Is this normal to come across? I just picked up some F6 fins and boxes, yet the fins do not fin in the futures boxes, it seems the grooves on the leading edge are too shallow, is this normal? Ill probally just cut the groove a bit deeper to make them fit snugg. Thanks dave
Its probably obvious, and I’m sure you know already, but just in case…
Futures center boxes are 1/2" deep while sides are 3/4"…fin bases are accordingly sized. Did the shop give you the proper boxes for the fins? If they gave you side fins & a pair of center boxes, they wouldn’t go in deep enough to engage the slot, for example 
No thats not the problem, the fins don’t fit in the boxes in length, but thanks for the reply, I almost ordered the fins like that haha live and learn. Thanks Dave
Another “duh?!” thing to check, make sure the set screw isn’t protruding into the box when you are trying to put the fin in. Make sure the grub screw is unscrewed enough so it’s not blocking the fin from going in.
Sounds like you got the right idea though, either, lengthen the hole or sand the other end.
I’d double check all the clearances though, and first find out where it’s binding.
Hi dave,
Yah, sometimes they don’t fit. Just need a bit of sanding until they slip in. Dont’ take too much off. Mike
on my vectors rtm’s I had to sand them down to fit into their respective boxes
This may also seem obvious, but before you sand or grind anything, check them against other stuff…
It may be the fins are too big, or the boxes are too small. If the fins are big, and you grind them, you’ll be fine - they should then fit other boxes too and standard fins will still fit your boxes.
But if the fins are big and you grind the boxes, than all other futures fins would be too loose…make sense?
Thanks for the replies everyone, im going to just sand the notches out abit, and they should fit snug. Thanks Dave