Can I sharpen a knife with a file?

Yes, you can sharpen a knife with a file. Using a file to sharpen knives is an effective and relatively easy way to put a new edge on dull blades. Files come in different shapes, cuts, and coarseness levels, so choosing the right type of file is important for getting the best results. With some patience and the proper technique, a file can restore a sharp edge to your knives.

How Does Using a File Sharpen a Knife?

A file works by essentially grinding off material from the knife’s edge. As you rub the file against the blade at the correct angle, tiny amounts of metal are removed. This gets rid of nicks and dull areas along the edge, creating a new, clean edge. The abrasive surface of the file provides the grinding action that removes the metal.

Files have rows of teeth that form cutting surfaces. These teeth cut into the metal as you slide the file along the blade. The size, shape, and coarseness of the teeth determine how aggressive the filing action is. Finer files will remove less material for a more precise sharpening, while coarser files quickly remove metal.

Choosing the proper file depends on the current condition of your knife and how much sharpening it requires. A very dull or damaged blade may need a more aggressive file at first, then switch to a finer file. The filing motion is also important – keeping a steady angle and using the full length of the file results in an even, sharp edge.

Advantages of Using a File

Compared to other sharpening tools like stones or electric grinders, using a file to sharpen knives has some useful benefits:

Removes A Lot of Metal

The filing process rapidly removes material from the knife blade. This makes it well-suited for dealing with very dull or damaged edges. If your knife is extremely blunt, a coarse file can reshape the edge much faster than rubbing it against a stone.

Puts a New Edge on Damaged Blades

Along with removing a lot of steel, filing also fixes irregularities or defects along the blade edge. Chips, cracks, and warped sections are effectively smoothed out and straightened by the filing action. This repairs the edge so it’s uniform for the full length of the blade.

Leaves a Very Sharp Edge

Properly using a file can put an extremely sharp, clean-cutting edge on a knife. The teeth on a fine file cut a precise edge profile. Finish by draw-filing the blade – dragging it perpendicular over the file length – to hone the edge. This leaves the knife razor sharp and ready for use.

Inexpensive Sharpening Option

Good quality sharpening files are available at very reasonable prices, especially compared to electric or wet grinders. A basic set of files in varying coarseness can be purchased for less than $20. Files also have a long usable lifespan if cared for.

Portable for Touch-ups

A file takes up little space and is light enough to keep in your pocket or tackle box. For a quick touch-up sharpening without any accessories, a small file is handy. You can sharpen your fishing knife on the spot or your chef’s knife during a break at work.

Easy Freehand Use

Filing a knife is a simple manual process. No vises, guides, or electricity are required – just hold the file and blade. The freehand method gives you flexibility to sharpen various blades. Once you get the right angles down, it’s straightforward to sharpen different knives.

Choosing the Right File

Picking a quality file designed for sharpening is essential to get good results. These factors should be considered when selecting a knife-sharpening file:

Shape

The shape and dimensions of the file will determine how you’re able to use it. For sharpening knives, small triangular and square needle files are commonly used. The triangular shape allows sharpening the entire edge in a single pass. Flat or curved files can also be used.

Length

Longer files 8 inches or more are preferred for sharpening knives. The length provides a stable filing surface to create an even, consistent edge. Shorter files under 6 inches are more suitable for detailed handwork.

Cut

The cut refers to the pattern, spacing, and depth of the file’s teeth. For initial sharpening, a Single Cut or Double Cut file quickly removes metal. Switch to a smoother Second Cut or Smooth Cut file for finishing the edge. A Bastard Cut file has moderately coarse teeth for working very dull edges.

Coarseness

The coarseness is indicated by the number of teeth per inch. More teeth equal a finer file that removes less material. Coarse files(under 40 TPI) work well for repairing damaged edges, medium files (40-60 TPI) are good general purpose, and fine files (over 60 TPI) put an extra-sharp polished edge.

Materials

Better quality files are made from hardened tool steel or carbon alloy steel. These withstand the wear from knife sharpening and keep their teeth. Lower grade ones use softer steel that dulls quickly. Needle files are typically carbon steel for strength.

How to Sharpen a Knife with a File

Sharpening a knife with a file involves holding the blade at the proper angle and using consistent strokes. Follow these steps:

Secure the Knife

Clamp the knife securely in a vise with the edge facing upward. The blade should be perpendicular to the vise jaws. This prevents the knife from moving during filing. Optionally, you can hold the knife with a secure grip.

Select the Right File

Choose a file that matches the current condition of the knife. A coarse file is used for repairing a very dull or damaged edge. Use a finer file for knives that just need a touch up. Make sure the file is clean.

Find the Bevel Angle

Determine the bevel angle of the blade. Most knives are ground between 15-30°. Hold the file against the edge to estimate the angle. Match this when filing to maintain the bevel. Consistency is key.

File with Steady Strokes

Hold the file horizontally at the bevel angle you found earlier. Start filing using steady, full strokes from heel to tip. Apply light pressure. Let the file do the work of cutting the steel. Maintain the angle all the way through each stroke.

Use Crisscross Strokes

Once the edge is straight, use crisscross strokes to sharpen the edge fully. Switch to filing from the opposite direction, alternating stroke directions with each pass. The crisscross friction refines and polishes the edge.

Draw File for Finishing

Finish up by draw filing at a lower angle to further refine the cutting edge. Lightly drag the file straight across perpendicular to the blade. Repeat alternating draw strokes on each side of the edge. This straightens and polishes the edge for maximum sharpness.

