I need to learn a bit about knife geometry. Why are different knives shaped the way they are ? Especially when you look at the point and the edge geometry seems to have a purpose.

A few days ago I was checking some fixed blade knives and saw one with a "typical" shape, but when touching the edge it was not sharp, rather it was thick !!! Then I realized that it was the other (straight) side that was sharp !! It had a sheath and attached sharpener just like a hunting knife but I dont think it is practical for hunting or camping, or am I wrong ?

I have seen some small elctrician (folding) knives with straight edges, but not a six-inch fixed blade . Isnt that strange ? And what it is used for ?

I have seen gardening knives shaped like this, I also have a Buck folding serrated blade in this shape. I find it to be a very stong blade.

The edge may also be "safer" as mine has no sharp point, I often use it to cut rope in a marine enviroment where often the rocking of the boat makes using a knive tricky. Rescue knives may also have this rounded point feature to protect both the user and the rescue victim.

Mike

I'm guessing you were looking at a wharncliff blade. The edge is straight and the spine is curved.... like a drop-point where the "drop" just continues all the way down to the edge. I've never seen one in a six-inch blade, though...

Santoku style Chef's knives are shaped this way.

Yes, it is like the blade on the left but is about six inch fixed blade.

In any case, I need some knife education. Blades have different shapes for a purpose. Looking at this two blade folding knife in the picture , where would you use each blade ?

Chisel,

Take a look at this:
http://www.beckwithsblades.com/encyclopedia.cfm?Term=24

also look at A.G.Russel's website for some good information on blade styles and metals used.

Joe

I like using straight edge blades for wire/coaxial work. It helps keep the cut around the sheath and the outer conductor clean and even. It also seems to work better at ripping material, like carpet or belting, as the material being cut doesn't slip as easily off the tip of the blade.

Probably why I use a utility knife a lot for that kind of stuff...

Hi Chisel,

When I was 15 I had my first "real" job at a place that was a combination bakery/campground/nursery and also had about 2 acres of indoor commercial rose garden. The workers who harvested the roses used folding Victorinox knives with a single "sheepfoot" blade, they looked like this SAK Gardner but with black scales, http://www.sosakonline.com/index.php?option=com_wrapper&Itemid=40

I carried one of these knives for a while but it had been sharpened so many times that the blade tip was exposed when closed, it cut a hole in my pocket and I lost it quickly.

Mike

A very late ( Thank You ) guys. Partly because I am not very regular on this forum.

Sometimes I feel guilty for coming here inly to get info and ideas, and when I get some, I disappear. Baaad boy !

The question of knife shape still challenges me. The links above didnt all give pictures of different models and I visited websites like blade forums but it was too much info and I didnt want to have a PhD in knives.

So, I have a few simple questions about knife shape.

First the partially seerrated edge.

Do you really find it practical ? I have seen a few folders that are a few inch long and HALF of the edge is straight and half is serrated. I mean each part is not long enough to do any good. Or am I wrong ?

Seems to me that a folder with two blades, one serrated and one straight is better. Dont you think ?

Second is the tip

Well MOST OF THE TIMES, the tip comes on the spine side (on the "upper" side) , and there are knives with the tip just in the middle , and RARELY - as in our example above- the tip comes in the "bottom" ( meaning blade side)

Let's ignore the last one, would you prefer the tip to come in the center or "upper side" and why ?

Third but not least there is the area between the tip and blade. Mostly it would be round. However, there are a few models ( like in some survival or combat knives) where a part of the blade is like a 45 degrees chisel. I'll find a picture to illustrate and would appreciate to know the function and putrpose of each design.

Third but not least , look at the Tanto knife



It is a fighting knife, so is this ( 45 degree chisel) design for the fighting purpose? There are other combat knives without this feature

Any ideas and insights ?
Thanks.

Form follows function.
The tanto knife supposedly is better for stabbing you with.
Blades like the sheepsfoot can be better for harvesting (think sickle like)
Serrations have their champions and their detractors. I would generally avoid serations in a bushcraft knive, but would consider for something like duty work.

A sheepsfoot blade was also preferred by past generations of tall ship sailors. These men were often barefoot and a sheepsfoot blade, if dropped, was less likely to stick into their foot. Tantos are meant more for stabbing, however a straight tanto, as opposed to a curved, was meant to make throat cutting easier, while the curved blades are better for slashing.

The only place I've found I prefer a serrated edge is when cutting something like rope. Even for this an inch or so near the joint is sufficient. Everywhere else they either aren't a help or get in the way. Ymmv.

Thanks everyone
I already feel better educated about knives

At last , I found a knife that looks like what I have mentioned in the first post.
It is the Wharncliffe blade



From what I have read, it is mainly used to cut line and seems to be the last choice in my case.

The Tanto design, however, has a potential for a survival knife. While I am not looking forward at stabbing a grizzly with it, I think it can be a good tool for diggging in the ground if your are in an emergency. The tip is less likely to break with this design. Plus, if the straight edge is meant to cut throats, then it is great for cutting game meat. It may not be so great for skinning though.

I agree about the serration. Most serrated bladdes I use around work and home (opening boxes, cutting cardboard and such), and for most of these jobs a full serrated blade is needed (not an inch or two). Even outdoors, if you have to use a serrated blade as a saw, two inches of serration won't help you much.

Now, another question about short-wide blades. What are they used for? I have seen one and like it very much but have to learn its ups and downs before making decisions.

It looks like this