# Designing a Turntable and Roundhouse, from scratch.



## Scottychaos (Jan 2, 2008)

Anyone have any information about the geometry involved in designing a turntable and roundhouse?
I know there are specific mathematical rules involved, but a google search isnt bringing up anything useful..

Im considering building a 1/29 scale, standard gauge turntable and roundhouse..if it will fit into the space I have in mind.

the turntable would probably need to be a 70 footer..for my Alco PA's and other large diesels..
so thats about 30" diameter..maybe make it 36" just to be safe..
and the stalls would need to be just as long..maybe even 100 feet..(40 inches)

the space im considering putting it would be inside a 12-foot diameter circle:










Im thinking a modern "late steam" standard gauge style, like this HO scale version:
http://www.marklin.com/newprod/2004/images/72881.jpg

probably about 5 stalls would be reasonable..
any suggestions on where to start?

I guess I could take some locos and track out on the driveway, with a piece of chalk,
and draw and measure some outlines!  and I will probably do that..
but im also wondering if there are more scientific methods..

thanks,
Scot


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## Gary Armitstead (Jan 2, 2008)

Scot,

I could draw-up a plan for you like we did the pyramid trellis. E-mail me with your ideas and I can get the plans to you in pdf format.


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## Semper Vaporo (Jan 2, 2008)

I designed this one using Google SketchUp. Each element, turntable, apron (between the TT and the doors) and the round house stalls are each 3-ft, making the whole thing 15 feet in diameter. A bit big for your specified space, but once the idea is started in SketchUp it is pretty easy to alter the dimensions. I just wanted it to be symetrical and still hold my Aster Mikes which are 32 inches long... I added the other 4 inches just in case I ever got a longer engine.

Some real roundhouses started with this equal proportions but then a 'dog house' was added either to the apron side or back side of some stalls to handle longer engines.

Other sites paid little or no attention to such symetry.


The diameter of the TT can also be altered to handle longer engines, but you then have a shorter apron between it and the doors, but that is really of non-consequential.

There is the consideration of keeping the tracks far enough apart at the doors such that all the stuff fits, but at the turntable they can overlap (frogs where the rail cross to reach the circle of the TT) which would be an expense when building, but not non-prototypical. There is one diameter that would not work and that would be where the rails meet, but a small change in the TT diameter takes care of that.


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## Scottychaos (Jan 2, 2008)

Gary, 
I might just take you up on that!  
thanks.. 

Sepmer, 
interesting.. 
so really one should design the roundhouse first..to fit the locomotives you want to fit, 
then the turntable, of many different possible diameters, fits in the middle.. 

I was thinking of "turntable first" then trying to fit the roundhouse to the turntable.. 
but I see now the opposite makes more sense.. 

stay tuned for photos of Alco PA's out on the driveway!  

scot


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## Dougald (Jan 2, 2008)

Scott 

Your 12 foot area may possibly hold a 5 stall roundhouse and table but it will be tight.

The mathematics and geometry are fairly easy.

The table you said was to be 3 feet and the roundhouse stalls at least that size. It was normal to allow at least an engine length or more from table to house making this much at least 9 feet. I have not included table approach tracks and in the prototype world there was a minimum of two (inbound, outbound/ready) and usually a third for flexibility.

To calculate the house size - and it will be big - place the stalls on 10 degree centres. Now the house will cover 50/360 of a 7.5 foot foot circle minus a 4.5 foot circle for the house approach tracks. This will be a big but not impossible area and this will likely just fit inside your 12 foot circle of track. Note that a full circle roundhouse of 33 stalls and 3 approach tracks would not fit.

Lay it out on paper and do the calculations before you begin the detailed design of both table and house. Make sure the geometry of the inbound and outbound tracks works with your trackplan ... and if possible leave room for engine service models (coal sand water ashes cleaning/lubing for steam and washing fueling sand and supplies for diesels)

Regards ... Doug


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## paintjockey (Jan 3, 2008)

My friend did as you first suggested. He laid out his track on a sheet of 4x8 cardboard, drew out the circle for the turntable then moved everything around until it fit. When he was done the card board was a perfect footprint of what he wanted. 

Terry


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## Semper Vaporo (Jan 2, 2008)

5 stalls, 3-ft long, plus 3 outside storage tracks (optional)
3-ft apron area
3-ft turntable
Inbound and outbound turntable access tracks.

All in a 12-ft DIAMETER circle.

You may have to alter the position of the access tracks to best mate with the existing track. Note that these access tracks are best (and almost always were) if they align with one of the tracks into the roundhouse so a dead engine could be shoved in using another engine on the opposite side of the turntable. With a wide apron that was not necessarily required but was often done anyway just as a matter of course.

Note the widths shown for the narrow (front) and wide (back) ends of the roundhouse stalls.

EDIT: Replaced graphic... I couldn't stand it... I had to draw the loop of track as "track" and connect the access tracks. 
EDIT AGAIN! Rotated it so it looks better.


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## Scottychaos (Jan 2, 2008)

Thats awesome!








thanks Semper! 

