Thanks again David. Good ideas and photos, as usual.
The brass stock I'm using is 3/32 x 3/16 OD, and the wall thickness is 0.014" IIRC. (As per Bryan's Sep/Oct 2007 NSR article.) It's almost identical to the MT 905 box, by chance. Could you tell me the inside dimensions of the Full Throttle box?
With the AccuMates and McHenrys, the 3/16 width is perfect for the centering springs, and I put an MT truck washer under the shank to make the height a good snug fit. It works beautifully, but the coupler heads are just too d@mn Big for my taste. I think there should be some margin in how close the width has to be to the design width since that would mainly affect centering tension, but I don't know how much margin.
One nice thing about the tubing is that the length is entirely customizable for applications like extended draft gear on box cars, or for tank cars where you'd like to mount to the solid tank instead of the flimsy end platform.
Cheers,
Gary