i had a huge Oak (50' +) taken down by a buddy who climbed it... looking at my pile now, most logs are about 20"-24" lengths. so i need to get these down to 16-18" lengths for the stove. what is best method to cut slices off these? or to keep the log stable? I been cutting them but they seem to roll alot which is probably not too safe. im comforatable with a chainsaw but not an expert by any means.