http://www.tomatoville.com/showthrea...light=grafting
This was just discussed recently here if you have not read already.Consensus is to stagger scion and rootstock germ/plantings to get the right diameters.I myself have do not graft maters but do graft mangoes,lychees,etc here in FL.We do the "cleft"graft as ChrisK mentioned in the above posts and works the best.More surface area,no slippage and misalignment.Punch in grafting in the search block and you will get years of info posted here(if you have not done already).