Beginners Guide to Rapid Traverse for CNCs

Key Points

  • Rapid traverse is full speed movement
  • Rapid travel and rapid traverse are the same thing
  • The G code for rapid traverse is G00 on CNC mills and lathes
  • The rapid speed can be adjusted using the rapid override

What is rapid traverse?

Rapid traverse, sometimes referred to as rapid transverse or rapid travel, is used for moving a machine tool around the workpiece as fast as possible. 

Depending on the type of machine tool, this is accomplished in different ways. See below for more information related to CNC and manual machines.

How fast does the machine move in rapid traverse?

First let’s talk about speed.

Rapid traverse speeds vary based on the machine.  A good quality desktop CNC will usually be capable of speeds around 100 inches per minute (IPM).

homemade cnc router machine
Homemade “garage” CNC

Larger, industrial grade CNC can often move at speeds of 1,000 inches per minute or more. 

industrial cnc machine
Industrial grade CNC mill

No matter what type of CNC you are using, you will want to make sure that nothing is in the way when these moves are being made in a CNC machine. 

Crashing a CNC at normal speeds is bad enough, crashing a CNC at rapid speeds could be catastrophic.

Can rapid traverse speed be adjusted?

cnc control board with rapid travel dial identified with arrow
Rapid Override Dial

Most CNC machine controls have an adjustment to dial back the rapid travel speed. This is often referred to as Rapid Override or something similar. This override allows the CNC operator to adjust the rapid speed, usually in the form of a percentage of the full speed.

Some shops need to run full speed. Time is money after all, but many machine shops will dial things back a little for safety.

How does the CNC move during rapid travel?

straight line movement example

Newer CNCs will move in a true straight line fashion, however some older CNCs can process the command in different ways.

Some machines may only move one axis at a time while others will move in other strange ways. The most important thing is to be aware how your specific CNC control will process the rapid travel command and create your program to account for this movement.

Because various machines will process commands in different ways, this means you may not be able to take a program and a setup and run it on a different machine.

What is the G code for rapid traverse?

rapid traverse code example

The G code for rapid movement is G00. 

This applies to both CNC mills and lathes. 

In the example above, G00 is the code for rapid traverse and the X and Y values are the position that the machine is to rapidly move to.

Rapid movement can happen in the Z axis as well.

What should you think about when using rapid travel?

When you are zipping your CNC back and forth think about:

  • Part location – it can be easy to forget about a step in your part and attempt to move over the top of you part at a Z height that is too low
  • Fixturing – similar to your part location, remember that you often have clamps, vises, etc. that will be in your machine and it’s best to avoid them
  • Removing material – don’t cut in rapid mode, it will result in size issues and poor surface finishes at best

Rapid traverse in manual machining

bridgeport milling machine with rapid power feed pointed out
Power feed marked by red arrow

Many manual machines, such as a Bridgeport mill, use a power feed to rapidly move around the workpiece. 

These power feeds are not as fast as a CNCs rapid moves but they are still much quicker than the standard speed which usually involves cranking a handle to position the machine. 

Related articles

For more information see these related articles:

Beginner’s Guide to Micrometers – Get Started

a 0-1" outside micrometer
A standard outside measuring micrometer

What is a micrometer?

A micrometer is a precision measuring tool. 

They are used in manufacturing, machine shops, automotive work and the construction industry. 

“Mic” is shorthand for micrometer.

Mics are very accurate measuring devices. 

Micrometers are used to take measurements with an accuracy of ~.0001″ or better in inches. 

Measurements in millimeters can be made down to .01mm or .001mm.


How accurate are micrometers?

Most micrometers have an accuracy of +/- 0.0001″, commonly referred to as a tenth of an inch in machining.

The standard metric versions would come as +/- 0.001mm or +/- 0.002mm.

They can be found with worse or better accuracy but what is usually seen .

When to use a micrometer

Three of the most common precision measuring devices used by a hobbyist or a machine shop are calipers, micrometers and dial test indicators. 

Calipers have the least accuracy of the three and the largest measuring range.

a mitutoyo digital caliper with the display on
Mitutoyo digital caliper

The dial test indicator has the most accuracy and least measuring range. 

Micrometers are in the middle for both accuracy and measuring range. 

While still very accurate, one downfall of the micrometer is that they usually come with a 1″ measuring range (3-4″, 4-5″, etc.).

Because of this they are often sold in sets to cover a larger measuring range. 

A 0-6″ micrometer set will cover the needs of most applications while a 0-12″ set is more than most people, especially hobbyists will need. 0-3″ sets are also common.

Parts of a micrometer

a micrometer with all of its part identified

How to use a micrometer

Before using your micrometer, ensure that the measuring tool and surface to be measured are free of dirt, debris, chips, etc.

Everything should be clean.

The micrometer thimble should spin freely. No hangs up or anything similar.

a micrometer with the thimble identified

Open the thimble to place the part you want to measure between the anvil and spindle.

Spin the thimble until it closes on the part. 

You aren’t trying to clamp down on the part. 

closeup of a micrometer with the ratchet stop identified

Use a gentle, consistent amount of force when spinning the thimble. Using the ratchet on your micrometer can make this easier. Try spinning the thimble until you get three clicks on your ratchet.

This will help you get repeatable measurements. You want to be consistent in your measuring so you know your readings are good.

This is why taking multiple measurements is so important.

When possible, measure the part multiple times to be confident your readings are accurate.

A little practice on a cheap gauge block can help here. Measure that same gauge block a bunch of times and you will become more repeatable in your measurements. You’ll also see how easy it is to change your reading.

a micrometer with the anvil and spindle identified

As the spindle closes on the part being measured, it can be beneficial to slightly rock the micrometer in an effort to seat the micrometer on the part.

Be careful: this technique isn’t right for surfaces that could be scratched or damaged easily.

Once you have closed the part in the micrometer, it is time to take your measurement reading.

How to read a micrometer

The most common variety of micrometers measures to one ten-thousandth of an inch (.0001″).

Measurements are taken by identifying where the lines on the micrometer line up.

You will need to take 4 readings and add them together to get your measurement.

These readings are the 0.1000″, 0.0250″, 0.0010″ and 0.0001″ readings.

Machinists refer to these as the hundred thousandths, 25 thousandths, 1 thousandths and lastly the tenths readings.

Let’s get started.

Along the sleeve of the micrometer will be graduations similar to a ruler. The graduations at every fourth interval are most often numbered 0, 1, 2 and so on. 

These numbers represent .100″ or one hundred thousandths of an inch. 

closeup of a micrometer with the 0.100" graduations identified

Whichever hundred thousandths reading you are past is your reading. In the pic above, the hundred thousandths reading would be 3 which equals 0.3000″.

Once you have taken your hundred thousandths reading then you will need to take the 25 thousandths reading.

