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Distance of Roundhouse From Turntable Locked

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Distance of Roundhouse From Turntable
Posted by richhotrain on Wednesday, August 29, 2018 2:47 PM

I have the Walthers Non-DCC 130' Turntable (933-2829) and the Walthers Cornerstone 3-Stall Modern Roundhouse to which I have added 6-stalls, so it is now a 9-stall Modern Roundhouse.

I am in the process of fitting these structures on a new layout that I am building.

Does it matter exactly how far from the turntable pit I install the roundhouse? It seems to me that it doesn't really matter, and the instructions are silent.

Your thoughts and comments?

Rich

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Posted by peahrens on Wednesday, August 29, 2018 3:44 PM

Rich,

I presume that each stall has a flat door section (wall) that faces the turntable.  Seems to me that a curve, the intersections (corners) where each front wall meets its neighbor, would define a radius from the turntable center.  If the roundhouse were too close or too far from the correct spot, the leads from each stall, if centered in each, would not line up with the turntable track.  Or if lined up with the turntable track, the lead (centered at the door) would not be centered farther into the stall if lined up with the turntable.  

Can you measure that curve?  If you have "x" stalls that make 90-degrees, that would be an easy way to measure the curve from lines extending from those stalls.  The intersection would be the turntable center.

Paul

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Posted by cuyama on Wednesday, August 29, 2018 3:48 PM

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.

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Posted by gmpullman on Wednesday, August 29, 2018 4:10 PM

richhotrain
Does it matter exactly how far from the turntable pit I install the roundhouse? It seems to me that it doesn't really matter, and the instructions are silent.

Yes, it matters significantly.

In its final setting, there isn't much "free-air space" between the pit wall and the roundhouse front wall:

 RH_fini by Edmund, on Flickr

I used a laser to shoot the track center lines from stall #1 and stall #9 to meet the turntable center pivot and set the roundhouse accordingly.

 Laser_RRtt by Edmund, on Flickr

There really isn't any wiggle room.

 RH_laser2 by Edmund, on Flickr

There is a tiny tick mark at the center shaft of the turntable (mine is a Diamond Scale 130 footer). Once I had these center lines I routed out the dados for the pits.

 RH_pits2 by Edmund, on Flickr

Good Luck, Ed

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Posted by 7j43k on Wednesday, August 29, 2018 5:36 PM

richhotrain

Does it matter exactly how far from the turntable pit I install the roundhouse?\ 

There is only one possible distance from the turntable pit to the roundhouse for any particular roundhouse and turntable.

You have no choice.

 

 

Ed

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Posted by richhotrain on Wednesday, August 29, 2018 5:55 PM

Yikes, it matters?  Nuts, I set up the turntable/roundhouse 14 years ago, and I have no recollection how I succeeded then. Didn't measure the curve, didn't extend the center of the roundhouse tracks to where they cross the center of the turntable, didn't shoot a laser to the turntable center pivot.

7j43k says that there is only one possible distance. Our other Ed says it matters significantly and includes a photo. Let me ask this.  How far are the fronts of the roundhouse stalls from the edge of the pit in that photo?  There must be a simple way to place the roundhouse, no?

Rich

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Posted by BigDaddy on Wednesday, August 29, 2018 6:37 PM

The turntable stalls are at a certain degee 9 or 11 or something in between.  What I see on the Internet is 10 degrees for the Walther modern RH. 

From the backwall to the center of the turntable pit is the same distance, no matter what size the turntable.  Get yourself a protractor and draw some lines at 10 degrees.  

I have a small Details Associates RH that I am going to use with a 90' CMR turntable.  I'm going to have to curve the two outside rails inward, because I think it was made for a 65' turntable.  It might look a little weird but I can deal with that.  A bigger RH that is too close or too far will have clearance issues with the doors and curves.

Henry

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Posted by richhotrain on Wednesday, August 29, 2018 7:17 PM

BigDaddy

The turntable stalls are at a certain degee 9 or 11 or something in between.  What I see on the Internet is 10 degrees for the Walther modern RH. 

From the backwall to the center of the turntable pit is the same distance, no matter what size the turntable.  Get yourself a protractor and draw some lines at 10 degrees.  

OK, I understand what you are saying, Henry. 

Yes, the Walthers Cornerstone Modern Roundhouse stalls are set at 10 degrees. So, my 9-stall roundhouse is a 90 degree structure.  

Let me mess around with drawing some lines at 10 degree angles.

I appreciate the help and advice. I really need it.

Rich

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Posted by BigDaddy on Wednesday, August 29, 2018 7:36 PM

If you've already mounted your turntable, work with some kraft paper.  Once you figure out where the back wall has to be, and you know the depth of the RH, you will know where the front wall has to be.

