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Distance from Turntable to Roundhouse, Walthers

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Distance from Turntable to Roundhouse, Walthers
Posted by JDawg on Saturday, July 17, 2021 11:38 AM

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. My calculations show about a foot between, but that seems extreme. How much space should I plan for?

JJF


Prototypically modeling the Great Northern in Minnesota with just a hint of freelancing. Smile, Wink & Grin

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Posted by JDawg on Saturday, July 17, 2021 11:40 AM

I don't know if this matters, but it will only be 3 stalls. 

JJF


Prototypically modeling the Great Northern in Minnesota with just a hint of freelancing. Smile, Wink & Grin

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Posted by BATMAN on Saturday, July 17, 2021 11:58 AM

It is 15cm.

I printed off this template from the Walthers website and made up a paper RH/TT template and glued it to a piece of cardboard so I could move it around to find the best fit.

 

 

Brent

It's not the age honey, it's the mileage.

https://www.youtube.com/user/BATTRAIN1/videos 


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Posted by JDawg on Saturday, July 17, 2021 2:19 PM

BATMAN

It is 15cm.

I printed off this template from the Walthers website and made up a paper RH/TT template and glued it to a piece of cardboard so I could move it around to find the best fit.

 

 

 

 

Thanks. I'll plan for 6 inch's (15cm). 

JJF


Prototypically modeling the Great Northern in Minnesota with just a hint of freelancing. Smile, Wink & Grin

Yesterday is History.

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Posted by The Milwaukee Road Warrior on Saturday, July 17, 2021 5:36 PM

I have the same turntable (90') and the same roundhouse, although I bought 2 RH to give me 6 stalls.  Using a metal straightedge after I put the roundhouse halves together, I found that the lines centered thru all 6 bays converged at a point in the center of the turntable that left me with 6" between the edge of the turntable and the front edge of the roundhouse.

Andy

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Posted by Lastspikemike on Saturday, July 17, 2021 5:59 PM

The resulting distance has nothing to do with the size of the turntable. 

The length of the tracks connecting the edge of the turntable to the roundhouse doors depends on the angle of the roundhouse stalls. 

The most reliable way to get this number is to measure from the center of the turntable. For any given roundhouse angle the required length of track will be the distance from the roundhouse door to the center point of the turntable minus the radius of the turntable. In fact, the position of the center of the turntable is determined by the positions of the back walls of two sections of the roundhouse. 

You should place two or three sections of your roundhouse floor or a template of the floor sections onto your layout to get the angle, mark the center of the turntable and draw lines down two or three of the roundhouse track center lines all meeting at the center of the turntable.

The angle of the roundhouse sections sets the distance required. Then you place the turntable into the layout, place the roundhouse and cut lengths of track to fit just as you would for any track fitting problem. 

The smaller the turntable the longer the tracks will be. The difference in track lengths required for different sized turntables will be exactly the difference in radius of the various turntables. The roundhouse determines everything because it has only one correct position relative to the center of the turntable. The roundhouse stays put regardless of the turntable size.   

Alyth Yard

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Posted by SeeYou190 on Saturday, July 17, 2021 6:25 PM

Lastspikemike
The resulting distance has nothing to do with the size of the turntable. 

Yes it does.

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.

It was either Ed or Byron that had an excellent graphic showing the distance from the different turntables to the doors on the Walthers Modern Roundhouse, which I believe is 15 degrees between stalls.

I thought I had captured the image, but I guess I didn't.

Hopefully one of them can chime in with the right answer.

-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 selector on Saturday, July 17, 2021 6:40 PM

Lastspikemike

The resulting distance has nothing to do with the size of the turntable. 

...

Think this through.  Suppose you have everything as you envision it should be, but instead of a turntable you have a walnut where the bay rails converge.  Would the walnut's comparatively smaller size than our 90'er make the bay extensions to the edge of the walnut shell longer or about the same? Wink

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Posted by gmpullman on Saturday, July 17, 2021 6:59 PM

SeeYou190
It was either Ed or Byron that had an excellent graphic showing the distance from the different turntables to the doors on the Walthers Modern Roundhouse

Yes, I do:

 Pit_to_doorRH by Edmund, on Flickr

130 foot turntable.

However, I believe, as often happens, the replies are getting muddied by misunderstandings.

I believe Alyth Yard is refering to the TT center point, not so much the distance from the pit wall to the front roundhouse wall.

 Laser_RRtt by Edmund, on Flickr

 My former roundhouse at this location was the old Heljan kit. The front WALL of the roundhouse is set back from the pit wall a bit farther. This only results in a greater distance between the door openings.

 Roundhouse4 by Edmund, on Flickr

Both the Heljan and the Walthers Modern used 10° stall centers*.       