Each mark along the sleeve is 0.025″ or 25 thousandths.

closeup of a micrometer with the 0.0250" graduations identified

Next is the reading from the thimble. This is the 0.0010″ reading or one thousandth of an inch reading. 

In the pic above two lines are shown past the three so the 0.0250″ graduation value would be 0.0500″.

In the end we are going to add all of our individual measurements up for our final reading.

closeup of a micrometer with the 0.0010" graduations identified

Note the 0.0010″ reading on the thimble and lastly take the tenths reading from the spindle.

Here we have 15 thousandths.

This makes our measurement so far 0.300″ + 0.0500″ + 0.015″ = 0.3650″.

closeup of a micrometer with the 0.0001" graduations identified

The last reading to take is the tenths reading. If the lines matched up at the 6 tenths mark, then we would have a reading of 0.0006″ which we need to add to our previous readings.

0.3650″ + 0.0006″ = 0.3656″ or three hundred and sixty five thousandths of an inch and six tenths.

Frequently asked questions about micrometers

What kinds of micrometers are available?

There are a ton of different micrometer types available

Often specific industries have their own special type micrometers such as the auto related micrometers on our list of the most common micrometers below:

  • Outside micrometers – measures various lengths, widths, thicknesses and diameters
  • Inside micrometers – measures hole diameters, slot widths
  • Depth micrometer – measures depth of holes, step locations
  • Thread micrometers – measures various thread characteristics
  • Crankshaft micrometer – specific measuring range for measuring crankshafts
  • Disc brake micrometer – measures thickness of brake rotors
  • Blade micrometer – measures slots, keyways and grooves

Are cheaper micrometers as good as expensive ones?

The cheaper off-brand micrometers have gotten much better in recent year, but they haven’t quite caught up to the best manufacturers yet. 

Starrett and Mitutoyo still reign supreme in terms of quality and accuracy.

You can always look for used options on Craigslist or Facebook marketplace to save a buck.

What makes a good micrometer?

A good micrometer needs two things: precision and accuracy. 

Some adjustments can be made with most micrometers to account for small errors in accuracy but nothing can be done to fix a tool that isn’t precise. 

Quality micrometers will turn smoothly without any drag. This is the telltale sign of a good tool. If your micrometer ever feels like it is rubbing internally, we recommend disassembling the micrometer and cleaning per the manufacturers instructions to eliminate any possible contamination that may be causing the issue

How to adjust a micrometer

If your micrometer is in need of adjustment, most micrometers can be adjusted by using the wrench that came with your tool to spin the sleeve of the micrometer. This is usually done in the zero position. This can be especially useful for adjusting for the touch or feel of a mic when it does not include a ratchet or friction stop. 

If you no longer have a wrench or spanner for adjustment, replacement wrenches can be purchased from most manufacturers or on Amazon.

How often should my micrometer be calibrated?

How often you need to calibrate your micrometer will vary depending on a few factors such as what you are measuring with it, how often you are using it, and what type of environment it is in.

Check out our guide to micrometer calibration to get a better understanding of the how, where, when and why of calibrating your mics.

Micrometers and Calipers [Similarities, Differences & Everything Else]

micrometers vs calipers

Micrometers and calipers are both precision measuring tools.

The difference between these tools lies in their accuracy and the types of measurements they can take.

Check out the table below for the main differences between the two tools and then keep on reading to gain a better understanding of what those differences mean when it comes time to use them.






Measuring Range

1" increments


Types of Measurements

Outside Measurements

Inside, Outside & Depth Measurements

Micrometer and caliper comparisons


Micrometers are more accurate. 

A typical micrometer is accurate to 0.0001″ and a caliper is only accurate to 0.001″.

This makes a micrometer 10x more accurate than a caliper.

Just keep in mind that you can buy cheap versions of both tools that have worse accuracy. Also, if you were to buy a larger versions of these tools they will often have lower accuracy. 

A 17-18″ micrometer might only be accurate to +/- 0.0002″ and a 0-24″ caliper may only be accurate to +/- 0.002″.

To sum it up, realize that there is some variation in accuracy but in general you will find that micrometers are 10x more accurate than calipers.

Measuring range

starrett micrometer set in case with reference standards
0-6" Micrometer set

Micrometers come with 1″ measuring ranges. 0-1″, 1-2″, 2-3″ and so on. 

The most common measuring calipers measure over a 0-6″ range. Larger varieties can be also be found with 0-12″ and 0-24″ measuring ranges. There are some different ranges available such as 0-4″ and 0-8″ also but they are much less common.

This difference in measuring ranges means that you would need a set of micrometers to measure over the same measuring range a single caliper is capable of. 

Calipers have larger measuring ranges but they are less accurate.

Types of measurements they are capable of

Caliper measuring internal hole
caliper depth base attachment

Most calipers will measure inside, outside and depth measurements. 

digital caliper measuring coin
Standard outside diameter being measure with digital caliper

Micrometers are capable of only performing one type of measurement. 

The most common type of micrometer is an outside micrometer, usually referred to as simply micrometers or sometimes mics.

anytime tools 1-2" micrometer
0-1" outside micrometer

Inside micrometers and depth micrometers are also available to take internal and depth  measurements.

Calipers are capable of taking a much larger variety of measurements.

Depth micrometer with multiple rods for different size measurements
mitutoyo inside micrometer set
Inside micrometer with multiple attachements for different size measurements

Ease of use

To maintain the added accuracy that a micrometer has requires taking more care when using them. 

Something as small as the amount of force you use to close the micrometer can change your measurement. Many micrometers will have a ratchet or friction stops that help alleviate this problem. 

When you are working down to a tenth (machinist lingo for 0.0001″), even temperature comes into play. Metals expand and contract with changes in temperature. To protect against this, most micrometers have plastic pieces that can be used to help insulate your from the tool.

outside micrometer

A good micrometer stand can help keep you accurate as well.

The same factors affect the accuracy of a caliper but the effects aren’t as noticeable because they aren’t as accurate.


Calipers are quicker to use than micrometers. The jaws can open and close in a split second.

Micrometers need to spin the thimble around 40 times to cover an inch of travel. 

Cost comparison

A micrometer and a set of calipers have similar price points. Take for example a 0-1″ micrometer from Mitutoyo and a 0-6″ set of calipers from Mitutoyo.

The difference would be that to cover the same measuring range of a set of calipers, you would need a 0-6″ set of micrometers. A good set of micrometers is going to cost quite a bit more than your typical 0-6″ caliper.

More info about micrometers and calipers

Parts of a micrometer

parts of a micrometer

The part being measured will be placed between the anvil and spindle of the micrometer. The spindle is adjusted in and out by turning the thimble clockwise or counterclockwise. 

Depending on the micrometer being used, the lock nut, lock ring or lock lever can be used to hold the micrometer at a specific size. Some tools will not have any locking feature. 

Measurements are read using the scales on the sleeve and thimble. 

The frame of the micrometer can vary across brands and types of micrometers. Some are made specifically to have smaller frames for different measuring applications. 

