Hello and Happy New Year!
The new support framework for my expanded loop is composed entirely of 2x4 lumber, with no nails or wood screws used anywhere.
I used 3/8" hex bolts, nuts, and washers for the major structural members, and 5/16" lag bolts for the horizontal braces.
The structure is anchored to the game room wall with 3/8" lag bolts going into the wall studs.
It is a very rigid assembly.
Bad Order Hal
(The 3rd image is for the original loop structure, for the 36" radius loop)