Okay, so I'm in the man cave laying roadbed... Cutting, gluing, pinning... I stopped to pin down some flex track on my WS inclines so I could trace around it and use the tracing as a guide when I get back to the road bed. I discovered that the pink foam is just enough higher than my incline that I need to sand it down a bit... no problem.... I went back to the other end of the table to start laying roadbed again and my eyes fell on the outlined location for my atlas turntable and then shifted to the concor roundhouse I built 20years ago for a different turntable on a different railroad... the two are not compatable in the space I have and it would look ridiculous to put it far enough away that I could curve flex track to the stalls... So I'm standing there looking back and forth between the small turntable and the big roundhouse and cursing the manufacturers over five degrees...
So then I remembered last Years Walthers catalog had a rather extensive article on assembling their new larger turnatable and roundhouse kit. I pulled it out flipped around until I found it and then stood there looking at the article and turning the old roundhouse (with cat damage)over and over in my hands and a thought and some questions started to form so here goes...
I need a, no scratch- that I want a new roundhouse and I can either buy the atlas kit, or (concievably, the new Walthers modern kit as both at set up on 10 degree stalls...
Or
I can scratchbuild one, you know I have a lot of free time (not). Which is the option that most appeals to me... But, I don't know how to build one from scratch. But I do know a few things about how to get started, I think...
1. I think I need to put a sheet of oversized paper down on the layoutunder the edge of the turntable and pin them both in place.
2. Then take 6 12" pieces of straight track and pin them down at six consecutive track positions, and pin these in place.
3. Trace around the edge of the turntable and the tracks, measure and mark a spot 2 inches from the edge of the turntable for each track. This point will be the front of the roundhouse.
4. Then find track centers at both the 2 inch point and the far end, mark as such. This will be the track center for each stall.
5. Measure and mark the center point between the track centers.
6. I will take the measurements for the distance from the end of the track to the back wall from the Con-cor one and use a similar width marking this on the template along with the meaurement of the distance from track center to the outer wall from both ends for both outer stalls as well.
7. Because I have a PA Unit and a 2-6-6-2 Mallet which are taller than my Mikado, or RS-7 or any F unit I will mkake sure that my outer walls, door openings, and roof supports between stalls are tall enough to accomodate the tallest loco.
8. I like the looks of brick on the modern roundhouse, but like the shape of the old Con-cor. I'm not in love with either so I'm thinking wood...
9. Tin roof will either be the corrugated variety or some white evergreen board & batten styrene, skylights and vent stacks I'll probably recycle...
10. I like tilting windows on the roof step, ....
Well there it is, I wonder when I'll get to it... I probably ought to have some track down and trains running first....
DON'T MAKE THIS ANY MORE DIFFICULT THAN IT HAS TO BE!!!!!
You could break your neck trying to follow your procedure!
You are dealing with a basic trigonometric operation here. As a point of enlightenment if you are talking about a roundhouse with a 10° bay separation and you want the front portals of that roundhouse set back two inches from the lip of the turntable pit--I do assume that we are talking Horribly Oversized-Scale here and further assuming that we are talking 15 feet as a portal width--then your turntable is going to have to be an HO-Scale 19.44 inches in diameter or a prototype141 feet 1 5/16 inches. This, by the way, exceeds N&W's 140 foot turntable constructed at their Shaffers Crossing facility in Roanoke. Onion Specific only used a 126 foot turntable at Ogden, Evanston, and Rock Springs and sometime later at Laramie for turning their Challengers and 4-8-8-4s.
Set your roundhouse back three inches from the turntable pit and you are talking about a turntable 17.44 inches in diameter which scales to 126 feet 7 1/8 inches on the prototype.
Four inches? Fifteen and 44/100 inches HO-Scale; 112 feet 31/32 inches on the prototype.
This, I dare say, is just a little bit more reasonable.
Your formula is this:
the adjacent--the distance from the center of your turntable to the portal of your roundhouse = 1/(10°tan) X 15 X .137795--that's 3.5mm X .03937-- minus the setback distance for the roundhouse X 2. This gives you the HO-Scale diameter for your turntable
Let's look at this from another angle; assuming you want a 100 foot turntable. What will be your offset from the turntable pit?
1/(10°tan) X 15 minus the radius of the turntable X .137795
In this case we come up with a setback of 35 feet 27/32 inches or 4 and 13/16 inches.
As an example using a 100' turntable you can compass a circle equal to a 50' diameter; extend your compass another 4 13/16 inches to locate the portals of your roundhouse; set a protractor at the center of your turntable and mark off 10° increments and there you have it!
