Sanding With Grinder (Angle Grinder as Sander)

Preparing wood for your next project often requires taking away mill marks or sanding the surface to smooth out any rough edges. And while the angle grinder may not be the first tool you think of for sanding wood, it is a versatile device that can do many things in your workshop.

Can I Use an Angle Grinder for Sanding?

Yes, you can use an angle grinder for sanding. By attaching an abrasive flap disc you can turn the angle grinder into a sander and use it for sanding wood, metal, welded joints etc. The drawback is that, you cannot use it to flatten an uneven surface like a belt sander. While it is not a method to produce accurate results, it works well to remove material fast.

There are two methods you can apply to use your angle grinder to sand.

The first and the most common method is by using the flap disc. The second method is to utilize an orbital sander attachment. While the second option is more complex and require more investment, it offers best results in terms of surface quality.

Let’s start with the first method. While this technique is commonly used in metalworking, it can also be used for sanding wood. Of course, you will need the right type of disc when using the angle grinder for snading. This is where the flap disc comes in. This is a common sanding pad used for the angle grinder which makes removing the top layer of materials much easier to accomplish.

Sanding with Angle Grinder

Keep in mind that you can use the angle grinder for sanding a wide variety of materials from wood and wooden floors to decking, metal, concrete, fiberglass, and more. Another popular use of the angle grinder is to strip away the paint from surfaces such as wood and metal.

Method #1: Use a Flap Disc

The flap disc is a sanding disc that consists of overlapping sections or flaps that are spaced across the surface of the disc. When used on an angle grinder, the flaps can quickly sand large areas in a relatively short time. They are exceptionally well-suited for pallet or reclaimed wood as they can quickly smooth away the surface area.

Type of Flap Disc

You may have noticed there are two basic types of flap discs, flat and angled. The flat version is designed to sand at angles up to 15 degrees. As the name suggests, it is flat across the entire surface area. This is often called a Type 27 flap disc.

The Type 29 flap disc is flat in the center, but then angles downward towards the edges. This flap disc is perfect for sanding at 15 to 25-degree angles. The angle of the disc allows you to sand steeper areas easier and with more consistency compared to a Type 27.

Disc Size

There two sizes to consider; one is the grit size of the abrasive and second is the actual size (diameter) of the disc. To use the flap disc, you will need to find one that is the right size for the job you want to accomplish without being too big or small to be attached to the angle grinder.

Grit Size:

A smaller grit size denotes course grain which removes material at a higher rate, but with a rough finish. For instance, a 30 – 40 grit wheel can be as effective as grinding. For wood, I recommend you start with a 60 or 80 grit wheel and work your way up to 120-grade disc for smoother finish. Be sure to purchase a flap disc that is best suited for your needs.

How to Use an Angle Grinder to Sand?

Step-1: Attach the Flap Disc

Now that you have the right flap disc for the job, attach it securely to the angle grinder. The flap disc operates essentially in the same manner as the grinding discs.

Step-2: Wear Safety Equipment

Be sure to take the proper safety precautions which includes wearing eye protection and ear protection. You may also want to use a pair of safety glove.

Step-3: Match the Angles

Switch on the grinder and gently apply the flap disc to match the angle of the flap disc to the surface. The grinding angle of Type-27 flap disc is approximately 5° to 15° whereas the Type-29 disc requires you to work at angle ranging from 15° to 35° on a relatively flat surface.

Step-4: Let the Disc Do the Work

Do not apply too much pressure on the workpiece. When working with metal, excessive pressure on the flap disc will result in tearing of the flaps. In woodworking this may cause gouging and burn marks which will be very difficult remove.

So, put light pressure and let the disc do the sanding. Then using back and forth motions sand off the top layer of the workpiece.

Step-5: Finish Sanding

Once you have removed the surplus material with the rough disc, switch to a higher grit flap disc to finish your work.

Method #2: Orbit Sander Attachment for Angle Grinder

For top-down sanding, an orbital sander is the preferred device to use. However, you can turn your angle grinder into an orbital sander with the proper attachment. This is an attachment that extends the working distance of the device, so you can create internal curves, profiles, and shells. While the attachment itself is rather small compared to a standard-size orbital sander, it does allow you to do most of the work for far less expense.

The attachment is essentially an arm-extension of the angle grinder. It extends the sanding pad outward by enough distance so you can use it at any angle. This overcomes one of the issues with using an angle grinder in which the device itself gets in the way of making certain types of sanding possible. By extending the sanding pad away from the grinder, you put enough distance away from the device to make any type of sanding motion you want.

Sanding Attachment for Grinder – Click Here to Get One

You can choose an orbit sander attachment that contains a flexible backing pad. This creates a smooth finish to your work. If your goal is to sand without scarring, blemishing, or scratching the wood, then this is the attachment to use.

Warning: The attachment extends out of the safety guard. Wear proper safety equipment including a face shield.

The downside is that the device is still angled compared to the sanding pad. As a result, you have less control over the sanding action. This also means, you cannot press your weight into the pad as you would with a traditional orbital sander. Plus, the pad itself is relatively small, so it is best used on materials that are also small or have tight corners that would be tricky for a larger sanding pad to reach.

Pros & Cons of Using Angle Grinder as a Sander

There are several advantages to using an angle grinder for your sanding needs.

Pros

The first and foremost is the design of the angle grinder itself which allows for quick sanding of surfaces. The open design allows you to work the flap discs at any angle, so you can quickly sand surfaces.

Another strong advantage is that flap discs are relatively inexpensive and will last for a considerable amount of time under normal use conditions. The design of the flap disc combined with its inherent strength means that you can use a single disc for a considerable time before having to change it out.

Changing out flap discs is another advantage of the angle grinder. Its easy access allows you to quickly remove and attach new discs securely in place. This means that you can increase your work productivity by spending less time attaching and detaching discs.

Cons

Of course, the angle grinder does have some limitations compared to traditional sanders. The most obvious is the inability to work on uneven surface to make it flat. You could use the angle grinder to sand the high points and to remove lot of material quickly. But if you are trying to achieve a smooth flat surface, get a real sander.

Another disadvantage is the relatively small size of the discs available. This limits the angle grinder to small and moderate-size pieces of wood for sanding purposes. If you are sanding larger surfaces, such as plywood or large planks, then a belt sander or a random orbital sander is a better tool for the job.

Finally, the design of the angle grinder itself makes it more likely to suffer damages or abrasions because of the lack of control as compared to orbital sanders and other devices.