to unevenly cover the walking surface inside the building, and then used fine sandpaper to remove most of the paint in the high traffic areas.  The floor alongside the track areas should remain grimy black, especially near where the locomotives would be. 

The Right Wall
In addition to the modifications needed in my particular situation, this section will cover any issues relating to preparation and painting, as they will be the same as those for the back and side walls. 

If you are going to be making any modifications to any of the walls, do so before painting.  If you are going to be painting any walls, do so before assembly. 

Cutting Corners.
The right wall of my roundhouse has an angle in it, to avoid hitting the concrete sky just behind it. 

I began by selecting a place on the wall next to one of the pilasters (is that the right word?) where an angle might logically be found. 

Starting on the inside of the wall, I used the back edge of a hobby knife to scrape a vee-shaped groove almost entirely through the wall.

I painted the roundhouse walls with PollyScale Boxcar Red, and highlighted the mortar lines with Woodland Scenics Concrete as outlined elsewhere in this page. 

The window frames are a close fit in the wall, but not so close that the bowed clear window material couldn't push it back out.  Rather than wait for the Testors clear part glue to dry, I applies a little Tenax to the underside of the window sill and the top edge of the frame and held it for 30 seconds. 

The Back Walls
The instructions might lead you to think all three back walls are the same.  Wrong! There are actually three different kinds of back wall.  You will find them marked as 04A, 04B and 04C on the inside of the wall. 

I didn't notice this until after I had narrowed 04B to allow for the cut-off corner. 

The sketch on the right (not to scale) shows the cuts I made (in red) and the areas I removed (in blue) to narrow the wall.  To keep calculations easy, I used bricks as a unit of width. 

The total width removed worked out to 7 bricks, so I removed 3½ bricks from each side of the window.  That was a mistake.  It resulted in two adjacent rows of bricks above the window that were not properly staggered.  I should have removed 3 bricks from one side and 4 bricks from the other.

And yes, that cut below the window is not horizontal.  That area will be covered by a trim piece, so the gap will not be a problem.  The angle makes sure there will be no interference between the two pieces. 

I pieced it back together using pieces of half-round sprue on the inside of the wall to strengthen the joints. 

Step 2 in Atlas's instructions assumes the modeler will be using the office annex.  If you are not going to add the office, Atlas does provide enough window frames and clear window material for all nine large windows in the roundhouse. 

If you are going to be using the office annex, it can be placed against any of the back walls and the window of that wall should be at least partially bricked up.  When I get to that step, I plan to investigate cutting the window smaller, and installing it and part of the brick-up piece in the wall. 

The Left Wall
The left wall has a doorway, but the Garden Track leaves no room for the stairs.  Rather than have a door leading to a two-foot drop-off, I used material removed from the shortened back wall to fill in the opening.  Assuming the Garden Track was part of the original plans for the roundhouse, there would never have been a doorway there, so the work had to be done carefully to completely obscure the doorway's existence.

The Front Wall, Roof, and Skylights
The glass for the skylights seemed a little large, but it might be because I put the paint on the frame around the window a bit thick.  I filed the edge of the glass a little, and it seemed to help. 

I think the sky light windows in a real roundhouse would have been hinged at the top so they could be opened for improved ventilation.  To model this, I attached two of the panes to the window pieces by applying the Testors Clear Parts cement around the middle pane, rather than the perimeter of the frame and placing them into the window openings. 

When the cement had set, I popped them out and applied more Testors Clear Parts cement to the outer edge of the window pieces, where it was drawn in by capillary action. 

Smoke Jacks
Don't worry if the smoke jacks don't line up with your steamer's stack.  Smoke jacks typically had funnels below the ceiling so they could catch smoke from a variety of sizes of locomotives.
The Roofs
The roof was almost the right color, but it was a bit shiny for my taste.  I gave it a coat of Polly Scale Grimy Black, and painted the gutters along the back edge of the main roofs PollyScale Signal Green. 

I painted the bodies of the smoke jacks PollyScale Signal Green, and plan to add rust stains to them.  Coal smoke is nasty stuff where metal objects are concerned.

The Garden Track
The HO Atlas turntable is designed take track sitting on ¼" (6.35mm) roadbed.  That used to be the standard size for cork roadbed, but I have not seen ¼" roadbed for decades.  You could use ¼ plywood, since sound dampening is not an issue at such low speeds.  You could also use card board shims under commercial roadbed.  Don't use corrugated board, it will wilt over time.  Use the kind used to made cereal boxes, soft drink cartons, and such. 

Once all the pieces are painted, it will be time to start construction. 

Walls (Steps 3 through 9/9a)

Roofs & Skylights (Steps 10 through 12)

Foundation and Trim (Steps 14 through 17)
The Trim pieces are applied to the floor, and the Foundation pieces are applied to the walls. 

There are two kinds of Part 57 the Base Trim along the back edge of the floor: two 57A and one 57B

There are two kinds of part 40, the Foundation pieces for the back walls: four 40A and two 40B

There are two kinds of Part 42, Foundation pieces for the side walls: 42A and 42B

Roundhouse Interior Decorating.
I studied lots of photographs of roundhouse interiors, to see what they had lying around, and here's what I found, along with some ideas on how to model it:

I hope this gives you some ideas for your roundhouse.

Begun October, 2008, last updated 3/23/2014.