5.4: Files and Rasps

5.4 Files and Rasps

Machines are excellent for removing material quickly, but many woodworking shapes still require hand tools.

Files and rasps allow you to work directly on a surface and remove material exactly where it is needed.

They are especially useful for:

• refining curves;
• shaping interior openings;
• correcting small irregularities;
• blending transitions; and
• preparing a shape for sanding.

Learning Outcomes

After completing this section, you should be able to:

• Explain the difference between a file and a rasp.
• Identify several useful file and rasp shapes.
• Choose a tool appropriate to a flat, convex, or concave surface.
• Use files and rasps as part of a coarse-to-fine shaping sequence.
• Recognize when to stop shaping and begin sanding.

Rasps

A rasp has relatively large, raised cutting teeth.

Rasps remove wood quickly.

They are useful when a saw cut has established the rough shape but significant material still needs to be removed.

A rasp is generally used before a file or fine abrasive.

Files

A file has smaller cutting teeth and generally leaves a smoother surface than a rasp.

Files are useful for refining a shape after the rough work has been completed.

Depending on the type, a file may be used on wood, metal, or other materials.

Keep woodworking files clean and in good condition so they continue to cut effectively.

Common Shapes

A few shapes cover many woodworking situations.

Flat File or Rasp — Useful for flat surfaces and outside edges.

Half-Round File or Rasp — Has one flat side and one curved side. Useful for both flat surfaces and curves.

Round File — Useful for holes and tight concave curves.

Different sizes and cuts remove material at different rates.

Choose a tool that roughly matches the shape you are trying to create.

Match the Tool to the Surface

For a:

Flat surface — Use the flat face of an appropriate file.

Convex outside curve — A flat or half-round tool may work well.

Concave inside curve — Use the curved side of a half-round tool or a round file.

Trying to force a flat tool into a tight inside curve can create unwanted flat spots.

Secure the Work

The workpiece should be stable while filing or rasping.

Whenever practical, secure it with:

• a vise;
• clamps; or
• another appropriate work-holding method.

A secure part allows better control of the tool and better feedback from the cut.

Work From Coarse to Fine

A good shaping sequence might be:

Band Saw → Coarse Rasp → Fine Rasp → File → Abrasive

Not every project needs every step.

Choose the tool based on how much material remains.

If you still need to remove 1/8 inch of wood, fine sandpaper is probably not the efficient tool.

If the shape is already correct and only small tool marks remain, a coarse rasp may remove too much.

Use the Entire Tool

When possible, make long controlled strokes that use much of the cutting surface.

Repeatedly using one small section of a file or rasp wears that area quickly and can make it more difficult to produce a smooth surface.

Check the Shape Frequently

Stop often.

Look at the work from different angles.

Run your hand across the surface.

Check for:

• flat spots;
• bumps;
• abrupt transitions;
• uneven curves; and
• areas where too much material has been removed.

Hand shaping works best when you remove a little material and reevaluate often.

Know When to Switch Tools

The goal is not to make the wood perfectly smooth with a rasp or file.

Once the shape is correct, move to abrasives.

Do not continue filing simply because tool marks remain if the next sanding step can remove them efficiently.

Check Yourself

1. What is the basic difference between a rasp and a file?
2. Which tool would usually be used first?
3. Why is a half-round tool useful in woodworking?
4. What tool shape works well on an inside curve?
5. Why should the workpiece be held securely?
6. When should you stop filing and begin sanding?