Finish sanding is often the first thing many DIYers think of when they are looking for a new sander, but a belt sander is better for working with rough material and gradually increasing the smoothness, to the point where you can start finish sanding with a palm sander or orbital sander. It's also one of the most effective tools for stripping paint, stain, and varnish, allowing you to refinish old furniture and update the aesthetic of your home without investing in new items.
However, the power that a belt sander uses to cut through layers of paint will also remove large amounts of material at a rapid pace, so you need to be in complete control of the tool to avoid damaging the project. Before tackling a sanding or staining project with a belt sander, it's important to learn how to use a belt sander properly.
What Is a Belt Sander?
There are several different sanders that are commonly used by DIYers, so it can get confusing if you aren't familiar with each type. A belt sander has a pair of rotating drums that rapidly turn a sanding belt. These tools can either be handheld or stationary and they are typically used to aggressively remove wood, metal, or plastic. They are also very effective for stripping paint, stain, and varnish.
Belt Sander vs. Orbital Sander
An important part of taking on a sanding project is knowing which sander to use at what point, because many sanding projects actually require you to use at least two different sanders to get a completely smooth finish.
Belt sanders are very powerful sanding tools that are best for stripping paint or stain. They are also the right choice for removing several layers of rough material in a hurry. However, belt sanders can be difficult to manage on surfaces that are not flat. Additionally, the rotation speed is too aggressive to achieve the same smooth finish that is possible with an orbital sander.
Orbital sanders are smaller sanding tools that are designed for use on flat or curved surfaces. They can be used for stripping paint or sanding through several layers of rough material, but be prepared to work for a long time to achieve the same results a belt sander can accomplish in less than half the time. Instead of stripping or fighting through rough material, orbital sanders are better for finish sanding. After using a belt sander to prepare the material, switch to an orbital sander to get the final smooth finish for your project.
Belt sanders have a continuous loop sand belt circulating between two rotating drums, while an orbital sander has a rectangular head that rotates to get rid of the undesired material.
The main purpose of belt sanders is removing or minimizing a large number of materials from a workpiece at a high rate. In contrast, an orbital sander aims to achieve a smooth surface finish, especially at edges.
Better for sanding large, flat surfaces.
Significantly more powerful than an orbital sander.
Removes material with a rapidly rotating sanding belt.
Best for stripping paint and removing rough material.
Designed for small, flat or curved surfaces.
Lacks power, but has better control than a belt sander.
The sanding head quickly orbits to achieve a smooth finish.
Intended for sanding delicate material and finish sanding.
Parts of a Belt Sander
In order to learn how to use a belt sander, you should understand what the various parts are, including the trigger, switch, handle, sanding belt, tensioning lever, and drums.
- Trigger: Similar to the trigger found on other tools, the trigger on a belt sander is used to activate the belt. Squeeze the trigger and the belt will begin to rotate. If you release the trigger, the sanding belt will no longer be powered, but it will still take some time for the belt to run out of inertia.
- Switch: Stationary belt sanders tend to have a switch instead of a trigger. This just means that you will not be able to control the speed of the belt. Flip the switch and the belt sander will turn on, quickly increasing the speed of the belt up to the maximum speed.
- Handle: Portable belt sanders typically require two hands to control, so while one hand grips the trigger, the other hand needs to hold on to the forward handle. Use this two-handed grip to ensure that you have full control over the belt sander and to avoid damaging the material.
- Sanding Belt: Fit the sanding belt on to the drums and tighten the belt with the tensioning lever to ensure that it doesn't slip off during use. The sanding belt rotates rapidly when the belt sander is on, quickly stripping paint or removing layers of material. Make sure to change the sanding belt if the sandpaper is clogged, or the abrasive has worn off.
- Tensioning Lever: This part of the sander increases the distance between the two drums in order to ensure the sanding belt is tight enough that it won't slip off during use. Releasing the tensioning lever allows you to replace the sanding belt when necessary.