I also drew up a drawing last night, but its not as good as yours: 










I think my "apron area" is too short..and the tracks are farther apart than they need to be, 
which makes the whole roundhouse larger than it needs to be.. 
its just a crude mockup, just to see how things fit.. 

I like your drawing better! 
thats gives me a great plan to work with.. 
thanks! 

Scot


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## Dougald (Jan 2, 2008)

Scott

As you will discover when you calculate, the size of the house is sobering. And given your climate, it must be built strongly as the snow loading especially mixed with some rain will assume proportions of the real thing not just the model.

Regards ... Doug


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## Scottychaos (Jan 2, 2008)

Posted By Dougald on 24 Jul 2009 06:31 AM 
Scott

As you will discover when you calculate, the size of the house is sobering. And given your climate, it must be built strongly as the snow loading especially mixed with some rain will assume proportions of the real thing not just the model.

Regards ... Doug






Doug,
yeah, its going to be BIG! 
might be worth it though..if I can build what im envisioning..

Looks like it will fit..that was the first hurdle..
next I need to think about HOW to build it..with what materials..

Snow wont be an issue..I will store it in the basement over the winter.
(maybe built it in two halves for easier transport)
I dont plan to run outdoors during the winter anyway..

November - March will be my "On2 indoor layout" season! 

Scot


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## Scottychaos (Jan 2, 2008)

Some Roundhouse Readings: 

Noel's Roundhouse (Indoor layout) 
http://www.noelsbigfour.com/roundhouse02.pdf 

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Ron's Roundhouse, Part 1:
http://www.mylargescale.com/Communi...C_ID=49951

Ron's Roundhouse, Part 2: 
http://www.mylargescale.com/Communi...fault.aspx 

(why dont the attachments work?  
Ron, did you delete the pics? if so, can you restore them? 
or is it something screwey with the forum code? I dont really know how "attachments" work here..I never use them..) 

Ron's Roundhouse, Part 3: 
http://www.mylargescale.com/Communi...fault.aspx 


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Rudy's roundhouse, part 1: 
http://www.mylargescale.com/Communi...fault.aspx 

Rudy's roundhouse, part 2 
http://www.mylargescale.com/Communi...fault.aspx 


Great stuff! 
thanks guys! 

Scot


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## Semper Vaporo (Jan 2, 2008)

I think turning the whole layout the way you have is a really good idea. It puts you closer to the turntable in case there is a problem. And it presents the roundhouse from a better viewing perspective.

The width of the apron between the TT and RH is not of great importance. It is mainly what is left over after the desired TT length is in place and the roundhouse door spacing accomodates the track spacing. In the real world it was all about cost and so the shortest (cheapest) TT was installed to fit the biggest engine it might have to turn. Same for the roundhouse, it was only built big enough to handle the size and number of engines that might need to be in it.

Just for fun, I rotated my drawing to see how much room I could get out of it. There is plenty of room for water and coal towers and a sand house on the outbound track, and an ash pit on the inbound track. The inbound track is still lined up with one roundhouse stall. I also put in a supply spur for the coal and sand.










Of course, "Layout" is one thing... BUILDING it is an entire other matter!!!!!


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## aceinspp (Jan 2, 2008)

The Jan/Feb issue of Garden Railways dated 1991 had some good info on building turntables. Later RJD


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## Nicholas Savatgy (Dec 17, 2008)

Scott,
Heres one i bought from Dan at Eaglewings ironcraft he made it to my specs of 48 inchs, all steel pit and bridge, rides on roller bearins and is motorized and all powder coated.......







SWEET


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## Ron Senek (Jan 2, 2008)

Scott The attachments are of the inside of the roundhouse the frame work. i can't retrieve them either. I can repost them if you want them. 
Ron


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## Ron Hill (Sep 25, 2008)

Scotty, if you make a stub off of the turntable every 8 to 9 degrees, the individual tracks should clear. But make a mock up first to make sure. We had a turntable here in Cleveland and one in Water Valley where I grew up and both had 75' turntables. The stub tracks were at 8 to 9 degrees around the pit. You may need to adjust them because of the scale of the trains we work with.


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## Ron Hill (Sep 25, 2008)

Scotty, if you make a stub track off the turntable every 8 to 9 degrees the tracks should clear. But make a mock up first to check the clearances. There was a turntable here in Cleveland and one in Water Valley where I grew up that had 75' turntables. The stub angles were both 8 to 9 degrees off of the pit. You might need to adjust the degree because of the scale of the trains we work with.


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## K7 (Jul 10, 2010)

im putting a round house in to my return balloon loop. its an 8' diameter. im thinking 4 tracks in the round house? im going to have a 3 foor turn table and round house a bit longer. any help is appriciated thanks


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## John J (Dec 29, 2007)

I didn't think 12 diamater was enough room. Good work guys . Looks great


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## Semper Vaporo (Jan 2, 2008)

Posted By K7 on 29 Jul 2010 11:56 PM 
im putting a round house in to my return balloon loop. its an 8' diameter. im thinking 4 tracks in the round house? im going to have a 3 foor turn table and round house a bit longer. any help is appriciated thanks 

Have you seen this thread? http://www.mylargescale.com/Communi...spx#176834

Do search this site for other references to "Roundhouse".


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