Help on O gauge track geometry

    O31     14.14"

    O42     20.17"

    O54     26.6"

    O72     35.88"

Fastrack

    O31     15.5"

    O36     18"

    048     24"

    060     30"

    072     36"

    084     42"

Rob, everything looks right on except fo the 072 tublar at 17.94 inches. Don't have any to measure correctly, but it's probably around 34.5 inches...

Thanks

Bruce

I have no idea how that got there.  It is O72 at 35.88".

Thanks so much for your help.

I was pretty sure the Fastrack diameter was actually measured to the centerline.

I seem to recall the O31 meant the 31" was to the outside of the ties but where was the 72" supposed to be?  From your answer the 72" seems to be a little past the centerline (measured from the outside of the center rail to the outside of the center rail?).

Just curious.

Thanks again.

Don

O-72 and T-Rail("Model Maker's Track") shared geometry, so it was probably intended to be 36" radius.  I've always used 35.88" with perfect results, this came from calculations on an old DOS track geometry calculator.