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How to Cut Ductwork with an Angle Grinder – A Complete Guide

Thinking of fitting new ductwork or taking it out? An angle grinder could be used to cut through them.

How do you cut ductwork with an angle grinder?

Begin by getting organized and setting the appropriate cutting disk. Then, you make sure everything is fully functioning and begin cutting. Lastly, sand out the rough edges for a smooth surface.

Surely, this level of info won’t cut it. We’ve put together a guide on how to cut your ductwork using this tool. For a more in-depth tutorial on the know-hows of an angle grinder, read on.

Let’s get to it!

Purpose of Using An Angle Grinder 

An angle grinder is a multipurpose tool used for Grinding, Cutting, and Sanding. They work especially well on metallic surfaces.

It can be a perfect alternative to a wide range of tools. For instance, using a jigsaw to cut ductwork would result in a mess. You’d have to clean the dust and metal shreds which are health hazards.

Their wide range of cutting disks and cutting speeds makes it very versatile. Its most notable feature is its guard. The adjustable guard can be rotated to control the direction of sparks and debris.

However, there are safety measures you have to take before using one. As a high-powered tool, it can cause serious damage if misused. 

This is why angle grinder mishaps are very common. Not following these guidelines may botch your ductworks. This may render you to choose a replacement for your duct boards.

Fret not! We have you covered.

We’ve provided a complete guide on how to use an angle grinder. We’ve also added a few hacks and tips for the tool.

We’ve also added the type of disks you’ll need to get the job done.

Step by Step Guide to Cutting The Ductwork

Now that we’ve gone over the basics it’s time to get into the details. Before even attempting to cut ductwork, we must make preparations.

So let’s get into the grimy details!

Step 1: Safety First!

Using an angle grinder generates a lot of sparks and debris. So, it’s essential for you to follow these safety tips when using power tools.

Always wear safety glasses and a face shield to protect your face and eyes. It’s wise to wear ear-muffs or earplugs to cushion the grinder’s deafening sound.

When using an angle grinder there is a potential fire hazard. This is why you should wear fire-resistant sleeves or jackets. Don’t forget to wear heat-resistant gloves too.

If you’re unsure about which gloves to invest in, take a look at our picks below:

Glove 1
Glove 2 

Now that you’ve put your gloves on, you can move onto the next step.

Step 2: Initiate Test Run on Angle Grinder

Inspecting your angle grinder is one of the steps you can’t ignore. Making sure your tool is fully functional will reduce the rate of accidents.

First, make sure the grinder is not connected to a power source. After unplugging it, make sure the cord does not have any frays.

Next, check the guard of the grinder along with its handle. Make sure the guard can move freely and the handle is sturdy.

Move on to checking the cutting disks. Watch out for any cracks or knicks as they may cause the disk to shatter.

After you’ve checked all the components, run the grinder at a distance. Run for at least 5-10 seconds to see if everything goes smoothly. Look for any wobbles in the disk and reinstall if it wobbles.

Now, we move to the next step, cutting the ductwork.

Step 3: Commence Cutting the Ductwork

The cutting wheel has a 4 and a half-inch diameter and is perfect for cutting thin metals. The maximum thickness this wheel can cut is ¼ of an inch thick.

For sheets thicker than this, use a plasma cutter. You can also use a Dremel to cut ductwork as it can cut through ½ inch thick bolts.

After you’ve secured the piece onto the work surface, you may begin cutting. Cut in straight lines as twisting and turning may cause the wheel to disintegrate.

When your wheel begins to jerk, turn off the power switch. Wait for the disk to stop rotating and pull it back. If your wheel gets jammed, twist and break the wheel to take it out.

Now, we move onto the final step which is the finishing touches.

Step 4: Sand and Polish the Ductwork

This is a step that is mostly overlooked. That is you must always sand out the rough edges.

For this, you have to install a velcro pad and sand-paper (220 Grit) to commence sanding. Finish off by installing the polishing disk for a shiny finish.

This is how you cut ductwork with an angle grinder. We hope this post was helpful in learning the know-hows about angle grinders.


Question: How do you cut Ductworks without power tools?

Answer: You can cut them by using a step drill-bit. Alternatively, you can use a hammer and screwdriver to make an incision. Then you can use tin-snip to cut along the tears.

Question: Why are ductworks so costly?

Ans: Because ductwork is connected throughout your whole house. The size of the house is an important factor in the estimated cost.

Question: What is the estimated time needed to install ductwork?

Answer: It takes around one to two days, on average to reinstall new ductwork. This is because it involves changing the entire house’s ductwork.


Now you know how to plan to cut ductwork with an angle grinder. Hopefully, you have realized how to properly carry out the task.
Let us know which suggestions came in handy when cutting your ductwork. Till then, stay safe and good luck!