Die Grinder Guide: Everything You Need to Know

From woodworking to metalworking, die grinders are one of the most versatile tools that can be used to machine almost any material when combined with the right attachment.

A die grinder is a power tool that consists of a rotating spindle coupled with a collet chuck to hold the cutting tool. It is a versatile tool that can be used for applications such as grinding, polishing, honing, and sanding, intricate patterns, or internal profiles.

This article tells you everything you need to know about die grinders and how to use them.

Die Grinder: How to Use it?

A die grinder consists of an encased motor that drives the rotating spindle, with a collet chuck gripping the shanks of the grinding tool.

When operating the die grinder, the spindle rotates the cutting tool, which is then brought in contact with the workpiece to remove the material and perform the desired machining operation.

The die grinder's real capabilities are often not appreciated due to its name.  By using appropriate cutting tools, a die grinder can also be used to drill, cut, or polish a workpiece.

The ability to control the speed of the spindle makes it suitable for machining wood as well as metal workpieces.

Apart from that, with proper tool selection, it can also be used to machine plastics or to produce markings on glass.

Types of Die Grinders

Parameter	Electric Die Grinder	Pneumatic Die Grinder
Performance	Good	Best
Long-term operation	Not suitable	Suitable
Portability	High	Low
Cost	High	Low

Electric Die Grinders

Electric die grinders consist of an electric motor that rotates the cutting tool to perform the required operation.

However, electric motors are prone to overheating when subjected to prolonged usage.

As a result, these die grinders are suitable for small-scale applications where prolonged usage is not required.

Generally, electric die grinders have a rated power of about 800 W and a maximum permissible continuous usage of 4 minutes.

Therefore, when using an electric die grinder, it is important to stop the grinder, allowing the motor to cool, thereby prolonging the life of the equipment.

The maximum size of the collets that is compatible with an electric die grinder is 1/8”.

However, these grinders are available in wireless variants, which provide high portability, making them suitable for remote applications.

Die grinders, such as Makita GD0601 provides the ability to operate on both, AC and DC power source, enhancing their flexibility.

Pneumatic Die Grinders

These grinders offer better flexibility in terms of design. The pneumatic grinder's speed is usually controlled via a throttle present on its handle.

Using nearly a 20-gallon compressor, you can run it for quite a long period without any heating issues.

These grinders are preferred tools for machinists or pattern makers because they can produce heavy torque and offer more considerable material removal.

The cost of a pneumatic die grinder of similar capability is comparatively less than an electric die grinder.

Apart from that, these die grinders offer better efficiency, because no energy is wasted in terms of unwanted heat generation.

However, pneumatic die grinders require bulky compressors to operate, thereby reducing their portability.

Applications of Die Grinder

Cleaning of Machined Surface

Manually cleaning the metallic chips from the surface of the workpiece, post-machining, is usually tedious and time-consuming.

Instead, a die grinder with a soft brush mount can be used for quicker cleaning. It also provides added safety to the machinist by reducing the chances of injuries from sharp chips.

Removing Rust and Paint.

Whether it’s a body of heavy machinery or a car, it is always prone to rusting over time, damaging the surface.

Using a die grinder with a wire cup brush provides an efficient and quick way of removing or stripping rust and unwanted paint from large flat areas.

The wire wheels can also fit smoothly in corners and crevices, which otherwise are difficult to reach with traditional sandpaper, increasing the efficiency of the process.

Buffing Weld Lines in Metalworking.

Weld lines can be annoying in terms of surface irregularities. A die grinder mounted with a suitable burr can quickly get rid of the excess weld material along the weld line to obtain a smoother surface.

Sculpting Wood into Shapes

Carbide burrs-mounted die grinders can effectively carve a wooden workpiece into various artworks and shapes.

It offers better mobility for creating intricate designs than heavy tools used in woodworking.

Similar to removing rust in the case of metal, a die grinder can also be used for finishing or sanding wood workpieces using the mounts like a drum sander.

Shaping Plastics

Apart from metal and wood, the die grinder can be applied to shape plastics.

However, you should keep in mind when shaping plastic, a fine burr must be employed at slow speeds to avoid workpiece burnout.

This is because plastic is a soft material that is prone to melting due to the frictional heat generated at high-speed machining.

Apart from that, the chips produced can jam the teeth of the burr. Therefore, a burr with fewer flutes is advised for easy chip clearance.

Cutting of Metal Bolts and Sheets

Die grinders with cutoff wheels made of aluminum oxide or ceramic grits can cut down metal bolts and sheet metal.

The wheels are relatively less expensive than the other tools, used for the same purpose.

