How To Use A Combination Square (Beginner To Pro)

There are few things worse than looking at a frame (mirror, painting, picture, window, door) or a tabletop or desk that is out of square.  

Fortunately, we have squares to help us, as well as accurate measurements.  In the category of squares, we have many to choose from. There are a number of squares to choose from, and each has its talent(s) to apply to our woodworking project.  Each is an excellent tool to have handy

We’ve written about the essential beginner’s list of tools for the shop, and of course, the list included a square.  We’ve also written about many types of squares for the shop. 

What Are The Different Types of Squares Used In Woodworking?

Among the more common types of squares we use in our woodworking shop are:

Try squares

Try squares are used for checking the squareness of edges and faces. They are typically made of steel or brass and have a blade that is fixed at a 90-degree angle to the handle.

Try squares are available in a variety of sizes, from small squares that can be used for checking the squareness of small pieces of wood to large squares that can be used for checking the squareness of large pieces of wood.

Speed squares 

Speed squares are triangular-shaped squares that are used for marking lines, checking for squareness, and measuring angles. Speed squares are typically made of aluminum or plastic and have a blade that is adjustable to a variety of angles. Speed squares are a great tool for use with circular saws and jigsaws.

Framing squares 

Framing squares are large, L-shaped squares that are used for checking for squareness and measuring angles. Framing squares are typically made of steel or aluminum and have a blade that is adjustable to a variety of angles. Framing squares are a great tool for use with framing lumber.

We’re interested in focusing on one particular square for today’s article, though – a combination square.

What is A Combination Square?

A combination square is a multi-purpose measuring and marking tool used in metalworking, woodworking, and stonemasonry. It is composed of a rule and one or more interchangeable heads that can be attached to the rule. Other names for the tool include adjustable square, combo square, and sliding square.

This layout tool is as versatile as they come. The rule is made of steel, easily removed from whatever head you are using.  It slides through an adjustable head or anvil and is set along the rule by an adjustable knob. We remember protractors from our high school geometry classes – for me, it was Mr. Daggett’s class.  

The most common head on a combo square is a square head, which is used to check for squareness. The square head is typically made of hardened steel and has a 90-degree angle.

Other heads that may be found on the square include a protractor head with its depth gauge and plumb bob.  Cast iron heads, also referred to as an anvil, ensure a very stable and rigid element in a tool we want for those qualities when measuring square, angles, lines, etc.

The steel rule is removable and is calibrated the same way a wooden ruler is calibrated.  On a combo square, the rule is broken down into the most common measurements we use in woodworking – by inches, eights, sixteenths, and thirty seconds.

The rule is slotted in its center for the easy movement of the head along it to whatever length your measurement calls for, and then the head is locked in place by an adjustable knob you can tighten with your thumb and forefinger.

These squares are used for a variety of tasks, including:

• Checking for squareness
• Measuring angles
• Marking lines
• Measuring depths
• Transferring measurements
• Plumbing

Combo squares are an essential tool for any woodworker, metalworker, or stonemason. They are versatile and accurate tools that can be used for a variety of tasks.

Here are some of the benefits of using a combination square:

• Accuracy: Combination squares are very accurate tools. The square head is typically made of hardened steel and has a 90-degree angle. This makes it ideal for checking for squareness and making precise measurements.
• Versatility: Combination squares are very versatile tools. They can be used for a variety of tasks, including measuring angles, marking lines, measuring depths, and transferring measurements.
• Durability: Combination squares are made of durable materials, such as hardened steel and brass. This makes them resistant to wear and tear, so they can last for many years.

How Is A Combo Square Used?

We know now what a combo square is, and we know what it can be used for in the shop.  Just how, though, do we use it to accomplish all of those tasks?

• Checking for squareness: To check for squareness, place the square against the two surfaces you want to check. The square should fit snugly against both surfaces, with no gaps. If there are gaps, then the surfaces are not square.
• Checking for plumb:  The protractor head has a level bubble encased within it.  We all know how to use the bubble, but in this case, we don’t necessarily have to reach for a separate tool because the combo square’s head already has one.
• Measuring angles: To measure an angle, place the square against the two surfaces you want to measure. The square should fit snugly against both surfaces, with no gaps. The angle between the two surfaces can then be read from the scale on the square. 90-degree and 45-degree angles are measured easily and very quickly with a combo square; the rule makes it easy to mark lines on your workpiece, too.  The heads are wide enough and extend far enough on either side of the rule so you can about the piece being measured and keep the angle’s or length’s measurement accurate. 
• Marking lines: To mark a line, place the square against the surface you want to mark. The square should fit snugly against the surface with no gaps. Use a sharp pencil to mark a line along the edge of the square.
• Measuring depths: To measure a depth, place the square against the surface you want to measure. The square should fit snugly against the surface with no gaps. The depth can then be read from the scale on the square.
• Transferring measurements: To transfer a measurement, first measure the desired distance with the square. Then, place the square against the surface you want to mark. The square should fit snugly against the surface with no gaps. Use a sharp pencil to mark a line along the edge of the square at the desired distance.

Straight edge, angles, depths, and marking lines are tasks we are all called upon to measure and ascertain in our shops, and they are all very easily performed by a combination square quickly.  

Video Demo For Combination Square Beginners

It’s a short video, a little over 4 minutes, but very informative as the videographer walks you through the basics for using a combo square.  

The combo square is as versatile a measuring tool you can have in your woodworking shop, and many of us consider it virtually irreplaceable in a single tool.

The price range for combo squares runs from around $12 for a 12-inch rule from Empire all the way up to $150 for a Starret; the latter is considered the “gold standard” for combo squares.