NDDan
Guest
Rumble comes from material sliping over top of helicals. Yes I think sharp edges on flat helicals will help (better yet channel helicals on thresher side also). I know some helicals can be switched around to get new edge against crop and you could always have them hard surfaced and squared back up. If swithing to channel helicals and cage doors getting thin you can flop them around to get least worn front one in most wore rear location. Welded in one just behind concave would have to be replaced. I think your right about greener crops are hear to stay. Good luck