O-72 Layout in tighter space

What size space are you working with?  You need at least 6 feet for O-72.

Agreed. Unless you're doing a point-to-point type of layout, you're going to need at least a 6 foot diameter on your layout to use O-72. 

-Eric Siegel

Ron045 posted:

What size space are you working with?  You need at least 6 feet for O-72.

You need more than 6 feet. Have to account for overhang. I'd say 78" is the minimum to keep it off the wall.

If you dont have room for a 6.5 foot circle, then you aren't going to run O72. Its not like you can force it smaller and still say its O72. 

That said, I doubt that a 4-6-2 needs O72 in order to run. If all you want to do is incorporate SOME O72, then use an O72 curves as an easement into a smaller diameter curve such as O54, such that it fits in whatever space you have available.

Thanks for the replies, I'll see if I've got at least 78" to work with.

If the Lionel product info page is correct, that engine needs a minimum curve diameter of O-54.

The first modules I built were 180 degree curves on plywood originally cut for twin beds ... 75" x 39" as I recall.  The outer loop was O-72 tubular squeezed to fit within that space with a 3" border.  (Tubular curves can flex a bit).  One of the O-72 tracks was cut to trim the curve at the edge of the board.

Even though the diameter is less than O-72, Big Boys, PRR T1s, and other long engines run fine.  The only problem engines were scale brass from Weaver.

So whether you squeeze the O-72 to fit, use a mix of O-72 and O-54, or go with O-54, or FastTrack O-60, you should be fine.

I'm currently using O-72 tubular track. I have determined that I have enough space. I plan on sticking with O-72 though for the sake of future-proofing the layout (like if I get a scale Big Boy some day).

With that being said, if I were to have some sort of siding or switch track that had a smaller diameter, such as O-31 or O-48, how bad would the overhang be? The largest locomotive I have currently requires O-48.

I figured my track to track clearances based on the overhang of long locos and the under-hang of 18" passenger cars and came up with 5-1/2" between center rails as a safe clearance for O-72 and O-54 corners.  My club's modules are 4-1/4" between centers.  The corners are O-72 minimum and we seem to operate without scraping sides of the equipment but we avoid running long overhang locos on adjacent tracks.  FastTrack curves provide 6" between centers - and that may be needed for RailKing Big Boys and similar long overhang equipment operating on O-36 and O-48 curves.

jhend1000 posted:

I plan on sticking with O-72 though for the sake of future-proofing the layout (like if I get a scale Big Boy some day).

Fyi...if you get a Big Boy you will need to have at least 5.5" spacing from center rail to center rail on O72 curves to avoid bumping into other trains.  This will give you an idea of how the overhang will effect adjacent scenery:

-Greg

I've  seen several track plans using 072", some were 9' x 9' (108" x 108") several loops, and usually operator sits inside with controls there.

SCARM is nice for track planning, but I've found that setting up the track and running trains on it actually proves whether a track plan will work or not. Long cars and articulated steamers also require more space- Greg Houser is absolutely correct about track spacing. I have 5.5" track centers on some of my curves and my VL Challenger barely clears 21" cars if it's on the inside main and the long cars are on the outside track.

Geno

I was given a "small space" challenge on another forum a few years ago and came up with these done with MTH ScaleTrax and a minimum of 36" radius (O-72) curves: