Rasps as abrasive tools have been used for centuries. Bronze rasps were found in Egypt (1200 – 1000 BC) and iron rasps in ancient Assyria (7th century BC). Rasps were handmade until the 1850s, after which machine-made variants were introduced.
Today, almost all rasps are made by machine, though handmade ones are still produced to shape and smoothen wood angles.
What is a rasp?
A rasp is a hand tool used in shaping wood and other materials. This tool is a coarse form of file used to smooth or shape a surface through abrasion. It’s made of case-hardened steel with an individual tooth punched into its body. The body of the rasp has a tang at one end where a handle is fitted.
You’ll find rasps in rectangular, round, or half-round shapes and vary in coarseness. They are typically used in woodworking in removing material rapidly while maintaining ease of control.
Rasps function to profile or curve the wood in a fast and efficient manner. Still, the result of the rasping process is rough, leaving the surface ready for finer tools, such as files.
Types of rasps
“Rasp” is a general term that describes the whole range of items with similar characteristics. But, there are actually types of rasps that vary according to where and how they’re used.
- Cabinet rasps. This type is the most popular and comes in different lengths, widths, and shapes. The cabinet rasp is ideal for initial shaping. At this stage of the work, speed and material removal are the important considerations. The particular type of cabinet rasp you need depends on what you are working on.
- Round rasps. This type varies in diameter and length, with each type suitable for a particular situation or job, such as carving or shaping in acute angles or tight spaces.
As implied by its name, this rasp is round with teeth cut throughout the usable length and around the circumference. This type is best for carving detail or working on circular shapes. It’s also used for making spiral patterns in the wood. Round rasps are known as rat-tail files.
- Three-square rasps. This type is either square or triangular in shape, with teeth punched into its usable length. Its main use is in shaping and smoothing notches or angular shapes in wood. Other uses include squaring drilled circular holes and smoothing out joints.
- Knife rasps. This type looks much like a knife with a wide body that tapers to a thin point. The top of this rasp is flat. Its body is double cut, which means the teeth runs in two different directions. The knife rasps are ideal for cutting narrow slots in wood.
How to use the rasps to shape and smoothen wood angles
The main function of a rasp is to help you create good flowing curves and shapes in your wood material. Another use is in cutting notches and angular shapes.
To achieve your desired effect, choose the correct type of rasp for your work. For instance, use a flat one for flat surfaces. The guide below will help you work effectively with your rasps:
Secure your work tightly. Securing your work means the material you are working on is tightly gripped to prevent any movement while you’re working.
Mark the working area. Mark the area you want to work on with pencil. Be sure the mark is accurate since you cannot glue the material back once you are done.
Start shaping your material. With your dominant hand, hold the rasp’s handle and with the other hand, hold the material firmly between your thumb and index fingers. Have the tip of the rasp on your working area and work by pushing it through and across the wood. Avoid pushing the tool down. Continue working until you get the desired shape. Don’t worry about the rough finish at this point.
Smooth out the shape. To work on smoothing out the shape, use a finer grade tool, choosing the middle of the range. Hold the rasp and start running it across the surface. Check your work regularly to see how smooth the material is or that you are not taking too much of the material off.
Finishing and final smoothing. This is the final stage where you want to see a smooth and fine finish of your work. At this stage, use a fine grade sandpaper. Test the sandpaper on a small area to make sure you’re using the right grade of sandpaper.
You might think the rasp to be a simple tool that you can use on any material. However, getting the right type of rasp, as well as the right shape and coarseness, for a particular job should be your first consideration if you are to make the most of your woodworking project.
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