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Cutting Ductwork With a Jigsaw [A Step By Step Guide]

Oh, snap! The ductworks in the attic are damaged! Thinking of repairing it yourself? Well, that might be a hassle for you. But don’t worry, we’ve got your back with a guide!

How to start cutting ductwork with a jigsaw?

Take out your tools, safety gear and get ready. Next, we need to choose the right jigsaw. Then onto the steps. This will include- taking measurements, cutting, and cleaning the ductwork. And the end result is going to be perfectly cut ductwork.

Now, put your craftsman hat on, and stay tuned!

Which Type of Jigsaw Blade Should You Choose?

The jigsaw comes with a lot of variety. Its use depends on its blades, object’s thickness, and blade speed variability. As a result, different jigsaws are perfect for different works.

But in general, this machine is a versatile one. Even a newbie can operate it with little knowledge.

So, when planning to cut metal ductwork, you should consider the jigsaw blade.

Ductworks are mainly made of metal. So, for sheet metal, a finer blade with 21-24 teeth per inch will be best. You can also cut ductwork with Dremel.

Jigsaws with high cutting speed and long blade strokes are good choices too. But they are a bit expensive. 

For instance, bayonet-style blades are best for cutting laminates.  If you use this kind of blade to cut metal, that won’t be a perfect selection. 

Once you’ve chosen your jigsaw, let’s move onto cutting the ductwork!

5 Steps of Cutting Ductwork with a Jigsaw

Now, it’s time to get to work. But before starting the cutting process, you’ve to prepare the essential tools.  

Gather the Necessary Tools

When cutting ductwork, a jigsaw isn’t the only tool that you’ll need. 

There are some other tools as well that you should keep with you. These will make the whole project hassle-free.

Here goes the list of the required tools:

An important suggestion here, always try to keep your tools cleaned and oiled. This is because they are prone to rust. And can become a burden while attempting the project.  

Because we’ve explained the working process in simple words. Therefore, you’ll be able to cut the ductwork quite easily.

So, let’s take a look at the 5 steps on how to do the guide below-

Step 1: Taking Proper Safety Measures

The whole project can be a bit of heavy-duty work. Since it involves machines and heavy instruments. So taking safety measures is a must. 

Before starting, make sure you have taken the necessary safety steps.

We tried to put down all the necessary measures in the list below:

  1. Wear a proper PPE dress made of thick clothing like denim. This will keep your body safe from the metal shreds. 
  2. Try to use thick gloves for the work as the metal edges are very sharp. You can wear the same nitrile gloves used for cutting asbestos siding
  3. Don’t forget to put on a good mask or face armor. This can save you from harmful dust. 
  4. Use safety glasses to save your delicate eyes from the harm of metal shreds.  

Now, there’s a catch-

You can’t just use any safety glasses. To protect your eyes, you’ve to choose the best one. That’s why we’ve mentioned our top picks regarding the safety glasses:

KleenGuard Maverick Safety Eyewear

Check Latest Price

Crews BK310AF BearKat 3

Check Latest Price

Therefore, grab the glasses and start working!

Step 2: Taking the Measurements

For instance, you’re aiming to replace old/damaged ductwork with a new one. Or even attaching a vent to ductwork. Then take measurements of the old and the new pipeline/vent. See how much of the new duct needs to be cut for a perfect fit.

In case of new ductwork, measure and mark the installation area with tape. Taking a measurement is also necessary while splitting flex duct. You should use metallic marker pens for this. So that the mark doesn’t fade away while working.

Note down how many pieces of ductwork you’ll need. Finally, cut it with a jigsaw. 

One wrong measurement can ruin the whole project. You better avoid assuming the measurement or depending on your eyesight. 

So take measurements using the right tape and noting them down!

Step 3: Fastening Down the Ductwork Before Cutting

If you are installing new ductwork, this step isn’t for you. You can cut it first by setting it up on a sawhorse.

Otherwise, it’s important to fasten down the ductwork to avoid any mishaps. If the piece is light-weighted, you can need to hold it. Or better yet, ask someone else to hold it for you.

For heavy pieces, it might lead to a serious accident if the duct piece slips. So use a vise or a clamp to hold it in place.

Now comes the actual work!

Step 4: Using the Jigsaw

Now that we’ve fastened down that ductwork. Let’s start using this tool. But using a jigsaw can be dangerous just like soldering ball valves. So you must be careful.

Jigsaw has a triggering switch that can be enabled and disabled by squeezing. So rev up that machine. Then you can direct it through the marked area. 

Since ductworks are mostly metal-based, a jigsaw can cut it just fine. 

Step 5: Cleaning the Dust and Shreds

After finishing the cutting, you need to clean the dust and metal waste. Otherwise, they will cause pollution and health hazards.

Also, you shouldn’t use an electric vacuum cleaner to clean the dust. Because metal shreds might lead to an accident. Hence, using a hand broom would be easier and safe.

Now, it’s time to finally install your cut duct!

In case you also had questions regarding buying a 10″ table saw or a smaller one. It depends on your budget and if you want to use a lightweight saw or not.


Question: Why does my jigsaw not cut straight?
Answer: Putting extra pressure to direct the jigsaw causes this problem. Let the jigsaw blade cut at its own pace. You’ll see that the tool cuts straight through any material.

Question: Can you cut through metal with a jigsaw?
Answer: A jigsaw with 21 to 24 teeth per inch can cut through metal. It can also cut through metal up to 10 gauge thick. So it depends on the blade and the thickness of the metal.

Question: Do jigsaws cut straight?
Answer: Jigsaws can cut straight lines. But it can also cut in angular or circular motion too. But to cut in a straight line, you need long and front-to-back blades. 


Hopefully, after coming along this ride with us, the process has become easier for you. So, what’s stopping you from cutting ductwork with a jigsaw?

Good luck, and have a safe experience cutting your ductwork!