Die Grinder, Air Grinder, & Straight Grinder: FAQ Guide

This FAQ and answer style guide will be extremely valuable if you are looking at:

  • Buying or using a Die Grinder, Air Grinder or Straight Grinder AND
  • You want to know What Is A Die Grinder (or Air or Straight Grinder), and How To Use one of these tools

We will answer for you the Who, What, When, Where, How, Why, Can and Do of buying and using Die Grinders, Air Grinders and Straight Grinders.

If you are looking to buy a die grinder, you can check out Best Die Grinder, Straight Grinder and Air Grinder: Buyer’s Guide and Reviews.


Die Grinder FAQ: What Is A Die Grinder, Air Grinder or Straight Grinder & How To Use?


Contrary to what you might have been told, or what the many others refer to these tools as – die grinders, air grinders and straight grinders are all different terms that essentially describe the same type of tool (they are most often referred to as a die grinder though).

The die grinder is the main name for the tool – with an air grinder being one of the forms of power for the tool (the other being electric), and a straight grinder being one of the die grinder tool shapes (the other being an angle headed die grinder)

We’ve decided to do one big guide for all three as opposed to splitting them up, as there is a lot of information overlap.

Dremels perform very similar functions (and belong to the same rotary tool category), but are slightly different, and we will discuss them in another article on Tooljuice.com.

Angle grinders are from the same tool grinding family as Die, Straight and Air Grinders, but they are bigger and are just a different tool altogether in many ways (although angle grinders can sometimes be air driven/powered too).

If you are interested in learning more about angle grinders, check out Angle Grinder FAQ: What Is An Angle Grinder & How To Use It?


What…Die Grinder?


What is a Die grinder?

A die grinder is a handheld power tool that works as a type of rotary tool.


What are the different types of die grinders?

They come in two power types:

  • electric (plugged into a mains supply via a cord), or
  • pneumatic (air driven) – most die grinders are air die grinders. Air powered die grinders are run with a suitably sized air compressor and an air hose running to the tool –  refer to the cfm required for the tool for more information on this.

They can also have a straight shaft with a straight head, or a straight shaft with a right angle head (the head is where the die grinder attachment is secured and rotates/spins).

When people talk about a straight grinder or an air grinder, they are often referring to a die grinder.


How did die grinder get their name?

Die Grinders get their name from one of their original uses – tool and die work, where they were used to create the precise contours of dies or molds.

These days they can be used with a range of different attachments, wheel or bits to cut, grind, sand, shape, polish/clean + more, on a range of materials including but not limited to metal, wood and plastic.


What does a die grinder do/what is a die grinder used for?

Die grinders can be used for a wide range of applications – basically whatever you have the bit of attachment for, you can do with a die grinder.

These applications might include grinding, cutting, sanding, honing, polishing, sharpening, sculpting, burring or machining material (typically metal, but also plastic or wood).

They can be used by a range of people and professions, but are heavily used by metal workers, machinists, automotive professionals and restoration tradesmen.

So, those working with metal and wood might use them extensively.

Die grinders are much small than an angle grinder which have large discs. The small size of the die grinder attachments makes them great for accessing tight spaces and performing finer, more precise grinding, cutting and shaping/forming tasks that angle grinders simply can’t do.


Die Grinder Uses – Examples

Some specific tasks you can perform with a die grinder include:

Polishing stainless steel

Removing rust or paint on iron or steel

Finishing, sanding and shaping woodwork and furniture

Sculpting Ice

Remove welds or grind out welds

Porting car engines – cleaning and contouring, or modifying

Machining metal e.g. enlarge holes on a metal locker to allow a padlock

Cut sheets, bars or blocks of metal, steel, plaster and wood

Burring materials

Sharpening axes or chainsaws with a grinding stone attachment

Cleaning various items


What size air compressor for die grinder?

It depends on the die grinder you buy, but it is generally not recommended to go with an air compressor with a tank capacity of anything less than about 25 gallons or 95 litres, otherwise you may not be able to use your die grinder while you’re waiting for your air compressor tank to refill.

Check the air consumption requirements of the die grinder you buy (should be listed in the product information), and understand that different air compressors pump air at a different rate per minute – so check that too (in addition to the overall tank capacity).

Note that a standard air die grinder functions at about 90psi.


What is the best die grinder?

To find out the best die grinder for your particular needs, you can check out Best Die Grinder, Straight Grinder and Air Grinder: Buyer’s Guide and Reviews.


What is a pneumatic die grinder?

A pneumatic die grinder is an air operated (via an air compressor) die grinder.

They are distinguished from electric die grinders.


What is an angle die grinder?

