If it's any consolation, you don't need a hard helical in your fletch if your arrows are properly matched to your bow--it will just slow the arrow down some and increase the feather noise. As long as I get a decent release, I can shoot my arrows 20 yds easily with no fletch at all.

Now, that being said, you might try this. Put the arrow in the clamp and place it on the jig. Loosen the two allen screws on the side that are for adjustment. Not so much that they slip completely down--loose enough that you can move it by hand, but enough tension so it stays in place. Tinker around like that, and you should be able to get it adjusted to the point you can put a lot of helical if you want.

Chad