Many micrometers also have a ratchet stop or friction stop that limits the amount of force applied to the thimble. This allows more consistent measurements.

Parts of a caliper

The jaws for external measurements are used to measure features such as length, width and thickness.

The jaws for internal measurement are used for measuring features such as hole sizes and slot or groove widths.

The rod for depth measurements is used for measuring depths of holes, counterbores and step heights. 

The scale and dial indicator face are used together to obtain measurement readings.

The slide of the caliper which consists of the moveable jaws along with the dial indicator face are slid along the beam.

The lock screw can be used to hold the caliper at a specific size for repetitive measurements.

Digital vs analog micrometers

Digital micrometers are great for the speed at which measurements can be read. Their display means very little training for the operator. 

Another benefit of a digital micrometer is how quickly measurement values can be converted between inch and metric readings. A simple button press can save time and do the conversion for you. 

starrett 0-1" micrometer
Starrett analog micrometer
mitutoyo digital micrometer
Mitutoyo digital micrometer

The downfall is that they tend to be quite a bit more expensive than a standard analog micrometer and they are more susceptible to contaminants such as water and coolant. Some models are offered with resistance or protection from different contaminants. 

In recent years, prices have dropped for digital micrometers making them more affordable. 

Analog micrometers tend to be a very dependable tool and many have been in use for generations. This also means that there are many used options on the market for analog micrometers. 

If cost is your primary concern, I recommend going with an analog micrometer. If ease of use and operation is important then go with a digital micrometer.

Digital vs dial vs vernier calipers

mitutoyo 6 inch vernier caliper
Mitutoyo vernier caliper

Vernier calipers are the most resilient type of calipers. They will be the least affected by things such as dirt and water or coolant. Unfortunately they are the most difficult to take measurements with. Learning to read the scales takes some practice. 

Dial calipers are a good middle ground with measurements that are relatively easy to take with the dial indicator face. They are reasonably resistant to contamination though they should still be handled with care. 

anytime tools dial caliper dial face
Dial caliper

Digital calipers are by far the easiest to use. The LCD display takes any guesswork out of reading your measurement. They are also the most susceptible to damage from things such as dirt and coolant. 

Unless they are being used in the harshest environment, I recommend getting digital calipers. Digital calipers can be purchased with ingress protection if needed.


While they are both precision measuring tools, there are some key differences between micrometers and calipers. 

Micrometers are more specialized and have a smaller measuring range. As a result they are generally more accurate and often capable of measurements to .0001″. 

Calipers are more versatile. They have a much larger measuring range. To achieve this they sacrifice accuracy and most often take measurements to an accuracy of .001″. 

As you can see they both have their strengths and weaknesses but in the end they are two of the most important precision measuring tools you can have in your toolbox.

Beginner’s Guide to Blueprint Reading

Learning to read blueprints can be hard. That’s why we’ve broken down the process into bite size chunks. All of the basic components of an engineering drawing are detailed below with links throughout to give you more info on each subject.

Use the table of contents below to jump straight to your topic of choice and if you don’t find what you are looking for please leave a comment at the bottom and we will tackle any blueprint related questions we may have missed.

Components of a drawing

Title block

title block example
Title block example

A blueprint title block contains the high-level identification information. The title block of a blueprint can vary quite a bit across different companies. In general, the title block can be found in the bottom right of the blueprint and will include the following:

  1. Drawing or part number and revision
  2. Part name
  3. Company name
  4. 1st or 3rd angle projection
  5. Scale

Tolerance block

tolerance block example
Tolerance block example

The tolerance block, sometimes referred to as the general tolerance block, is usually located in the bottom right or bottom middle section of the blueprint. The tolerance block identifies the tolerances associated with dimensions that are not directly listed on the drawing.

This can include items such as the blueprint dimensional units (imperial or metric) or surface roughness requirements.

Units of measurement

The units of the print are very important because there is a huge difference between 25.4mm and 25.4 inches. The measurement units will often be called out in the title block or tolerance block but occasionally will be in another section of the blueprint such as in the notes.

Angular units are important also but there is usually less confusion associated with them because decimal degrees and degrees, minutes, seconds are so different.

Types of projections

Projections are different ways of representing parts on a blueprint. Basically this means there are different methods of showing the same part.

1st angle projection, sometimes referred to as the European convention, is a method of displaying the various views of the part as if the part has been flipped to each side.

Notice how the car is flipped below in each view of a 1st angle projection blueprint.

1st angle projection car example
1st angle projection example - click to enlarge

3rd angle projection, the American convention, is a method of displaying the various views of the part as if the part is placed in a bowl and rolled in the bowl to the other views.

Notice how the car is flipped below in each view of a 3rd angle projection blueprint.

3rd angle projection example - click to enlarge

Projections can be hard to describe in words. Just remember that 1st angle projections are a flop method and 3rd angle projection is a roll method. 

Types of tolerances

There are multiple ways of tolerancing a dimension. Below are the ways of directly dimensioning a feature with standard tolerances. GD&T tolerances are a separate topic altogether.

Limit tolerances

limit tolerance example
Limit tolerance example

Limit tolerances list a range that the dimension must fall within. No calculation needed. Simply keep it between the numbers.

Unilateral tolerances

unilateral tolerance blueprint example
Unilateral tolerance example

Unilateral tolerances are given when the allowable variation is in a single direction such as the example below. In this example, the part cannot have a diameter that is over 6mm.

Bilateral tolerances

bilateral tolerance blueprint example
Bilateral tolerance example

Bilateral tolerances, often referred to as plus or minus tolerances, have a nominal size and a tolerance in the positive and negative directions. Often this tolerance will be equal in both directions, but it doesn’t have to be. Sometimes you will see bilateral tolerances that allow more variation in one direction.

Notes section

Notes on a blueprint can have a huge impact on the component requirements. The notes are often where surface treatment requirements such as heat treating, anodizing and other similar requirements are documented.

Literally anything can be listed in the notes section and the items listed can have a large bearing on the complexity of the part.

Pay attention to your notes section, there are often critically important features and characteristics relative to the part listed.


A wide range of symbols are used to create engineering drawings. There are also specialty blueprint symbols associated with items such as welding or electronic components, but I will only be covering the standard blueprint symbols including those related to geometric dimensioning and tolerancing (GD&T).

Center lines

Center lines, such as the center of a thru hole are depicted on a drawing with long and short lines spaced alternately.

In the example below, the centerlines are shown as blue lines.

hidden and center line blueprint example
Center lines and hidden lines example

Hidden lines

To show features in a blueprint view that would not actually be visible, hidden lines are used. These hidden lines are show on a drawing as lines made of dashes.

In the example above, the hidden lines are shown as red lines


Diameter Blueprint GD&T Symbol o with line through it
Diameter symbol

Diameters are round or cylindrical features. Features such as the outside diameter of a part and the size of a hole or counterbore are examples of diameters. They will be referenced using the diameter symbol shown below.


