What Does a Fuller Do on a Knife or Sword?

A fuller on a knife allows you to remove material from the blade without weakening the steel core. As a result, the overall weight of the cutlery feels lighter, more balanced, and stable.

Fullers also improve the aesthetics of knives, making them more good-looking and stylish. However, fullers on blades of 12 inches or shorter are purely for ornamental purposes.

There are many misconceptions about what does a fuller do on a knife, but this article will clear all of those doubts for you. I’ll cover the main benefits of fullers as well as some of the myths revolving around this topic.

What is a Fuller on a Knife?

fuller on knife

A fuller is a groove cut or forged into the length of a blade. Blades can have either one fuller on both sides, multiple fullers on both sides, or a different fuller amount on any side.

Another name given to fullers is blood grooves, which is a term that carries several myths with it. However, the main purpose of fullers is to remove stock from the blade without compromising its structure.

Before going more in-depth, it’s important to clear out that knives of certain sizes don’t benefit from fullers.

What a Fuller Does on a Knife?

A fuller is purely for decorative purposes on blades below 12 inches of length. 12-inch blades and below that range don’t have stiffness issues, and they certainly wouldn’t lose that much weight after applying a fuller, either.

If anything, adding a fuller to small blades may cause the blade to experience a less acute grind angle. Ultimately, this issue would make the knife less effective for home tasks like slicing or chopping.

The same goes for hunting knives. This type of knife often has fullers on both sides of the blade. Besides emulating the look of a fine sword, there’s nothing more to that.

Adding a fuller to knives this size would bring barely perceptible weight loss or stiffness improvement.

But what does a fuller do on a knife with a blade longer than 12 inches? There are three main benefits you can expect.

1. It Makes the Blade Less Heavy

Applying a fuller to a blade requires the removal of material, which naturally leads to less weight.

From a technical perspective, a high-quality steel blade put through hardening and tempering processes can reduce its weight between 25 and 30 percent after applying a fuller.

Even better, a fuller significantly reduces the weight of a knife without losing the strength or integrity of the blade.

This process won’t make the blade stronger, but it won’t make it weaker either. The knife will virtually remain as strong as it was without the fuller.

2. It Increases the Blade Stability

Fullers grant stability to knives by providing new balanced properties to the steel blades.

Initially, the design principle of a blade is that bending deals considerably more stress around the edge or back of the blade instead of the center. By forming a fuller, you can remove material out of the neutral axis. Besides feeling lighter, the knives also feel more stable.

3. It Beautifies the Blade

A fullered blade looks stylish and professional. This is a benefit in all types of knives, but more so in survival or hunting knives.

Knifemakers are well aware of that, as they include grooves in their knives as a marketing strategy. Plus, you can customize your own knives by adding unique fuller styles using different tools.

Fuller grooves can also cover mistakes in welded steel. Therefore, it’s a useful technique to cover impurities on blades.

Takeaways

Some good-looking fuller styles are the short rounded top groove, two parallel grooves on the same blade, two thin grooves, etc.

Read Also: What Are the Notches on a Knife for?

What Does a Fuller Do on a Sword?

The fullers reduce the sword’s weight while maintaining the blade’s structural integrity and strength. There’s also another reason, which is to change the sound that the sword blades make to give the wielder more control.

Katanas are a good example of a sword blade that proves this theory. These swords have fullers on both sides of the blade. While swinging it, the sword can make different sounds.

  • If the wielder hears one whistle, then it means only one fuller is whistling.
  • In case the swordsman hears two whistles, it’d mean that the blade’s edge and one of the grooves are making the whistle.
  • Three whistles would mean that there’s perfect alignment between the blade and the direction of the cut.

Fuller and Blood Groove: Are They Same?

Fuller and blood grooves are the same thing, but there’s a common misunderstanding of what a blood groove is. For instance, some people believe that a blood groove helps channel blood out of a wound, making the blade more lethal. This statement is not true.

After stabbing, flesh contracts immediately and closes up around the fullered blade; therefore, blood will come out neither faster nor slower.

When comparing the fuller vs. blood groove, it’s clear that the blood grooves serve the same three purposes of fullers: reduce the weight, improve strength, and enhance aesthetics.

How to Put a Fuller on a Knife?

You can put a fuller on a knife following one of three methods:

  • Forging – To forge a fuller, you can get toolsets designed for this specific purpose. These tools are the fullering dies, and they include hardy tools, power hammer sets, etc. Put the blade through heat treatment, place it between a couple of fullering dies, and proceed to hammer them in. Use this method for making a larger fuller.
  • Grinding – You can also use a wheel of the right size mounted on a belt grinder, perhaps even a stone. Using a grinder creates a thin and consistent fullered blade.
  • Carving – Lastly, you could carve the fuller with fullering tools featuring sharp blades. These tools are similar to a hand plane, a tool seen in woodworking fields. Using a specialized scraper to carve a fuller is also possible, but it will consume a lot of time.

What is the Purpose of a Blood Groove on a Knife?

The blood grooves help reduce the weight of blades while maintaining the original strength.

It was a common belief that blood grooves drained blood faster or made it easier to draw swords out of the flesh in medieval times.

Nonetheless, it’s more conceivable that fighters added these grooves to their swords to make the blades more lightweight and better looking.

How Does a Fuller Strengthen a Blade?

Technically, the fuller doesn’t strengthen the blade of swords or knives. Putting a fuller on a blade requires you to remove material, which would make the steel weaker in other normal circumstances.

However, a fuller removes material to lighten a blade without losing the original blade integrity.

Final Verdict

And there you have it! Here’s all you need to know about what is the purpose of a fuller on a knife, with advantages and disadvantages included.

Realistically, most kitchen knives don’t gain a lot if you add a fuller to their blades. The majority of this cutlery is already lightweight. A fuller would reduce the weight anyway, but only slightly.

The good news is that now you have a better grasp of what a fuller is and what it can do. For larger blades, this cut-out groove is definitely something that could improve your time using it.

Think I missed out on something or want to share your opinions? Leave it in the comments!

Brian M. Casey

Product reviewer & passionate blogger. Besides writing for this blog, I spend my time crafting research-based content for HuffingtonPost, Lifehacker & Forbes!

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