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- Nov 29, 2005
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- 887
Ontario FF6 review tang failure
Last night I had tang give way on an Ontario FF6 Freedom Fighter Fighting Knife. I was practicing snap cuts on a soft pine post, when the pommel flew off.
The knifes construction was as follows: blade is steel stock, I believe 1095, 3/16 inch thick. Tang passes through, and is enclosed by, a kraton handlebasically a tube made out of kratonand screws into a steel pommel.
Tang is ½ inch wide for the 4 inches immediately behind the blade, and is then abruptly narrowed to ¼ inch to the end of the tang. This 1/4 inch section is threaded, so that it can be screwed into the pommel, which is basically a mushroom-shaped piece of steel whose stem is inserted into the tubular kraton handle; the stem has a threaded hole into which the threaded part of the tang is screwed.
Inspection showed that the threaded, ¼-inch section of the tang had broken off between the place where the tang thins down from ½ inch, and the place where the threaded portion screws into the pommel. My theory is that this is a design issue that Ontario may wish to address, because at the point where the tang is narrowed and threaded, the only other support is the rubber-like kraton handle material. This means that the force of any lateral impact is essentially going to be borne by a quarter-inch threaded rodwhich obviously was not up to this use.
I will mention that the chops in question, though not light use, were also not remarkably heavynot like I was flailing away recklessly, trying to break the blade, etc. In my opinion, they were within the range of impacts that a utility or fighting knife should be reasonably expected to endure. It was also the first such use to which Id put the knife, so metal fatigue was probably not an issue.
By way of full disclosure, I had modified the handle somewhat prior to this event, by means which did not involve the part that snapped. I had narrowed the kraton part of the handle side-to-side using a belt sander, as the original shape was a little too large and round for my easiest use and retention; and I had likewise used a bench grinder to narrow the circular pommel into more of an oval shape. Though I can imagine that the removal of some of the kraton on the sides of the handle could have made the rubber a little more flexible, perhaps hastening the fracture, I have trouble imagining that the same thing wouldnt have happened not too far into the future, without the modifications.
Ontario mentions an NSN number (NSN: 1095-01-515-9874 ) for this knife on its website, which I think implies that one branch or another of the U.S. military uses this model. If so, I am a little dismayed to know that something with a critical part this weak is being relied-upon by our servicemen. My backyard martial-arts practice is one thingbut where those guys use their knives, this kind of fracture would pose real problems. I would recommend that Ontario consider stronger attachment systems, such as those used in traditional military-issue Ka-Bar utility knives, or USAF survival knives. Any system that retained the half-inch tang width throughout the tangs length would strengthen the knife considerably.
Last night I had tang give way on an Ontario FF6 Freedom Fighter Fighting Knife. I was practicing snap cuts on a soft pine post, when the pommel flew off.
The knifes construction was as follows: blade is steel stock, I believe 1095, 3/16 inch thick. Tang passes through, and is enclosed by, a kraton handlebasically a tube made out of kratonand screws into a steel pommel.
Tang is ½ inch wide for the 4 inches immediately behind the blade, and is then abruptly narrowed to ¼ inch to the end of the tang. This 1/4 inch section is threaded, so that it can be screwed into the pommel, which is basically a mushroom-shaped piece of steel whose stem is inserted into the tubular kraton handle; the stem has a threaded hole into which the threaded part of the tang is screwed.
Inspection showed that the threaded, ¼-inch section of the tang had broken off between the place where the tang thins down from ½ inch, and the place where the threaded portion screws into the pommel. My theory is that this is a design issue that Ontario may wish to address, because at the point where the tang is narrowed and threaded, the only other support is the rubber-like kraton handle material. This means that the force of any lateral impact is essentially going to be borne by a quarter-inch threaded rodwhich obviously was not up to this use.
I will mention that the chops in question, though not light use, were also not remarkably heavynot like I was flailing away recklessly, trying to break the blade, etc. In my opinion, they were within the range of impacts that a utility or fighting knife should be reasonably expected to endure. It was also the first such use to which Id put the knife, so metal fatigue was probably not an issue.
By way of full disclosure, I had modified the handle somewhat prior to this event, by means which did not involve the part that snapped. I had narrowed the kraton part of the handle side-to-side using a belt sander, as the original shape was a little too large and round for my easiest use and retention; and I had likewise used a bench grinder to narrow the circular pommel into more of an oval shape. Though I can imagine that the removal of some of the kraton on the sides of the handle could have made the rubber a little more flexible, perhaps hastening the fracture, I have trouble imagining that the same thing wouldnt have happened not too far into the future, without the modifications.
Ontario mentions an NSN number (NSN: 1095-01-515-9874 ) for this knife on its website, which I think implies that one branch or another of the U.S. military uses this model. If so, I am a little dismayed to know that something with a critical part this weak is being relied-upon by our servicemen. My backyard martial-arts practice is one thingbut where those guys use their knives, this kind of fracture would pose real problems. I would recommend that Ontario consider stronger attachment systems, such as those used in traditional military-issue Ka-Bar utility knives, or USAF survival knives. Any system that retained the half-inch tang width throughout the tangs length would strengthen the knife considerably.
