I just got the tender up onto its temporary wheels and checked the coupler height at each end. The rear looks okay, but the front is perhaps .010” too high. I’m wondering if a slight joggle in this coupling is okay, or will that have a tendency to lift the tender?
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Pembroke:87 
well, I’m no engineer, let alone skilled at loco design/modelling, but . . . based on what I can tell from the photo, the joggle makes sense. when I try to remember what I learned about fulcrums and levers, I don’t remember anything saying that the shape of the lever will change the bearing points. As shown in your photo, it appears that the lower back edge of the loco (which is further back than the attachment point by a smidgen(correct?) is potentially serving as a fulcrum. Your joggle idea would eliminate that.
Thanks Rob. Yes, the centre of bolt is inset from the edge of the draw bar by almost 1/8″. Things definitely get complicated when forces aren’t in a straight line.
Speaking as an engineer, under tension the tilt will want to straighten – lifting the loco and / or pulling the tender down. When backing, the opposite will occur – it will tend to lift the tender. Introducing a joggle in tthe bar won’t change those effects.
I doubt it’s enough to matter, but ideally the two ends would be aligned vertically.
Thanks Stephan. It’s a shame it’s asymmetrical or else you could use it to improve adhesion when pushing a heavy train (or pulling if the tender were lower than the engine).