  *(± .0005°)


 History:

 

http://cs.trains.com/mrr/f/11/t/271752.aspx

 

 

Good Luck, Ed

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Posted by JDawg on Saturday, July 17, 2021 7:13 PM

So, with the 90 foot table what should I figure for? the walthers site lists 11 and 15/16, which seems like a lot. 6in seems reasonable, but now I'm not sure. 

JJF


Prototypically modeling the Great Northern in Minnesota with just a hint of freelancing. Smile, Wink & Grin

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Posted by BATMAN on Saturday, July 17, 2021 7:16 PM

I have 30cm from RH wall to the centre of the 90' pit.

 

Brent

It's not the age honey, it's the mileage.

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Posted by BATMAN on Saturday, July 17, 2021 7:24 PM

I lined up the RH floor and TT and then built the rest of the RH. I made it movable so I could work at the desk and it would be easy to pack up as a unit if I move. 

 

I would move it back and forth.

When I was finally finished, I left it in place and taped up the cracks and put down the ground cover.

 

Brent

It's not the age honey, it's the mileage.

https://www.youtube.com/user/BATTRAIN1/videos 


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Posted by Pruitt on Saturday, July 17, 2021 9:18 PM

The 11 15/16 dimension is from the center of the turntable to the doors, not from the edge of the turntable.

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Posted by JDawg on Saturday, July 17, 2021 9:58 PM

Pruitt

The 11 15/16 dimension is from the center of the turntable to the doors, not from the edge of the turntable.

 

That makes much more sense! Thanks You! Now I feel sort of silly for not thinking of that.Stick out tongueEmbarrassed

JJF


Prototypically modeling the Great Northern in Minnesota with just a hint of freelancing. Smile, Wink & Grin

Yesterday is History.

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But today is a Gift, that is why it is called the Present. 

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Posted by Lastspikemike on Sunday, July 18, 2021 2:27 PM

selector

 

 
Lastspikemike

The resulting distance has nothing to do with the size of the turntable. 

...

 

 

Think this through.  Suppose you have everything as you envision it should be, but instead of a turntable you have a walnut where the bay rails converge.  Would the walnut's comparatively smaller size than our 90'er make the bay extensions to the edge of the walnut shell longer or about the same? Wink

 

My point was that the measurement you need is from the center of the turntable to the roundhouse entry. Then you deduct the radius of the particular turntable you have. The question as posed didn't seem to realize that the roundhouse stall angles determine everything.

That does assume the fronts of the roundhouse stalls are the same width regardless of stall angle but there will be small variations there from style to style. 

Center of the turntable to the roundhouse doorways minus the radius of the turntable is the way to calculate the length of the connecting tracks. 

Alyth Yard

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Posted by SeeYou190 on Sunday, July 18, 2021 2:36 PM

JDawg

 

Pruitt

The 11 15/16 dimension is from the center of the turntable to the doors, not from the edge of the turntable.

 

 

 

That makes much more sense! Thanks You! Now I feel sort of silly for not thinking of that.

 

The 90 foot turntable bridge will be about 13" long, or 6 1/2" to center.

That should give you about 5 1/2" of track between the turntable and the roundhouse (if my math is OK).

-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 BATMAN on Sunday, July 18, 2021 3:04 PM

I only got a B+ in Math 12 and high school is as far as I got. If I can get things lined up properly anyone can.Laugh

The biggest surprise from this electronically challenged person was when I wired it up and plugged it in for the first time, it worked perfectly.Surprise

No photo description available.

Brent

It's not the age honey, it's the mileage.

https://www.youtube.com/user/BATTRAIN1/videos 


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Posted by Overmod on Sunday, July 18, 2021 3:44 PM

JDawg
How much space should I plan for?

Just to remind you, a consideration is to allow enough track that a locomotive on one lead does not foul one coming onto an adjacent one; another is that the centerline of the leads lines up with the centerline of the stalls, and structure between stalls at the entrance holds the roof, doors, etc. so there is a fixed width that must fit into the 'subtended arc' -- therefore a corresponding distance of radius.

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Posted by BATMAN on Sunday, July 18, 2021 4:51 PM

Overmod
another is that the centerline of the leads lines up with the centerline of the stalls

If your leads line up with a stall you can straight shot a loco that is too big for the TT straight across the TT into a stall like I do here with engine 2004.Cowboy

Brent

It's not the age honey, it's the mileage.

https://www.youtube.com/user/BATTRAIN1/videos 


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Posted by RR_Mel on Sunday, July 18, 2021 7:49 PM

For what its worth I have a HO scale Korber Roundhouse and a CMR 135’ Turntable.  I modified/kitbashed the roundhouse so it would hold my long Southern Pacific Articulateds.







