I wanted to use my grapple, but the spacing was 8" or so. It got the giant stuff fine, but not the smaller stuff. I then made an insert that was at around 2.5-3" spacing. This got the next size rock down but wasn't that great at truly separating things out. I made a sifter out of an old trundle bed and placing some metal fencing across the top. I just used wood on the first attempt to see if it worked and it did. It just takes some time. The bed frames actually provides some bounce to further help sift things. I have heavy clay and it had to be dumped slowly. I may re-make the sifter out of metal as my wooden frame gave up at the end of my last project. Just too much beating on it.