gd&t Archives - Machinist Guides

Geometric Dimensioning and Tolerancing Font – GD&T Keyboard Shortcuts

September 1, 2022September 1, 2022 by Brandon Fowler

How to insert symbols into a Microsoft Word document

To insert GD&T symbols into Word, take note of the codes in the table below.

There are two types of symbols below.

Some are alt codes (ALT+248) and some are Unicode characters (25B1 then ALT+X).

Alt codes are entered by holding the ALT key and pressing the number code. Unicode characters are entered by typing the code and then holding the ALT key and pressing X.

How to insert GD&T symbols into a Microsoft Excel document

Not all the codes listed below will work in Excel.

The ALT codes (ALT+248 style) work but the Unicode characters (25B1 then ALT+X style) do not.

The best way to insert the GD&T symbols into Excel is to copy and paste the symbols.

GD&T Symbols Alt Codes

Symbol Name	Symbol	Code
Straightness	▬	ALT+22
Flatness	▱	25B1 - ALT+X
Circularity	◯	25EF – ALT+X
Cylindricity	⌭	232D – ALT+X
Profile of a Line	∩	ALT+239
Profile of a Surface	⌓	2313 – ALT+X
Angularity	∠	2220 – ALT+X
Perpendicularity	⊥	ALT+8869
Parallelism	//	2225 – ALT+X
True Position	⌖	2316 – ALT+X
Concentricity	◎	ALT + 10686
Symmetry	⌯	232F – ALT+X
Circular Runout		2197 – ALT+X
Total Runout	⌰	2330 – ALT+X
Free state	Ⓕ	ALT + 9403
Least material condition	Ⓛ	ALT + 9409
Maximum material condition		ALT + 9410
Projected tolerance zone	Ⓟ	ALT + 9413
Regardless of feature size (RFS)	Ⓢ	ALT + 9416
Tangent plane	Ⓣ	ALT + 9417
Unequally disposed tolerance	Ⓤ	ALT + 9418

Common Blueprint Symbol Alt Codes

Symbol Name	Symbol	Code
Degree	°	ALT + 248
Plus or Minus	±	ALT+241
Diameter	Ø	ALT+0216
Depth	↧	ALT + 8615
Greater Than or Equal To	≥	ALT+242
Less Than or Equal To	≤	ALT+243
Counterbore	⌴	ALT+9012
Countersink	⌵	ALT+9013
Micro	µ	ALT+230
Surface Finish	✓	2713 - ALT+X
Centerline	℄	ALT + 8452

Break Edge – All About

May 6, 2022November 21, 2021 by Brandon Fowler

What is a break edge?

A break edge means the removal of material, usually in the form of a chamfer or radius to remove the sharp edge.

Machining a surface will often leave a corner which can be dangerous for both the part and the part handler. Many times there will be a burr (raised piece of material), left on the edge which can be razor sharp. Using a deburring tool can break the edge to remove the sharp

A broken edge is usually specified as a maximum value or with no value at all. If no value is specified, the break edge has not been constrained sufficiently.

A break edge callout with no maximum size referenced would normally be assumed to be approximately .005-.010” though in some instances it could be larger.

What does a break edge look like?

Break edge on a physical part

In the brass cube below, notice how the corners have all the sharp edges removed. This is an example of a break edge.

Break edge on a blueprint

Break edge symbol

There is no GD&T symbol for a break edge. Break edges are also not referenced in the engineering drawing standard ASME Y14.5.

Break edge callouts are specified directly on the drawing to reference a certain surface or as a note e.g. “Break all sharp edges”.

At times, the break edge specification may be contained in the general tolerance block such as shown below.

Break edge note example

How to make a break edge

Break edge on wood

Using 180 grit fine sandpaper is the easiest way to create a break edge on a wooden workpiece. This can also be used together with a block plane to chamfer the edge and then soften it with a light sanding.

