What is the outer limit of fuller width? How wide is the widest historical example?

Lets assume a hexagonal cross section, a width of 2.5" and a thickness of 1/4". If the edge to fuller distance is, say, 5/8", then the fuller would be 1 1/4" wide. If we increase width to 2 3/4" and towards 3", obviously we increase either fuller size or skirt size.

Now, if the cross section became true lenticular, a 2.5" x 1/4" lenticle/oval, it would reduce the blade thicknesses of the two shoulders (the edges of the fullers) by some 32nds of an inch.

At what point do you start to lose the benefit of I-beam construction and invite structural weakness?

im designing a custom is why Im asking. Thanks!

It's a trade-off between aesthetics and structural considerations.

The aesthetics of the matter are not really something worth discussing because it's a highly subjective thing. Some people like very thin fullers, some like very broad fullers, others like multiple fullers... it's really a matter for the individual taste to decide.

Structurally, however. The rule of thumb, I think, is that you have to balance the thickness of your blade material with the width of the fuller and blade. If your fuller is excessively wide, your edge bevel will be fairly thick and cutting will suffer. But if you have a very narrow fuller on a very wide blade, especially a thin one, then your edge will be pretty thin-- it'll be a monster of a cutter but it'll have serious issues with damage. If you try a thin fuller on a wide but thick blade, it'll be more durable-- but it'll be very heavy.

Frankly the best thing to do is tell your bladesmith you want a wide fuller on however wide of a blade, and let them do their job. If they're good, they'll know how best to accommodate your wishes.

Historically, most blades never really went above 3" wide IIRC. Fuller width would be up to 2 inches or so as there was typically between 1/3 to 3/4 of an inch of edge bevel on each side. It's hard to tell with most examples that we have though as we suffer from not having many examples in non-corroded condition. A general estimate can be made, though.

EDIT: Just to be clear, I am talking about Viking era through roughly Oakeshott X type swords. After that, it's all over the map. Viking/Frankish/whatever swords tended to have a fairly consistent wide fuller upon their blades, so I am assuming that this is generally similar to the type of sword that the OP is looking for. If I'm wrong, I'm wrong :)

Check out Geibig typology. It has quite accurate measurements of fuller and blade widths for different types of swords from 9th to 13th century...

The outer limit is T-spined blades and their relatives. One could say that a T-spined blade has a triangular fuller from the T-spine to the bevel on the edge. It works. Can give 400g swords with 27" blades, with respectable rigidity. Note that these are single-edged blades, so don't suffer from the problem with either blade too thin or edge too thick (or both at once) that Jeffrey described.

For a double-edged blade, too avoid those problems, use a central ridge with a fuller on each side. Which is, of course, a hollow ground blade when the fullers go all the way from ridge to edge.

Michael,

The sword below in the Musée de l'Armée has one of the widest fullers I've seen:

[ Linked Image ]

[ Linked Image ]

The blade is very broad for it's length and supposedly very thin, but I've never seen a good picture of the edge. As you can see, the fuller spans nearly the width of the blade (~3in).

Wow if thats a 3 inch wide blade... then my design should work fine =D. Thanks Ive never seen it before!