I’m not sure, Mel, but I think that mine sat in its box even longer than that.
Wayne
This is the results using your dimensions.
Maintaining the 17⅝” wall and 10° spacing and the 2” front. The dimensions on the drawing are what came out of the CAD program.
Using your dimensions of the turntable the distance between the front walls/doors to the turntable matches the mathematical guys calculations.
Mel
My Model Railroad
The formula calls for using the distance between the front and rear walls, not the length of the side wall.
If the length of the side wall is 17.625", and the angular track spacing is 10 degrees, then the distance between the front and rear walls will be 17.555".
Ed
well a huge thank you to all who chipped in here. im in the process of building the three stall roundhouse kit with the 130’ tt and of course came upon this very question. just eyeballing it I figured about 3", so the ~2.7" from the braniacs here was very encouraging indeed.
thanks again…great source/resource for information
Ed
Interesting conversation, and the math behind it.
I like the old HelJan roundhouse, primarily because of the set back from the pit. It just looks more prototypical to me. When I was placing it, for a six bay house, I put long track pieces into the two outer bays and use them to line up to the turntable, moving the house back until it fit right. Took only a few minutes of testing.
On my next layout, I’m kitbashing the two HelJan houses I have, and with parts from another, building a 14 stall house with 4 deepened stalls for longer engines, as well as adding a side building for office/supplies/loading.
The formula is useful if you’re drawing a layout plan.
If you actually have a layout and a roundhouse or kit for one you just need two lines on your layout.
Take the longest floor piece for one stall. Place that floor piece on your layout. Mark the back wall position of the roundhouse. Draw two converging lines, one along each long side of that roundhouse stall floor piece. Where they intersect will be the center of your turntable.
It doesn’t matter how big the roundhouse is, how wide the doors are nor how large the turntable is. The location of the back wall of the longest roundhouse stall determines the location of the center of the turntable. That point depends only on the angle of the stalls.
That sounds like an interesting kit conversion project.
I hope you can share pictures. Please keep us updated.
-Kevin
The formula is always useful even on existing layouts. It may well be that someone is contemplating the purchase of a turntable and roundhouse but doesn’t yet own one in which case he won’t have the stall floor at hand.
Also, at least on the Walthers Cornerstone roundhouse, all of the stalls are the same length. Some kits include a few extensions for longer locomotives, but it is sufficient to measure the length of the standard stall.
The data derived from the formula is also useful in determining overall space for both the roundhouse and turntable. For example, using the 130’ turntable and the Walthers Cornerstone Roundhouse, a space of 38.5" would be required from the back of the roundhouse to the far edge of the turntable. A space of 26.3" would be required if using the 90’ turntable.
Rich
The formula is unnec
Well, that is just plain silly. Of course the formula is not necessary, but it is useful, and it certainly is helpful. A reader of this thread and the other related thread who is interested in purchasing a Walthers Cornerstone Modern Roundhouse and turntable now knows the distance of the tracks between the roundhouse and turntable regardless of the size of the Walthers Cornerstone Turntable, be it 90’, 110’ or 130’. How is this that not useful or helpful?
So, when JDawg in the other thread asks…
…He now knows how much space there is between the turntable and the roundhouse, thanks to the formula.
It’s not useful because it doesn’t matter. You just don’t need to know that information. ,
The roundhouse determines all the other distances.
You place the template of the roundhouse stall right on your layout (or draw it on your plan). Draw two lines and you’re done.
Sure about what?
The roundhouse fits or it doesn’t.
One pair of lines is all you need, no mockup required.
Agree 100%
-Kevin
Nope, you’re not done. You need to know the radius of the turntable pit, either by calculating it or by trial and error with the placement of the roundhouse.
Well, I’m certain to find out. Fairly soon hopefully. Our relocated layout is approaching completion of the benchwork and main tracks. We deferred fitting the turntable to the original layout when we learned we needed to move.
Good job we did delay installation because the approach tracks will be entirely different.
Byron gave the best and correct answer near the top of the first page.
-Kevin
I think that everyone agrees on determining the centerpoint, even LSM.
Rich
Per the OPs request…