47mm deflection. I'm very happy with that!
By direct comparison, this is the flex measurement for the original Yard, 97mm. Twice the deflection!
After sanding the spar round with the cut 40grit sanding belt (Quite a work-out!), I made 3 finishing sanders from used paint rollers. These were split and 3 different grades of paper bonded to the insides with PVA glue. They were a little small for the larger sections, but this is easily fixed by heating the tube with a heat gun and spreading the tube wider, like this:-
Nice comfy sanders they make too! Given the somewhat worn state of my fingertips from the sanding belt, this was a relief :)