027 1/2 curve

Not sure I understand the question but I'll still try to answer. You need to cut an 054 radius piece in half. Buying an 027 half curve will be too tight.

Annoyingly, the shorter track with smaller than O scale trains is called 0-27. That also happens to be a radius of curve track. It's just an annoying way to name things and I'll wager it just stuck when they started...so then it couldn't be changed.

No half 0-54 was ever made as far as I know. Even if it was, it probably would not be a half of a piece of track. Lionel’s half sections of tubular track were cut next to the ties. Since there was a tie in the middle of the track section, the cut was next to the tie, not in the middle. Cutting tubular track can be challenging. Best if you have an abrasive cut off saw. If not, clamp the track between two pieces of wood in a vice right next to the cut and use the finest hack saw blade you can get. Take your time.

It diameter, not radius.  O-54 is 54" in diameter; O-27 is 27" in diameter; etc.

@ogaugenut posted:

It diameter, not radius.  O-54 is 54" in diameter; O-27 is 27" in diameter; etc.

For sectional track planning purposes, O-54 is 26.2" radius, O-27 is 12.37" radius.

@Charlesp34 posted:

If I need 1/2 curve in 054 radius for my layout, did it come in 054 radius? Or, am I buying 027 1/2 curve? I know I can cut a piece of 054 radius to the size needed.

You will need to cut a section of your 26.6" radius O-54.

I’m using 054 tubular and I have cut numerous sections to size. The ties can be adjusted to accommodate the cut. Make sure you reposition the insulator under the center rail. Follow David Johnston’s instructions above.

Jay

A straight edge, a sharpy and a dremel cutting wheel and presto, you have a half O54 curve.  A hacksaw with a decent blade will do in a pinch.  Custom man.