To function properly your knife not only needs to be sharp, it needs to be razor sharp. In this article we’ll take a look at just what’s involved in this refinishing process; the equipment, the various procedures along with the final test.
This all starts a little earlier, in as much that we should never ill treat the knife’s cutting edge and we should look at refinishing it after every trip. Leaving refinishing too late is not only dangerous, it also reduces the life of the blade. This is due to much more material having to be removed to gain the correct profile. Once you are aware of how sharp a knife should be, it will be obvious when it’s just below par.
Different Types of Grind
There are a number of different grind types and angles. The grind types, along with the angles used are based on a number of things. The type of blade, what it will predominantly cut, the blade material, the blade thickness, the hardness of the blade and the edge durability are all considerations. The bottom line is this. The knife manufacturer will have chosen the grind type and angle that gives the best overall results for the blade material, heat treatment, hardness along with the designed use of the knife. It therefore makes sense to replicate this as close as possible, making only a slight change in the angle to suit your particular needs.
The Equipment Required
There are many different methods available to refinish a blade’s edge and now is a good time to sort out the dross. We are looking for an extremely sharp edge; well beyond what many would think possible. This eliminates the vast majority of methods such as hardened discs, mini grindstones, tungsten carbide blades and the like. Not only will these fail to give you the edge that you require, they are likely to damage the blade through excessive material removal. In addition to this, they cannot accommodate any change in edge angle. Arkansas stones are exceptionally good but to consistently maintain the correct angle freehand takes much practice. For this reason I feel that the DMT (Diamond Machining Technology) edge refinishing kit is the one to go for. There are other similar kits on the market but I know this one is good as I use one myself and also use them on the Edge Refinishing Course. This consists of 1 Black diamond plate (roughing), 1 Red diamond plate (fine), 1 Green diamond plate (extra fine), 1 Diamond plate holder and 1 Clamp/adjustable guide. You will also need a piece of flat rough leather and some honing compound to finish off and a thick, black marker pen to pick out the angle.
Let’s Get Down to It
First we need to set up the equipment. You may not need the rough plate all the time but we will assume a full refinish for the article.
1). Take the marker pen and cover the angled cutting edge on both sides of the blade from the handle to the start of the curve.
2). Clamp the guide onto the blade in the middle of the straight area you have marked. Set the angle to what you think it should be and try it on the marked part of the blade directly in front of the guide; you will see plainly by the marker’s ink if it needs adjustment one way or the other. The angle will only be the same when the plate is directly in line with the guide; however, this will not be noticeable over the short distance either side. As the curve of the blade moves away from the clamp to the point, the included angle will become more acute; this is not due to black magic, just the fact that the length has increased but the height has stayed the same, therefore the angle will be shallower. This helps us out quite a bit; let me explain. The vast majority of the cutting will take place on the straight part of the blade. It will also be where all the heavy cutting is done so this needs to be at an angle that not only gives a good sharp edge but also a robust, resilient edge. As the cutting edge carries on around toward the point its included angle will become more acute; this will give a sharper but less robust edge. This is ideal, as that part of the blade is only used for fine intricate work, skinning and possibly first-aid.
3). When you have set the angle correctly, use the black plate and gently stroke the edge using the guide to maintain the angle. There is no need to press hard with the diamond and the process should be done completely dry. When you have generated a complete, even edge all the way to the point, turn over and do the other side. Keep on until both bevels are identical in size and the blade is of equal sharpness along its total length.
4). Repeat with the red plate and then the green. You will now start to notice that the edge is becoming smooth and bright. Now, hold the knife in one hand and with the thumb of the other hand feel the edge by moving your thumb along the blade, as if you were trying to cut your thumb. Do this very lightly and carefully; you should feel a ‘bite’, even with the lightest of touch. This ‘bite’ should be present over the total length of the blade; if it isn’t, continue with the green plate until it is.
5). Now lay out the leather on a hard, flat surface and rub with honing compound. Hold the knife by the handle and drag the blade back away from the cutting edge at a slightly shallower angle than that of the bevel; this allows for the compression of the leather. Make sure that the blade’s path is smooth and continuous so as to hone the total edge from handle to point. Turn the knife over and repeat. Continue on alternate sides until each side has been honed three times. Now feel the edge with your thumb as before. The first time you get this right it will send a tingle down your spine!
Rub a little spit on the side of your calf and slide the blade lightly up your leg once, for about an inch; the hair should be on the blade and your leg should be as smooth as a baby’s bum.
Now feel the blade again and remember what it feels like. That way you will know when a blade is finished correctly by using your thumb, your hairs can then stay where they should be… On your legs!
Don’t be disheartened if you struggle a little with this (refinishing the blade, not shaving your leg), it is unlikely to come straight away. Unfortunately, you have little choice but to stick with it as a sharp knife is so important on your adventures.
A little word on safety is never a bad thing where cutting tools are involved. When refinishing a blade on any tool to this standard your hands have to become extremely close to the edge. A simple slight slip can easily cut you down to the bone. In the early days I have cut my fingers badly on more than one occasion through being a little careless. If I can instil the importance of this now, hopefully your injuries may be avoided. Always treat your cutting tools with great respect, especially now that you can refinish their edge properly! One last thing that may help in ensuring your safety when using your knife… Never put your free hand or any other part of your (or anyone else’s body) in front of the blades direction of travel when cutting.
This is quite a difficult thing to explain in words and a few photos; indeed, it’s hard enough when you are actually with someone! I hope it makes sense and is at least some use. As always, if you are unsure about any aspect please feel free to email me (if you can type with your heavily bandaged fingers) and I’ll do my best to help.
Now that you can put a shaving sharp edge on your cutting tools you could open a shop shaving ladies legs! You would probably get away with using the knife but I’m not sure about a 3.3lb felling axe. Women are strange creatures you know!
Take your time and stay safe.