Remember, I was using a portal diameter of fifteen feet. More or less than that figure is going to adjust the distance from the portal of they roundhouse to the center of the turntable. For instance with a 15' portal that distance is going to be 85.07'; with a 16' portal that distance will increase to 90.74 feet.
Hope this helps!
From the far, far reaches of the wild, wild west I am: rtpoteet
Hey,
I appreciate your reply, and I will add your method to the hand book, I hadn't thought about doing it that way, let me explain why...
I have the Atlas turntable and the track positions are molded into the rim. I knew it was 10 degrees only because it said so on the box... I got the turntable as a gift from my wife who is trying to cope with being married to a model railroader, so I'm going to use it, though for myself I would have bought the Walther or Concor...
I'm just learning to scratchbuild some things, (joking)because I've threatened to release my own line of affordable structures for other cheapskates...LOL So far I've done a really nice shotgun house and I guess I bit off a lot for my second attempt with a roundhouse for a small turntable, but ambition is what drives me...
I'll post photos of the project as it comes along, you have given me some excellent information, and another way to look at this... As dumb as this might sound, I'm documenting every step of the process of building my railroad textbook fashion. Thank heaven for digital cameras... The writing and photography is the easy part, learning the best way to do some of these things is the hard part, because you don't know what you don't know until you ask...
I really appreciate your reply, though you only had to say it once... Oh and if I weren't so dense I'd have mentioned before now that I model in N scale.
I have the Atlas RH and 90' Walthers TT. I made a new base for the RH out of foam board and moved it closer to the TT to get the stall angles to line up. (and to lower the RH to table level.) It sits about one and three quarters inches from the TT edge. You could do a little jury rigging along those lines and make yours work too. To paraphrase RT, It ain't rocket science!Moving the RH closer takes up less of a foot print too.
I didn't remember what scale you were modeling in but it really doesn't matter. In HO-Scale your per foot decimal is .137795; in N-Scale it's .075--the formula remains the same.
Just for the sake of argument I set the turntable in place and used an old chalkboard compass to measure off track positions, nevermind that they are molded into the rim of the Atlas turntable, but I wanted to try out the method you detailed... It worked like a charm... and I marked my points on the foam for future reference...
I ran into trouble trying to position the old roundhouse. It is the old Heljan/ConCor after which The Walthers Union City Roundhouse is cloned, its set up for a larger turntable and its stalls are on a 10 degree position. no positioning of the roundhouse allows me to use all six stalls, my personal best after three falls was curving fles track to the two outer stalls and using one center stall, leaving three without access... In other words, unworkable...
So, as Lothar pointed out you can use the Concor 90' turntable and the Atlas roundhouse, because it isn't pre indexed. Atlas has decided that they want you to buy their roundhouse so they pre indexed their Turntable... But I have news for them...LOL
I made a pattern for the first stall base, it wasn't as difficult as my instructions made it sound...LOL, Thanks to your help.
As I get into this project its quite a lot of fun.
I model in HO, so take this with a grain of salt. (I can't. High blood pressure. No salt.)
I have an Atlas turntable and Atlas roundhouse. They work perfectly together. But, they are small. Big steam won't fit on the turntable, and it won't fit in the roundhouse, either. Short steam and 4-axle diesels are fine, which takes care of all but one of my engines. I can live with that.
The HO Atlas turntable has a 15-degree indexing, so I'm stuck with that. That's the main reason I chose the Atlas roundhouse, but in all honesty, it's a nice model, reasonably priced, and it looks very nice with a bit of detailing, weathering and other effort.
IMHO, a turntable and roundhouse is one of the most striking features you can have on a layout. I'm glad you've chosen to model one. Please keep us posted on your progress.
It takes an iron man to play with a toy iron horse.
My Walthers catalog specifies Atlas' turntable as being 7.5" in diameter--100 foot--15°, not 10°, indexing. Their roundhouse is designed around this indexing factor; keep in mind that if you scratchbuild a roundhouse and you set it back 2" from the edge of this turntable you will be be designing 1.5"--20 foot--portals at the front. Those are, I believe, pretty big portals but there may be a prototypical example for that size. If you change the setback to 1" you will be designing 16 foot 7 inch portals, a more prototypical size I do believe. I don't know how many bays your planning on but you are designing a mighty big roundhouse.
