Hot knives, or hot knife rope cutters, are extremely versatile tools that can be found everywhere; from basic household toolkits to industrial workshop machinery. Whilst they may seem like a niche piece of equipment, hot knives are far more handy than you think. 

However, whether you’re trimming bungee cords down to the perfect size, finishing materials for your latest craft project, or preparing rope to put in your camping backpack, knowing how to use a hot knife rope cutter safely is the most important thing to consider. 

Keep reading as we discuss what a hot knife is, how it works and twelve helpful tips on how to safely cut your synthetic material of choice. 

What is a hot knife?

A hot knife, or hot knife rope cutter, is a specialised tool used for cutting synthetic ropes, bungee cords, webbing, and fabrics made from materials such as nylon, polyester, and polypropylene. It features a heated blade that melts through the fibres, preventing fraying and ensuring a clean, sealed edge. The heat-sealing capability of the hot knife also helps in maintaining the integrity and performance of the cut materials.

How do hot knives work?

Hot knife rope cutters work by using a heated blade to slice through synthetic materials. When the blade heats up, it reaches temperatures high enough to melt the fibres of the material being cut. You then press the heated blade against the material, which melts and separates cleanly underneath the heat. 

12 hot knife safety tips

When using a hot knife, safety is paramount. Here we share our top 12 safety tips for using a hot knife rope cutter. 

1. Educate yourself on how to use a hot knife

Learning how to correctly use a hot knife rope cutter is one of the best ways to use it safely. Incorrect or improper usage of a hot knife could result in damage to your surface, a fire or injury to yourself. 

2. Wear protective gear

When using a hot knife, you should always remember to wear protective gear, such as heat-resistant gloves and safety goggles, to protect yourself from potential burns and flying debris. 

3. Ensure proper ventilation

Using a hot knife rope cutter in a well-ventilated space will help you avoid inhaling any harmful fumes that may be produced when melting certain materials. These fumes could be toxic and result in serious health problems, otherwise. For additional care, wear an industrial mask to help prevent fume inhalation. 

4. Inspect the knife before use

Before using your hot knife, you should first check it for any signs of damage, such as frayed cords or cracked blades, as this damage could cause injury when used or start a fire. If the hot knife is damaged in any way, do not use it. 

5. Secure your workspace

You should always use a hot knife in a clean, tidy environment. This includes ensuring the area is free of any flammable materials and that the knife’s cord if corded, does not pose a tripping hazard. 

6. Heat and cool properly

When using a hot knife rope cutter, you should always follow the manufacturer’s instructions for heating and cooling times. Using the knife before it has heated enough could damage the material you’re attempting to cut, and not letting it fully cool before storing it could cause a fire. 

7. Use a stable cutting surface

A stable, heat-resistant cutting surface for hot knife cutting is paramount in preventing the knife from slipping, causing a fire or any injury to yourself. Check your surface for any wobbles or movement, and invest in a heat-resistant cutting surface, such as glass, before using. 

8. Handle with care

Always handle your hot knife with care, even when not in use. This includes keeping fingers away from the blade, storing it correctly, keeping it out of reach from children and allowing it to cool completely. This will help you avoid any injuries, alongside damage to the hot knife rope cutter. 

9. Keep a fire extinguisher nearby

In the event of any accidental fires caused by your hot knife rope cutter, you should always keep fire equipment – such as an extinguisher or fire blanket – on hand in the area it is used, Make sure you always have a telephone nearby, if you need to call the emergency services, and that someone knows where you are and what you are doing. 

10. Unplug and store when not in use

When the hot knife is not in use, it should be unplugged and stored away somewhere safe and out of the reach of children. This will help you prevent any accidents or injuries occurring, as well as preventing any damage to the hot knife rope cutter.

11. Learn first aid for burns

In the unfortunate event that someone, or yourself, is injured when using a hot knife rope cutter, you should ensure that you are familiar with basic first aid for burns. This includes having cool running water nearby to treat the burn, cool packs and bandages in a first aid kit, and a telephone nearby to call the emergency services if required. 

12. Keep up with regular cleaning and maintenance

Regular cleaning and maintenance of hot knives keep them in good working, and safe working, condition. This includes removing any leftover debris from the blade, cleaning the blade with a mild solvent or alcohol, replacing the blade when needed, and inspecting the whole apparatus for any signs of damage. 

Frequently asked questions about hot knife cutters 

Will a hot knife cut plastic?

Yes, a hot knife rope cutter will cut through plastic. This is because it is designed to melt through synthetic materials, like plastic. Please though be aware that some synthetic materials will melt at a lower temperature and can release toxic fumes. Always do your research on the material you intend to use, before doing so. 

What surface can you use a hot knife on?

You should always use your hot knife on a heat-resistant surface. This could include; a heat-resistant cutting mat, glass, ceramic tile, a metal sheet or plate, or a specially-designed heat-resistant workbench. 

Avoid using a hot knife rope cutter on surfaces made from wood, plastic, or fabric, as these could melt, burn or cause a fire.

Can a hot knife cutter be used on natural materials?

No, hot knives cannot be used on natural materials. This is because the fibres in the material will burn underneath the heated blade, damaging the material and potentially releasing toxic fumes or causing a fire. 

Can I sharpen the blade of a hot knife cutter?

Some hot knife blades can be sharpened, but it’s often easier and safer to replace them when they become dull. You should always check the manufacturer’s recommendations for your specific model for instructions and advice on how and when to do so.

How long does it take for a hot knife cutter to heat up?

The heat-up time for a hot knife can vary by model, however, it typically ranges from a few seconds to a couple of minutes. Always wait until the blade reaches the desired temperature before starting your cut. Check the manufacturer’s instructions for the specific heat time for your model. 

For more ways to safely DIY, read some of our informative and inspirational articles on The Bungee Store blog, or feel free to contact our friendly team today for expert advice!