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?
I don’t know if this matters, but it will only be 3 stalls.
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).
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.
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.
Yes it does.
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
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? [;)]
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
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.
I have 30cm from RH wall to the centre of the 90’ pit.
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.
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.[:P][:$]
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.
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
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.[(-D]
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.[:O]
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.
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.[C):-)]
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
My Model Railroad
http://melvineperry.blogspot.com/
Bakersfield, California
I’m beginning to realize that aging is not for wimps.