As I previously have related here on the forum I have a "IF-I-HAD-A-MILLION" N-Scale layout that is, of course, too large practically to build for a one man operation but which I found fun to design. My Ohio River terminal hosts a substantial sized yard and a roundhouse originally built circa 1905 with a 100 foot turntable and 110 foot lead tracks. This turntable had had to be expanded to 110 feet in 1915 when my road acquired it's first 2-8-8-2 locomotives; it had had to be expanded again to 120 feet in 1942 when the road ordered its Class P locomotives, copies of C&O's H-8s. The net result of this is that the portals of the roundhouse, originally 110 feet from the lip of the turntable pit, are now only 100 feet back and no longer able to hold the road's longest locomotives completely outside the turntable.
In designing the turntable-roundhouse I indexed the stalls at 5.356°--that's a deflection of 1" in 10 11/16 inches--which gave 15 foot wide portals. The pre-1915 maintenance bays were 125 feet long; 18 of the 35 bays were expanded to 137 feet 6 inches; eight of those were subsequently expanded to 150 feet so currently--mid-50s--this roundhouse has seventeen 125' bays, ten 137' 6" bays, and eight 150' bays and is 44 5/8" wide at its widest point.
PB&J... Here's what I did. (With apologies to R.T.... Math gives me the hives!)
I started about where you are. I'm in N scale, and I got the Walthers Built up TT with the 130' table.
I started as you say, by laying out the fan tracks to get the basic arrangment down. I wanted as many tracks as I could squeeze into my space, so the angle is less than 10 deg. This is fine, because the Walthers driver is infinitely programmable. I ended up with six full length stalls, and 1 switcher stall. I made sure the tracks were radiating out in a straight line by moving the turntable into position, then checking the track alignment with a straight edge. The first position I checked was the through track that runs from the main line at the top of the photo, across the tt and into the fuel racks.
Next, now that I knew where the track had to be, I took a piece of card stock, and traced out a template for the wedge shape between two of the tracks. I measured from outside of the rail to outside of the rail, since this would become the "pavement" of the interior floor. I then moved this template into position between each of the track to double check that my alignment was right, and made any minor adjustments that became apparent.
Once satisfied that the template fit everywhere it was needed, I got out the handy dandy paper cutter my wife bought when she was doing crafts for her Girl Scout troop. Using the template as a guide, I carefully cut out the six wedge shapes from a large sheet of styrene. I trimmed the 6th one to make the jog at the short stall, then cut a half wedge for the outer wall at the bottom of the image.
From there, it was a matter of building up the floor to clear the track ties, and do some other stuff to make things like inspection pits and other details. I'm using code 55 rail, and the styrene sheet is .050, so it worked out pretty well. The picture above shows the underside, with the inspection pits and track wiring in place. I used old signs as the source of my styrene, as evidenced by the lettering...
Once the floor was assembled, I added a 1" strip to the outside edge to provide some room for the shop crews, and built in some home made bumpers (They catch the locomotive pilot on either side of the coupler). I then scribed some expansion joints for the "concrete" floor, and painted the whole mess.
After that, I secured it to the table top around the turntable, and I got lucky wherein the inspection pits fit snugly into the cut out I made in the homasote, so it all is in with a friction fit. So, if I ever need to pull it out to fix something or to build a new engine terminal, I won't have to tear up the tracks!
After that, I used Evergreen H channel and I-Beams to create a frame, and Evergreen corrugated siding to start in on the walls.
I still have to finish up the exterior walls, do some interior detailing, and build the roof. But generally speaking, it's turning out pretty much the way I envisioned.
Hope this is useful.
Lee
Route of the Alpha Jets www.wmrywesternlines.net
I'm on my way to bed, Off to work early in the morning... Let it suffice to say I have learned some things tonight sitting here with my pen and paper... Doing the math at 2" the portals are almost 21", pretty big... I'm closing that distance to an inch.
I'm planning a six stall roundhouse... I'm brain dead tired...
RT I'd love to see pictures...
This has truly been an interesting, informative and instructional exercise.
I appreciate all the response, and encouragement, but most of all the information.
RT, I took my sketch and brought my lines down to one inch from the edge of the turntable a scale width of 16 feet and change... I'm knocking a bit off the length also, to about 135 scale feet...
I designed the end walls, and the roof panels... I am still thinking about skylights and vents, I have tons of leftover kit parts, I think I have some skylights from a machine shop kit , if not I'm sure I can get some from Walthers....
This is shaping up to be a very nice project... Over the years my tastes have changed with the trains, but I've always admired those who could build their own stuff... I don't have the patience to handlay track, but I think I can do structures...
Oh and one more thing... I finished laying the last of the roadbed on my mainline.