How to Cut Hard Plastic Without Breaking It: Full Guide

Last Updated on March 16, 2024 by John Patterson

Nothing can be more frustrating than the sound of your work material breaking. Yet we have all been there. It is insane how easy it is to end up with broken pieces of hard plastic, instead of clean-edged sections, when you were simply trying to cut it.

As such, if you are looking for a useful guideline on how to cut hard plastic without cracking it, you have just come to the right place.

No matter if you are a hobbyist or a professional wanting to hone their knowledge, this article can help you achieve those clean and precise results that everybody loves.

How to Cut Hard Plastic without Breaking It

So here’s our recommended cutting hard plastic without breaking techniques for you:

Best Way to Cut Plastic

Be it a flat acrylic sheet or a PVC pipe or the body of an RC car, cutting hard plastic can be quite a tricky task. There are quite a few techniques that can be used to successfully cut a thick piece of plastic, the most popular ones being:

• Using a saw
• Drilling
• Slicing with a thread

To effectively cut a hard piece of plastic, you have to follow the precise rules of each of these techniques. No matter how much you love being creative and doing things your way, not following the right way to cut hard plastic can end up ruining your whole project.

Best Saw for Cutting Plastic

Sawing Plastic Using Various Saws

Using a saw is one of the best ways to cut plastic without breaking. Sawing gives nice, smooth results and takes relatively less time and effort.

It is especially great for cutting thick sheets or flat pieces of plastic. A saw can cut through hard plastic sheets effectively and easily. Still, as hard plastics are prone to cracking or breaking while being cut, you do need to be very careful when using a saw.

The different types of saw that can be used to cut through hard plastic include:

• A hacksaw
• A circular saw
• A jigsaw

No matter which saw you go for, make sure to fix it on your work table using clamps or tapes. Also, be sure not to put too much pressure on the plastic while you are securing it in place.

Or else, it might just crack or break from the pressure alone, and all your efforts will be in vain.

The Hacksaw Technique

Using a hacksaw to cut plastic without breaking is quite easy once you have got the hang of it. For this method, you need a hacksaw and a plastic cutting blade to go with it.

• On your work surface, secure the plastic using clamps or tapes, or use a saw vise if you have one.
• Hold the handle of the hacksaw with your dominant hand, and the other end with your other hand to simply guide the saw in the right direction.
• Gently make your first couple of cuts onto the surface of the plastic. This initial bit can be tricky, but after this, it is a methodical job going forward.
• Now simply keep sawing along the line where you want to cut the piece of plastic. You can use the forward and backward strokes both while cutting, but don’t put any pressure on the backward stroke as it can eventually dull the blade.

Circular Saw Techniques to Cut Hard Plastic

A circular saw-like Rotorazer is a great power tool to use for cutting through thick hard plastic. It is great because it takes very little effort on your part and gives a quality finish.

• Choose a blade that is meant for cutting plastic. The blade should have a tooth number of at least 70 or more. This will give you clean, smooth edges.

Also, if you can, go for a coated blade to keep it from overheating. The heat from the friction of the blade can melt the edges of thick plastic. So it’s best to avoid it when possible.

• If the plastic you are cutting has a protective film on it, do not take it off until after you have finished cutting the plastic.
• Do not stop while cutting using a circular saw as it can lead to overheating of the blade, and can melt the plastic as a result.

Cutting Plastic with a Jigsaw

You can use a jigsaw to make straight or curved cuts on your heavy-duty plastic material. Jigsaws are better for cutting in curves than straight lines. So if you have a lot of detailed work to do, a jigsaw would be a good tool to go for.

• Be sure to use a blade that is specifically designed for cutting plastic, the density of teeth being 13 TPI or more. The length of the blade should be at least an inch longer than the thickness of the plastic you are going to cut.
• Use the jigsaw at a lower speed level. This will prevent the blade from heating too much.
• Apply gentle forward movement to continue cutting in a straight line. Cutting in curves can take a little bit of practice to master.
• You can use masking tape along your cutting line to keep the plastic from chipping or getting jagged edges.

How to Cut Plastic Without a Saw?

Let’s know how to cut hard plastic easily using a drill and others tools.

Cutting Plastic Using a Drill

 

A drilling machine is an excellent thick plastic cutter.

Drilling a few holes onto your plastic piece before cutting it can reduce the chances of it breaking. You simply need to make a series of holes along the line you want using a corded power drill and a small bit. Then use another cutting tool to finish cutting.

• First, to mark where you want to cut the plastic, draw a line to use it as a guide.
• Drill some holes near each other along the line on the plastic. Use the drill at a slow speed, and the diameter of the bit should be one-eighth of an inch or less.
• Once you are done drilling the holes, it’s time to connect them. Using a saw or a utility knife, cut from one hole to the next. And remember you should carry a sharpening stone to sharpen your knife for better results.

This method of cutting hard plastic is time-consuming yet effective. The holes keep the rest of the plastic from breaking at other places, thus keeping your pieces intact.

Slicing Plastic with a Thread

This is the cheapest technique you can use to cut through hard plastic. If you are on a budget but have a lot of time on your hands, this could be the best way to cut thick plastic for you. All you will need is a spool of polyester or cotton thread, and indeed, a lot of patience.

