Ok folks, it's been a while since my last edgy monologue on things sharp.
More precisely, on things which should be sharp ... and I hope it's worth the wait. It's got more words than my earlier posts cuz it's on a topic that's got a lot more dimensions to it ... [pun cheerfully intended].
As promised some time ago [yes, Ted ... a looooooooong time ago], I'll begin looking at some of the qualities and design features which can make a knife more [or less] useful in a variety of situations.
The three most basic of these are blade length, width and thickness [thinness?].
We'll also begin looking at blade shape ... and that is an area which will probably require several return visits in future installments of this little slice of heaven.
Back in some of our earlier examples, we looked at edge geometry & grinds with an eye toward what *sharp* really means ... and we saw that a particular grind could be very good for one purpose [like shaving] and very bad for other purposes [like carving a roast or chopping wood].
Now we're going to take a step back and look at blade geometry and see how that can enhance the usefulness of a knife in both specialized [like skinning, boning or filleting] and more ... um ... general situations.
Let's begin with an activity that can benefit from a fairly specialized design and see how we can tailor a blade to make it just a bit easier to get the job done ...
Say you're a hunter, and you've just bagged a nice elk. The easy part is now done and it's time to haul it home and turn it in to dinner ... well, quite afew dinners, but I digress ...
After you've wrangled the carcass home and got it hanging up, you need to work on breaking this rather large and complex hunk of meat, bones, skin and other goodies in to manageable chunks that will fit in your freezer, look good on your trophy room wall and perhaps get turned in to a pair of moccasins or a nice bag for you or a friend.
Without going in to gory detail ... ahem ... this means that you've got to open up your prize & clean out the internal organs without getting any nasty fluids [or solids] on the meat you plan to eat, separate the parts you want to put up on your wall from the rest of the hide and separate the hide from the parts you want to eat ... cuz it's easier to do a good job of butchering when you don't have skin in the way.
For the moment, we'll assume you've taken care of the innards ... and we'll move to the skin removal portion of the show.
To do this with minimal damage to the skin you need a blade that is sharp [what a surprise!] and won't get in your way when you're working in tight areas ... that way you'll maximize the amount of usable hide and minimize waste.
Remember our earlier examples of the razor and the axe ?
It's time to apply those principles again ... and to add another couple of dimensions to the mix just for good measure.
You need a blade that is sharp, but won't bind ... so a razor-like profile is out, and you need to be able to make reasonably precise cuts and change direction easily [quickly, too if you're not being careful] ... so a thick blade isn't a great idea, and depending on your level of skill at this kind of thing ... it probably wouldn't hurt to keep the length of the blade on the shorter side so that you've got better control over where the tip is in relation to the handle.
Another consideration here is that there aren't many straight lines in this kind of work ... and since you want to maximize the amount of usable hide you get out of this, you'll want to be following the natural curves closely.
Ok ... now we've got the requirements, let's look at how to meet them ...
Thin enough for good cutting, thick enough to support edge geometry that won't bind while you're working, short enough to give you tight control over where the blade is going and curved enough to help you follow the curves that are already there ...
Where do we go from here ?
Let's start with length and profile, since those are features we haven't discussed in our other examples ...
For my own use [and discussion here], I've got a set of working criteria that I apply to blade length ... those of you who have spent time around horses will should pick up on this very quickly, cuz it's what you folks already use to measure those lovely critters ... it's the hand.
When I think of a small knife, I'm usually picturing one with a blade of 5 inches or less [12.7cm, give or take, for the metric folks] and that's 1.1 hands ... a shade more than the width of my own hand. Very convenient for measuring, since I take them with me everywhere ...
By that same roundabout process, I think of a large knife as having a blade of 2 [or more] hands in length ... which leaves a reasonable middle ground and gives us some starting points for more discussion later on.
So ... let's take a length of 5 inches and move on to width.
Just as length can help or hinder, the width of the blade will also have effects on the ease &/or precision of the cuts we'll be making ... so we should be looking at enough width for strength [just like blade thickness,blade width is a factor in both durability and flexibility of a knife], but not so much that it prevents us from working in tight areas.
For a knife with a 5 inch blade, let's begin with a width of 2 inches ... a bit under half of the length of the blade. At this point it's an arbitrary decision but a reasonable one, and we'll check back on this from time to time to see if this width is still reasonable as we add in the other features and dimensions of the knife.
The next dimension is a little tricky ... blade thickness.
Blade thickness could be pretty much anything from as thin as a razor blade [with the obvious drawback of not being very durable] to as thick as an axe which would tend to limit the precision of our cuts & overall 'handling' ofthe knife, especially in tight areas.
For fixed blade knives, blade thickness [measured at the spine] typically ranges from about 1/8 of an inch [approx. 3.175mm] to 3/8 of an inch for 'heavy duty' blades which may be expected to double as lightweight hand axes in an emergency situation.
Back to our current design problem ... we want something that's thin enough to allow the blade to move easily as it's separating skin from meat & bone, and thick enough to take a little punishment if we accidently run in to some-thing tougher than skin or meat [like a bone].
Let's start at 3/16 of an inch [approx. 4.763mm] as a good compromise for giving us a relatively thin profile, but still having enough substance to take some punishment without causing severe damage.
Our theoretical skinning knife is now made from 3/16 inch stock, is 5 inches long [not including the guard & handle] and 2 inches wide ... but what shape [or profile, if you prefer] is it ?
Back again to what it will be doing and how it will be used to do it ...
Most likely, the cuts you'll be making with this knife will be gently curved, cuz there don't seem to be too many straight lines in this kind of work ... [at least at this early stage] ... and since human arms & hands tend to work in arcs, a blade that is too straight will probably wind up getting in your way sooner or later.
A common gentle curve for this type of knife gives us something called a trailing point, which means that the point of the blade follows [or trails after] an imaginary line drawn from the base of the blade's spine [where it would meet the guard] forward past the end of the blade and off in to space.
Contrast this with a drop point [or leading point] design, in which the point of the blade is forward of this same imaginary line.
Why a trailing point instead of a leading one ... ?
Imagine you're peeling something apart ... and to help things along, you're running your index finger along the line of separation ... it's kinda tough to see exactly where the very tip of your finger is, but it's not too hard to see where it was ... right?
Now replace the tip of your finger with the point of a knife ... and give that knife a curve which allows you to work in an arc [say, pivoting from your elbow] ... if the point is leading, you don't really know where it is and this may increase your risk of poking a hole [or holes] in one or both of the layers of stuff you're trying to peel apart.
If that point were trailing, you'd still be able to maximize the work you're doing by taking advantage of the arc of movement from your elbow, but you'd also have the ability to see where the point of the knife was while you were working ... and that would tend to minimize the risk of poking a hole in it while you were working.
There is a lot more to blade geometry ... but I think that's enough to chew on for now, so I'm going to wrap this up and save a little bit for our next installment.
As always, all y'all can post specific questions &/or suggestions for new topics ... and I'll see about answering them directly or maybe including them [with answers &/or comments of my own] in a future installment.
Y'all come back now, y'hear ...