Henry

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Posted by 7j43k on Wednesday, August 29, 2018 8:36 PM

There's a relatively simple formulat for calculating the distance from the roundhouse to the pit.  I started to develop it, but none of you guys are going to actually do it, so I'm not, either.

My point, however, is the same:  there's only one distance for a given roundhouse and pit diameter.

If the roundhouse is already built, and the turntable's in, you can move the building around until you can sight down the roof discontinuities between stalls and move it until you sight down the pit center.

 

 

Ed

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Posted by gmpullman on Wednesday, August 29, 2018 8:55 PM

I get a little under 2.75 inches from my pit wall to the edge of the floor:

 Pit_to_doorRH by Edmund, on Flickr

The rail ends and feeders haven't been tucked & trimmed yet.

The former roundhouse at this site was a Heljan model and the front wall sat back a bit further, still 10° track spacing, though.

 

 Roundhouse4 by Edmund, on Flickr

 Roundhouse3 by Edmund, on Flickr

Notice that there's about four-feet of brick between each door hings where the Walther's Modern roundhouse there's barely a foot.

The C&NW's Erie Street turntable was so small and the track spacing so tight that frogs were used at each track.

http://industrialscenery.blogspot.com/2015/07/cnws-passenger-yard.html

Scroll down or click a photo to see them all.

 Part of a Wallace Abbey photo:

 CNW_RHcrop by Edmund, on Flickr

Regards, Ed

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Posted by richhotrain on Wednesday, August 29, 2018 9:34 PM

7j43k

There's a relatively simple formulat for calculating the distance from the roundhouse to the pit.  I started to develop it, but none of you guys are going to actually do it, so I'm not, either.

My point, however, is the same:  there's only one distance for a given roundhouse and pit diameter.

If the roundhouse is already built, and the turntable's in, you can move the building around until you can sight down the roof discontinuities between stalls and move it until you sight down the pit center. 

Ed

Ed, thank you very much. It has finally sunk in. If you measure the distance from the edge of the pit to the front (or the rear) of the roundhouse for the two outermost stalls so that they are the same distance, then all 9 stalls will be the same distance.  And that can only occur at one point. Any shorter or longer distance for the two outermost stalls will result in the inner stalls being a different distance away from the edge of the pit.

Rich

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Posted by richhotrain on Wednesday, August 29, 2018 9:39 PM

gmpullman

I get a little under 2.75 inches from my pit wall to the edge of the floor:


Ed, thanks for the measurement and the photo. This is extremely interesting because I came up from my layout to read your reply after concluding that the distance needs to be approximately 2.75 inches. So, I take great comfort in your measurement. Actually, you noted that it is a bit shorter than 2.75 inches, and I was concluding that it needs to be just over 2.75 inches, around 2.875. So, the exact measure is somewhere in that vicinity.

Rich

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Posted by richhotrain on Wednesday, August 29, 2018 9:40 PM

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

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Posted by gmpullman on Wednesday, August 29, 2018 10:02 PM

richhotrain
Actually, you noted that it is a bit shorter than 2.75 inches, and I was concluding that it needs to be just over 2.75 inches, around 2.875. So, the exact measure is somewhere in that vicinity.

I wouldn't worry about carrying out the decimal places to hundred thousandths based on my measurement, Rich.

As I mentioned earlier, my TT pit is a Diamond Scale 130 footer and it may not match Walther's plastic pit. Mine is plaster.

Still, you're on the right track.

Cheers! Ed

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Posted by RR_Mel on Wednesday, August 29, 2018 10:05 PM

I made CAD drawing of my roundhouse and turntable.  I inserted a 90’ circle so you can see what happens with the tracks.  My Korber roundhouse has 7½° stall spacing.  I extended the roundhouse to 130’ to accommodate my Rivarossi Cab Forwards.  My turntable is a 135’ CMR.
 
 
 
 
 
 
Mel
 
 
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Posted by richhotrain on Wednesday, August 29, 2018 10:31 PM

gmpullman
 
richhotrain
Actually, you noted that it is a bit shorter than 2.75 inches, and I was concluding that it needs to be just over 2.75 inches, around 2.875. So, the exact measure is somewhere in that vicinity. 

I wouldn't worry about carrying out the decimal places to hundred thousandths based on my measurement, Rich.

As I mentioned earlier, my TT pit is a Diamond Scale 130 footer and it may not match Walther's plastic pit. Mine is plaster.

Still, you're on the right track.

Cheers! Ed 

Ed, I plan to take that measurement out 7 decimal places.  Laugh

Rich

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Posted by richhotrain on Wednesday, August 29, 2018 10:34 PM

Mel, that is interesting that you were able to extend the tracks between the turntable and the roundhouse to nearly 10 inches. I assume that is because the stalls are 7.5 degrees, and there are only 5 stalls.