Break edge on metal

Because metal tends to be more durable, you have more choices for creating a break edge on your piece of metal.

You can use:

A chamfer deburring tool which is a specialty tool designed to remove burrs from the edges of parts

A file to knock the edge off a part
Sandpaper
A grinding wheel

A rotary tool such as a Dremel

Break edge on glass

To create a break edge on a piece of glass, use one of the following:

Diamond file

Grinding wheel
Rotary tool with diamond wheel

How to measure a break edge

Which measuring tools to use

The size of a break edge is measured the same as a standard chamfer or radius. If a measurement is required, a pocket comparator or eye loupe with a reticle are the most common inspection tools to use.

An optical comparator with or without an overlay could also be used. See the examples below to better understand how the size of a break edge would be determined.

How to measure the break edge based on your blueprint

On the left is a chamfered break edge. The size is measured from the left edge of the part to the intersection of the break edge and the top of the part. This is done in both the x and y directions (up and down, left and right).

On the right is a break edge created by a radius. The same measurement technique applies with the exception that the intersection would now be called the tangent point or point where the radius meets the straight edge.

Break edge compared to similar features

Break edge vs chamfer

The difference between a break edge dimension and a chamfer dimension is generally in the tolerancing of the two. A chamfer is usually thought of as being toleranced in a way that places tighter constraints on the feature.

Often a chamfer callout will have a tolerance associated with the angle and a break edge will not.

Break edge vs radius

A break edge can be a radius. Many times, the person or company machining the part will round the edge using a variety of techniques including tumbling, specialty tools or even sandpaper.

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 MachinistGuides.com readers get an exclusive discount on training!

For more information see these related articles:

Beginner’s Guide to Blueprint Reading

Beginner’s Guide to GD&T Symbols

Chamfer and Chamfering Guide [Learn Quick]

July 1, 2022June 30, 2021 by Brandon Fowler

What is a chamfer?

A chamfer is an angle on the edge of a workpiece.

They are created for mainly for protecting the chamfered object as well as anyone who might come in contact with the object.

The edge can be the outside of the part, where a hole breaks through a surface or where any two surfaces meet.

Notice the chamfered edges in the picture above.

The cube above has chamfered corners where all the main faces intersect.

Chamfering those intersections reduces the sharpness of, or softens the corners.

Types of chamfers

Leg length chamfers

The most common way to spec a chamfer is by giving its leg length size and the chamfer angle.

In the picture of a triangle below, the legs are the a and b sides of the triangle.

If no angle is given, the chamfer angle would be assumed to be 45 degrees. This can be a dangerous assumption though. It is always best to confirm the chamfer angle when not directly specified.

Face width chamfers

Occasionally, a chamfer will be specified as being measured as a face width. This can be seen abbreviated as F.W. on some blueprints.

In the picture below, the leg length of the chamfer would be the length of the a and b sides. These would be equal in a 45 degree chamfer. The length of the c side would be the face width of the chamfer.

If a chamfer is called out as a face width, then it is to be measured along the hypotenuse of the chamfer.

To convert a leg length dimension to face width simply multiply the leg length value by 1.414. To convert from a face width dimension to a leg length dimension, reverse the process and divide by 1.414.

It should be noted that these conversion factors only work if the chamfer is at 45 degrees (the most common chamfer angle). If you need to calculate the face width of a chamfer at a different angle use a triangle calculator.

Chamfers compared to similar features

Chamfer vs bevel

A chamfer and a bevel are the same, especially in the case of machining.

Some will debate this point and argue that a chamfer takes the sharp corner off the part and that a bevel would do the same but all the way to the opposite side surface.

While there are some diagrams available online that will show this as true, this is incorrect. Merriam-Webster clearly defines a chamfer and bevel as the same thing.

Chamfer vs break edge

Chamfers are often left as an afterthought for blueprint drafters.

Many times they have no functional requirement but are merely added to protect the part and anyone who might come into contact with it from damage. Deburring an edge is very similar.

