How To Sharpen a Knife – Blog and Video Tutorial
I am sure you have heard the phrase ‘A Blunt Knife is a Dangerous Knife’. In practice that is true in so many ways and as such I do make sure all our blades are ready for work. For now, in this article, I will concentrate on sharpening the humble pocket knife. The only thing I would say is that a sharp knife cuts deeper! A blunt knife will be the cause of the accident as you can slip while struggling to cut anything a little tough. Here you will learn how to sharpen a pocket knife and the French Opinel folding knife
What is the Best Knife Sharpening Angle?
So many knife owners want to get a really sharp edge and to do that you will need to get an appropriate grind angle.
The truth is there are many different angles that will suit different knives. You have to select the best angle for your knife which may be influenced by the steel and the intended purpose.
Knife Sharpening Angles
- Less than 10 degrees for cutting soft organics and good for thin blades used for filleting or cutting soft materials. Often used for theatre surgery instruments and razor blades including the cut-throat razor. These tools have an edge that can easily dull and require a high grade of tool steel.
- 10 to 20 degrees is used as a standard grind angle for kitchen knives but is often lost through poor sharpening.
- 22 to 34 degrees is a good range for survival or hunting knives but making a good choice for you angle selection is key.
- Just going for a shallow grind and final edge that will provide the sharpest blade is not always the best option available. You should consider the best most practical angle for the intended use.
- Edge angles of under 30° will give a very sharp but not durable blade edge.
The final angle will influence edge durability.
Double-bevel edge showing 20+20=40 This is the most commonly chosen knife sharpening angle. When you have a knife with a double grind of 20 degrees the total grind for both bevels is 40 degrees.
This angle is the angle that is made when the knife is in contact with the sharpening stone.
Asian knives are often only sharpened on one side. 20-degree angle sharpened to the stone on one side equals a total edge bevel angle of 20 degrees.
Asian knives that are often intended for the western market are ground on both sides but this is not traditional for Asia.
How to sharpen an Opinel knife with an oilstone!
My favourite option for sharpening a knife is the humble Oil Stone. Frankly the cheapest considering most woodworkers and DIYers already have one for another tool sharpening. The two videos in this blog post are for both types of common pocket knives. Here we demonstrate the French Opinel and the more regular double ground folding knife. Easily the Opinel can be sharpened with a stone using the flats of the blade as a guide.
The Double Ground Pocket Knife
The double ground blade requires more accuracy and some skill is required for both the first then the second grind. This is the most common knife grind and found on most cutting edges. You can sharpen these knives with good effect by hand. But if you do not have a steady hand then a knife grinding guide will help. Sometimes a new first grind is needed if the blade is in poor order. The first grind can be done by a large diameter bench grinder such as a #Tormek. You could use a linisher or belt sander mounted on a bench. If machine grinding is required you should have a pot of water ready to cool the blade as you go. Try not to allow the edge to get hot and turn blue as this will affect the hardness of the steel.
What tools do I need for sharpening knives?
Sharpening tools are necessary if you are going to do a good job keeping a good edge on your handy knife. On searching online there are many a magic sharp type machines on offer. But if your out in the field without power machines are practically useless so a manual option is necessary. Sharpening stones come in many forms. For instance natural wet stones and oil stones. Since industrial diamond has become affordable #DMT diamond sharpeners are also available in different sizes and abrasive grits.
Aluminium Oxide sharpening stones
I don’t mean a pebble but a good stone like an ‘India Stone’ which is made from the man-made abrasive aluminium oxide. India stone is a trading name for the well-known abrasives manufacturer Norton. These #NortonAluminiumOxide sharpening stones come in tan, brown or orange in colour. Not a fashion choice but the colour only depicts the abrasive grit and the type of abrasive.
Silicon Carbide sharpening stone
Norton’s Crystolon stones are made using silicon carbide and grey in colour. This distinguishes them from Norton’s Crystolon (silicon carbide) Stones which are grey in colour. So while all India Stones are aluminium oxide, not all aluminium oxide stones are technically India Stones.
DMT is recognised as a world leader in #diamondabrasives and #knifesharpeners and rightly so. For the average Joe who does not want to pay the high-end price, there are cheaper options. I do myself use both DMT and budget options. Though DMT is the best the cheap options also work and often sold in three abrasive grits for little cost. The beauty of these diamond sharpeners is that they can be made very thin. Trend makes a Diamond sharpener in the form of a credit card. These are superb for sharpening router cutters. Other pocket sharpeners are on offer such as my pen type which I keep in my pocket.
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Sharpening with a drill attachment or make do’s
Now let’s get real here and look at the logic. Now if you sharpen an edge that is relatively straight or even a gentle curve with a round sharpener or grinder you will have problems. Regular sharpening with a round sharpener will make your knife have a rollercoaster edge, yes that is bad. In this video, you will see if you analyse the edge of the kitchen knife you will see the evidence of a badly sharpened blade. To be fair to the author of this video is demonstrating alternative sharpening methods.
Using a car window, mug or rock?
Yes, this can get you out of trouble if you have a dull edge then it may be a ‘get out of jail card’. By no means do I recommend this as a method of regular sharpening. Do I have to ask if you really value your expensive new ‘Buck’ blade if you are considering this method?
How to sharpen a knife with a stone!
My favourite option for sharpening a knife is the humble Oil Stone and frankly, the cheapest considering most woodworkers and DIYers already have one for another tool sharpening. The video in the blog post for both types of common pocket knives the French Opinel and the more regular double ground folding knife. The Opinel can easily be sharpened using a flat stone using the flats of the blade as a guide. The double ground blade requires more accuracy and some skill is required for both the first and second grind.
How to sharpen a knife without a sharpener
Yes, it is possible and although technically still a sharpener but a little less specific. You have a few alternatives to the traditional blade sharpener. Could be helpful if you need to sharpen a knife in the field or you just forgot to bring a knife sharpener with you.
- A smooth stone or at least harder than the steel of the knife blade.
- Steel similar to what a chef uses
- Large HSS drill bit shank to reproduce the blades burr used just like a chefs steel.
- Emery board of around 180 grit, you can make your own by glueing glass paper to a piece of plywood or other flat board.
Sharpen a knife with a sharpener
Like I mentioned earlier it is always best to sharpen a little but often but sometimes it is not always convenient. These sharpeners come in different forms. There are some weird and wonderful looking knifes sharpening systems. Like you would expect some are better than others. Some are just gimmicks. So let’s address some of the:
In Conclusion, How Should You Sharpen your Knife
Well your not going to like it. In my experience, I have to say that the time served methods are best. First, you need to master the art of sharpening with a flat stone. The Flat stone such as a diamond or Norton India stone is the best way to learn. A cheap stone to practice on then upgrades to a better quality oil stone or diamond sharpener of three progressive abrasive grits.