Countersink Blueprint GD&T Symbol two lines pointing down
Countersink symbol

Countersinks are a chamfer on a hole that allows a fastener such as a screw to sit flush or below the part surface. The blueprint symbol for a countersink is shown below.

countersink blueprint example
Countersink callout example


Counterbore Blueprint GD&T Symbol u shape
Counterbore symbol

A counterbore is a circular hole that is deep enough to allow the head of a fastener to be recessed. Counterbores will be shown on a blueprint with a diameter and depth symbol associated with them.

counterbore blueprint example
Counterbore callout example


Radius callout example

Radii show up on prints for many different reasons. The most common application of a radius is to specify the maximum radius allowed in the bottom of a slot or hole. They are frequently used as a form of edge relief similar to a chamfer. While these are the most common radius uses, radii can be dimensioned for all kinds of internal and external features.

When a radius smoothly blends into a surface, it will occasionally be called out as a full radius or full R. A full R callout does not change the way a radius is measured or add any additional requirements.


thru hole blueprint example
Hole callout example

Holes are about as simple as they come. They come in two varieties, thru holes and blind holes. When shown on a drawing they will usually be referenced by their size and location to the center of the hole.


Datum Blueprint GD&T Symbol a in a box with arrow
Datum symbol

Datums are reference points for measurements and are utilized in many GD&T callouts. You will find datums shown on a drawing to identify the feature as a datum or as part of a GD&T callout in a feature control frame.

GD&T Symbols

gd&t symbols
gd&t symbols

Basic dimensions

Basic Dimension Blueprint GD&T Symbol dimension in a box
Basic dimension example

Basic dimensions are the theoretically perfect size or location of a part feature. The variation from this “perfect” size or location will be used to measure another characteristic of the part such as true position or profile. Basic dimensions do not have a tolerance themselves and instead are controlled by another GD&T callout.

Reference dimensions

Reference Dimension Blueprint GD&T Symbol dimension in parentheses
Reference dimension example

Reference dimensions are just what they sound like. They are placed on a print for reference only. They have no requirements associated with them and no tolerances either. They generally get used in one of two ways, they will be used to highlight something that might not be immediately clear without the reference dimension listed or they will be used to show the approximate dimension in another unit system (metric vs imperial units).


chamfer callout blueprint example
Chamfer callout example

Chamfers are used to remove the sharp edges of a part. This provides safety for both the part and the person using the part. Chamfers are frequently specified in many different places. They can be listed directly on the part, in the notes section or in the general tolerance block.

When the chamfers are small, at times they will be listed as a break edge.


spotface example on mechanical blueprint drawing
Spotface callout example

Spotfaces are a small counterbore that is machined so that a fastener can sit flat on the part. They are essentially just shallow counterbores and will be dimensioned as such.

Bolt hole circles

basic dimensions for a bolt hole circle
Bolt hole circle callout example

A bolt hole circle will be shown on a print using multiple dimensions. This will include the size of the individual holes, the angle between the center of the bolt hole circle and the individual holes along with the size of the bolt hole circle itself.


knurling blueprint callout examples
Knurling callout examples

Knurling is a textured pattern on a part. It is added for visual appeal or added grip. Knurls will be called out by the pitch, diameter, and type of knurling.

Surface finish/surface roughness

Surface Finish Blueprint GD&T Symbol check mark
Surface finish/roughness symbol

The surface finish quality is specified with the use of a check mark on the surface. The number above the start of the check is the required surface finish. If there are two numbers present, the surface roughness must fall within the range specified. If only one number is specified, the surface roughness must be less than or equal to the specified value.

Surface finish requirements are frequently specified directly on the applicable surfaces as well as in the notes section and general tolerance block.


Threads will be specified in either the ISO metric format or Unified National Coarse (UNC) thread format. This article clarifies the details of thread callouts.

Want to learn more?

GD&T is a complicated subject and understanding it correctly can be the difference between a perfect part and scrap.

The best way to learn GD&T is from experienced teachers who can break down the material into manageable pieces.

Luckily, we know someone.

And readers get an exclusive discount on training!

Related articles

Dial vs Digital Calipers – Which Is Better?

Somebody is going to get mad about this one. I just know it.

I have had many discussions with coworkers over the advantages and disadvantages of dial vs digital calipers.

What I have learned is that most people have a preference and that there isn’t anything that will change it. I am going to try and put aside any preference I have as I outline the differences between these two types of calipers.

Keep reading to find out more about the differences between digital and dial calipers. When you’re done, maybe you’ll have your own preference. But please, keep a more open mind than my coworkers.

What is a dial caliper?

A dial caliper is a mechanical inspection tool for measuring sizes accurately. Most models are capable of taking internal, external, step and depth measurements to an accuracy of +/- .001” or +/- .02mm.

The most common variety measures from 0-6” but they come in many different measuring ranges including 0-4”, 0-8”, 0-12” and 0-24”.

They can take quick measurements and are a very versatile inspection tool. For many machinists, a set of calipers will be the most frequently used measurement device.

The biggest differentiator for a dial caliper is the rack and pinion system which drives the indicator needle seen on the dial face.


  • No batteries required
  • Tried and true design


  • Can’t switch between inches and mm

What is a digital caliper?

mitutoyo digital caliper display in inches
Mitutoyo Digital Caliper

Digital calipers are the same sort of inspection tool as a dial caliper. They have similar accuracies and are available in comparable measuring ranges.

The main difference is that digital calipers require batteries which power their LCD display. The difference in displays between a dial and digital caliper can be thought of as the same as the difference between a standard analog clock and a digital version.


  • Instant measurements
  • Can measure inches and mm


  • Dead batteries
  • Electronics susceptible to damage

Are dial calipers more accurate than digital?

This can be a tricky question to answer because there are so many different models and manufacturers of both dial and digital calipers out there. In saying that, the short answer is no.

When comparing dial and digital calipers from the same manufacturer there is generally no difference in the accuracy of the tool.

Are digital calipers easier to use than dial calipers?

igaging ip54 digital caliper display mm
Digital Caliper Display - Notice the Button to Switch Between Units

Yes, digital calipers are easier to use than dial calipers. This is because the LCD display gives readings that can be instantly interpreted. Dial calipers require reading both the dial face as well as the scale to determine your measurement value.

Another added benefit of digital calipers that makes them easier to use is that most models are capable of switching between inches and mm at the push of a button. This saves the user from needing to convert measurements to another form of units.

This is an excellent feature for many users because it removes a step from the process which cuts down on the time needed to take a measurement. Removing the conversion step also eliminates the possibility that an error is made in the conversion calculation.

How to adjust or zero a dial caliper

parts of a caliper

To adjust a dial caliper, move the caliper until the jaws are closed.

