Magnetic Drills - What are they? When to use one? How to use one?

A magnetic drill, or mag drill, is a portable drill press machine designed to primarily drill precise holes in metal surfaces. It uses a powerful magnet to attach firmly to the workpiece, allowing accurate drilling – even in horizontal, vertical, or overhead positions.

How a Magnetic Drill Works

1. Magnetic Base

   1. The base of a mag drill uses an electromagnet (needs an electric current to activate) or a permanent magnet to clamp the drill securely to ferrous surfaces. Many drills use this as the first line of defense in their suite of safety features. Without proper adhesion of the magnet, a good mag drill won’t operate. Although, it should be noted that no matter the safety features built into the magnet, a safety chain/strap should always be used when operating the drill.

   2. Some specialty drills have unique bases designed to tackle a specific job. This can range from the popular low profile drills that are great for drilling in tight spaces, to drills with a split base designed with two magnets that can straddle a pipe for safe drilling. You can even find drills that have swapped in the magnet for a vacuum when drilling on non-ferrous materials is required.

2. Motor & Drill Mechanism

   1. Mounted above the magnet on a fixed stand, the motor drives an annular cutter or other cutting tool, feeding into the material via a manual or automatic system. Magnetic drills are available with a variety of configurations (rpm’s, gears, etc.). Depending on the material of your workpiece and your cutting tool, the configuration required can be vastly different. If you are unsure of what configuration will be best for your job, consult with a professional.

   2. In order for a drill to be capable of tapping it will need to have a reverse on the motor. Since tapping puts considerably more strain on the motor than an annular cutter would, the maximum diameter for tapping will be much smaller. Before purchasing, make sure the machine you are looking at has the capacity you are needing.

   3. Some higher end drills will feature a swivel base, allowing limited rotation of the motor left to right as well as forwards or backwards. There are even drills available with the motor mounted on a cross table for some light milling work.

3. Optional Coolant System

   1. On most materials, coolants/lubricants are a necessary component of the machining process. A good magnetic drill will include a coolant system that feeds cutting fluid through the center of the arbor to enhance performance and extend tool life. This allows built in coolant systems to cool your cutter and workpiece much more effectively than any sort of exterior cooling system.

4. Common Safety Features

   1. Good safety features are an important part of any magnetic drill. The basic features that every drill should have are the cutter guard and safety chain. These should always be in use, and can quite literally be life savers.

   2. Magnetic adhesion protection is an incredible feature found on many drills that allows the drill to automatically shut off if it ever detects unsafe levels of adhesion. This can be caused from any number of reasons, such as insufficient power supply, sudden workpiece movement, or accidentally bumping the drill during operation.

   3. LED load indicators combined with overload protection are great features found on many nicer drills for keeping the feed pressure within the acceptable range the drill should operate in. If the feed pressure ever exceeds this range, the motor would shut off to protect the motor. Since this isn’t an uncommon occurrence for users, smart restart technology was developed on some drills to restart the drill automatically within seconds of it detecting the drill returning to acceptable feed pressure.

Common Drill Bits Used with Magnetic Drills

1. Annular Cutters

   1. Hollow core bits - used to drill new holes. Drills the exterior edge of the hole while leaving a solid slug behind in the middle that is ejected by a pilot pin. By far the most popular bit to use with a magnetic drill.

2. Twist Drill Bits

   1. Traditional solid bits - used for drilling smaller holes.

3. Countersinks

   1. Conical bits - used to make recesses on the surface of the workpiece. Most commonly used so a screw/bolt can sit flush with material.

4. Reamers

   1. Solid bits - used for drilling new holes, correcting alignment of existing holes, or enlarging existing holes depending on the style of reamer.

5. Tapping

   1. Threaded bits - used on an existing hole to create threads on the inside of the hole. Allows bolts to be securely fastened to the material.

Common Applications

• Structural steel fabrication

• Bridge and building construction

• Shipbuilding

• Maintenance and repair

• Any job requiring portable, accurate metal drilling

Key Advantages

• Highly portable and precise

• Works in tight or awkward spaces

• Faster setup vs. stationary drill presses

• Versatile for vertical, horizontal, and overhead drilling