Factors to Consider When Using a Die Grinder

Cutting Speeds

Die grinders are low-torque high-speed tools, suitable for applications where you don’t need to apply too much pressure on the workpiece surface to remove the material from its surface.

These are generally available in single-speed and variable-speed variants, with the variable-speed variant providing comparatively greater material flexibility.

Generally, variable-speed die grinders provide a range of 10,000 to 30,000 RPM. 

However, the optimal speed for the operation depends upon the type of cutting tool and the workpiece material.

Cutting Tool to be Used

Die grinders typically use a collet to grip the shank of a tool, and choosing a proper shank size is very important for a good grip.

For a shank size of 3/32” to 1/8”, the compatible collet is 1/8”. Similarly, for shanks of 1/64” to 1/16”, the preferable collet size is 1/16”.

Die grinders are compatible with a wide range of cutting tools, which makes it important to select the right tool for your application.

Burrs

Burrs are the most common tools mounted on a die grinder using a collet and chuck. The burrs are also known as rotary files.

These tools are generally made from tungsten carbide or high-speed steel, making them durable to machine a variety of materials including wood and metal.

Depending upon the size and shape of its teeth, burrs are classified into fine and coarse-toothed burrs.

Some typical applications of burrs include; carving, routing, milling, and engraving.

Brushes

Brushes made of steel, nylon, and brass wires are also available as mounting tools for die grinders.

They are employed primarily for cleaning purposes, wherein soft brushes are used on more delicate workpiece materials like wood, and steel brushes are used on metal workpieces for removing rust.

Grinding Discs

These are hard discs consisting of a solid mass of tiny grits (particles) of silicon carbide (SiC) or aluminum oxide (Al₂O₃).

Grinding discs are suitable for cutting and slotting metals (both ferrous and non-ferrous).

Apart from the above-mentioned tools, several other mountings, such as drum sanders, tiny drill bits, and polishing discs, are also available and compatible with a die grinder.

Optimizing the Speed for a Particular Cutting Tool

The net outcome of a die-grinding process depends on the correlation between speed and the tool head. For instance, a small tool with a higher speed is essential for a finer finish.

Another critical factor that also depends on speed and cutting tool head is the feed pressure.

For example, a 16-flute cutting tool, running at 24,000 RPM will create around 3,84,000 chips per minute, making it important to set the optimal chip load for the process.

In such a scenario, it is important to apply minimal force on the cutting tool, just enough to maintain contact between the tool and the workpiece.

Applying excessive force can increase the chip load, clogging the teeth of the cutting tool, and degrading the tool life and surface finish.

Die Grinder vs Angle Grinder

Factors	Die Grinder	Angle grinder
Design and size	Straight rotary tool.	The shaft and the tool head make a 90˚ angle between each other and need two hands to operate.
Source of power	Pneumatic, electric, battery.	Electric, battery.
Power	Usually less than 1 HP.	Can go up to 5 HP.
Speed	Can range between 10000 to 30000 RPM.	Can range between 6500 to 20000 RPM
Applications	Grinding and engraving different materials	Grinding, engraving, and cutting different materials
Price	Comparatively Expensive.	Relatively Inexpensive

The smaller size factor of die grinders makes them suitable for applications where grinding of tighter locations, such as intricate patterns, is required.

On the other hand, angle grinders are suitable for removing material from a comparatively larger workpiece and producing a larger cut.

Generally, angle grinders are suitable for machining the outer surface of the workpiece, while the smaller tool size makes die grinders suitable for machining internal dimensions, such as holes.

Moreover, the low torque and high-speed configuration of die grinders make them ideal for grinding and engraving applications on wood, plastics, metals, etc.

On the other hand, angle grinders provide comparatively much higher power output, suitable for grinding, as well as cutting operations.

Frequently Asked Questions (FAQ)

What is the difference between a die grinder and Dremel?

The difference between a die grinder and a Dremel lies in its size and power. When compared to a die grinder, a Dremel is much smaller and produces lesser torque and material removal rate.

What are the cutting wheel diameters used with angle grinders and die grinders?

The cutting wheel diameters used with angle grinders and die grinders vary from 2 inches to 9 inches. The angle grinders use larger cutting wheels with a diameter ranging between 4 to 9 inches. Whereas, die grinders use cutting wheels with a diameter from 2 to 4 inches.

What is the difference between honed and polished surfaces?

The difference between honed and polished surfaces lies in their texture. Honed surfaces are usually matte and do not reflect light. Whereas, the polished surfaces are usually shinier and are obtained by smoothing the surface repeatedly using proper abrasives and grit size.