Once in the zero position, check reading on the indicator needle. If it lines up on zero, then no adjustment is needed. You can proceed to verifying the tools repeatability as noted below.

If it does not line up on zero, loosen the bezel lock screw and turn the dial face until it lines up on zero. Once aligned, tighten the lock screw.

Now open and close the jaws to verify that the caliper repeatedly returns a zero reading.

Once this is verified, if available use a set of known reference standards such as a gauge block set to verify different readings across the calipers measuring range. For a 0-6” caliper, 0”, 2”, 4” and 6” would be a good start.

After the tool has been verified as accurate across its measuring range, you can proceed to take your part measurements.

How to adjust or zero a digital caliper

parts of adoric digital caliper

To adjust a digital caliper, move the caliper until the jaws are closed.

Once in the zero position, check reading on the digital display. If the display reads zero, then no adjustment is needed. You can proceed to verifying the tools repeatability as noted below.

If it does not read zero, press the zero button, sometimes identified as the origin button on some calipers.

Now open and close the jaws to verify that the caliper repeatedly returns a zero reading on its display.

Once this is verified, if available use a set of known reference standards such as a gauge block set to verify different readings across the calipers measuring range. For a 0-6” caliper, 0”, 2”, 4” and 6” would be a good start.

Once the tool has been verified as accurate, you can proceed to take your part measurements.

Things to consider when purchasing dial or digital calipers


Dial and digital calipers have comparable accuracies. There is some variation between makes and models of calipers, but most are accurate to +/- .001” or +/- .02mm. If you need something more accurate then you will likely need to look into purchasing a quality micrometer or micrometer set.

Most micrometers are accurate to +/- .0001” which makes them ten times more accurate than a typical caliper. The downfall is that they are more specialized and therefore are only capable of taking a single type of measurement (inside, outside, etc.) and have a smaller measuring range which is why a micrometer set is often needed to cover the measuring range of a single caliper.

Please note that cheap digital calipers often have reduced accuracy when compared to the usual gauge manufacturers such as Starrett and Mitutoyo. At the very least keep in mind the accuracy you need when purchasing because some of the budget priced tools are only half as accurate.

Measuring units

anytime tools 5 inch dial caliper with inch and metric reading dial
An Example of a Dual Unit Dial Caliper - Notice How It Has Two Indicator Needles

There are exceptions but most dial calipers are capable of measuring in a single set of units, either imperial (inches) or metric units (millimeters).

Some dial calipers are available that take measurements in both types of units, but they are clunky and often can not be calibrated so that both units are accurate. Stick with a single unit version.

Digital calipers are capable of taking measurements in both inches and millimeters while switching between the two at the push of a button. This is one of their primary advantages.

Many models are also able to take fractional measurements which can come in handy for some applications.

Measuring range

The measuring range of digital and dial calipers is similar. The most common version for both is a 6” caliper. Additionally, they can be found in ranges from 0-3” all the way up to 0-24” and beyond. Most will not find a need for measuring over 24”.

One point to keep in mind is that the cost goes up and the ease of use goes down as the caliper gets longer. For this reason, it is recommended to have multiple sets of calipers if you need to measure large sizes.

Imagine trying to measure a two-inch hole with a 0-24” caliper. It is going to be awkward and can easily lead to erroneous measurements. If you are in need of a set capable of measuring larger than six inches, then think about purchasing a quality 0-6” caliper as well as a 0-12” or 0-24” set.

The six-inch set will get the majority of the work and be easy to use and the larger set can be pulled out for use when the time is right.


button cell battery for micrometer
Digital Caliper Battery Example

Dial calipers do not require batteries. This means they will always be ready to use, no matter how long they sit in your toolbox between uses.

Digital calipers on the other hand do require batteries and unfortunately not the types most people keep on hand.

Digital calipers typically use a LR44, SR44 or CR2032 battery. They are available at most department stores as well as online.

Modern digital calipers, especially the high-quality ones from Starrett and Mitutoyo, have extremely long battery life. Many people have reported going years between battery changes with a Mitutoyo digital caliper.

For peace of mind think about keeping an extra battery or two around in your toolbox or junk drawer if you decide to go with a digital caliper. This way it will always be ready to use when you need it.


VINCA digital caliper in case unwrapped
Digital Caliper with Case

Both dial and digital calipers are precision measuring instruments. You will find that most are built well and have no problem handling everyday use.

Unfortunately, the precision nature of these tools means that they are susceptible to damage from contamination such as coolant, oil, or metal chips as well as damage from physical shock.

A caliper that has been bumped off a workbench or dropped on accident can easily damage the jaws of the caliper or affect the internal workings resulting in invalid readings.


gauge block set
Gauge Block Set

Calipers should be calibrated periodically at an interval of your choosing. In a machine shop atmosphere, this will be determined by the company. Normal calibration intervals will range from 3 months to 1 year and everything in between. Some shops will even base the calibration frequency on tool use as opposed to length of time.

For home use, I recommend verifying them before each measurement.

With critical measurements, at home or in the shop, this verification becomes even more important. You don’t want to find out that your engine was bored oversize because you neglected to check your caliper before using it right?

Verify your tools and if possible check them against a known calibrated standard such as a set of gauge blocks.

For more info on caliper calibration, please see our post on the Complete Guide to Caliper Calibration.

Calibration certificates

Some of the caliper manufacturers and resellers offer a calibration certificate with their tool. My recommendation would be to skip this unnecessary add-on.

At a minimum you should be verifying your tool when you receive it. Ideally, you would calibrate the tool yourself with a set of calibrated gage blocks.

A calibration certificate will only serve as proof that the caliper was accurate at the time of calibration. Since many tools get ordered online or through a catalog, the tool will get be in a shipping company’s hand between the time of calibration and when you receive it. They aren’t always known for being gentle.

A calibration certificate doesn’t provide much peace of mind when buying a new tool. It should be accurate anyways, that is what you bought it for after all. It would be better to take the added expense of calibration and apply it towards a set of gauge blocks or other reference standard.

Depth base attachments

caliper depth base attachment

Depth measurements with a caliper can be quite tricky. The size and shape of the tool means it is top heavy and as a result it can be easy to get incorrect readings when taking depth measurements.

A depth caliper base attachment can help alleviate some of this by providing a wider, more stable base to take your measurements from. Adding one will make it easier to get consistent, accurate readings.

The base provides stability that is more in line with that of a depth micrometer, thought the tool will still be less accurate than a quality depth mic.

Related articles

Beginner’s Guide To Reading Machine Shop Numbers & Values

math on chalkboard

Confused? If you’re reading this page then I’m pretty sure you are. Dealing with numbers, values and calculations when machining or 3d printing can be hard for those just starting. 

The lingo and terminology used by many people both online or at a new job can be hard to understand. My hope is that after this quick lesson in dealing with machine shop numbers, you will not only be comfortable reading your numbers and measurements but also will know how to perform some simple calculations using them. 