The roundhouse was 7½° stall spacing from Korber, I moved the rear sections back 4½” making the tracks about 7⅜°.


Mel



 
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Posted by richhotrain on Monday, July 19, 2021 5:57 AM

We had a discussion of this issue a couple of years ago regarding the placement of my Walthers Cornerstone Modern Roundhouse relative to the Walthers Cornerstone 130' turntable. Ed (7j43k) posted a formula in that thread which proved to be totally accurate. Here is that formula:

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  

Based upon that formula, the exact distance of the roundhouse from the edge of the pit on the 90' turntable would be 4.8125" (4 13/16 inches).

Rich

Edit Notes: The stall width is exactly 2" front, and 5" rear. The stall length is 17 5/8". The diameter of the pit is 13 3/16". 

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Posted by gmpullman on Monday, July 19, 2021 6:25 AM

richhotrain
We had a discussion of this issue a couple of years ago regarding the placement of my Walthers Cornerstone Modern Roundhouse relative to the Walthers Cornerstone 130' turntable.

I put a link to that discussion in my above reply. It is up to the reader to click the link and access the valuable information.

 

Regards, Ed

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Posted by richhotrain on Monday, July 19, 2021 6:38 AM

gmpullman
 
richhotrain
We had a discussion of this issue a couple of years ago regarding the placement of my Walthers Cornerstone Modern Roundhouse relative to the Walthers Cornerstone 130' turntable. 

I put a link to that discussion in my above reply. It is up to the reader to click the link and access the valuable information. 

Regards, Ed 

Sorry, Ed, I missed that when I browsed through this thread to see if my older thread had been mentioned or linked.

Rich

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Posted by Lastspikemike on Monday, July 19, 2021 7:41 AM

The (a-b) calculation gets you the effect of the stall angles. Or at least approximately. The formula provides a method of calculating the effect of the proportion of two hypotenuses: that of the right triangle within the roundhouse and the right triangle outside the roundhouse. The radius (d? not r?) of the turntable is then deducted from the length of the outside hypotenuse. Given the requirement for accurate track lengths I recommend using the cut to fit method instead. 

All you really need is the two measurements: The distance from each of the two back corners of the side walls of the roundhouse to the point on the layout where those two distances meet. That's the center of the turntable.

The depth of the roundhouse and the stall angles place the distance of the centre of the turntable to the back wall of the longest stall, which is the number you actually need to place the roundhouse. The length of the connecting tracks is then just a cut to fit problem.

As I tried to point out earlier, the real question to ask is where does the back wall of the roundhouse fit into the layout? The other dimensions all result from that point regardless of the size of the turntable. 

Alyth Yard

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Posted by SeeYou190 on Monday, July 19, 2021 8:11 AM

gmpullman
It is up to the reader to click the link and access the valuable information.

It is very valuable information.

I saved it this time!

Big Smile

-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 BATMAN on Monday, July 19, 2021 11:18 AM

Well, this is a lot of discussion for something so simple. The instructions I read were if you were using a **** size turntable install RH tracks so they stick out **** inches from the front edge of the roundhouse floor. That is what I did and the fit was perfect.

Brent

It's not the age honey, it's the mileage.

https://www.youtube.com/user/BATTRAIN1/videos 


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Posted by richhotrain on Monday, July 19, 2021 11:26 AM

BATMAN

Well, this is a lot of discussion for something so simple. The instructions I read were if you were using a **** size turntable install RH tracks so they stick out **** inches from the front edge of the roundhouse floor. That is what I did and the fit was perfect. 

If, indeed, the instructions say that, then no question it would all be so simple. I cannot recall if my instructions specified a distance. 

Rich

Edit Note: I dug up my instruction sheet and the turntable template. There is no mention of the distance.

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Posted by richhotrain on Monday, July 19, 2021 12:15 PM

Lastspikemike

The resulting distance has nothing to do with the size of the turntable. 

The smaller the turntable the longer the tracks will be. 

Aren't those two statements contradictory?

Alton Junction

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Posted by BATMAN on Monday, July 19, 2021 12:17 PM

I am pretty sure it was the RH instructions that gave that but I no longer have them. I could be wrong and it may have been somewhere else I read it other than the instructions, but I don't think so.

Brent

It's not the age honey, it's the mileage.

https://www.youtube.com/user/BATTRAIN1/videos 


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Posted by richhotrain on Monday, July 19, 2021 12:44 PM

BATMAN

I am pretty sure it was the RH instructions that gave that but I no longer have them. I could be wrong and it may have been somewhere else I read it other than the instructions, but I don't think so. 

That would surprise me if the roundhouse instructions specified the distance because the radius of the turntable is part of the forumula, so the rounhouse specs would have to account for different size turntables such as 130', 110', 90', etc.

Rich

Alton Junction

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