Best Die Grinder
Die grinders aren’t heavy-duty tools for knocking off weld slag like a right angle grinder. Rather, they’re detail tools, for those times where finesse is needed more than power. The small size and light weight of these tools make them ideal for fine finishing work, something that’s hard to do with a right-angle grinder.
Typically, a die grinder uses a 1/4 inch collet for holding a variety of tips. However, some of the smaller units such as cordless ones and pencil grinders use a 1/8 inch collet. They work with a wide variety of tips including grinding wheels, carbide cutting tips, sanding disks, and cut-off wheels. With the variety of tips available, these tools are very versatile and good for a wide variety of tasks.
Whereas angle grinders are normally only used for metalworking, die grinders (especially the smaller ones), have found a number of other niches including jewelry making, crafts, model making, and anywhere else a small cutting or grinding tool is needed. Our buyer's guide listed below can help you to pick the right die grinder for your needs.
Best Pneumatic Die Grinder:
Generally speaking, grinders are not considered fine finish tools. They are normally considered tools for rough finishing of work, especially used for removing weld slag. However, there are times when detailed work needs to be done with a grinder. Thats where a die grinder comes in.
Die grinders are much lighter and easier to handle than angle grinders, allowing you much greater control over the tip. The grinder itself is small enough to fit comfortably in one hand and light enough to use for a considerable amount of time, without tiring. A wide variety of carbide bits, stones and abrasive tips can be attached to the grinder, enabling you to find a tip that will fit the application.
The tips used with a die grinder are mounted on 1/4-inch diameter metal shafts. The die grinder itself has a 1/4-inch collet for these to mount into. Removal and replacement of stones is accomplished with wrenches.
In addition to these tips, die grinders can be used with a cut-off attachment. This attachment is more of a shield than anything else, protecting you from flying sparks. The cut-off wheel itself is a thin grit impregnated fiberglass wheel, which is designed for cutting off metal. While it is possible to use a die grinder and cut-off wheel without the shield, it is not recommended.
While most die grinders are inline, meaning that the tip is held in line with the motor body, a few manufacturers are now producing right angle die grinders as well. These should not be confused with angle grinders, as they cannot take angle grinding wheels, nor can angle grinders take the tips used on die grinders. The angled die grinders are also much smaller than even the smallest angle grinders, making them easier to handle for detailed work.
The advantage of an angled die grinder is that it is easier to control in some cases. A lot of this is personal preference, but the major difference is that the angled die grinder is more comfortable to hold when using it.
Another type of die grinder is called a pencil die grinder. These are essentially the size and shape of a magic marker. As such, they are the easiest to control; designed for fine detail work.
Die grinders operate at much higher speeds than other types of grinders, typically over 20,000 RPM. This helps make up for their lower power, but also helps with the control of the tool. With the tip turning so fast, there is little chance of it catching on a protrusion, such as a bit of weld slag sticking up.
Always use eye and ear protection when working with a die grinder. Gloves are a good idea as well. The hot metal sparks that are thrown up by a die grinder can cause burning and blindness.
There's a reason why this is called a "professional" die grinder. This is an excellent tool, built to be easy to work with and last for years. The grinder is also the quietest one around, which makes it nice to work with for long periods of time. Read Full Review
Some people can't decide between a straight die grinder or an angled one. Well, Astro Pneumatic has solved that problem for them, with this kit. Not only do you get both, but a nice set of carbide burrs as well. Read Full Review
Chicago Pneumatic calls this a "heavy duty" die grinder for a reason. It has a 1/2 HP motor, which makes it 50 percent more powerful than the standard 1/3 HP motor that everyone else is using. Read Full Review
Ball bearing construction ensures long life for this die grinder by Ingersoll Rand. It's also the fastest one we've looked at, with a top speed of 27,000 RPM. Read Full Review
This unusual die grinder is known as a pencil grinder, because of its shape and size. It is perfect for highly detailed work, using 1/8-inch shank tips. Read Full Review
Best Cordless Die Grinder:
Just like all the other power tools out there, die grinders are going cordless too. While that makes for a much larger tool than a pneumatic one, it gives you the convenience of not having an air hose to drag around. In addition, an electric motor has to be larger to develop the same amount of power than a pneumatic one does. Thus, there are both pros and cons to both types of die grinders.
There really isn’t a standard for these tools unlike many other types of power tools. The voltages range from 12 to 18 volts and collets can vary in size as well. While pneumatic die grinders all use 1/4-inch collets ( except for pencil grinders) you can find both 1/4-inch and 1/8-inch collets on these tools.
Like any die grinder, the most important specification is speed because the faster the die grinder, the faster it will cut. None of them cut really fast, so you want all the speed you can get. Power isn’t as much of an issue, as you really don’t apply a lot of pressure with a die grinder. Rather than being designed for taking off a lot of material, these tools are really designed for finishing work.
All of these units use Lithium-Ion batteries, which is especially nice for this application. The old Ni-Cad batteries tended to bleed off, allowing the tool to gradually slow down, until it reached the point that the user gave up. Li-Ion batteries stay close to their rated voltage up until they are ready to quit, meaning the tool keeps running at speed until it’s ready to die.
