Cut Plexiglass With A Knife With This Easy Guide

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You can easily cut plexiglass at home, as you long as you take the proper precautions, make the correct measurements, and use the right tools. But will a knife be sufficient to do the job?

You can cut thin plexiglass with a knife by drawing a cut line and dragging the knife over the marked line to score it. Then, position the sheet in a way that the portion you want to cut hangs over the edge, and simply apply downward pressure to snap it in two. 

While you can score and snap relatively thin plexiglass sheets with a utility knife, you may need a circular saw or jigsaw for thicker sheets. Let’s look at which knife is best for cutting plexiglass, whether a utility knife or a jigsaw is better, and how to cut plexiglass step-by-step, so that you can get smooth edges and accurate cuts every time. 

What’s the Best Kind of Knife for Cutting Plexiglass?

Colorful pieces of plexiglass

The best knife for cutting plexiglass is a utility knife with an extremely sharp blade, like this one from BIBURY (on Amazon). Make sure you never use a knife with a dull blade, as it will fight against the plexiglass, resulting in cracks and breaks — and an extremely rough cut edge. 

Utility Knife vs. Jigsaw: Which Is Better?

A jigsaw (on Amazon) is a better choice if you’re making rounded cuts in thicker sheets of plexiglass. The power tool looks very similar to a bandsaw, but it’s much shorter and makes cuts in a straight up-and-down motion. 

You can make both straight and rounded cuts with a jigsaw, so it’s a better option if you want to cut circular pieces or specific shapes out of your plexiglass sheets. However, if you want to make straight cuts in a thinner plexiglass sheet, then a utility knife is the way to go.

How to Cut Plexiglass With a Knife

The easiest way to cut thin plexiglass sheets is to score them with a knife and simply snap them. For a better understanding, here’s a detailed step-by-step guide you can follow: 

Step 1: Draw a Cut Line

Place your plexiglass sheet on a flat, even work surface and use a dry-erase marker (on Amazon) to make the cut line. It’s best to use a ruler and draw straight lines along the areas where you want to cut the plexiglass. Make sure the line is visible and that you don’t smudge the marker.

Step 2: Make the Cut

After ensuring that the plexiglass is stable and flat, apply firm pressure and drag the utility knife over the marked line, preferably with the help of a ruler, to score the plexiglass sheet. 

Make sure you run the knife around 10 to 12 times over the marked line until there’s a deep groove in the plexiglass sheet. Remember that the deeper your cuts, the easier it’ll be to snap the sheet in two. 

Step 3: Score the Other Side

Once there’s a deep groove in one side of your plexiglass, flip the sheet over to expose its other side. However, make sure you’re extremely careful when picking the sheet up, or it might warp or bend before you even snap it.  

Use your utility knife to cut along the same marked line to further score the plexiglass sheet. Keep dragging the knife along the marked line until there’s a groove on the other side of the sheet as well.  

Step 4: Properly Position the Sheet

Once you’ve successfully scored both sides of the sheet, position it in such a way that the entire portion you want to cut hangs over the edge of your work surface. This will make it easier for you to snap the sheet in two.    

Step 5: Firmly Secure the Sheet in Place

Clamp the portion of the sheet you don’t want to cut on your work surface with a C-clamp (on Amazon) or a spring. Make sure the clamp is firmly attached to both the plexiglass sheet and the surface you’re working on, so it doesn’t move when you snap it. 

However, be careful not to secure the plexiglass so tightly that it results in a divot or dent in the sheet. 

Step 6: Snap the Sheet in Two

With the plexiglass securely clamped in place, apply quick and firm downward pressure to snap off the piece you cut. This should cleanly break the sheet along the line you marked and scored. 

It’s also advisable to use one hand to brace the portion of the sheet that’s on your work surface and use your other hand to push down on the part that’s hanging over the edge. If the plexiglass doesn’t completely break along the line, use the utility knife to cut and fully break off the piece. 

Step 7: Finish the Edges

In this last step, soak 120-grit sandpaper (on Amazon) in water and then use it to sand the uneven edges of your cut plexiglass sheet. As the edge becomes smoother, start using finer sandpaper, until you progress to 600-grit paper. 

Once you’ve achieved the right texture, fit a buffer attachment to an electric drill and use it to polish the edge. 

How to Prep Your Workspace

Before you start cutting plexiglass, it’s important to properly prepare your workplace. Here are a couple tips to keep in mind:

  • Make sure you thoroughly clean the surface and clear away any objects that might impede the cutting process or potentially damage or mark the surface.
  • Use a stable and even surface that doesn’t wobble.

Safety Tips

Although plexiglass is extremely durable, keep in mind that it’s not completely unbreakable. Here are a few tips that can help ensure you cut plexiglass without injuring yourself or causing any irreversible damage to the material itself: 

Don’t Remove the Plastic Film

Plexiglass usually comes wrapped in a thin plastic film that helps prevent scratches as the material changes hands. Keeping that film on as you mark, measure, and cut will help prevent the sheet from scratches and cracks. 

Put on a Pair of Safety Glasses

Protective Glasses and Utility Knife

Cutting a plexiglass sheet can cause tiny particles and splinters to fly in the air. These slivers could enter your eyes and damage them, so make sure you wear safety glasses (on Amazon) before you start cutting. 

Keep the Blade Cool 

If you’re cutting plexiglass with a power saw or jigsaw, keep in mind that an overheated blade could crack and even break the plexiglass while you’re cutting it. While the plastic film protects the material to some extent, remember to pause and let the blade cool if it starts to overheat. 

You can also spray your plexiglass with a bit of soapy water for extra lubrication while cutting.   

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