Let’s say a certain fella, who will remain nameless, had the hole already cut and a 90 foot turntable sitting in it. There is just enough room for the Roundhouse that is under construction. Now this guy, who is always changing his mind, thinks he may just like a 130 foot turntable instead and that, of course, is gonna require a bigger hole. Now he can’t move the position of the Roundhouse, so enlarging the hole is going to take some of his track length between the RH and the ‘new’ pit edge…
Will doing this make any difference at all, or am I… huh… he… just going to lose some track?
Yeah, I think Jim’s right. The larger TT should just take of more space right in front of the House, but the house needn’t move to get the radials right. So, the matter is how to enlarge the hole for the pit in such a way that you don’t end up with a weird, oblong hole that no longer supports the pit lip as it should. Draw it out to fit the template that Walthers should include in the built-up box, and then use a jig saw. It worked for me. If you want to be sure, draw a sized paper TT pit, with lip, cut it out, and then place if centred over the one that you have. You may find that it works quite nicely, and that the bay radial tracks meet the bridge, quite well.
Well, do the two turntables index to the same increment? The shorter ones, like the Atlas, increment to 15 degrees, because that’s as close as you can space the tracks on a 9-inch circle. But if you go to a larger turntable, you can fit more tracks in by incrementing at 12 or even 10 degrees. If your two turntables index the same, then you’ll be OK. If not, the turntable won’t line up with the roundhouse tracks at all the positions.
JaRRell, I forgot to mention that, even with the extended rails on my bridge, the house bay rails extended beyond the lips of the bays another two inches, maybe more…I can’t quite recall. What I had to do in order to get the bay rails to line up with the bridge rails was to curve the two outer ones in an outwards curve. It ends up being about a 30’ radius curve at worst, but that gets the locomotive off the bridge and into the bays with no issues whatever. It may look odd, but that may be the only way you can match roundhouses and TT’s from different manufacturers.
So, my roundhouse bay doors would have been a good 6-7" back from the lip of the pit. With the rails curved outwards somewhat, and when the bridge aligns with those near ends, it all works very well. I cut a styrene wedge, a thin one, and jammed it between the bay channel walls on the inner wall, between the tie ends and the channel wall. I glued it in place once I had gotten it to the right length and shape so that it held the tracks in a curve. Once it is all painted up, you won’t notice it, and you’ll ge the function you want.
There is another issue which needs addressed here.
If you have a roundhouse that is 90 feet in depth then you are likely to have a 90 foot turntable - this is if you are expecting to be able to completely enclose each bay behind closed doors. Not a stupid statement, really. Expand your turntable by ten feet but keep the roundhouse length the same and you are going to have to let your locomotive tender hang out ten feet into the weather. Sooner or later the geometry of this equation is going to max out; your friend may find himself with a roundhouse too short to accomodate the locomotive length which he wants to turn on that 130 foot turntable. One hundred and thirty foot long turntables are indeed impressive but no railroad is going to build one just so they can say they’ve got one of that length. This is why you find roundhouses with, say, both 90 foot bays and 120 foot bays; as railoads bought longer and longer locomotives and had to build longer and longer turntables to accomodate them they found it necessary to build extensions onto (some of) their bays to accomodate their longer locomotives. If I understand it correctly - and some of you L&N fans chime in if I am incorrect in this regard - the thing which kept the Big Emmas in Kentucky was a combination of weight restrictions and turntable restrictions in other parts of the system.
Just 1 question. You do plan on useing the same hole center point for your 130’ that you were going to use for your 90’ right? Your drawing doesn’t reflect this but you do say it’s not to scale. Keep the same center point or you’ll have problems.
Perhaps if the feller wanted to turn longer locomotives, even two F units or two geeps, or even bring in a flat car into his shop, he woundent be hindered by a short one unit on teh shorter table. The 130 table is a perfect match for the larger Walters modern roundhouse. I think its a very easy fix and I woulndt worry about finding the center of the existing hole, other then making a perfect circle timplate out of heavy cardstock, draw center lines into the house and leads on it, thumbtack in place, scribe the outside dia and cut. I also wouldn worry about shorter tracks, account of passing clearence to ajacent tracks. Just a few thoughts, if ya can afford it go for it and enjoy. …John
I guess I’m one of those exceptions where I have a large RH, even with an extended stall… and a 90 foot turntable. I have a 2-6-6-4 that can’t be turned on the table so I’m thinking about the bigger model.
All you need to remember is that when the roundhouse is properly positioned, all the stalls tracks converge at the same point which is the center point of your TT. The critical measurement is the distance the roundhouse should be from that center point. All roundhouses I have built provide that information in the instructions. Enlarging the TT won’t change that measurement. Real railroads faced the same problem when they enlarged TTs to accomodate the larger late steam locomotives. They didn’t need to move the roundhouse, just enlarge the pit and lengthen the bridge. Usually that meant also lengthening the stalls which they did by extending the rear walls.
We had a 98’ that we replaced with the 130’. Since there is no compass point with the hole already there, we made a template out of cardboard and centered in on the hole. Traced it and used a jigsaw. We had to notch our support beams a little, but everything worked out ok. If your RH track is in place, that should help you with centering the template.
Goodluck, It was a mess. If you can get someone to hold the vaccuum while you are cutting it will help a little.