Battery size and recharge times are important, as these tools are on constantly when in use. Because of that, they tend to discharge batteries rather quickly. Li-Ion’s faster charge time helps ensure you can keep on working instead of waiting for your batteries to recharge. Even so, you definitely need two batteries to work with these units.
Due to the batteries, these units tend to be heavier than their pneumatic cousins. However, there is no cord or hose to drag around, which somewhat mitigates that problem.
Some of these units come with an electronic motor control to help maintain motor speed, even under load. In most cases, the trigger switch is or has a lock-on, which is very convenient for reducing operator fatigue when working for long periods of time.
This grinder from Metabo has features you won't find anywhere else, including a safety shutdown that disconnects power from the motor in the case of a jam and restart protection to avoid accidental starts. There’s also an air-cooled charger which provides fast charging without damage to the batteries. Read Full Review
With this unit, Makita has introduced a stepped nose on their cordless die grinder. While it makes the tool longer, it also provides the ability to fit it into tight spots. This 25,000 RPM tool also has electronic motor protection to maintain speed under load. Read Full Review
Bosch beats Makita out for weight, with their cordless die grinder coming in at a shade under four pounds. It works with Bosch's flexible power system, using both slim and fat pack batteries. Read Full Review
Although Milwaukee refers to this as a "rotary tool" it's really a 1/8 inch collet die grinder. Weighing in at only 1/3 of a pound, this compact and lightweight tool is very easy to use. Read Full Review
Even though most people don't think of a Dremel tool as a die grinder, that's what it is. Dremel pioneered the field of miniature die grinders and produces several cordless models including this one. Read Full Review
Die Grinder Buyer's Guide
The die grinder is the smallest of the various types of grinders that are made. Unlike the larger grinders, these are not intended for rough cutting as much as they are designed for detail-oriented work. Their high speed and variety of tips make them an ideal tool from fine finishing of a workpiece to adding details to the shape by hand.
Die grinders depend upon high speed for their cutting power rather than brute force. These tools are typically low power units, 1/3 HP or less. However, they run at speeds of 20,000 RPM or more with a few units that top 50,000 RPM. At those high speeds, it’s easier to do the fine detail work these tools are known for.
Options Available for Die Grinders
These tools are rather simple, without a lot of options to choose from. The options actually come about in the type of tip you put on the die grinder. However, there are some things you might want to consider when looking for a die grinder.
Die Grinder vs. Cutoff Tool
Die grinders are often sold as cutoff tools with the addition of a guard and the installation of a fibrous cutoff wheel. With a cut-off wheel, a die grinder can be used to cut metal bar stock and tubing. If you buy a die grinder, rather than a cutoff tool, you can easily convert it for cutting off metal bar stock and tubing by adding a shield to protect you from hot metal sparks. The only difference between a die grinder and a cut-off tool is this shield.
For this reason, you might want to consider buying a cutoff tool rather than a die grinder because that way you already have the shield. Just verify the tool comes with a 1/4" collet and that its speed is equal to the die grinder.
Variable Speed Control
Many die grinders are designed to allow the user to control the speed, even though they’re typically used at full speed. However, when cutting or grinding softer materials the variable speed helps prevent overcutting and potential destruction of the workpiece.
Straight vs. Right Angle
Traditional die grinders are straight, with the tool rotating perpendicular to the length of the tool. More recently, manufacturers have started making right angle die grinders and there’s even one manufacturer making a die grinder built at 30 degrees. While the angled head is easier to hold for some types of operations, both styles have their place.
These angled die grinders shouldn’t be confused with angle grinders which operate totally differently. A right angle grinder only works with grinding wheels which mount to a shaft. A right angle die grinder still has a collet for the various types of tips to mount into.
Pneumatic or Cordless
As with many other power tools, cordless die grinders are now appearing on the market,
for portability and ease of use. While cordless die grinders are longer than pneumatic ones, the not having to drag around an air hose or power cord makes it possible to get into areas with where pneumatic die grinders simply can’t reach.
Like most cordless tools, cordless die grinders are used more by contractors on remote jobsites, than by people working in a shop. The advantage of working off of battery power isn’t as apparent when you are in a shop with air power piped throughout. Pneumatic die grinders will run virtually indefinitely off of shop air as they use very little air. In the same situation a cordless die grinder would require stopping to change the battery periodically.
A sub-category of die grinders are pencil grinders. These are designed using a 1/8" collet, rather than a 1/4" one. The smaller collet allows for smaller cutting heads for finder detailed work. Typically these will be smaller, making them easier to hold like a pencil and use in the same way.
Pencil grinders come in pneumatic, electric and cordless. The electric ones may have the motor separate from the grinder head, running power through a flexible cable down to the head. This "flexible shaft" pencil grinder is popular with model makers and jewelry makers who need to do fine detail work without having a large motor-driven tool in their hands.
The dremel tool actually falls into this category although it has a larger body. Nevertheless, it comes with a 1/8" collet designed to be used with the same types of tips used on other pencil grinders. Even though it’s larger in diameter, the casing is designed to be ergonomic so it can still be held like a pen and used as easily as the other types of pencil grinders.