Rich

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Posted by gmpullman on Thursday, August 30, 2018 12:03 AM

richhotrain

Mel, that is interesting that you were able to extend the tracks between the turntable and the roundhouse to nearly 10 inches. I assume that is because the stalls are 7.5 degrees, and there are only 5 stalls.

Rich

 

It really has more to do with how far apart the doors are, center-to-center that determines how far away the front wall is from the pit.

15° spacing means you can fit 24 stalls in a full circle.

10° spacing means you can fit 36 stalls in a full circle.

7½° spacing means you can fit 48 stalls into a full circle.

None of the above has anything to do with how much track is exposed between the pit and the front wall of the roundhouse.

As the front wall of the roundhouse moves toward the pit the door centers HAVE to get narrower, away = wider.

Still, there's no choice unless you want to custom build or modify your roundhouse. Again, strike a line through the center of each radial track. They will intersect. At the point of intersection must be the center of the turntable pivot.

Regards, Ed

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Posted by richhotrain on Thursday, August 30, 2018 4:34 AM

gmpullman
 Again, strike a line through the center of each radial track. They will intersect. At the point of intersection must be the center of the turntable pivot.

What I should have done before cutting out the circle of plywood for the turntable was to mark the centerpoint of the turntable on the plywood. From there, I could draw lines on the plywood, radiating from the centerpoint at 10 degree angles. Then, I could locate and mark the exact location of the roundhouse.

I want to thank everyone who has contributed to this thread. It has been a great learning process for me.

Rich

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Posted by RR_Mel on Thursday, August 30, 2018 7:34 AM

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.
 
 
 
Mel
 
 
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Posted by wjstix on Thursday, August 30, 2018 8:40 AM

Keep in mind that a turntable and roundhouse kit from the same manufacturer may be set up so the edge of the turntable pit and the apron of the roundhouse come together without needing to do any calculations to line up the roundhouse tracks and the turntable. Not sure about Walthers, but I know that's how the Atlas RH/TT set up works.

Stix
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Posted by IRONROOSTER on Thursday, August 30, 2018 9:51 AM

If you're willing to curve the tracks, then the distance can vary.  There have been railroads (such as the V&T) that used square "roundhouses" and curved the tracks coming off the turntable. 

Paul

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Posted by snjroy on Thursday, August 30, 2018 10:48 AM

This has been a very interesting thread. A similar thread:

http://cs.trains.com/mrr/f/88/t/114871.aspx

Here is one quote from the above thread :

"I sent the 2 7/8 measurment to Walthers and I just got an email saying that is correct."

Simon

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Posted by 7j43k on Thursday, August 30, 2018 11:07 AM

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.

Anyway:

 

((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 RR_Mel on Thursday, August 30, 2018 11:41 AM

This is what I came up with digging around using Walthers Roundhouse.
 
 
Click to enlarge
 
The drawing should be pretty close.  The Walthers info is pretty vague .
 
Mel
 
 
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I'm beginning to realize that aging is not for wimps.
 
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Posted by 7j43k on Thursday, August 30, 2018 2:15 PM

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.

 

Ed

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Posted by RR_Mel on Thursday, August 30, 2018 2:32 PM

You could be correct Ed.  I could post my drawing on my Google drive so it can be downloaded.  All the measurements are from the program not me and a calculator.  I didn’t do any rounding and used what  Walthers Footprint dimensions I could find with Google Search.  The stall door opening dimension came from the program using the 17.75” depth which I missed at 17.7892” and didn’t correct it.   
 
 
 
Mel
 
 
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Posted by doctorwayne on Thursday, August 30, 2018 3:23 PM

I've got a Korber roundhouse, with five stalls, and the Walthers 90' turntable.  The front wall of the roundhouse is 9" from the inner edge of the turntable pit for the two outermost stalls, and about 9.125" for the three inner stalls. 
The roundhouse isn't yet permanently installed, but the positions of the house tracks at the turntable can be easily adjusted. 
I've motorised the turntable using the motor and gearbox from a scanner, and am running it with a surplus SCR throttle, powered by a 9VAC wall-wart. 
Indexing is "by-eye", so any variations in the positioning of the house tracks at the pit shouldn't be an issue...

Wayne

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Posted by RR_Mel on Thursday, August 30, 2018 4:13 PM

Wayne, the Korber roundhouse is a very nice kit and was very easy to extend to accommodate my long articulateds.  I bought a second 104 kit and chopped up the walls to extend the depth from 15” to 19”.  The added end wall sections had to have slightly smaller windows from the slopping roof.
 
 
I’m still working on the automated doors I have one installed and working using a SG90 servo.  This is the second door.
 
 
 
It’s a slow task installing the doors, I can’t crawl because of bad knees so it has to be done laying on my back for hours at a time.
 
 
Mel
 
 
My Model Railroad   
 
Bakersfield, California
 
I'm beginning to realize that aging is not for wimps.
 

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