Let's begin

First we need to understand what the numbers we are working with represent.

Whether they are a reading on a micrometer, a spec on a blueprint or a stack of gage blocks, the goal is the same.

We need to know how to read them and work with them. 

Below is a graphic that shows the name (including machine shop lingo) for different values.

Pay attention to how far each number is from the decimal place when looking at the chart.

Please note that not everyone will be working down to millionths of an inch but I included them for reference. Many will only work down to the the values shown in this table. 


Machinist Lingo

Technical Math Term


Thousandth or Thou

Thousandth of an Inch



Ten Thousandth of an Inch

Keep in mind that all these numbers and terms apply to imperial units (inches).

How to say the value

Machine shops usually speak in terms of thousandths of an inch. Because of this when we describe the value to someone else we will read it a little different than you might expect.

As noted above, if we give the example of 7.489136″ a machinist would describe the value as 7 inch, 489 thousandths, 1 tenth, 36 millionths. 

Read that last sentence over a couple times to really understand the terms your typical machine shop speaks in.

As a note, not all machine shops or hobbyists will deal in millionths of an inch and some might not even work with tenths but I have included them for reference.

Note: Thousandths of an inch is often abbreviated as “thou” especially when discussing values verbally. 

Machine shop number reading examples

Below are some more examples to show how machinists communicate values:


Machinist Lingo


1 inch 325 thousandths


500 thousandths 1 tenth


21 thousandths


653 thousandths 2 tenths


9 inch 792 thousandths 3 tenths 45 millionths

Gage blocks

A common scenario for someone new in a machine shop is learning how to set up a stack of gage blocks.

I’m not going to show you how to pick the right gage blocks for your stack here. If you need those instructions then head over to Starrett’s website. They have great instructions that show you how to select your gage blocks and make a stack of a specific height. 

The link also contains information related to the use and care of your gage blocks. Take care of your gage blocks people, those things are expensive.

How to setup calculations

Now I said I would show you how to work with these numbers, so let’s demonstrate how to do that.


The important part when dealing with numbers or values in a machine shop context is to line up the decimal point. Below you will see some examples of addition and subtraction of numbers:

Simple calculation examples

addition and subtraction of values

For practice, let’s list out how to say those answers!


Machinist Lingo


1 inch 610 thousandths


720 thousandths 6 tenths


624 thousandths 9 tenths

texas instruments ti-30xa calculator

There aren’t any other special tricks here. Once you line up the decimal places everything else is just like you learned early in school. Also consider yourself lucky we have calculators.

That’s it. Now you should know how to speak in terms that a machinist would understand and use the values in simple calculations. 

If you need more in depth training when it comes to machine shop math, check out the training linked below. It breaks all the hard subjects down into bite sized pieces to make them easy to understand.

Beginner’s Guide to Basic Dimensions

Basic dimensions are shown on a blueprint enclosed in a box. But what do they mean?

Keep reading to find out.

What is a basic dimension?

A basic dimension is a theoretically exact size or location.

Basic dimensions do not have a tolerance applied to them, this includes any general tolerance blocks.

Instead a separate is listed on the drawing that uses the basic dimension.

An example of this would be a true position callout for a hole or set of holes. The basic dimension(s) specify the location of the hole.

The true position of the hole is calculated based on the difference of the actual location compared to the basic dimensions theoretically exact location.

What is a basic dimension used for?

Basic dimensions are used for calculations. They are used to calculate various geometric dimensioning and tolerancing (GD&T) characteristics such as true position, profile or angularity.

In the example above, the 120 degree callout and the 42 diameter bolt circle are the basic dimensions and the true position of 0.2 is the characteristic controlling the basic dimensions.

Using basic dimensions

How is a basic dimension shown on a drawing?

basic dimension example

The symbol for a basic dimension is the dimension shown enclosed in a rectangular frame or box.

This is the convention identified in the blueprint drawing standard ASME Y14.5.

Some drawings may list a basic dimension not in a rectangular frame but instead the dimension will be followed by a Bsc. notation. This is more common on older drawings and does not change the way basic dimensions are used.

Basic dimension examples

basic dimensions for a bolt hole circle
This example has 2 basic dimensions. Both the size of the bolt hole circle and the angle between the holes are basic dimension.

Basic dimensions and tolerances

Can a basic dimension have a tolerance?

A basic dimension itself does not have a tolerance. General tolerance blocks do not apply to a basic dimension.

Instead its value is used to compute another characteristic such as angularity, profile or true position.

general tolerance block
An example of a general tolerance block

Basic dimensions compared to other types of dimensions

Basic dimension vs reference dimension

Basic dimensions are associated with another tolerance or dimension. While they don’t have a tolerance tied to themselves, they are used to calculate another toleranced feature such as the true position of a hole.

Reference dimensions are simply placed on a drawing or blueprint for reference. They have no tolerance associated with them. No matter how far off the given value a reference dimension is, it would never be cause for rejection.

A basic dimension being far off its nominal value would not be cause for rejection itself, but its effect on another feature referencing the basic dimension could be cause for rejection. So if a basic dimension was far off the nominal location, another tolerance would likely be out of spec. 

reference dimensions

Basic dimension vs regular dimension

Regular dimensions have a tolerance assigned to them. This can be directly assigned to the individual dimension or it can be the general tolerances. The regular dimension must fall within the limits of the tolerance.

A basic dimension is instead controlled by another characteristic. The basic dimension can vary by any amount but it must not deviate from the nominal value to the point that the other characteristic (true position callout, profile callout, etc.) is no longer within the specified limits.

How to measure a basic dimension

A basic dimension is measured just like any other dimension. The only difference is that the basic dimension doesn’t have a tolerance directly associated with it. Instead another dimension uses the basic dimension to calculate its value.

How to report basic dimensions

Do basic dimensions need to be listed on an inspection report?

While there isn’t a strict requirement anywhere to include them, I would recommend reporting their values on an inspection report. 

The features have been measured and you likely already have the values. By recording them, you will provide more information and value for your customer. 

You must report the feature control values such as true position, profile value, etc. that use the basic dimension to be calculated.

What about on FAIs?

The requirement for reporting basic dimensions is the same for first article inspection reports. Be aware that some customers may require them even though there is no requirement per AS9102.

Want to learn more?

GD&T is a complicated subject and understanding it correctly can be the difference between a perfect part and scrap.

The best way to learn GD&T is from experienced teachers who can break down the material into manageable pieces.

Luckily, we know someone.

And readers get an exclusive discount on training!

Reference Dimensions [Guidance and Examples]

What is a reference dimension?

single reference dimension

A reference dimension is just what it sounds like. It is a dimension shown for reference. In other words it is there for informational purposes only.

They are not a requirement in any way.

Reference dimensions can be used to clarify other dimensions on a drawing. In some instances, they make a drawing easier to understand.

Reference dimensions on blueprints

How are reference dimensions shown on a drawing?

