How to sharpen diagonal wire cutters – 2 Methods

When your diagonal cutters lose sharpness don't throw them away. Try to sharpen them using any of these DIY pliers sharpening methods.

Diagonal wire cutters are a type of pliers for cutting or snipping wires and small fasteners. They also double up as staple puller pliers or tack remover for pulling out staples, small nails, and tack strips from wooden floor and furniture. The pliers have pointed tips that let you get under the staples with ease. Furthermore, their slightly bent head provides good leverage.

Diagonal cutters have sharp cutting edges that slice through objects with ease. However, over time, the cutters get blunt and cannot cut effectively or cannot cut at all. You either have to sharpen the edges or replace the tool altogether.

I prefer to sharpen my cutters first before I can consider disposing of them. Unless the blades are damaged beyond restoration. Thus, in this article, I share the steps I follow when sharpening my dull diagonal pliers. But first, these are the signs that tell if the cutters need sharpening or replacement.

Signs of dull diagonal cutters or side cutters

You know your side cutters are blunt and need to be resharpened if:

  • The cutters cannot cut in one go
  • The blades press the wire instead of cutting
  • The cutters leave tails on both sides of the cut object
  • The cutting edge feels and looks flat and dull
  • The cutting edge is covered in rust

However, if the blades are overly nicked or do not close completely, I suggest replacing the pliers.

How to sharpen blunt diagonal cutters pliers

Method 1: Sharpening with flat file or whetstone

Step 1: Assemble the tools

You will need the following tools and supplies to begin the sharpening exercise.

  • Flat file or whetstone or diamond file
  • Blunt pair of dikes
  • Basin with a mixture of dish soap and water
  • Rag
  • Vinegar solution (optional)
  • Machine oil

Step 2: Clean the cutters

Clean the dikes with dish soap and wipe them dry with a rag. You can use an old toothbrush to remove gunk. If the pliers are rusty, soak them in vinegar or try any other rust removal method discussed in this ultimate guide for cleaning and maintaining pliers.

Step 3: Set up the dikes on a vise

Open up the blunt pair of dykes all the way and secure it in a vise. Clamp the open handles of the pliers with the vise so that the cutters point upward.

Step 4: File or whet the cutting edge

Pick up your hand file or whetstone and position it at the exact same angle as the bevel on the cutting edge. While applying a little pressure on the file, drag it across the cutting edge from the pivot to the tip in one direction. Maintain the same angle and pressure across the whole stroke to ensure consistency.

Start from the inside of one blade then outside. Make at least 5 strokes on each side of the two cutting blades.

Because you do not want to remove much material, use a smooth file and apply just a little pressure. Removing a lot of material from the edge may cause misalignment of the jaws and consequently render the pliers useless.

Step 5: Test the pliers

After you finish sharpening, remove the pliers from the vise and test to see if they cut better. Try cutting wires of different materials and thicknesses to find out if the sharpened pliers cut more easily or need more sharpening. If they still feel blunt, repeat the last step and test until they become as sharp as you need them.

Step 6: Wipe the blades

Wipe the blades with a damp cloth to remove metal filings and dust from the whetstone.

Step 7: Apply machine oil on the blades

Pour a few drops of machine oil on the metallic part of the pliers and spread it well to prevent rusting. Apply a few more drops of the oil around the hinge and open and close the handles to allow the oil to penetrate. This will free up the hinge and protect it from rust.

Now your side cutters are ready for the next cutting job. Lastly, make it a routine to sharpen and maintain your dikes to keep them in good shape all the time.

Method 2: Sharpening with a rotary tool

If you have a rotary tool such as a Dremel, you can use it to sharpen blunt diagonal cutters. All you will need is the right grinding disc. A diamond Dremel disc is the best for sharpening the hardened cutters of pliers. I have put a link below to the best diamond cutting wheel for a dremel tool on Amazon.

Steps

Step 1: Assemble the tools

Put together the tools you will need for the exercise and set up the workstation. The tools include the blunt cutting pliers, dremel too and cutting disc, vise clamp, and

Step 2: Clean the pliers

Clean the pliers with soapy water and wipe them dry with a piece of cloth. If they are rusty, start by soaking them overnight in a homemade rust removal solution such as vinegar. Alternatively, you can use a commercial rust remover solution such as Evapo-Rust. It works wonders and takes a shorter time to act on the rust.

Step 3: Secure the pliers in a vise clamp

Open the jaws of your dulled pliers all the way and secure the pliers on the vise by the handles so that the jaws point upwards. The vise helps to keep the pliers from moving when sharpening. This helps to sharpen all sides of the cutting edge uniformly to avoid ruining the pliers.

Step 4: Install the diamond cutting disc on the rotary tool

Install the diamond cutting disc on the dremel and power the tool. The reason for choosing a diamond disc is that you can use its flat surface to grind and it is tough on hardened surfaces.

Step 5: Grind down the cutters

Use the flat surface of the disc to grind. Simply place it at the same angle as the factory edge and work from the back of the edge to the tip. Move it slowly and do not apply pressure to avoid taking away a lot of material. Just grind until the edge becomes shiny. 2-4 passes are enough.
Grind both the inside and outside edges on both cutters and do the same number of strokes to prevent misalignment of the cutters.

Step 5: Test

Test the newly sharpened cutters by cutting wires to ensure they cut better. If they are not sharp enough, repeat the last step.

Step 6: Apply oil

A little bit of oil on the cutters keeps them from rusting and keeps the hinge from seizing up on you. If you make it a habit to apply a thin coat of machine oil on your pliers, they won’t rust and the jaws will open and close with so much ease.

If you try to sharpen your dykes but they still feel dull, the best solution is to get new ones. Also, if your pliers have dulled because of cutting zip ties and other light materials, don’t waste your time sharpening them. Just get yourself a decent pair of dikes. Check out this article to find out the best diagonal cutters for various applications.