Sharpening a tool with a file is a practical and effective method for restoring a dull edge, particularly for items like axes, shovels, lawnmower blades, and various garden tools. This process involves carefully abrading the metal to create a new, keen edge.
Why Choose a File for Sharpening?
Files are excellent for sharpening tools that require a more robust edge, are made of softer steels, or have larger bevels. They are also ideal for removing nicks and shaping the blade before a finer sharpening stage, if desired.
Essential Preparations for Filing
Before you begin sharpening, proper preparation ensures safety and effectiveness.
1. Gather Your Tools
- File: A mill file or a bastard file is commonly used. Choose one with a handle for better grip and safety. Files come in various cuts (e.g., single-cut, double-cut) and coarseness (e.g., bastard, second-cut, smooth). A bastard file offers a good balance of material removal and finishing.
- Vise or Clamp: Essential for securing the tool firmly.
- Safety Gear:
- Work gloves: Protect your hands from sharp edges and file teeth.
- Safety glasses: Guard your eyes from metal shavings.
- Wire Brush: To clean metal filings from the file.
2. Secure the Tool
Mount the tool securely in a vise or clamp. The part of the blade you're sharpening should be stable and easily accessible, preventing any movement that could lead to injury or an uneven edge. For instance, when sharpening an axe, secure the head so the blade edge points slightly away from you.
The Step-by-Step Sharpening Technique
The key to sharpening with a file lies in maintaining a consistent angle and applying steady pressure.
1. Determine the Bevel Angle
Identify the existing bevel angle on your tool's blade. Most tools have a single or double bevel, with angles typically ranging from 25 to 45 degrees. A common angle for general-purpose tools is around 30 degrees. It's crucial to try and match this angle with your file to avoid creating a new, less effective edge.
2. The Sharpening Stroke
This is the core of the sharpening process:
- Starting Position: Place the tip of the file on the left side of the tool head.
- Angle Alignment: Carefully align the file so its angle matches the bevel on the blade. If you're unsure, start with an angle slightly higher than the tool's back and gradually lower it until you feel it contacting the entire bevel.
- Push Stroke: Apply firm, consistent pressure and push the file forward and to the right. This motion should guide the file across the blade, concluding with the file resting on the opposite side, nearer to your hand.
- Lift and Repeat: Always lift the file completely off the blade on the return stroke. Filing in both directions can dull the file and create a less precise edge.
- Consistency: Repeat this motion, working your way along the entire length of the blade, applying the same number of strokes to each section to ensure an even edge.
3. Sharpening the Other Side (If Applicable)
For tools with a double bevel (like many axe heads), flip the tool in the vise and repeat the sharpening process on the opposite side, ensuring both bevels are sharpened evenly.
4. Removing the Burr
As you sharpen, a small curl of metal called a "burr" will form on the opposite side of the blade. This indicates you've successfully removed metal and created a new edge. You can feel this burr by lightly running your finger away from the edge (be cautious!). To remove the burr:
- Take a few very light, sweeping strokes with the file at a slightly flatter angle.
- Alternatively, you can use a fine sharpening stone or sandpaper on a flat surface to gently rub the burr off.
Checking for Sharpness
After filing, check the sharpness of your tool:
- Visual Inspection: Look for a consistent, bright edge along the entire blade.
- Paper Test: For very sharp tools, try to slice through a piece of paper. While a file alone might not achieve a razor-sharp edge, it should cut cleanly.
- "Thumb Pad" Test (Use extreme caution): Lightly rest the blade on your thumbnail. A sharp edge will feel "sticky" and resist sliding.
General Tips for Success
- Keep the File Clean: Metal shavings can clog the file's teeth, reducing its effectiveness. Use a wire brush frequently to clean the file.
- Use the Entire File: Utilize the entire length of the file's cutting surface to ensure even wear and maximize efficiency.
- Listen to the Sound: A consistent, grinding sound usually indicates proper contact and angle.
- Don't Overdo It: Stop once a burr is formed and the edge feels sharp enough for its intended purpose. Excessive filing removes too much material.
By following these steps, you can effectively sharpen many of your tools, extending their lifespan and improving their performance.