In cases where the requirements are not strict, you will often see a break edge or break all edges requirement listed.

This means the sharp edge should be removed from part, but it is not directly controlled. In cases where a break edge is specified, the drafter is generally looking for a chamfer size of .010″-.020″ and sometimes even less.

Break edge callouts will rarely be identified with an angle associated with them.

Chamfer vs countersink

Countersinks are chamfers applied to a round feature such as a hole.

The main difference between chamfers and countersinks is that chamfers are usually specified at 45 degrees and countersinks have a larger variety of common angles.

Countersink angles are also specified as the angle between two opposite sides of the feature. This results in the angle spec being doubled. A 45 degree chamfer would often be listed as a 90 degree countersink. Common countersink angles are 82, 90, 100 and 120 degrees.

Chamfer vs deburr

As I noted above, a deburr callout is very similar to a break edge. Deburring is the act of removing a sharp edge and often raised edges along the feature.

Tiny bits of raised metal can be quite dangerous. Deburring will remove these sharp bits. Similar to break edges, deburr callouts are usually pretty loosey goosey.

Chamfer vs fillet

A fillet is a rounded or radiused corner and a chamfer is a straight cut. Notice the difference in the picture above.

Chamfers do not have to be a 45 degree angle as shown in the picture above, but this is certainly the most common configuration.

How to specify chamfer dimensions

Dimensioning chamfers is done with a call out that specifies the length of the chamfer along with the angle of the chamfer. If no angle is given the chamfer is assumed to be at 45 degrees.

Chamfers can also be specified by giving both legs of the chamfer such as:

Chamfer all edges .025″ x .025″

Chamfer notation example #1

If the example above read “Chamfer all edges and corners .030”, the callout would be the same as it is written currently. Angles other than 45 degrees are used, but are much less frequent.

Chamfers are often specified in the notes of a blueprint such as in the example above.

Chamfer notation example #2

In this example, the chamfer would have a leg length of .020″ and a chamfer angle of 45.00 degrees.

Measuring chamfers

How to measure the size of a chamfer

A chamfer length or depth can be measured utilizing many different pieces of measuring equipment. Optical comparators and CMMs are often used in industry, but if you are reading this you will likely want to measure your chamfer with a gauge called a pocket comparator, often referred to as an eye loupe.

The pocket comparator uses a magnifying lens and reticle to enable the user to measure the size of the chamfer.

How to measure the angle of a chamfer

Chamfer angles are often assumed to be the same angle as the tool used to generate them. The most common chamfer angle is 45 degrees.

Depending on the part geometry, different tools can be used to measure a chamfer’s angle. The angle can be calculated using the triangle calculator referenced above or a protractor can be used.

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 MachinistGuides.com readers get an exclusive discount on training!

For more information see these related articles:

Best CNC and Machining Books

Thru Hole – All About

May 6, 2022March 16, 2021 by Brandon Fowler

What is a thru holes?

A thru hole, also known as a through hole, is a feature on a blueprint or drawing that identifies a hole to be machined with two open ends. The hole goes all the way through the part. In other words, the hole breaks through at two locations on the part.

In the picture below, the thru hole is on the right. The other holes are blind holes.

How to dimension a thru hole?

A thru hole is dimensioned by specifying the diameter of the hole along with a tolerance. Additional features can be added if needed such as a countersink or counterbore for the hole. No other features are required.

Thru hole vs blind hole

A thru hole has two open ends. A blind hole has one open end and does not go all the way through the part.

Thru hole symbol

There is no GD&T symbol for a thru hole though often it will be specified with the notation “THRU” on the engineering drawing.

Thru hole examples

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 MachinistGuides.com readers get an exclusive discount on training!

For more information see these related articles:

Blind Holes – All About

May 6, 2022March 16, 2021 by Brandon Fowler

What is a blind hole?

