How To Enlarge An Existing Hole In Metal? [Step-By-Step Guideline]

For metalwork, we need to make holes in metal pieces to attach different parts. But sometimes, we need to enlarge the existing holes in metal objects which is undoubtedly a ludicrous and harrowing experience to fit a larger metal piece in that hole.

Usually, a reamer is perfect for this job that does not cut holes in Metal but enlarges an existing one. For a professional, it is not a big deal to ream a hole. But what if you are not a professional metalworker.

Today we will discuss each and everything on how to enlarge an existing hole in Metal with the step-by-step guideline and how to make a hole in Metal. Keep reading this article; we hope it will make your project easier and will provide you sufficient knowledge regarding this topic.

What Do You Understand By Reaming A Hole?

When a hole is reamed in Metal to size, it is called reaming. It precisely expands the hole size with multi-edge tools. It is a vital process to enlarge holes in your metal device. However, firstly you have to make a hole using a drill machine.

Then you can precise it with the help of a reamer as per your required diameter. It is the finishing operation of an existing hole with high precision, accuracy rate, and close dimensional tolerance. It would help if you did not consider reaming only as the alignment and location correction of holes. The prime purpose of reaming is the fine-tuning of the hole dia in Metal.

Tool For Enlarging Holes


A UniBit is an outstanding tool for drilling or enlarging an existing hole in Metal. You can easily measure the diameter of the hole also as there are clear markings in each step of this tool. It is suitable for digging holes on stainless steel, aluminum, and sheet metal; it also works better on soft materials like plywood, acrylic, particleboard, and laminate.

A UniBit eliminates the tedious process of switching from one drill bit to another between each hole. Before starting working with this, you can drill a hole using a drill machine or punch an indentation with a center punch.

After that, attach the UniBit, settle it into the pilot hole or the indentation, and start drilling. This step drill bit with a stairstep profile will allow you to make a hole of multiple diameters. When you need to enlarge the size of a hole, you will have to use a more significant bit.


Holesaw is an excellent tool to cut holes and enlarge the size of the holes in the metal surface, plastic, wood, and other hard surfaces. It includes a sharp blade to widen holes in Metal efficiently.

Professional metal workers use this outstanding tool for making holes and enlarging existing ones in metals. However, it is a pretty challenging task and requires proper guidelines to perform your project using this tool.

Knockout Punch

Electricians use knockout punches to enlarge the existing holes or to create holes in metal toolboxes. It is a simple hand tool with a straightforward operating process.


A reamer is a rotary tool used for metalworks. There are both precision and non-precision reamers. With precision reamers, you can enlarge the holes slightly with a high accuracy rate to leave smooth sides behind.

On the other hand, non-precision reamers are designed for the basic enlargement of metal holes or the removal of burrs. Besides, some reamers are designed to be used as hand tools, and some in machine tools like drill presses or milling machines.

However, you can find different types of reamers based on their functions, like chucking reamer, adjustable hand reamer, straight reamer, rose reamer, shell reamer, and more. But the working principle is identical for all these reamers as they all follow the rotary cutting principle to make and enlarge holes in metal surfaces. High-grade carbon steel is used to make reamers so that they can work perfectly on hard surfaces.

How To Drill Hole In Metal [Step-By-Step Guideline]

Follow the below guidelines step-by-step to enlarge a hole on Metal.

How To Make A Hole Bigger In Metal

Step 1: Fix The Workpiece Securely

Start with securely fixing the workpiece to avoid feeling uncomfortable or being hurt while working.

Step 2: Select Appropriate Reamer

Then you have to select an appropriate reamer based on what material you need to ream, required diameter, accuracy, and finishing. You have to choose the reamer very carefully as it will significantly impact achieving the correct size hole.

If you accidentally select a broader size tool, it will be tough to shorten the metal hole width. However, reamers of different sizes are available to industrial suppliers; among those, you have to choose the appropriate one to perform your reaming job perfectly. We hope you have understood how crucial this step is.

Step 3: Fit The Reamer With The Drive Tool

Now equip the reamer with the drive tool duly. Ensure that you correctly fit the reamer with the drive tool as improperly or loosely attached reamers will negatively affect your working performance.

Step 4: Choose Right Adapter

While using a Holemaker Technology reamer with a socket wrench power tool, a magnetic drill machine, or an SDS drill machine, selecting an appropriate adaptor is important. After choosing the right one, fit the adaptor with the drive tool and inject the reamer. Then fit the reamer with the drill and secure it by tightening the screw accurately.

Step 5: Run The Reamer

Now it is time to widen the hole using the reamer. So, place the reamer on the hole that already exists, starts the drill machine, apply the pressure steadily, and cut the piece of Metal to enlarge the hole. Keep control over the device and follow a consistent pattern until you achieve the hole’s proper size. When your job is complete, stop the reamer and then withdraw it.

Helpful Technical Tips

• Never run the reamer in a reverse direction.
• Apply cutting oil while you are performing the reaming job.
• Wear safety equipment like goggles and hand gloves.
• Do sufficient research before selecting a reamer size.
• When you have to ream a blind hole, use pilot drills to drill a little deeper.
• Check the minimum amount of torque required for the tool you are using.
• Apply steady and firm pressure throughout the enlarging process.
• Avoid tilting to prevent damage to the tool.
• To set the correct RPM, follow guidelines keeping in mind that wrong RPM can lead to tool breakage.
• For faster work performance, use the reamer with impact wrenches or impact drivers.

Final Words

The reaming out process can make your job easier to enlarge a hole in a metal surface that already exists. And reamer is the best tool so far to enlarge the existing hole. By choosing the proper reamer size among hundreds of available options, you drill holes of different sizes on metal surfaces. In the above article, we tried to describe how to enlarge an existing hole in Metal in simple steps. Hopefully, it will be of great help to you.

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