To rake a fin by yourself: first change the angle of the front end of the tuttle box head of your fin. Than you must add some epoxy material on the back end to fill the missing gap. By this setup the tuttle box head of your fin will go on the front end deeper into the box. The back end should be on correct level. E.g. 10mm deeper at front end is app. 3,7deg. or 4,5cm at the tip for a 70cm fin.