A blind hole is a hole that does not go all the way through a part. A blind hole goes to a specified depth and stops.

How to dimension a blind hole

To specify a blind hole requires listing the diameter of the hole and a dimension to control the depth. The depth can be controlled by directly specifying the depth of the hole or by identifying the amount of material that will remain.

Blind hole vs thru hole

A thru hole, sometimes called a through hole, goes completely through a part. It has two open ends whereas a blind hole has one open end and does not break through to the opposite side. In the image above, the three holes on the left are all blind holes. The hole on the right is a thru hole.

Blind hole symbol

There is no GD&T symbol for a blind hole. A blind hole will be specified with a diameter and a depth specification or remaining amount of material. In the example below, the blind holes have a diameter of 0.25 and go to a depth of 0.40.

Can you make a flat-bottomed blind hole?

You can make a flat bottom blind hole, but it can be difficult depending upon what type of material is being drilled. A modified drill bit or an end mill can work. This video explains some tips.

Blind hole example

The example below has three blind holes. They all have a diameter of 0.500 but they have different depths. From left to right, the depths are 0.500, 0.250 and 0.100.

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 MachinistGuides.com readers get an exclusive discount on training!

For more information see these related articles:

Thru Holes – All About

Countersinks – All About

May 6, 2022February 16, 2021 by Brandon Fowler

What is a countersink?

A countersink is an angled taper applied to a hole that allows a fastener (usually a flat head screw or similar) to sit even with, or below the surface which has been countersunk. Occasionally, a countersink is used simply as a method of chamfering or deburring a hole.

Countersink symbol

The GD&T callout for a countersink is shown below. Some older blueprints may use the notation CSK to identify a countersink dimension.

If you want to type the ⌵ symbol, hold the ALT key and press 9013. See this list for other common keyboard shortcuts for GD&T and blueprint symbols.

How to dimension a countersink

A countersink is dimensioned by specifying the diameter of the countersink where it meets the surface and the included angle. In the above example, the part has a 0.5 thru hole and a countersink with a diameter of 0.7 and an included angle of 82°.

How to measure a countersink

Countersinks can be measured by many different gauges. The easiest tool to use, assuming the tolerances aren’t too tight, is a pocket comparator with a reticle. Optical comparators and CMMs are regularly used to measure countersinks with very tight tolerances.

What does a countersink look like?

Countersink vs chamfer

A countersink and a chamfer are very similar. A countersink is basically no different than a chamfer on a hole.

The main difference is that a chamfer is normally thought of as being at 45 degrees (though the angle can vary). A countersink is usually one of many different standard angle sizes.

The most common countersink angles are 82°, 90° or 100°.

Note that in the case of the 90° countersink, this callout is the same as a 45° chamfer because the countersink angle takes both sides into account, so it is twice the chamfer angle.

Countersink vs counterbore

The difference between a countersink and a counterbore is that a countersink has an angled bottom and a counterbore has a flat bottom. Countersinks are often used to recess a flat head screw. Counterbores are used to recess bolts, washers and other fasteners.

Countersink vs spotface

A spotface has a flat bottom like a counterbore while a countersink is angled. A spotface is used to create a flat area in a specific location to allow a fastener such as a screw or bolt to sit squarely.

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 MachinistGuides.com readers get an exclusive discount on training!

For more information see these related articles:

Counterbores – All About

May 6, 2022February 16, 2021 by Brandon Fowler

What is a counterbore?

A counterbore is a circular hole with a flat bottom which coincides with another hole. The counterbored section allows a bolt head or other fastener to be recessed.

What does a counterbore look like?

Counterbore symbol

The GD&T callout for a counterbore is shown below. The counterbore symbol will often be used together with the diameter symbol and the depth symbol. Older blueprints may specify a counterbore with the notation CBORE instead of the counterbore symbol.

If you want to type the ⌴ symbol, hold the ALT key and press 9012. See this list for other common keyboard shortcuts for GD&T and blueprint symbols.

