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We have all heard that a sharp knife is a safe knife, so it is not only good to keep your knife sharp to be able to cut easily, but also in the interests of safety. There are many ways to sharpen a knife to get it to the point of having a good edge, but can you do this without specialized sharpening equipment? Can you sharpen your knife with a file and get a good edge?
A file can be used to sharpen a knife as a stand-in measure by using the following steps.
- Secure the knife.
- Select your files.
- File the first edge with a shallow angle.
- Turn the knife over and file the other side.
- Check for a burr.
- Strop the knife.
- Check for sharpness.
Of all the methods available to knife owners to sharpen their knives, using a file to get the job done is probably one that is not at the top of anyone’s list.
There are certainly other methods available to get this job done the would produce a much finer edge on the blade than a set of files. However, by taking care during the process and finishing off the edge properly, you can get a serviceable edge back on your knife.
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Steps To Sharpen A Knife with A File
While a file is probably one of the most basic tools that you can use to sharpen a knife, you are going to need some additional equipment other than the files.
One of the most important additional tools that you will need is a method to secure the knife in position and keep it from moving around while you work on it with your file.
You are also going to need a method to finish off the edge properly to take the sharp edge to the next level of sharpness.
We will cover the additional equipment that you may need for the task as we go through each of the steps where that equipment will be required.
1. Secure The Knife
As we have already mentioned, securing the knife while you work on it is an important aspect of getting prepared to sharpen your knife with a file.
Having your knife secured will stop it from moving around while you push the file across the blade and will allow you to concentrate on the edge and the angles that you are filing at to keep them as even as possible.
It would be pretty much impossible to hold the knife in one hand and file the edge with the other and expect to maintain the filing angle and get a symmetrical edge across the length of the blade.
The best way to secure the knife properly to be able to use a file on the blade is by means of a bench vise. A bench vise will hold the knife securely in place, but there are a few things you need to watch out for when clamping your knife in a vise.
You will be putting the handle of the knife in the vise, so do not crank the vise too tight on the handle. You could crack or split the handle material.
The jaws of the vise could also mar the finish on the surface of the handle, so it would be best to place a piece of leather between the handle and the vise jaws to prevent this.
2. Select Your Files
Not all files are created the same, which means that you are going to have to be selective in your selection of files to sharpen your knife.
Files are made to remove material quickly, so most files are considered coarse abrasive. The ideal would be to have a set of files that progressively go from coarse to fine, which would help you to refine the edge without leaving deep scratches in the metal.
A medium coarse file would be the best one to use to start off with, as this one will remove material quickly but not put deep scratches on the edge.
If you have a fine file as well, you can use this one to refine the edge for your last few passes across the edge of the knife.
3. File The First Edge With A Shallow Angle
With the knife secured in the vise, you need to match the angle of the file as closely as possible and begin filing the edge.
Only file with push strokes, pushing away from the sharp edge. Pulling the file back across the edge will gouge the edge and even take chips out of it.
Count your strokes as you file, using long strokes across as much of the length of the blade as possible. If necessary, write the number of strokes that you performed on this side on a piece of scrap paper.
Depending on the coarseness of the file, once you have made 2 or 3 passes of the file across the edge, move on to the next step.
4. Turn The Knife Over And File The Other Side
Turn the knife over in the vice so that you can sharpen the other side of the edge. You may have to move it to the other side of the vise to still be able to perform the action with the file as a push stroke rather than a pull stroke.
File the second side using the same angle and using the same number of strokes as you did on the preceding side.
If you do an uneven number of strokes on one side, the sharp edge of the knife will be off to one side in relation to the spine of the knife, which will compromise the cutting ability of the knife.
TIP: Do you own forged knives? A lot of people are asking if forged knives can be sharpened. Find out the answer in the article below:
5. Check For A Burr
Once you have completed the same number of strokes on both sides, check that a burr has developed on the edge of the knife.
If a burr is present, then the knife is ready for the next step. If there is no burr present, then repeat steps 3 and 4 to refine the edge and establish the burr.
6. Strop The Knife
Once the burr has been produced, you are almost at the end of the process. The burr needs to be removed and the sharp edge polished.
The best way to do this is with a leather strop with a little rubbing compound or jewelers rouge on the surface of the leather.
Pass the edge of the knife over the leather strop 5 or 6 times on each side, maintaining the same angle as the edge of the knife and using only light pressure. This will remove the burr, polish the edge and enhance the sharpness of the edge.
If you don’t have a leather strop, a leather belt will work as a suitable stand-in or even a ceramic tile.
7. Check For Sharpness
The final step is to check that you have achieved the desired level of sharpness for your knife. The most common way to do this is to see how well it will slice through thin paper using minimal pressure.
If your knife can do this easily, then the knife should be sharp enough. If it cannot, and there are jagged areas on the edge that get hooked up on the paper, you may have to go back to the files to refine the edge and improve it that then repeat the stropping.
TIP: Have you ever wondered if it is possible to sharpen a knife with a cheese grater? If so, you will be interested in the article below!
Which Knives Shouldn’t De Sharpened With A File
Files are hard on knives and remove a lot of material during the sharpening process. For this reason, a file is generally not the best way to sharpen a knife.
If you have no other means of sharpening the knife, then sharpening it with a file would be preferable to working with a dull knife.
However, there are certain knives that should never be sharpened with a file. Kitchen knives that are made from thin steel and with a very shallow secondary bevel will be extremely difficult to sharpen successfully with a file. The file is too coarse and would simply damage the edge further.
The most appropriate knives to sharpen with a file would be a bushcraft knife or an outdoor-style knife that is made from thick steel that would handle the rigors of being sharpened with a file.
BTW: If you want to know more about Japanese and other types of knives and their sharpening check out the books listed above. These books are recommended by professional sharpeners and knife makers (Amazon links):
- Japanese Kitchen Knives: Essential Techniques and Recipes
- The Knifenerd Guide to Japanese Knives
- Knife: The Culture, Craft, and Cult of the Cook’s Knife
- Sharp: The Definitive Introduction to Knives, Sharpening, and Cutting Techniques, with Recipes from Great Chefs
While it is certainly possible to sharpen a knife with a file or a set of files, there are many other alternatives that would do a much better job on the edge, and that would be a lot easier to use.
Before you take a file to your favorite knife, consider some other less drastic methods, such as using fine sandpaper on a block of wood to re-establish the edge on the knife.
Sharpening with a file is more appropriate for heavier duty blades such as axes and chainsaws rather than fine-edged cutting tools such as a knife.
TIP: If you use your knives frequently, without regular maintenance, or by accident, they can become damaged. It is good if we can repair such damage. For example, do you know how to fix a broken knife tip or a broken knife blade? If not, find out in the articles below!