Bought a new board recently and the fin box (futures)snaps the leading edge fin point that makes contact with the box. I blamed myself for the first broken fin thinking I may have screwed it down to tight... Nope. There is definitely an issue with the fin box after the same box cracked a second fin screwed in just slightly. So not only did I spend 700 on the board, it's broken 2 expensive fins.
I am not sure what you mean exactly but I snapped a futures fin like this (see picture below) a few weeks ago. Not sure how. I didn't realize it until I got ashore -- so I was surfing for probably at least a half hour w/o one outer fin in my quad setup.
It was a challenge to remove, being I was traveling and I did not have all my tools, and there was nothing to grab. I was able to find a small screw and get it to "bite" and then pulled it out with pliers.
It's crazy, I slide the fin in the box, and with one turn, this is what happens. The fin doesn't get seated all the way in the box.
Might be a dumb question, but there are 2 sized fin boxes, depth wise. Usually the center fin, or trailers are like 1/4 inch and the fronts are 3/4 (I believe). Some fin sets though, the rears/trailer are also deeper. Thats probably not your issue but I dunno. Your not trying to put the deeper 3/4 rear fins into a shallower 1/4 box?
Never happened to me but I like all blues theory...but it's possible the box was routed too deep prior to box install/poorly installed and by torquing down on the front screw creating a bit too much pressure on the front of that fin...leading to a cracked fin.