I delivered the Bronze Frame Reel (blog post of July 14) to a rodmaker acquaintance, who was making himself a new 3 weight rod just for this reel. He had chosen a CRNS reel seat from REC Components, but found that the reel foot did not fit. Other REC reel seats, like CRN, did fit but he wanted the smaller seat with his small rod (and I agree). To troubleshoot, he sent me the CRNS seat.
Here I have attempted to engage another of my “standard” reel feet with the seat, and indeed it does not fit. The foot is just barely captured by the cap and ring, and will certainly fall off the rod if fished. My fly rods have locking reel seats, and they had never been a problem. I checked this reel seat with several commercial reels, and found that some fit and some did not.
The problem seems to be with the AFFTA Reel Foot Standard, which specifies a foot that is 2.5 inches long (A), .525 wide (D), has a .35 bottom radius (B), is .04 thick at the tip (E), and slopes up at 7.5 degrees (C). The problem with this drawing is that it says nothing directly about the top of the foot; what should its radius be? I assumed that it should be .39 inch (= B + E) and prepared a fixture accordingly. Up until now, there had been no reported problems.
The CRNS is probably typical of many cap-and-ring seats. The wood insert starts as a rod of .64 inch diameter, and then is “mortised” on one side to create the .35 inch radius that fits the bottom of a foot. This “mortise” is .08 inch deep at the centerline. The reel foot (at the centerline) becomes .08 thick at about 0.3 inch from the end of the foot.
It wasn’t until I drew this sketch that I could see the problem: my .39 inch top radius isn’t going fit inside a ring that is .64 or .65 diameter. The correct top radius should be .32 inch.
So I re-made my foot fixture, moving the upright part by .07 inch relative to the base.
Here I am using the modified fixture to make a new foot for the Bronze Frame Reel. I mill the top radius with cuts in the axial direction.
Update 2 Aug 2014: After checking a number of reel seats, I find that the smaller top radius is not a universal solution. For locking reel seats, the .39 top radius seems to be a better fit. Also for round wood inserts with pocketed butt caps. For a mortised wood insert, it depends on how deep the mortise is.
My conclusion is that the AFFTA standard is defective, in that it does not specify the top radius. To illustrate, consider a foot that is .042 thick at the center of the tip. If the top radius is 0.32, then the tip thickness at the edge is .013 inch. But if the top radius is .40, then the tip is .045 at the edge. Both of these feet meet the standard, but would likely need different reel seats.