It is an external sleeve that IS the female ferrule, the wraps reinforcing the end and the chamfer on to the rod blank. As I recall with the Grafteks, the reputation was that the sleeve split anyway, or the rod shattered elsewhere--in either case because of the particular graphite structure. A double wrap the length of the sleeve was an additional possible prevention any owner could make. No big deal if only the sleeve split, a replacement sleeve being easy to make--and from a more resilient, split resistant scrap of a fiberglass rod. Any old junker of a Shakespeare ugly stick--I used to get them at trash bins near boat ramps--made an indestructible 'glass sleeve ferrule. If the Grafteks were prone to breakage elsewhere, that's separate from the ferrule sleeve.
Problems like this were not uncommon at the beginning of the graphite era. So much so--although I don't know if there was any impetus specifically from the Graftek failures, that T & T fitted one of their early graphite models with a traditional high quality metal ferrule. If a sleeve ferruled rod failed there, it could also be repaired by fitting a standard metal ferrule set. Sleeves aren't unique to the Graftek--from a time when spigots weren't a proven, trusted design yet, especially in graphite, which needs a smaller diameter spigot. If anything, they were a common composite-to-composite ferrule type, best seen in the yellow Fenwick series and in Phillipsons.
A sleeve is slid down over the tip section and snugged to the blank--looking or probing inside, you can see the blank itself, seated such that the male end when inserted will have sufficient engagement with the sleeve and seat close to the end of tip section.
A chamfer on the upper end of the sleeve transitions it to the blank. It is wrapped down this thinned portion for reinforcement and from there on to the blank. In the pics of the Leonard, you can see a thread void where the chamfer meets the blank. This may be a careless wrap, but typically this is a sign that the blank has worked its way up out of the sleeve slightly, taking the wrap with it. Thus, the sleeve may have become seated too tightly on the blank, which may cause a split there. Not to alarm the owner; if the worst thing ever happens in using that rod is a split in the sleeve, it is an easy, easy, easy repair that will be better than new.
Just to see more about sleeve ferrules, easiest to observe in posts about the yellow Fenwicks and various Phillipson models.
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