How does one match a turntable of one brand with the roundhouse of another brand? Is there a formala to crunch the number/dimenions given for each?
The relevant measure is the angular separation between the stalls of the roundhouse, generally. The Atlas roundhouse, for example, has an angular separation of 15 degrees, which matches perfectly with the Atlas turntable's indexing of 15 degrees. Atlas supplies an "apron" which fits perfectly between the roundhouse and turntable, giving the proper separation.
Other roundhouses may only use a 12-degree spacing, allowing for more locomotives around a 360-degree circle or part thereof. Many turntables accomodate this by allowing user-defined indexing between stall tracks, or no indexing at all.
The Atlas turntable in HO scale is only 9-inches across, so this limits the size of locomotives that can be turned. I note this because the roundhouse is also quite small, and a nine-inch engine is about all it can accomodate.
It's pretty easy to see that a small turntable and small roundhouse will have a smaller overall footprint. Unfortunately, we have to live with this in our modeling worlds, so while we might want the ability to turn and house Big Boys and Challengers, sometimes we need to be realistic.
I think turntables and roundhouses are among the most interesting scenic items available for a model railroad.
It takes an iron man to play with a toy iron horse.
banjobenne1How does one match a turntable of one brand with the roundhouse of another brand? Is there a formala to crunch the number/dimenions given for each?
There are a couple of issues here. The first is whether the indexing of the turntable (if fixed) matches the spacing of the roundhouse stalls. For example, the Atlas, KATO (N), and Bachmann turntables have fixed track locations. So, for example, an Atlas turntable with fixed 15° track index locations will not line up correctly with a roundhouse like Walthers that is set up for 10° indexing.
Walthers (and many other) turntables, on the other hand, can index to any location, so they can be used with any roundhouse. But the distance between the edge of the roundhouse and the turntable pit varies depending on the combination of models chosen.
In order to figure out the arrangement of roundhouse and turntable from different suppliers, simply extend lines from the centers of the furthest roundhouse stalls. The point where they cross locates the center of the turntable.
Sharing more about which roundhouse/turntable combinations you are considering will help others help you.
Good luck with your layout.
Byron
Layout Design GalleryLayout Design Special Interest Group
RR_MelI wouldn’t think the roundhouse spacing would make much of a difference in the turntable.
It doesn't, unless the turntable has fixed track positions, as do the ones I mentioned.
Your CMR turntable can stop at any point -- that's the difference.