I bought a complete Walther's modern roundhouse on e-Bay some time ago and have the kit.  I have a question of anybody with the Walther's 130' turntable, though the 90' may answer the same question.  If I build the second roundhouse with the adjacent wall and glue the two walls together, will the turntable be able to index to the tracks in both roundhouses?  This may be moot as one roundhouse will have to be cut to fit the back wall and at least one stall will be far too short for any engine.  One, at the most two stalls will be useful - the two closest to the full size roundhouse. 
Gene

Gene

The 90ft table will index anywhere except at two 180 degree points that are clearly marked on the bottom of the tabe rim.

I'd think, and this is only a guess, that you may need to slightly bend the stall approach tracks to the table to make up for the what. 1/4" thickness of the double walls?  I'm having a problem figuring that out in my head.  It may need to be drawn on paper to figure it out. 

I have purchased a seconn Walther roundhouse, not the "modern" one but the older looking one so that when the GER expands, I san have a six stall Vs three stall roundhouse.  I was thinging of just adding "ledgers" to the existing exterior wall to mate the extention roof and walls of the addition to the exististing roundhouse thus, hopefully, avoiding the need for your question.

Either way, given the large number of indexes possible with the table, you won't have indexing problems.

I chopped one up like that too Gene, and ended up not even using it...yet. But, if you are certain you will put 2 kits together, don't start the one till you buy the other, as you are laying it (the floor) out, you will easily see what should NOT be assembled- IIRC, there was instructions for additional stalls??? did you open the box yet?? Have a read... 

Tony - one kit was bought assembled off e-Bay.  The other has the floor and nothing else assembled.  There are enough interior roof supports so that the "wall" next to the assembled wall could be a roof support and not a wall.  Unfortunately the instructions for assembly using the "add-on" kit say "Instructions for assembly using the add-on kit are in that kit."
but putting them side by side and checking the difference in measurement between tracks within each segment and between tracks on the adjacent sides of each segment sounds like a good idea.
Gene

I received a suggestion on the Yahoo steam locomotive group to build both of them separately and have a single open track between them - dead track, storage, whatever.  That would cover any indexing problem. 
Thoughts?  Also suggestion to paint the interior dark below the windows and a light color above it.   Sounds like a good idea, though there will be little chance of seeing interior detail due to the distance from the layout edge.
Gene

U R modeling 1957? I would say the whole interior was charcoal black by then. The track between 2 houses was - I would think- one of 2 reasons, one RH was older than a new one built much later in history, or like that optical illusion twin turntables, the open line was a lead to -something further inback... 'the back shop'? or another turntable, but something active enough it didn't just continue thru a stall. I wouldn't think it is going to be necessary, did you butt the two together yet? I bet there will be nothing to fret about..

The second one is the flooring and the painted interior bracing.  I'm liking the two round houses with a track open to the weather between them. 
Gene

Gene.  Most roundhouses were painted white, usually from about foot feet up from the floor with the lower foor feet painted at darker colour but not always.  Walls were white as were ceilings.  The interior of roundhouse never got overly dirty as few locos were stored in the roundhouse in steam and only went inside for maintenance and then in light steam, probably with little fire in the box.  After all, it was a workplace for the maintenance staff and the last thing they wanted in the roundhouse was a smoke beltching locomotive.

Look at photos, always the best bet when checking on details and ideas for modelling, and you'll see what I mean about clean(ish) white interiors.

Remember, never model other people's model railroads, always copy from the prototype.

Very true,  Roger.  And most had an enormous smoke vent over where the stack would normally be.  I know there was a locomotive with the fire up in the Scranton roundhouse when I was there and nobody was choking on smoke.  I like the fact that Walthers makes the walls in two pieces.  It will be easy enough to paint the interior wall one color (two colors) and the exterior wall a different one - at least for the one I'm constructing. 
And yes, I do have more than one caboose. 
Gene

Gene;
Unless they were being stored for an extended length of time, the firebox had a banked fire to keep things "to heat" for the next run.  One of the night watchman's jobs was to keep an eye on those fires.  This was easier than starting a fire from cold, as it took an extraordinarily long time to do that.  I am not sure of the usual status, but unless there were mitigating circumstances I would tend to believe that the locomotives were fueled and watered before their stall time and kept that way, banked fire.

Rich, I have an idea as to how long it took to bring a locomotive up to full pressure.   I've painted the interiors (or am painting) a light gray down to the bottom of the windows and then natural brick below that.  A compromise as I don't think the interior is going to be very visible any way.  And I'm almost probably going to leave the two sections with a track running between them - going to the second turntable. 
Gene

Gene;
I have to hand it to you-you are a lot more ambitious than I.  I have just started working on my coaling tower for the main terminal-roughly resembling that facility at New Haven, so I am just starting laying out the whole terminal-which will be surrounded on two sides by "water".  I think that may look pretty neat.

Rich, the track between the round houses will go ... nowhere.  But it may be I will have six useable stalls - even if one is only good for 0-6-0. 
Gene

I know nothing about turntables or roundhouses, but speaking in a geometric sense, the centerline of all exit tracks must be precisely in line with the pivot point of the table.  Relate this to radius lines of a circle, "X" degrees apart, all lines emanating from the center pivot.

You might have to remove the adjoining walls and modify the floor and roof to maintain the radius symmetry.  

If I was to scratch build the roundhouse as a 6 stall unit, I would get the track and floor right, then build/modify the rest of the structure to fit. 

Hope this helps  

Bob

You mentioned the center track not going anywhere, wouldn't that make a good RIP track (Repair in place), for cars that need minor repairs?

Bob