How to dimension a counterbore

A counterbore is dimensioned by including the diameter of the counterbore along with specifying the depth. The two ways to specify the depth are to specify how deep the counterbore is or the thickness of the remaining material. Both methods are acceptable and commonly seen.

In the example below, the part has a .250 hole and a .500 diameter counterbore to a depth of .100.

How to measure a counterbore

Counterbores can be measured with many different types of gauges. The simplest inspection tool to use, assuming the tolerances aren’t too tight, would be a caliper.

Pocket comparators, gage pins, and depth micrometers are other types of measuring equipment that are frequently used to measure counterbores.

Counterbore vs countersink

The difference between a countersink and a counterbore is that a countersink has an angled bottom and a counterbore has a flat bottom. The angle of the countersink can vary with many different angles used such as 82°, 90° and 100°.

Counterbore vs spotface

A counterbore and a spotface are very similar. A counterbore is used to recess a fastener while a spotface is used to create a flat surface located allow a fastener to be used. A spotface is used to let a fastener sit flat and in a specific location. A spotface is basically a shallow counterbore.

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 MachinistGuides.com readers get an exclusive discount on training!

For more information see these related articles:

Best CNC and Machining Books

Tolerance Blocks – All About

May 6, 2022January 30, 2021 by Brandon Fowler

What is a tolerance block?

The definition of a tolerance block is a section on an engineering drawing or blueprint that identifies tolerances for a dimension that aren’t specifically called out on the print. Notice how the 17.5 dimension below has a tolerance directly associated with it.

Now look at the 12.5 dimension and notice that no tolerance is specified. Because there is no tolerance called out, the tolerance in a tolerance block (general tolerances) would be applied to this specific dimension.

Note: The contents of the tolerance block are often referred to as the general tolerances. Depending on the units used on the blueprint, the tolerance block can be specified in metric or imperial (inch) units.

Tolerance block examples

How to read a tolerance block

Most tolerance blocks are identified based on the number of decimal places of the feature on the blueprint.

Using our previous examples again, notice that the 12.5 dimension has one number after the decimal place. Based on the tolerance block, this would assign the +/- 1 mm tolerance to the dimension.

If the dimension was instead 12.54 then the tolerance assigned would be +/- .5mm. Angular dimensions often are specified in the same way. In our example, all unspecified angular tolerances would be assigned the =/- .5° tolerance.

Other names for a tolerance block

Default tolerances
General tolerances
Standard tolerances

Title block tolerances

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 MachinistGuides.com readers get an exclusive discount on training!

For more information see these related articles:

Micrometers vs Calipers

Full Radius – All About

May 6, 2022January 20, 2021 by Brandon Fowler

What is a full radius?

A full radius is a radius that smoothly blends into another surface. Full radius is most often specified in a rounded slot feature or a feature that mimics a rounded slot.

A full radius sometimes noted as a true radius or full R is outdated language and not part of the current revision of the drawing standard ASME Y14.5. The full radius callout is referencing a smooth transition from the radius to an adjacent surface.

How to measure a full radius

Because no reference standard documents the requirements of a full radius, there are no specific requirements for the callout.

When a full radius, true radius or full R is called out on the drawing, the blueprint drafter is attempting to control the blend into and out of the specified radius.

What is a full radius?

A full radius is a radius that smoothly blends into another surface. Full radius is most often specified in a rounded slot feature or a feature that mimics a rounded slot.

How to measure a full radius

Because no reference standard documents the requirements of a full radius, there are no specific requirements for the callout.

When a full radius, true radius or full R is called out on the drawing, the blueprint drafter is attempting to control the blend into and out of the specified radius.

Full radius vs radius

There is no difference between the drawing callouts of full radius, true radius and radius. Because there are no specific requirements for a full radius referenced by any drawing or GD&T standards, there is no difference in the requirements of a full radius or full R vs a radius or R. A full radius does not have a tolerance. A radius if drawn correctly will have some form of a +/- tolerance or be controlled through a GD&T requirement such as profile or cylindricity.

