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Distance of Roundhouse From Turntable Locked

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Posted by SeeYou190 on Thursday, August 30, 2018 4:43 PM

I have only lined up one roundhouse with a turntable in all my layout building experience. It was in N scale for a friend's N&W layout.

First we figured out where the turntable center would be.

The roundhouse stalls were 12 degrees I believe. We drew a bunch of lines at 12 degree seperations from the turntable center.

Then we mounted the turntable in the correct spot using yellow string to get the center correct. This was before lasers for homeowners.

Then we mounted the roundhouse so all the track center lines were on the lines we drew previously.

We had 100% success with no math.

-Kevin

Wink Happily modeling my STRATTON & GILLETTE RAILROAD. A Class A line located in a personal fantasy world of semi-plausible nonsense on Tuesday, August 3rd, 1954.

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Posted by 7j43k on Thursday, August 30, 2018 5:26 PM

SeeYou190

 

We had 100% success with no math.

 

 

I had 100% success WITH math.

And it only took about 3 minutes.  For one person.  Without a roundhouse or turntable.

 

 

Ed

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Posted by doctorwayne on Thursday, August 30, 2018 8:02 PM

Your photo of the Korber roundhouse looks great, Mel!

I could have sent you some wall sections for lengthening the stalls, as I shortened four of mine by 1 1/2 panels, and shortened the other one down to just two panels.  The longest loco using the roundhouse is a Bachmann USRA Light Mountain, which fits easily in the longer stalls, while I have some Moguls and Ten Wheelers that can use the short stall....

I put the roundhouse together using Weldbond epoxy, in conjuction with machine screws. as some of the walls were badly warped (the kit had been sitting, unbuilt, for several years)...

I'll add trusses to the top of the posts shown in the overhead view, but make them part of a one-piece removeable roof.  I've ordered some Grandt Line doors, but they won't be operated remotely, as the roundhouse is almost at the edge of the upper level of my layout.

I also used some parts, left-over from a Walthers kit, to add a small annex to the rear of the building...

Wayne

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Posted by RR_Mel on Thursday, August 30, 2018 9:33 PM

I appreciate the offer Wayne but I built my Korber kit 18 years ago back when it cost $40.  It’s been through three overhauls and it’s on it’s second turntable.
 
My LHS had it in stock or I probably would never have bought it, I hadn’t heard of Korber back then.
 
 
 
 
Mel
 
 
My Model Railroad   
 
Bakersfield, California
 
I'm beginning to realize that aging is not for wimps.
 
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Posted by RR_Mel on Thursday, August 30, 2018 10:44 PM

Ok I think I got it correct this time.
 
 
The dimensions should be correct providing the roundhouse wall is 17.75” (128’ 10”) and the turntable is 17.9104” (130’)
 
 
Mel
 
 
My Model Railroad   
 
Bakersfield, California
 
I'm beginning to realize that aging is not for wimps.
 
 
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Posted by richhotrain on Friday, August 31, 2018 5:17 AM

RR_Mel

Rich
 
I could make you a CAD drawing if you Post or send me the stall width measured at the doors.
 
EDIT:
 
Include the stall depth too.

The stall width is exactly 2" front, and 5" rear. The stall length is 17 5/8".

For what it is worth, the overall diameter of the turntable is 19 1/8", and the diameter of the pit is 18 1/4".

Rich

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Posted by richhotrain on Friday, August 31, 2018 5:21 AM

7j43k
 
richhotrain
 
7j43k

There's a relatively simple formula for calculating the distance from the roundhouse to the pit.   

Ed, any chance you can publish that formula for all of us to reference. 

Rich 

ALL?  Right.

Well, yes, for ALL. At this point, it would only be of passing interest to me since I have found the right distance thanks to the replies to this thread. But, the mathematical calculation will benefit ALL of the members and guests who may be following this thread.

Rich

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Posted by richhotrain on Friday, August 31, 2018 5:22 AM

7j43k

I believe that the distance to the pit in the above drawing (2.5986) should be 2.7966.  Assuming all the other dimensions are accurate.

That sounds about right.

Rich

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Posted by richhotrain on Friday, August 31, 2018 5:29 AM

7j43k
 
richhotrain
 
7j43k

There's a relatively simple formula for calculating the distance from the roundhouse to the pit.   

Ed, any chance you can publish that formula for all of us to reference. 

Rich 

((b X c) / (a - b)) - d 

a = one half of width of rear wall of one stall

b = one half of width of front wall of one stall

c = distance from rear wall to front wall (NOT length of roundhouse wall)

d = radius of pit 

Ed 

Based upon that formula, and my calculations, the distance between my roundhouse and turntable should be 2.625 inches. That is a little less than the 2.875 inches that I have determined without the formula, so I will place the roundhouse at this mathematical distance as a trial.

Rich

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Posted by SouthPenn on Friday, August 31, 2018 10:04 AM

I used two pieces of flex track. I made them as straight as possible and put them into the outer engine stalls. I centered them inside the stalls and where they intersected became the center of the pit. Everything worked out fine.

In this picture, some of the tracks don't line up correctly. The track was not attached to the base and I knocked them out of whack trying to get the engines on the tracks. Anyone with arthritis in their hands will understand. 

   P2050009.jpg

 

South Penn
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Posted by doctorwayne on Friday, August 31, 2018 10:58 AM

RR_Mel
...I built my Korber kit 18 years ago back when it cost $40....

