So why use the short turntable with the big roundhouse? Why not use the smaller roundhouse, or a larger turntable. I know you said the 130' wouldn't fit, but what about the 110'?
Mike
gtingaNow place the floor of the round house where you want, place the three wood strips over the track slots in the floor, move the fan forward and back until the strips exactly cover the track slots and the nail will mark the center point of the turntable.
I found an inexpensive laser to be handy for this task, too.
Laser_RRtt by Edmund, on Flickr
Laser_RR by Edmund, on Flickr
Good Luck, Ed
The extended centerlines of the roundhouse tracks converge at the nominal center point of the turntable. Unless the turntable has fixed indexing (like Atlas or KATO), most turntables will work with most roundhouses. But depending on the design (stall spacing) of the roundhouse, there may be a long distance between the turntable and the roundhouse (for a relatively smaller turntable) or the turntable might overlap the aprons of the roundhouse (for a relatively larger turntable).
Byron
Layout Design GalleryLayout Design Special Interest Group
The easy way to do this is to cut three pieces of 1/8 inch wood the width of the track. Cut it into three lengths twice the length of the turntable. An inch from one end of each drill a small hole centered on the width. Join the three with a finishing nail such that they will fasn out from the nail center. Now place the floor of the round house where you want, place the three wood strips over the track slots in the floor, move the fan forward and back until the strips exactly cover the track slots and the nail will mark the center point of the turntable. Tada!!
I have the 90' indexed t/t from 2006. It was not a perfect fit for the Cornerstone three-stall roundhouse. I fiddled with placement until all I had to do was to curve the outer two bays' tracks as they exited the doors. Try that. You have to cut some small styrene wedges to wedge against the ties and the concrete apron outside the bay doors. Once you get it all to line up, with the roundhouse about three or four inches back from the edge of the t/t, you can craft a plaster 'concrete' apron extension, and sit the bay tracks onto that.
Meanwhile, you can glue the tracks so that they stay curved but remove the wedges once the tracks are adhered firmly; you wouldn't want the wedges to remain visible.
If this all sounds too much, or confusing, it isn't. I could try to explain a bit more, perhaps with some photos of my installation.
The Walthers 90' turntable can be made to run smoothly. Here is a thread I did on the subject a couple of years ago:
http://cs.trains.com/mrr/f/88/t/261225.aspx
I just did a mock up using Walthers roundhouse #933-3041 with 10 degree spacing and Walthers 90' turntable. The rails end up 5/16" apart at the edge of the turntable pit so there is no need for frogs. The space between the roundhouse doors and the pit wall was 5 1/4". To explain it differently, the distance between the center of the 130' turntable and the pit wall is 65' (130 /2). The distance between the center of the 90' turntable and the pit wall is 45' (90/2). The distance from the center of either turntable to the point where the rails intersect is 32' at 10 degrees.
The above assumes that all the rails will be straight from the pit wall to the roundhouse.
Dave
I'm just a dude with a bad back having a lot of fun with model trains, and finally building a layout!
gmpullman I have the modern roundhouse with a 130 foot Diamond Scale turntable. Here is a photo I took a while back when there was another thread here about track spacing. I believe you will be OK with the 90 foot turntable. I can make more measurements if you'd like. [edit] I just checked with a scale ruler and 45' from the center of the pit comes to 5.25" on the ruler shown in the photo above. It will be tight but should work. You may find some further info here: http://cs.trains.com/mrr/f/11/t/271752.aspx Good Luck, Ed
I have the modern roundhouse with a 130 foot Diamond Scale turntable. Here is a photo I took a while back when there was another thread here about track spacing.
I believe you will be OK with the 90 foot turntable. I can make more measurements if you'd like.
[edit] I just checked with a scale ruler and 45' from the center of the pit comes to 5.25" on the ruler shown in the photo above. It will be tight but should work.
You may find some further info here:
http://cs.trains.com/mrr/f/11/t/271752.aspx
Rich
Alton Junction
I think it will work to use the 90’ turntable, but there may be some complicated track work. It would look fine if you have some space between the turntable and the roundhouse. The only problem will be that the 90’ turntable likely can’t fit the same number of tracks as the 130’ table, so the tracks will be very near to eachother as they get close to the turntable, so you will likely need to hand lay some sort of frogs or at minimum modify the track to make it fit.
It would seem to be that if you can fit a roundhouse designed for the 130’ turntable, you should be able to fit the 130’ turntable if you can fit the roundhouse, so look into that. If you could post you track plan that would be helpful.
Regards, Isaac
I model my railroad and you model yours! I model my way and you model yours!
Pit_to_doorRH by Edmund, on Flickr
There were actually turntables I've seen in 1:1 life where there was a frog at the end toward the turntable. That would be a challenge on a model.
CNW_RHcrop by Edmund, on Flickr
I see a problem with the degree separation of the tracks in the roundhouse. If it is designed for a 130' turntable, then moving it closer is a problem. If you have room to move the roundhouse away from the turntable, there is no problem except it might not look prototypical.
Overlapping tracks could be a problem if you move it closer or the tracks would have to curve slightly to be centered in the end stalls of the roundhouse. You might want to tape several pieces of paper together and draw your turntable and your roundhouse footprint to see if it will fit.
Henry
COB Potomac & Northern
Shenandoah Valley
Thanks wayne, right now im more concerned with the geometry and not having the radial tracks overlapping at the edgs of the pit. i do plan on powering it but im not worried with indexing
Lone Geep
\
I'd guess that the compatability issue would be for the indexing (if your turntable is powered and has indexing included).
I bought a Walthers 90' turntable, non-powered, for my engine terminal on the upper level of my layout, but used a motor and gearbox out of a defunct scanner to run the bridge, using an SCR walkaround throttle to power it. There was no automatic indexing.While the throttle worked well, and the motor/gearbox combo was smooth-running, the bridge lurched and bumped very noticeably when in motion. I looks to me that the wheels in the bogies at the ends of the bridge are out-of-round, and also have a parting line in the middle of the wheels' circumference, contributing to the poor running qualities. I removed the motor and gearbox, and use my finger to manually rotate the bridge when using the turntable, and it's definitely smoother than it was when powered, but it could be a lot better. I'll eventually remove the bridge, and either fix the wheels or replace them, as they're not satisfactory as-is.
I'm not familiar with Walthers indexing system, so can't offer any advice on whether or not it can be modified to work with your roundhouse.Since my other turntable (scratchbuilt) is manually operated and its indexing by-eye, I'll likely make the Walthers one permanently manual, and also with indexing by-eye.
Wayne
Its been about a year since i had to take down my old model railroad and am now preparing to build another one. I made a plan with Xtrakcad with a roundhouse has the center point. i made the plan using the walthers modern roundhouse and the 90 ft turntable since the 130 ft one would be too long, this weekend i stopped by the hobby shop and picked them up. I just got around to reading the instructions and to my horror, the turntable instructions say that it is meant for the other roundhouse and the modern roundhouse ones say to use tge 130 ft turntable. Will is still be able to make it work?