There is no GD&T symbol for a reference dimension. Reference dimensions are shown on a drawing as a value enclosed in parentheses.

An alternate method is to follow the dimension with “Reference” or “Ref”. The use of “Ref” or enclosing the dimension inside parentheses are by far the most common notations used. These notations are specified in ASME Y14.5 the Dimensioning and Tolerancing standard.

When to use a reference dimension

Reference dimensions are useful for clarification purposes. Their inclusion can make it clear how another dimension should be inspected or manufactured.

At other times they are included to make the drawing easier to read. It isn’t always immediately clear what a part looks like by looking at the blueprint.

A very common use of reference dimensions is to provide a conversion of the length units of the drawing from either metric to inches or vice versa.

Watch out for these conversions! Too often they are rounded excessively and not accurate. Reference dimensions should never be used for acceptance..

Reference dimension examples

reference dimensions

These examples show some of the variety you might see on your blueprints to call out reference dimensions.

Reference dimension measurement

Do reference dimensions have tolerances?

Reference dimensions do not have tolerances. Additionally, the general tolerances you find in a tolerance block do not apply to them.

Are reference dimensions measured?

Reference dimensions can be measured and the results recorded but this is not a requirement. Often reference dimensions will be recorded more as a note.

Reference dimension vs basic dimension

Reference Dimensions

Basic Dimensions

Shown in parentheses or with Ref notation

Shown enclosed in a box

Informational only

Controlled by another tolerance (GD&T)

Do not need to be measured or recorded

Will need to be measured for calculation

Basic dimensions are used in GD&T tolerancing. associated with another tolerance or dimension.

While they don’t have a tolerance tied to themselves, they are used to calculate the tolerance of another feature such as the true position of a hole. If the location of a hole was controlled by basic dimensions, you would never reject it for the hole location but instead for violating a GD&T requirement such as true position.

In other words, basic dimensions don’t have their own +/- tolerance but they are controlled by a different tolerance requirement.

single reference dimension
An example of a reference dimension
basic dimension example
An example of a basic dimension

Reference dimensions do not have a +/- tolerance and are not controlled by another requirement. They have no tolerance associated with them. No matter how far off the given value a reference dimension is, it would never be cause for rejection.

A basic dimension being far off its nominal value would not be cause for rejection itself, but its effect on another feature referencing the basic dimension could be cause for rejection.

Basic dimensions are identified with a rectangular frame around them such as in the example below.

Want to learn more?

GD&T is a complicated subject and understanding it correctly can be the difference between a perfect part and scrap.

The best way to learn GD&T is from experienced teachers who can break down the material into manageable pieces.

Luckily, we know someone.

And readers get an exclusive discount on training!

Essential Tools Every Machinist Should Own

Every trade has its own toolset. Mechanics, carpenters, and electricians all have special tools associated with the profession. Being a machinist is no different.

There are many tools that a machinist uses in their everyday work. Below is a list of the most important tools for a machinist to own along with some tips to consider.

My quality control experience probably makes me biased, but the most important tools you can have are pieces of inspection equipment. The logo says it all, “If you can’t check it, you can’t make it”


mitutoyo digital caliper
Digital caliper

Calipers come in many forms. The most common types are vernier calipers, dial calipers and digital calipers.

For a long time, the best choice was dial or vernier. This was largely because digital calipers were prohibitively expensive. Times have changed.

Nowadays, a quality digital caliper can be had for as low as $25! Even the top quality, super dependable digital calipers aren’t that expensive anymore.

I always recommend that anyone thinking about a caliper at least considers a digital caliper. The only real downside is batteries die.

The truth is they die, but not that often. The budget calipers have batteries that last months. The top shelf calipers from manufacturers such as Mitutoyo have batteries that last years.

Enough about digital calipers already.

dial caliper
Dial caliper

Dial calipers are nice option too because they don’t have any electronics to die. What they do have is moving parts. Keep them clean though and you shouldn’t have any problems.

In fact, keep all your tools and gauges clean! This is important.

Dial calipers are fairly easy to read, though in my opinion still slower. I doubt fractions of a second matter but personally I prefer the instant measurement of a digital caliper.

The best comparison of the difference taking a measurement with a dial caliper to a digital caliper is a normal analog clock to a digital clock. There is very little time in the calculation of the value, but it is there.

vernier caliper measuring thickness of brass part
Vernier caliper

The last type of calipers are vernier calipers. Don’t get mad at me (OK, yell at me in the comments if you must) but I don’t like them. They take far too long to read. Maybe it’s because I haven’t practiced with them enough, but I don’t see the benefit. I keep my tools clean and have never had an issue the moving parts of a dial caliper.  Never had an issue with a digital caliper either. With all the pros and cons and constant rush, rush, rush of your typical machine shop, I have always preferred digital options.

In the end it is all about personal preference. There is nothing wrong with vernier, dial or digital calipers. If you pick a quality tool, then they will all take reliable measurements.

If you are just starting out, I recommend going with digital calipers to lessen the learning curve and speed up measurement reading, but keep in mind that this isn’t a huge jump in speed.

Outside micrometer

outside micrometer

A 0-1” micrometer is hugely important for machining. Calipers may get more use but it is only due to their versatility. Calipers can measure inside and outside dimensions along with depth measurements. When we talk about micrometers, generally we are talking about outside micrometers.


A 0-1” micrometer is going to compete pretty fiercely with a 0-6” caliper in everyday use.

Normally, a 0-1” micrometer will measure 10x tighter tolerances at .0001” increments and a caliper will measure at .001” increments. For this reason, a good micrometer is vitally important to have.

Getting the best micrometer you can afford in the 0-1” measuring range is a good idea. If budget is a concern, going a little cheaper for larger sizes that won’t be used as often is wise. A decent 0-6” micrometer set from someone like Anytime Tools will perform almost as well as one from companies like Starrett or Mitutoyo at a fraction of the price.

Dial indicator

dial indicator
Dial test indicator

Dial indicators come in a few different forms including dial test indicators and drop indicators.

Dial test indicators work great for inspecting tight tolerances of specific features on a part. The downside is that they will often take more time to setup when compared to using a caliper or micrometer.

Dial test indicators can also be used to check the form of surfaces. Flatness, parallelism and total indicator runout (TIR) are just a few of the feature controls that can be measured.

Another application for dial test indicators is to align setups both in machining and inspection.

Dial test indicators are available in assorted accuracies such as .001”, .0005” and .0001” with even higher precision models available.

mahr drop indicator
Drop indicator

Drop indicators are generally used as part of a snap gauge or another type of inspection fixture. They are often used when a specific dimension(s) needs to be measured very accurately.

Parts being run to a tight thickness tolerance could be checked with the use of a drop indicator attached to a height stand. A setup such as this would allow the inspection of a large number of parts to a high degree of accuracy.