Switch to Finer Files

Move down to successively finer files as you get closer to the final sharp edge. This removes scratches left by coarser files. Finish with an extra-fine file for a polished, razor-sharp edge. Take care to maintain a steady angle.

Clean and Oil the Blade

Once sufficiently sharp, wipe away any metal filings with a soft cloth. Apply a thin coating of honing oil or silicone to protect the sharpened edge. Avoid vegetable or mineral oils which can go rancid. The knife is now ready to use.

Maintaining Proper Angles

The most important aspect of filing a knife sharp is maintaining a consistent angle. Here are some tips for keeping the file at the right angle along the blade:

– Use blade width as a guide. For a 20° angle, the file should be 1/3 of the blade width from the edge.

– Cut cardboard templates matching your angle to check your file position.

– Attach angled guides to the vise jaws to hold the blade steady.

– Use permanent marker to mark the angle position directly on the blade.

– Pick a landmark like a logo or handle contour to use as a reference point.

– Stack coins or use a feeler gauge to quickly match an angle.

– Mark the file handle or your thumb with tape to constantly monitor the angle.

Common Filing Technique Mistakes

It’s easy to mess up the blade edge if the proper filing technique isn’t used. Avoid these common mistakes:

– Failing to secure the knife leads to a wobbly, uneven edge. Clamp it down firmly.

– Using too much downward pressure warps the edge and causes scratches. Let the file do the work.

– Holding an incorrect angle results in a beveled edge that’s too obtuse or acute.

– Filing back-and-forth instead of full tip-to-heel strokes creates flat spots.

– Not cleaning the file causes filings to get trapped between teeth, damaging the edge.

– Continuing to use a worn file dulls and scratches the edge. Replace files once worn.

– Forgetting to lubricate the edge after sharpening can lead to corrosion over time.

Best Files for Knife Sharpening

Here are some top files to consider using for sharpening knives:

File Details
Nicholson 8″ Mill Bastard File General purpose coarse file
Bahco 8″ Second Cut File Removes less metal for finish sharpening
Grobet 12″ Swiss Pattern File Aggressive cut repairs damaged edges
Irwin 8″ Triangular Needle File Sharpens entire edge in one pass
Nicholson 10″ Curved Sharpening File Contoured for sharpening gut hooks

These files are made from hardened tool steel to resist wear. Their length and coarseness options fit the needs of most knife sharpening jobs.

Guide to Selecting Files for Sharpening Knives

Use this guide to pick files suited for sharpening knives based on their current sharpness:

Knife Condition File Characteristics
Extremely dull, damaged 8-12 inch extra-coarse file
Very dull, small chips 8 inch coarse file (40-50 TPI)
Dull, needs new edge 8 inch medium file (50-60 TPI)
Slightly dull 6-8 inch fine file (over 60 TPI)
Like-new sharpness 6 inch extra-fine needle file

Start with a more aggressive file and work up to finer files as the edge improves.

Types of Files for Sharpening Knives

In addition to straight mill and pillar files, there are other file designs suitable for knife sharpening:

Triangular Files

Triangular-shaped files can sharpen a knife edge in just one pass. The three cutting faces let you file sides and tip without repositioning. Good for precision work.

Diamond Files

These have small diamond particles bonded to the file surface instead of teeth. The diamond grit cuts aggressively for heavy stock removal. Use with water.

Ceramic Files

Ceramic files maintain a smooth cutting face compared to steel. Leaves an extra fine edge and doesn’t load up with filings. More fragile than steel files.

Needle Files

Tiny needle files fit tight spots and sharpen areas near the handle. Can be flat, square, round, half-round, and triangular shapes. Use in a handle for fine detail work.

Curved Files

The curved filing surface matches profiled knife edges and serrations. Provides the right contour for sharpening gut hooks and other curved blades.

Using Water Stones for Further Honing

While a file puts a sharp edge on a knife, you can get it even sharper using water stones. Switch to a fine or extra-fine stone after filing to really refine the edge. Here’s how to integrate using water stones into the filing process:

– File the blade to desired sharpness using your finest file.

– Soak the water stone for 5-10 minutes before using.

– Lay the blade flat on the stone, holding it at a 10-15° angle.

– Use gentle strokes and minimal pressure when sharpening.

– Sharpen one side until a burr forms, then flip and repeat on the other side.

– Finish by using very light alternate strokes to polish the edge.

The water stone removes a tiny amount of steel, honing the edge to hair-popping sharpness. It also polishes the edge for maximum cutting performance.

Caring for Your Sharpening Files

To retain their sharpening abilities, files must be cleaned and stored properly after use:

– Use a file card brush to remove filings lodged between teeth.

– Wipe the file’s surface with an oiled cloth to prevent rusting.

– Store files individually or with protective covers to avoid contact.

– If a file gets wet, dry thoroughly and apply a thin coat of oil.

– Periodically dress the file teeth when they start to wear down.

– Don’t use files for prying, chiseling, or activities that can damage the teeth.

With proper care and maintenance, a quality sharpening file can last for years.

Conclusion

While not the fastest or flashiest method, using a file to sharpen knives is an effective technique. Files are inexpensive, simple to use by hand, and portable for convenient sharpening anywhere. Start with a coarse file to repair the edge, then use finer files to create an incredibly sharp edge. With practice to perfect your angles and technique, you’ll be able to sharpen all your knives and tools with a file. Just take care when filing and utilize the full length of the file in smooth, even strokes. The result will be knives that retain their edges longer and are always ready for service when needed.