- Drums: The sanding belt fits on the two drums. Once it is in place, the belt sander can be turned on. The drums rotate at a very high speed, driving the sanding belt through the target material.
Belt sanders function by driving the belt and the attached sand paper at aggressively high speeds to rapidly remove layers of wood. Make sure to wear appropriate personal protective equipment (PPE) including safety glasses, a mask, and gloves. A long sleeve shirt, long pants, and closed-toe shoes are also a good idea to help prevent the sander from accidentally coming into contact with your skin.
How to Use a Belt Sander
Select the Sandpaper
The first thing you need to do before starting a sanding project is determine the sandpaper you need to use. Belt sanders use sandpaper belts that come in a range of grits. Typically, a belt sander is used for stripping paint or rough sanding, so you will likely be starting with a sandpaper belt that has a coarser grit. Look for 40, 80, or 100 grit to start the project, then work up to finer grits for a smoother surface.
If you are going to be using a finish sander after using the belt sander, then you probably won't need to exceed 120 grit, but if you will only be using the belt sander, then consider increasing the grit to at least 180 for a smoother finish.
Prepare the Work Area and Material
Belt sanders are powerful tools. This means that it isn't enough to grip the tool tightly with both hands while you work, you also need to ensure the material cannot be flung across the room. To make sure that you aren't throwing wood across the workshop, clear a space on a workbench and use clamps to secure the material.
If you feel like the clamps will get in the way, then you can use a fence or block at one end of the material to prevent it from moving. Just make sure that you don't change the direction you are sanding unless there is a fence or block at the other end as well.
Flip the switch or squeeze the trigger on the belt sander to start the motor. If you are using a stationary belt sander, keep the material away from the belt until it is up to full speed, then gradually bring the material into contact with the belt to start sanding.
If you are using a portable or handheld belt sander, hold the tool away from the material you intend to sand until the belt is up to speed. Bring the rear of the sander down to the surface of the material, making sure that you grip the sander tightly to prevent it from slipping out of your hands. Lower the front of the sander and start moving the tool across the surface of the material.
Strip or Sand the Material
You can usually rely on the weight of the belt sander to provide enough downward force for sanding, but you do need to maintain a firm grip on the tool while you work. Sand with grain to help avoid creating noticeable lines in the material. If you are leveling an uneven surface, then you can sand diagonally, but as the material becomes level, it's recommended to switch to a finer grit sanding belt and begin sanding with the grain. This extra step removes any scratches that are created by diagonal sanding.
Try to use long, even strokes while maintaining steady pressure to get a smooth, level finish. Keep in mind that applying too much pressure can result in deep gouges. Leaving a belt sander in one place too long will quickly wear down the material. Keep the sander moving in the direction of the wood grain for an even finish. Take it slow and check your work frequently. Clean away any debris that may be obscuring your vision to help prevent damage to the project.
Belt sanders create a lot of debris. Some models are made with a built-in vacuum outlet that can connect to a shop vac or a workshop vacuum system to suck up the dust and debris as it's created. However, if you don't have a connected vacuum system, then you are left to clean up after the project is finished.
Use a shop vac, broom, or brush to clean up the sawdust and debris. Make sure to clean out the belt sander as well. If debris is left under the belt, it can cause uneven sand patterns in your next project.
When to Replace Your Sandpaper
A belt sander is a very powerful tool, but if it doesn't have a fresh sandpaper belt, then it won't be able to strip or sand with the same results. You can tell if the sandpaper needs to be changed by simply checking the abrasive. If the abrasive is completely worn off or if it's clogged with wood dust, paint, or any other material, then it's time to replace the sandpaper.
If you are desperate to finish a project and don't have any extra sandpaper on hand, you can clean clogged sandpaper with a stiff brush or even an old toothbrush. However, it should be mentioned that this is a temporary fix. It's recommended to switch to a new sandpaper belt as soon as possible to get the best results.