There is no difference between the requirements of the example below or the previous one.

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 MachinistGuides.com readers get an exclusive discount on training!

Get the Best GD&T Training Available

For more information see these related articles:

GD&T Symbols Quick Reference

Facebook Twitter Youtube

Full radius vs radius

There is no difference between the requirements of the example below or the previous one.

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 MachinistGuides.com readers get an exclusive discount on training!

For more information see these related articles:

Best CNC and Machining Books

TYP & Typical on Blueprints [What They Mean & How to Inspect Them]

May 6, 2022January 20, 2021 by Brandon Fowler

What does typical mean on a blueprint?

Typical on an engineering drawing identifies a repeated feature. This is identical to a feature which is identified as 2x or 5x.

A typical dimension callout will occasionally be followed by a 2x, 5x or similar, to specify the quantity of features which are tolerance the same.

The typical callout will most often be used as part of a repeating pattern such as a bolt hole circle, to identify the hole sizes or angle between the holes.

Another common application is to identify a common chamfer size on a component. It should be noted that the notation of “typical” is not a part of the current revision of the ASME Y14.5 standard and therefore not a recommended notation for use on an engineering drawing. There are however countless blueprints in the wild which may already use this language.

What is the symbol for a typical dimension?

There is no GD&T symbol for a typical dimension. A typical dimension callout is identified with either TYP. or TYPICAL. In the example below, the typical notation is used to reference that the slot on both sides of the part is to be machined to the same depth.

A better way to identify the same dimension would be as shown below. It is best to not leave anything to the imagination of the person interpreting the blueprint.

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 MachinistGuides.com readers get an exclusive discount on training!

For more information see these related articles:

Best CNC and Machining Books

A Beginner’s Guide to Calipers – Dial and Digital

How to insert symbols into a Microsoft Word document

How to insert GD&T symbols into a Microsoft Excel document

GD&T Symbols Alt Codes

Common Blueprint Symbol Alt Codes

Related Articles

What is a break edge?

What does a break edge look like?

Break edge on a physical part

Break edge on a blueprint

Break edge symbol

Break edge note example

How to make a break edge

Break edge on wood

Break edge on metal

Break edge on glass

How to measure a break edge

Which measuring tools to use

How to measure the break edge based on your blueprint

Break edge compared to similar features

Break edge vs chamfer

Break edge vs radius

Want to learn more?

Related Articles

What is a chamfer?

Types of chamfers

Leg length chamfers

Face width chamfers

Chamfers compared to similar features

Chamfer vs bevel

Chamfer vs break edge

Chamfer vs countersink

Chamfer vs deburr

Chamfer vs fillet

How to specify chamfer dimensions

Chamfer notation example #1

Chamfer notation example #2

Measuring chamfers

How to measure the size of a chamfer

How to measure the angle of a chamfer

Want to learn more?

Related Articles

What is a thru holes?

How to dimension a thru hole?

Thru hole vs blind hole

Thru hole symbol

Thru hole examples

Want to learn more?

Related articles

What is a blind hole?

How to dimension a blind hole

Blind hole vs thru hole

Blind hole symbol

Can you make a flat-bottomed blind hole?

Blind hole example

Want to learn more?

Related articles

What is a countersink?

Countersink symbol

How to dimension a countersink

How to measure a countersink

What does a countersink look like?

Countersink vs chamfer

Countersink vs counterbore

Countersink vs spotface

Want to learn more?

Related articles

What is a counterbore?

What does a counterbore look like?

Counterbore symbol

How to dimension a counterbore

How to measure a counterbore

Counterbore vs countersink

Counterbore vs spotface

Want to learn more?

Related Articles

What is a tolerance block?

Tolerance block examples

How to read a tolerance block

Other names for a tolerance block

Want to learn more?