"It might be that I need to hand riddle it, but that will be much easier after the big riddle has done the donkey work."
And so it proved. On the left is a riddle full of earth that has already passed through the big riddle. To the right is the same, after riddling. So there's still a lot of stones, (pea sized, mostly) and a few bits of glass. It means I have to riddle it twice, but it's worth it because the big riddle also breaks up any clods and separates out most of the perennial roots still lurking in the soil. Below you can see the big riddle, v1.1; (v1.2 has a wheelbarrow to catch the bigger stones and shards of glass - it was tiresome to gather them all up for use in the rubble drain). And below's a photo of 2 heaps of earth. The foreground one is after passing through the big riddle. I took that through the hand riddle, it took at least 2 hours, and added it to the hand riddled heap at the back, which has of course almost doubled in size now: it's about 1m high and 2m diameter at the base, which if my secondary school geometry is ok means 4 cubic metres of beautiful ...