How to Use a Random Orbital Sander

One of the more common tools that can be found in many DIYer workshops is the random orbital sander. This power tool is used primarily for finishing woodworking pieces, though it also has the capability of being used for stripping paint and stain. Random orbital sanders were developed as an improvement over standard orbital sanders. The difference between them is that, instead of simply rotating in a circle (which tends to create swirl marks on the material), the sanding disc on a random orbital sander moves in a circle and it moves in an oval orbit around the sander's Z-axis.

This combination of movements is more random than a simple orbit, reducing the chance of creating distinct sanding patterns in the material. Whether you are working on plastic, metal, or wood, it's a good idea to learn how to use a random orbital sander to get smooth, scratch-free finishes on your creative DIY projects.

Random Orbital Sander vs. Belt Sander

There are many different sanding tools, but two of the most common sanders are random orbital sanders and belt sanders. However, despite falling into the same tool category, these two tools have distinct jobs in the workshop.

Random orbital sanders are made for fine sanding or for working on smaller pieces. Due to this purpose, they are less powerful and not as effective at stripping paint or stain. Random orbital sanders are designed to sand in a combined movement pattern so that they do not create swirls or other distinct sanding patterns. They can also be used on plastic, metal, and wood and typically cost about $50 to $200.

Belt sanders should not be used for finishing work. These powerful tools are made for stripping paint, stain, and several layers of wood off of large pieces, making them ideal for quickly and effective sanding rough surfaces on large, flat pieces of wood. They can easily gouge the material you are working on if you don't pay attention to the amount of pressure you are applying to the sander. You can expect to pay between $50 to $250 for a belt sander.

Parts of a Random Orbital Sander

In order to better understand how to use a random orbital sander, it's necessary to have an idea of what the various parts are called and the purpose of each part.

• Power Switch: Use this switch to turn the sander on or off. Just make sure that the sander is plugged in or the battery is charged.
• Palm Grip: The top of the sander is commonly called the palm grip. It can be used to hold the sander in the palm of your hand in order to control the movement of the tool over the material.
• Body: The body of a random orbital sander is where the motor is housed. It can also be called the barrel grip because most random orbital sanders have a narrow body that can be used to hold and control the movement of the tool instead of the palm grip or D-handle (if applicable).
• Lip Seal: A lip seal is a rubber seal between the body of the sander and the sanding pad. It prevents sawdust from entering the internal motor of the device.
• Sanding Pad: The sanding pad is located on the base of the sander. The pad moves in an oval orbit around the Z-axis of the sander and also rotates to create a random orbital movement. Attach a sanding disc to the sanding pad to sand or strip material.
• Power Cable: Plug this cable into an available electrical outlet to provide power to the sander.
• Battery: If the sander is battery-powered instead of corded, it will have a rechargeable battery that can be removed and recharged when the tool runs out of power.
• Dust Bag: Some random orbital sanders have a built-in dust bag that collects sawdust, metal shavings, and other debris created by the sander.
• D-Handle: This is a secondary handle that is positioned at the back of the sander. The name of this part, D-handle, refers to the shape of the handle. Not all random orbital sanders have a D-handle.

Safety Considerations

Whenever you are using a power tool, it's important to take certain safety precautions in order to ensure that you can finish your project without incident. Using a random orbital sander is no exception. Wear a protective mask so that you are not breathing in airborne sawdust, metal shavings, or plastic shavings while you work.

It's also a good idea to wear gloves that can help dampen the vibration of the tool and safety glasses to protect your eyes from flying debris. Loose clothing, jewelry, or hair can get trapped in the moving parts of the tool, so make sure to tie back long hair, take off jewelry, and wear appropriate clothing while you use the random orbital sander.

How to Use a Random Orbital Sander

1. Attach the Sanding Disc

   Random orbital sanders use a sanding disc instead of a piece of sandpaper. The sanding disc can typically either stick to the sanding pad, if the disc has a peel-and-stick backing, or the sanding disc may have a hook-and-loop backing that attaches to the sanding pad.

   Make sure to choose the correct sanding disc grit for the job. Keep in mind that some projects may require the use of a coarse, medium, and fine sanding disc to produce the desired results.

   • 20-36 grit is considered coarse and it's ideal for stripping stain, paint, or as the first step to smooth a rough surface.
   • 40-60 grit is a medium grit sanding disc that can be used for light stripping or coarse finishing. It's best when used on a finishing project as a midway point between a coarse-grit sanding disc and a fine-grit sanding disc.
   • 150-180 grit is used for finishing woodworking and metalworking projects. This fine grit sanding disc ensures the surface of the piece will be smooth when you are done.
     

2. Secure the Workpiece

   Before stripping or sanding a workpiece, it's necessary to secure the material to the workbench, workhorses, or worktable in order to prevent the piece from moving while you work. It's also a good idea to either connect a vacuum to the sander, if it has a vacuum port, or set up a shop vac that can be used to quickly clear sawdust away from the project so you can see the material as you work.
   

3. Turn on the Sander and Start Sanding

   With the sandpaper loaded and the sander plugged in or equipped with a rechargeable battery, you can turn the random orbital sander on. It's recommended to try sanding a test piece of wood until you get the feel of the tool in order to avoid damaging the workpiece.

   The rotational force of the sander can quickly eat away layers of wood if you aren't careful, so when you begin sanding it's important to keep the sander moving across the material, using even pressure to sand the workpiece.

   You can pass over flat surfaces in a back and forth motion. If you’re sanding a piece of furniture, you can follow the lines of the furniture. When you’re done, you’ll have a smooth and consistent finish free of any swirl marks, especially when you work your way down to fine-grit sandpaper.

   Nearly all modern random orbit sanders have a ventilation system with a dust bag for collecting excess sawdust. Using the dust bag keeps your work area clean and tidy and the air breathable.

   Place the sander onto the workpiece, grip it firmly, and then switch it on. Begin moving the sander in long overlapping movements.
   

4. Move the Sander Across the Workpiece Surface

   A random orbital sander doesn't have the same power as a belt sander, but it can still gouge the material if you put too much pressure on the sander or keep the sander in one place for too long. Move the sander across the material and keep it moving continuously while paying attention to the surface of the material to get the desired results.

   Move the sander back and forth over flat surfaces and make sure to follow the grain lines on wooden furniture. Try not to tilt the sander as you move it around, as this can create divots and uneven marks in the wood. Leave the edges of the workpiece for last. When you're finished sanding you can use a technique called "grain popping" where you take a warm damp cloth and wipe it on the sanded surface to open up the grain of the wood to better receive any stain.
   

5. Remove the Sander and Clean Up

   Once the project looks like it is finished, remove the sander from the material and use a vacuum to clean away any excess sawdust. Double-check the material to ensure that you are satisfied with the result, then clean the sander and put it away. Make sure to unplug a corded sander or charge the battery on a cordless sander.
   

   Tip

   There is some debate about whether the sander should or should not be in contact with the material when it's turned on or turned off. The bottom line is that it shouldn't matter when the sander is turned on or turned off as long as you are continually moving the sander while it is in contact with the material so that it doesn't have the opportunity to form a pattern in the wood, plastic, or metal.