Surface plate

Surface plates are the accurate reference that so many measurements are taken from. They are essential for inspection work. This isn’t something you need to own but it is something you will want access to.

Surface plates come in a wide variety of sizes (usually 6” or 12” increments) along with multiple accuracy grades (AA, A & B). While smaller surface pates are reasonably priced, they get exponentially more expensive as the size increases.  

Gauge blocks

gauge block set
Gauge block set

Unless you are only doing very light machining work, you will want a good set of gauge blocks. If you are working in a machine shop, then you already know that you need calibrated gauge blocks to check your tools.

For home use, a gauge block set is good to have when working with indicators or tight tolerances (< 0.001”). In a shop atmosphere, the gauge blocks will be sent out at a set frequency to be calibrated by a calibration laboratory, but this is overkill for most hobbyist. Just follow one simple tip.

If you notice corrosion on your gauge blocks, think about replacing them. If kept clean and out of harm’s way, they should last a very long time.

The best way to protect your gauge blocks is to store them in a safe, dry place where the temperature is relatively stable. Extreme heat or cold will affect the size of the gauge blocks as the material (usually steel) expands and contracts due to temperature swings.

Depth micrometer

mitutoyo depth micrometer
Depth micrometer

Depth micrometers are great for measuring hole and slot depths along with various location or thickness checks. The downside to depth micrometers is that they are not as versatile as many other tools and are substantially more expensive.

Depth micrometers will not get as much use either which moves them down the list in importance. Because they don’t get used as much, a 0-3” set can be a good starting point for beginners or 0-6” set if you want to go all out. Don’t spring for a full 0-12” set unless you know you truly need it because it will set you back a pretty penny.

Take good care of your depth micrometer because the thinner rods or blades of some depth micrometers can be bent rather easily which will affect the accuracy of the tool.

Steel ruler

steel ruler
Steel ruler

It can be easy to overlook the importance a decent ruler but it is an excellent tool to use in laying out your work. No need to break the bank, just find one you trust. Starrett has made good ones for a long time.

One tip: don’t leave it in your pocket. Too many rulers have been broken because someone left the ruler in their pocket and sat down on it.

A tape measure can work too but if taken care of you’ll find that a quality steel ruler will last much longer.

Pocket comparator

eye loupe
Pocket comparator or eye loupe

Sometimes called an eye loupe, pocket comparators are invaluable for checking chamfers, bevels and features with very loose tolerances. Inevitably, someone will over spec a chamfer that could simply be a break edge and this will be the tool you’ll need to measure it.

Most pocket comparators have reticles that can be changed also. This is good for when the reticle becomes too scratched from use.

Something to think about: White reticles can be handy to use when measuring darker materials that make seeing a standard black lined reticle almost impossible.


With all these quality tools hanging around, it is a good idea to keep them safe. Having a nice toolbox to put them away safely will do wonders for protecting them for years to come.

Look for one that is lockable because good tools have a bad habit of walking away in some shops.

A good benchtop box is a solid start, no need to go all out with a huge rolling cabinet.

Gauge pins

gauge pin set
Gauge pin set

Gauge pins are a great tool for measuring hole sizes among other uses. They are also good to use for calibrating other tools such as your micrometers or for use in creating inspection fixtures.

Telescoping bore gauges

bore gauge set
Telescoping bore gauges

Telescoping gauges are used in conjunction with micrometers to check measurements of internal features such as slots or holes.

The gauge is opened up and locked in place then a micrometer is used to check the measured size once the gauge is removed.

Edge finder

Edge finder or wiggler

Edge finders are commonly used for locating workpieces when setting up for milling. While spinning, they can be slowly moved towards the workpiece until they are forced off center by the pressure from the workpiece.

Once this happens, you know that the edge of your part is one half of the diameter of your edge finder away from the current machines position.

Deburring tool

afa tooling deburring tool with replacement blades
Deburring tool

Anyone who has worked in the machine trade knows the pain that comes with slicing your hand on a razor sharp metal burr.

These wonderful little gadgets zip that bad boy right off to protect you and the part. Most shops will have a deburring tool at every machine station.

Machinist vise

machinist vise
Machinist vise

There are many different types of work-holding equipment for a machinist to use. Various vises for different situations.

Benchtop vises are great for hand operations such as filing or modifying tooling.

Precision vises such as a flanged or swivel vise are great for use when machining. Vises are excellent tools for inspection use also.

V block

v block
Precision v block

V blocks are indispensable for inspection purposes. They are perfect for holding round parts especially during inspection operations. Many parts will be placed in a v block and rotated for runout, circularity, cylindricity and concentricity checks.

Machinist square

two machinist squares
Machinist squares

Simple machinist squares are great for layout work. Combination squares allow you to do even more complex operations. They aren’t meant for use with extremely precise tolerances.

Precision/vernier protractors fit in this same category and are mostly for reference only.

Right angle plate/knee block

knee block
Knee block

Knee blocks allow a workpiece to be located in different positions by clamping it to the knee block at various angles.

It is useful in the inspection of many parts to have a known square surface.

Engraving pen

All of these much needed tools unfortunately have a habit of disappearing when you need them most. A good engraving pen comes in handy for marking your property. 

Double up by stashing your tools in a lockable toolbox and marking them with your name.

Other tools

Did we forget any critical machining and/or inspection tools? If so please let us know in the comments below.

Things to consider

Which tools are best for a beginner machinist to start with?

The best tools to start with are a good set of calipers and a quality 0-1″ micrometer. After that, a couple indicators with varying accuracies and a depth micrometer will be the best additions.

What you need beyond these initial tools will largely depend on the work you are doing, but larger micrometers (like a 0-6″ set) and a set of bore gauges will likely be needed.

Where can you buy used machinist tools?

Used machinist tools can be purchased from a variety of sources. Craigslist and eBay are great sites to watch. Yard sales and estate sales are an often overlooked place to score nice tools.

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Ultimate Guide to Digital Micrometers

Digital micrometers are one of the most accurate measurement devices available for precisely measuring parts of all sizes.

Machinists and hobbyists around the world use them in their everyday work. A good 0-1″ micrometer is likely the only precision measuring tool that can compare in use to a set of digital or dial calipers.

Because they get so much use, it is important to make sure you get a quality set of micrometers and more importantly, that you know how to use them to achieve the accuracy they are capable of.

Check out our guides and tips below to further your understanding of digital micrometers.

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A Beginner's Guide to Micrometers

Everything you need to know to get started with digital micrometers. Includes all of the frequently asked questions that come up when working with digital micrometers.

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Digital Micrometer Buyers Guide

Find out which digital calipers top our best of list. Includes an extensive list of things to consider when purchasing a digital micrometer.

Digital Micrometer Info Guides

Explore our selection of informational guides to expand your knowledge of digital micrometers.

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Digital Micrometer Reviews

Check out the latest digital micrometer reviews from well-known brands such as Mitutoyo, Starrett, Anytime Tools, and many more.

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