What Mike said. When I first started fletching years ago I was told to fletch left helical becasue I shoot right handed. That is what I did and still use the left hand clamp as I don't want to spend $30 for a new clamp. My brother shoots right helical and my tips don't unscrew any worse than his do.

I use Blazer's and fletch helical. It takes some adjusting but you can get a fair twist on them. Mine look similar to Txjourneyman's.