• Secure the piece of plastic to your work surface using a clamp or masking tape, or simply hold it firmly in between your knees. Keep in mind that too much pressure from the clamp can break the plastic, so put just enough pressure to hold the plastic steady.
• Take a firm piece of thread that is about 60cm long, and slide it back and forth at the point where you want to start cutting. Eventually, it should make a groove on the plastic.
• Now simply continue pulling the thread back and forth along the groove until you have finished cutting the plastic. This method generally produces quite smooth and clean edges.

Tips to Cutting Hard Plastic without Breaking It

Here are a few tips for cutting the plastic without breaking it.

• Don’t Put Too Much Pressure

Anyone who knows how to cut thick plastic will tell you not to put too much pressure while securing the thing in place. While clamping, use just enough pressure so that it does not wobble or move from its place.

• Draw a Line to Use as a Guide

It is easy to lose track of where you are cutting once you start using your tool. So, be prepared beforehand and mark the line you want to follow on your piece of hard plastic.

• Choose Proper Tools

You can use a hot knife or a hook knife to cut thin layers of hard plastic such as thin acrylic and polycarbonate sheets. For thicker ones, a circular saw is the best option for a quality finish. Use a jigsaw for cutting curves or a hole saw for cutting circles.

• Go Slow

You want to go slowly not only to minimize melting but also to keep it straight and not wander away from your intended line of cutting.

• Take Safety Measures

Always wear safety glasses and gloves while using a saw or a drilling machine. To keep your workspace clean while working, you can use a dust blower or a vacuum machine.

Frequently Asked Questions

Here we have some of the most commonly asked queries regarding the topic:

Question #1. How to cut plastic with a knife?

Answer: You can use a utility knife or a hobby knife to easily cut through thin sheets of hard plastic. To cut the plastic, simply lay it down on a clean, flat surface and draw a line where you want the cut to be.

Then, using your knife, score the line from start to finish. Do this a few times until a nice groove forms along the line. Now flip the plastic sheet over.

On the other side, score along the same path with the knife. Once you are finished, lay the sheet on a table or any flat elevated surface with the groove lines up with the table edge. Clamp it properly, then snap off the part hanging over the edge, and you are done.

Question #2. How to cut plastic glass?

Answer: To cut plastic glass, you can either use a glass cutter, utility knife, or a powered saw, depending on the thickness.

For thin sheets of plastic glass, you can use either a glass cutter or a utility knife to score. To cut using a knife, score both sides before snapping off one side. And if you use a glass cutter, simply scoring on one side about 10 to 12 times is enough.

Then simply clamp one side like before and use a downward force to snap off the hanging part.

As for thicker sheets, you need to use a circular saw or a jigsaw with appropriate blades. Be careful to not overheat the blade, and go at a slow speed. Don’t forget to use safety gear while using these.

Question #3. How to cut plastic bottles?

Answer: There are a few ways to cut a plastic bottle. The simplest is to just use an X-Acto knife to cut off at the desired place. Start by cleaning the plastic bottle properly, so no grease or adhesive remains on the surface. You can use grease to remove adhesives, and then use a detergent to wash away any grease.

Then use a marker to draw the lines where you want to cut. You can also use masking tape to use that as a guide for cutting.

Next, carefully make a hole using an X-Acto knife along the line and start cutting. At this point, you can also use a pair of scissors to cut the rest of the way. You can also use a bandsaw to cut through plastic bottles.

Question #4. What is the best way to cut polycarbonate?

Answer: When it comes to polycarbonate material, the best way to cut it depends on its thickness.

If it’s a thin sheet of polycarbonate that is not more than ⅜ inch, you can use a hook knife or a hot knife to cut through it. Use a ruler to score in a straight line. Make repeated passes along the same line until the groove is deep enough. Then you can just snap the parts off with your hands.

As for polycarbonate that is thicker than ⅜ inch, you will need to use a circular saw or a table saw for best results. Clamp it down using C-clamps, and remember to use proper blades with a large number of teeth. Keep your work surface clean using a dust blower when you use a saw.

Question #5. How to cut Lexan Polycarbonate?

Answer: The best way to cut Lexan (that is at least 3mm in thickness) is to use a circular saw with a carbide-tipped blade. Make sure the tooth spacing is no more than ½ inch.

When using a circular saw, clamp down the sheet on the workbench like usual and be careful to go at a slow speed. Follow the line you want to cut through until you are finished. Also, remember to not stop in the middle of cutting, to keep from overheating the blade.

To cut curves on a Lexan sheet, you will need to go for a jigsaw or a bandsaw. As usual, choose the appropriate blade.

Wrap up

Now that you are equipped with all this knowledge on how to cut hard plastic without cracking it, you can now go on to cut away all the hard plastic you need. And for an extra tip, try buffing the edges using wet and dry sandpapers for a professional-looking finish.

Like all things, practice will make you better when it comes to cutting hard plastic. So, don’t waste any more time and start cutting right away with the right tools and the proper techniques that we have laid out for you here.

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