I'm not sure, Mel, but I think that mine sat in its box even longer than that.

Wayne

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Posted by RR_Mel on Friday, August 31, 2018 11:00 AM

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   
 
Bakersfield, California
 
I'm beginning to realize that aging is not for wimps.
 
 
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Posted by 7j43k on Friday, August 31, 2018 11:16 AM

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

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Posted by Ed A on Friday, January 4, 2019 8:27 PM

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 

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Posted by MacTrom on Monday, March 4, 2019 8:58 AM

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. 

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Posted by richhotrain on Monday, July 19, 2021 5:53 AM

7j43k
 
richhotrain 

Ed, any chance you can publish that formula for all of us to reference. 

Rich 

((b X c) / (a - b)) - d 

a = one half of width of rear wall of one stall

b = one half of width of front wall of one stall

c = distance from rear wall to front wall (NOT length of roundhouse wall)

d = radius of pit 

Ed 

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Posted by Lastspikemike on Monday, July 19, 2021 8:15 AM

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. 

Alyth Yard

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Posted by SeeYou190 on Monday, July 19, 2021 8:21 AM

MacTrom
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. 

That sounds like an interesting kit conversion project.

I hope you can share pictures. Please keep us updated.

-Kevin

Wink Happily modeling my STRATTON & GILLETTE RAILROAD. A Class A line located in a personal fantasy world of semi-plausible nonsense on Tuesday, August 3rd, 1954.

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Posted by richhotrain on Monday, July 19, 2021 11:55 AM

Lastspikemike

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. 

 

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

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Posted by Lastspikemike on Tuesday, July 20, 2021 9:45 AM

richhotrain

 

 
Lastspikemike

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. 

 

 

 

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 unnecessary. The footprint of the turntable and roundhouse is determined by the roundhouse. The dimension you need is the distance from the back wall of the roundhouse to the center of the turntable. You never need to know the component dimensions used in that formula just to install the roundhouse and turntable.

I would say the formula is handy if you're drawing a layout plan. Otherwise it is not helpful.  

Alyth Yard

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Posted by SeeYou190 on Tuesday, July 20, 2021 10:15 AM

I still think that building a 1:1 Mock Up is time well spent just to be 100% sure.

-Kevin

Wink Happily modeling my STRATTON & GILLETTE RAILROAD. A Class A line located in a personal fantasy world of semi-plausible nonsense on Tuesday, August 3rd, 1954.

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Posted by richhotrain on Tuesday, July 20, 2021 11:04 AM

Lastspikemike
  

The formula is unnecessary. The footprint of the turntable and roundhouse is determined by the roundhouse. The dimension you need is the distance from the back wall of the roundhouse to the center of the turntable. You never need to know the component dimensions used in that formula just to install the roundhouse and turntable.

I would say the formula is handy if you're drawing a layout plan. Otherwise it is not helpful.   

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...

JDawg

I am trying to plan for a roundhouse/turntable on my condo layout. I am looking at the walthers 90ft and the matching roundhouse. How much space is there between the Turntable and the roundhouse. How much space should I plan for? 

...He now knows how much space there is between the turntable and the roundhouse, thanks to the formula.

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Posted by Lastspikemike on Tuesday, July 20, 2021 11:34 AM

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.  

Alyth Yard

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Posted by Lastspikemike on Tuesday, July 20, 2021 11:35 AM

SeeYou190

I still think that building a 1:1 Mock Up is time well spent just to be 100% sure.

-Kevin

 

Sure about what?

The roundhouse fits or it doesn't.

One pair of lines is all you need, no mockup required. 

Alyth Yard

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Posted by SeeYou190 on Tuesday, July 20, 2021 11:39 AM

richhotrain
Of course the formula is not necessary, but it is useful, and it certainly is helpful.

Agree 100%

-Kevin

Wink Happily modeling my STRATTON & GILLETTE RAILROAD. A Class A line located in a personal fantasy world of semi-plausible nonsense on Tuesday, August 3rd, 1954.

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Posted by richhotrain on Wednesday, July 21, 2021 6:38 AM

Lastspikemike

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.   

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.

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Posted by Lastspikemike on Wednesday, July 21, 2021 8:33 AM

richhotrain

 

 
Lastspikemike

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.   

 

 

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. 

Alyth Yard

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Posted by SeeYou190 on Wednesday, July 21, 2021 9:00 AM

cuyama
Extend the centerline of the roundhouse tracks. Where they cross is the center of the turntable. I'm pretty sure that anything else won't line up.

Byron gave the best and correct answer near the top of the first page.

-Kevin

Wink Happily modeling my STRATTON & GILLETTE RAILROAD. A Class A line located in a personal fantasy world of semi-plausible nonsense on Tuesday, August 3rd, 1954.

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Posted by richhotrain on Wednesday, July 21, 2021 9:16 AM

SeeYou190
 
cuyama
Extend the centerline of the roundhouse tracks. Where they cross is the center of the turntable. I'm pretty sure that anything else won't line up. 

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

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Posted by tstage on Wednesday, July 21, 2021 5:31 PM

Per the OPs request...

https://tstage9.wixsite.com/nyc-modeling

Time...It marches on...without ever turning around to see if anyone is even keeping in step.

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