Pommels peened/recessed nut/threaded
Jun 21, 2009 21:54:56 GMT
Post by brotherbanzai on Jun 21, 2009 21:54:56 GMT
There have been a few threads recently regarding different pommel attachment methods. It seems that for many people the different methods are not very well understood, which seems reasonable, after all how many people understand how an internal combustion engine works, yet most all of us have vehicles that use one. But pommels aren't nearly so complicated and there are some very important points which I don't think are widely know. I'm no engineer but I'll explain it as I understand it and hopefully I'm not too far off base.
I'll start with a brief description of the common methods, as illustrated below.
Peened has the tang keyed into the pommel. The end of the tang has been hammered, usually while hot, to spread it out and hold the pommel firmly wedged onto the tang. A recessed pommel nut has also been keyed but the pommel is held onto the tang by a long threaded nut which firmly wedges the the pommel onto the tang. Threaded has the end of the tang shaped into a threaded rod and the pommel is screwed on.
A couple of other methods are illustrated below.
First is what I would call a fake peen. Yes, technically the end of the tang has been peened, but it's still just a small rod extending through the pommel. (I was a bit horrified to see that a sword from one maker had this design) This totally defeats the advantage of a normally peened pommel, which is that it is keyed with a large section of the tang. It's also possible to have a recessed/non-recessed pommel nut on a non-keyed threaded rod, which would be about the same as a simple threaded pommel. Yeoldegaffer has suggested I add in the keyed pommel nut (pictured above)which would be along the same likes, structurally, as the keyed recessed pommel nut and the keyed peen. There are other combinations and lots of slight differences possible but these are the basic categories.
Now onto the reason why these design differences matter and why one method might be better than another. This is from a structural standpoint only and doesn't take into account whether or not something is or is not more or less historically accurate.
There is force applied to the pommel's connection to the tang from simply swinging a sword around. The blade is pulling away from your hand, and the pommel keeps it from sliding out of the hilt and becoming a helicopter of death. That force is in the direction shown below.
This force, while strong, is not the one of most concern. When a sword hits something (say, the zombie you're swinging it at) there is a very strong force acting on the tang in this direction.
When striking very close to the COP, the sword rotates around a point very close to the pommel. When striking further forward from the COP or even at the tip of the blade, the sword rotates around a point closer to the cross-guard. (you can feel the difference in your hand if you strike a hard target with a blunt)This puts a great deal of stress on the tang as the pommel must quickly change direction. This is the force that's going to break the tang loose from the pommel. The extra width of tang in a keyed pommel is better able to resist breakage than is a thinner rod of a non keyed pommel.
It seems that there are some swords being marketed as "peened" by still using a thin rod and just not threading it, drilling the pommel all the way through, and then putting a little peen on the end. Now they can say the sword has a peened pommel since that seems to be the trend of what people want. But a sword put together in this way has less structural integrity than the plain old threaded pommel.
edited to add yeoldegaffer's pic
I'll start with a brief description of the common methods, as illustrated below.
Peened has the tang keyed into the pommel. The end of the tang has been hammered, usually while hot, to spread it out and hold the pommel firmly wedged onto the tang. A recessed pommel nut has also been keyed but the pommel is held onto the tang by a long threaded nut which firmly wedges the the pommel onto the tang. Threaded has the end of the tang shaped into a threaded rod and the pommel is screwed on.
A couple of other methods are illustrated below.
First is what I would call a fake peen. Yes, technically the end of the tang has been peened, but it's still just a small rod extending through the pommel. (I was a bit horrified to see that a sword from one maker had this design) This totally defeats the advantage of a normally peened pommel, which is that it is keyed with a large section of the tang. It's also possible to have a recessed/non-recessed pommel nut on a non-keyed threaded rod, which would be about the same as a simple threaded pommel. Yeoldegaffer has suggested I add in the keyed pommel nut (pictured above)which would be along the same likes, structurally, as the keyed recessed pommel nut and the keyed peen. There are other combinations and lots of slight differences possible but these are the basic categories.
Now onto the reason why these design differences matter and why one method might be better than another. This is from a structural standpoint only and doesn't take into account whether or not something is or is not more or less historically accurate.
There is force applied to the pommel's connection to the tang from simply swinging a sword around. The blade is pulling away from your hand, and the pommel keeps it from sliding out of the hilt and becoming a helicopter of death. That force is in the direction shown below.
This force, while strong, is not the one of most concern. When a sword hits something (say, the zombie you're swinging it at) there is a very strong force acting on the tang in this direction.
When striking very close to the COP, the sword rotates around a point very close to the pommel. When striking further forward from the COP or even at the tip of the blade, the sword rotates around a point closer to the cross-guard. (you can feel the difference in your hand if you strike a hard target with a blunt)This puts a great deal of stress on the tang as the pommel must quickly change direction. This is the force that's going to break the tang loose from the pommel. The extra width of tang in a keyed pommel is better able to resist breakage than is a thinner rod of a non keyed pommel.
It seems that there are some swords being marketed as "peened" by still using a thin rod and just not threading it, drilling the pommel all the way through, and then putting a little peen on the end. Now they can say the sword has a peened pommel since that seems to be the trend of what people want. But a sword put together in this way has less structural integrity than the plain old threaded pommel.
edited to add yeoldegaffer's pic