Die grinders come in two configurations as far as shape goes – straight, and angled:

1) A straight die grinder has a straight shaft/body with a straight head (the head is where the attachments go)

2) An angle die grinder or right angle die grinder has a straight shaft/body, and a right angle head


What is the best angle die grinder or straight die grinder?

It depends on you and what tasks you want to be able to perform – you can get a better idea by reading Best Die Grinder, Straight Grinder and Air Grinder: Buyer’s Guide and Reviews.


What is a straight die grinder?

A straight die grinder is a die grinder that has a straight body and a straight head, as opposed to a straight shaft/body and an angle head (right angle).


What is a mini die grinder?

A mini die grinder is smaller in length and weight than a standard die grinder.

They are often labelled as a mini, small or micro die grinder by their manufacturers.


What is the best electric die grinder?

It depends on you and what tasks you want to be able to perform.

We are currently writing a guide on the Best Die Grinders, Air Grinders and Straight Grinders – so check back here shortly once it’s finished to find the best angle die grinder for you.


What are some of the die grinder bits or die grinder attachments available?

Die grinder bits and attachments include but are not limited to:

Stone grinding bit

Brass wire wheel

Nylon bristle wheel

Brass cup brush

Nylon bristle cup brush

Diamond wheels and bits

Different shaped rasps

Twist Burs

Regular metal and wood cutting/cutoff wheels

Sanding disc

Sanding Drum

Wool polishing wheel/polishing pad

Grinding wheels


Sanding drum mandrels

Sharpening stone


What are some similar tools to a die grinder?

As a comparison, a die grinder might sit in between a Dremel rotary tool (read Dremel guide), and a Angle Grinder (read angle grinder guide) in terms of size, performance and the types of applications you use it for (on a light to heavy scale)

A Dremel for example is a type of finishing rotary tool – used for lighter tasks.

A die grinder is a step up from a Dremel, with more powerful motors and heavy duty parts for heavier tasks such as grinding welded metal, or porting engines for example.

A step up from a die grinder would be a tool like an angle grinder.


When…Die Grinder?


When to use a die grinder? – Die Grinder vs Angle Grinder

It is best to use a die grinder when:

1) A handheld saw or hacksaw is too small or not powerful enough for the job

2) An angle grinder is too big or heavy for the job

3) You need to perform precise or finer functions in small areas that an angle grinder can’t (angle grinders are generally for larger surface areas and bigger jobs).

For example, a die grinder will be much better at engraving or contouring on a block of wood than an angle grinder. On the other hand, an angle grinder is built much better to cut through concrete and tiles than mot die grinders.

4) Your profession or work is specialised and calls for you to have the capabilities and features that a die grinder delivers


Where…Die Grinder?


Where to oil die grinder?

On a pneumatic die grinder, there is usually a grease fitting at the head of the tool.

All you do is place a small grease gun inside the fitting and grease up the die grinder – pretty simple.

Some people also like to grease the squeeze lever and air inlet screw piece, but this is a personal preference.


Where to buy die grinder?

You can buy a die grinder online, or in tool stores locally near you.

We wrote a guide on buying a die grinder online – Best Die Grinder, Straight Grinder and Air Grinder: Buyer’s Guide and Reviews.


Why…Die Grinder?


Why is it called a die grinder?

Die grinders get their name from one of the first lines of work they were used in – tool and die making, which is part of the machinist category.

Die grinders were initially used to create precise contours on dies and moulds.

In modern times, tool and die makers fabricate jigs, fixtures, dies, molds, machine tools, cutting tools, gauges, and other tools used in manufacturing processes.


Why use a die grinder?

Whether you use a die grinder will depend on your personal preference, but generally people use die grinders to perform precise tasks over very small areas, compared to angle grinders which are used for larger area, and much more imprecise cutting, grinding and so on.


How Die Grinder?

How does a die grinder work?

The die grinder operates with a small motor (if electric) and gears inside the grinder unit, that drive the main shaft attached at the head to a type of attachment chose by the user.

If the die grinder is pneumatic, it has an air intake at the bottom of the shaft which powers the rotary disc/attachment.

This attachment like a grinding bit, or a cutoff wheel, spins/rotates at a high speed and is applied to different materials for different uses.


How do air die grinders work?

An air die grinder works in the following way:

1) A regular air die grinder has a shaft with an air inlet at the bottom, a control lever on the middle of the shaft, and a head at the top with collets that you attach your grinding bit to.

2) Once the air hose from the air compressor has been attached to the air inlet on the bottom of the air die grinder shaft, you now have power

3) Release the safety on the lever and pull down on it

4) The collets mechanism will spin, causing your air die grinder bits to spin, and the air die grinder is working!

Make sure to grease the air die grinder routinely.


How to use a die grinder?

Follow the steps above and read ‘What can you do with a die grinder?’.


How does die a die grinder work?

Air die grinders work as described above.

