Just recently extended my frame, and running the calibration found some new problems to share.
I’m using mostly simple Aluminium box section for my frame. Because it’s the cheapest thing I can get here.
At the top of the frame are the new anchor points.
When the load goes on to these new anchor points the aluminium sections warp as shown by the janky arrow. The result is somewhere around 1.5-2mm relative movement in the anchor point.
So I’m now adding a solid bit of timber to the back of each upright. And then I’ll also add some other bracing from just behind the anchor point back across to the top of the frame.
So yeah, very definite frame flex issue.