Scrape metal, make sharp.
But to really understand how to go about sharpening your survival axe, we have to dive into the world of friction, with a pit-stop in the realm of metallurgy. It’s nothing to be intimidated by. I’d offer to hold your hand, but that’d be weird.
It’s All In Your Head
Consider this: Survival axe heads can be made of any hard and heavy material. Unless you’re building your own survival axe out of granite or scavenged bison skull, your cutting edge is going to be hardened steel. This is because hard steel holds an edge better than soft steel, and is less likely to be damaged.
When a blade “holds and edge” it simply means it resists changing shape. This is great when you’re in the field chopping through a wild boar carcass. Not so great when you’re trying to sharpen your survival axe. So be patient. The harder the steel you’re using, the slower the sharpening process will be, but the longer it will stay sharp.
Gettin’ Gritty Wit It
With some elbow grease and a long afternoon, you could sharpen your survival axe with nothing more than a cinder block. While I wouldn’t recommend taking that route, it would work, and it would work because of grit.
Grit is the particulate matter that removes the metal from the blade. Grit is the difference between sandpaper and toilet paper. Grit is good for the one, not so much for the other.
The grit material’s hardness, size, and spacing will dictate the speed and degree of sharpness your survival axe can achieve. To understand the size and spacing, look at this high quality, professional illustration below.
On the left, we have a lot of small grit, closely spaced, as you’d see in a “fine” sharpening stone. Using a sharpening stone like this will take longer to sharpen a survival axe, but give a very fine, uniform sharpness. This is exactly what you’d want to see when putting a finishing edge on a survival axe.
On the right, we have much larger grit, spaced further apart, making for the aggressive material removal you’d expect in a “course” sharpening stone. This is great for reshaping the survival axe blade, or to begin sharpening a severely dull axe head, while finishing with a finer grit afterwords.
In addition to size and spacing, the actual material the grit is made from is a key factor. Generally, the grit material is going to be harder than the metal you’re sharpening. Diamond, cubic boron nitrite (CBN), silicon carbide, and tungsten carbide are all used as grit in sharpeners because of their hardness.
The most common material used in synthetic sharpeners is aluminum oxide. That’s the same stuff in most sandpaper. It’s not nearly as hard as, say silicon carbide, but as it grinds down, it leaves a sharp edge, effectively resharpening itself.
A Gritless Existence
Many an old-timer eliminated the need for grit altogether by using a good old metal file. These are made of hardened steel, and do a great job of sharpening anything you need to put an edge on. You’ll never get as fine an edge as with a whetstone, but since we’re talking survival axes here and not precision scalpels, a file can do just fine.
Are Those Real?
Sharpening stones, commonly called whetstones, come in natural and synthetic versions.
Natural sharpening stones are rocks quarried from the ground. Some of the world’s finest stones are natural stones. They’re going to be a little less uniform in grit size, spacing, and even material, but you’ll only know that from examining it under a microscope. These stones will perform well, whether sharpening a survival axe or you favorite garden sheers.
Synthetic sharpening stones consist of a manufactured grit attached to a flat plate. Diamond sharpeners fall into this category, along with many sharpeners sporting the hardest grit materials. These are my favorite, as they’re affordable, and fast, and hold up well to heavy use.
A word on lubricants:
Water or oil are not used in the sharpening process to lubricate, but to remove swarf and heat. Heat damages the blade. Lubrication opposes friction, and is not what you’re after when sharpening.
Those Grits are Shaping Up
Now that you’ve got your grit, its time to decide how best to put it to use. The two most common methods for putting that grit to good use are the sharpening block and the sharpening wheel.
Swarf is the waste generated by the sharpening process. Akin to wood shavings in a carpentry setting, swarf is the combination of metal filings and grit that accumulate on a sharpening medium. Generally this waste to be removed during the sharpening process, but some sharpeners rely on this build up to provide added grit.
A grinding (or sharpening) wheel is exactly what it sounds like: an abrasive material that spins in a circle, accomplishing the grinding in record time with minimal effort. A bench grinder, Dremel tool, angle grinder, or ye olde tyme grinding wheel are all examples. This is my preferred style (the bench grinder, not ye olde tyme grinding wheel), as it’s fast and I’ve always gotten great results, provided I’m careful. Since these units spin at tremendous speeds, it takes no time to sharpen even the dullest axes. In the same way, it takes no time to mess up a blade if you get sloppy.
When using a grinding wheel of any kind, you have to be very aware of the heat that’s being created. Friction always creates heat, and heat will destroy the temper of steel.
Be sure to frequently cool the axe head if you’re going with this method.
The other option is the sharpening block. This will take longer, but is much more precise, and more forgiving. By removing smaller amounts of axe head material at a time, you’re less likely to make an egregious error, and more likely to catch an error while it’s small.
Sharpening blocks, commonly called stones, come in many shapes but two varieties: oil stones and water stones. The difference is what you use to transfer the heat (or “lubricate” as most people would incorrectly say).
A Whetstone Haiku, Just For You:
Water your whetstone
for once you’ve oiled a whetstone
oil stone it shall be
- require an oil-based solution to operate properly
- tend to be a little less expensive
- messier to clean up
- slower cutting rate
- must be kept wet with water during the sharpening process
- softer, which means faster cut rate, but more frequent re-flattening
Paper Rock Rock… More Rock… Too Much Rock. Just Stop.
As you can see, there is a plethora of sharpeners to choose from, varying in shape, material, and price. Honestly, it’s a little daunting. If you’re overwhelmed, you can just buy Smith’s Axe Sharpener and you’ll be good to go.
What’s Your Angle?
I’ll just go ahead and say this: there is no proper angle for sharpening an axe. That’s because people want their survival axes to be good at different things. If you use yours primarily to cleave or to field dress a critter, you need a different degree of sharpness.
A dull axe is a dangerous axe. It’s more likely to glance off your target rather than bite into it. Whatever edge you decide to go with, keep it sharpened to that degree whenever possible.
Sharpness is determined by blade angle. The narrower the angle, the sharper the axe, and the quicker it looses its edge. If it’s kept a little on the duller side (think splitting maul) the more consistent it will be, the longer it will keep that “lesser” edge, but you’ll have more trouble using it for fine cutting work.
So you decide, are you likely to do more splitting, or more slicing, and determine your angle accordingly. An angle in the less than 20 degree range is more knife-like, while splitting mauls clock in over 40 degrees. 25-30 degrees is considered a good general use angle. Adjust accordingly from there.
Every axe is different. Every user is different. Field test it to discover your survival axe’s “sweet spot.”
To Grind an Axe
It does not matter what direction you scrape the blade. No, really, the metal does not care. Go in one direction. Go in both directions. Go back and forth. Unless you’re using a file, it doesn’t matter. What matters is consistency of the angle.
Following the bevel of the axe blade, begin scraping away the dull. The number of strokes needed will depend on the dullness of the blade, but I typically take 10-20 on one side before doing the same on the other. Continue alternating sides of the blade until you have a decent edge.
Continue moving from courser stones or files to finer ones, until you’re using the finest one you’ve got. If you only have one, that’s fine too. How will you know when you’re done? With one of these handy-dandy contraptions.
Simply press your blade into the slots, each marked with the appropriate degree. You’ll know if you need to keep sharpening or if you can call it a day.
So there you have it. With a little know-how, and a bit of grit, you can get your axe as sharp as you need it, no matter how you plan to use it.