Electric die grinders either have a plugged in, or battery power source. They have a motor and gear arrangement which propel a shaft that runs the length of the unit to the attachment at the top – when the motor is on, it spins the attachment via the head mechanism.


How many cfm to run die grinder?

As an example, we looked at one of the most popular straight die grinders, and it said depending on the duty cycle you require, if you use the die grinder at full throttle, you will need about 3.0 cfm. You most likely won’t always use a die grinder at full throttle though, so this cfm number will commonly be lower in actual operation.

In addition, a standard die grinder needs 90psi air pressure to operate.

It is generally not recommended to go with an air compressor with a tank capacity of anything less than about 25 gallons or 95 litres in total. Check the air pump rate per minute of the air compressor you have.


How to oil die grinder?

Refer to question above – ‘Where to oil die grinder?’.


How to use a pneumatic die grinder?

Refer to question above – ‘How do air die grinders work?’.


How to repair air die grinder?

Sometimes it is cheaper and takes less time to simply replace the air die grinder.

But, if you think repairing the air die grinder will benefit you, the rebuild and parts instructions should have come with the box/package you bought your tool with.

If you can’t find them, look on the manufacturers website for a diagram and parts list. This should tell you where the relevant screws and nuts are that hold the main unit together, and how to put the parts back together when you have it fixed.


How to grease a die grinder?

Refer to question above – ‘Where to oil die grinder?’.


How to change die grinder bit?

The head of most die grinders come with collets or screw mechanisms to attach the die grinder bit or disc.

All you do is screw your attachment in, and/or fasten or loosen the attachment at the head with the die grinder bit changing tools (usually two wrenches).

Note that die grinder bits are extremely small and spin extremely fast when in use – much smaller and faster than angle grinder discs and bits.


Can…Die Grinder?


Can you cut wood and metal with a die grinder?

Yes – buy the relevant die grinder cutting disc or attachment.

Use the diamond attachment if cutting demanding materials.


What can you grind with a die grinder?

You can grind, shape and hollow out (form holes and spaces within metal and wood) with a die grinder.

For regular grinding, use the relevant grinding wheels.

For cleaning and removal type grinding, use the wire cup or wire wheel attachment.

For forming and shaping holes, use the flame tip or block tip attachment.


Can you polish with a die grinder?

Yes – use wool polishing wheels.


Can you sand with a die grinder?

Yes – use a sanding disc.


Can you sharpen mower blades or axes with a die grinder?

Yes – use a stone sharpening bit.



What…Straight Grinder?


What’s the straight version or straight equivalent of a grinder?

As discussed above, a straight die grinder is the straight version, whilst an angle/right angle die grinder is the angled version.

An angle grinder is a different tool altogether.


What is a Straight grinder used for?

Straight grinders can get into enclosed and small spaces that angle grinders and some angle die grinders can’t.

There are also the ‘pencil’ type straight grinders that are extremely small and precise with the work you can do with them.


What does a Straight grinder do?

Straight grinders are especially great for fine contours, getting into tight spaces to grind welds, cut bolts, machine metal and more.

They can also perform alot of the functions that a regular die grinder can.


How…Straight Grinder?


How to use a straight grinder?

Refer to question above – ‘How do air die grinders work?’

For electric straight grinders, they are plugged into a power source.



Who…Air Grinder?


Who makes the best air grinder?

There are various brands that make great air die grinders which you can view in Best Die Grinder, Straight Grinder and Air Grinder: Buyer’s Guide and Reviews.


What…Air Grinder?


What is an air grinder used for?

Refer to question above – What is a die grinder used for?


What is an air die grinder?

An air grinder is an air powered grinder tool. Air grinders are mainly manufactured in the die grinder form, but there are a few air angle grinders out there.


What size air compressor for air grinder?

Refer to question above – What size air compressor for die grinder?


What is the best air grinder?

Refer above to ‘Who makes the best air grinder?’.


What is a air angle die grinder used for?

Because the heads on an angle die grinder and straight die grinder are different, you hold the tools slightly different.

Angle die grinders are held more like a hammer, whereas straight grinders are held more like a pencil.

Air angle grinders are probably used more for grinding, polishing and sanding than straight grinders are.


What is an air pencil grinder?

Air pencil grinder are a form of die grinder. They are usually very small, have a straight head and you hold them like a pencil.

They are usually used for very fine tasks like contouring.


How…Air Grinder?


How to use air grinder?

Refer to question above – ‘How do air die grinders work?’

For electric straight grinders, they are plugged into a power source.


How to oil or grease air grinder?

Refer to question above – Where to oil die grinder?


How does an air grinder work?

Air grinders are connected to an air hose which is connected to an air compressor.

The air spins the attachments in the head which turn the air grinder bits.



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