Combination squares are an essential woodworking and metalworking tool that every craftsperson should have in their toolkit. As useful as they are versatile, combination squares have been relied upon for precision layout and measurement work for over 140 years.
But not all combination squares are created equal when it comes to withstanding the test of time. This article will cover why combination squares are so indispensable, provide a background on the tool, explore what to look for when selecting one to last a lifetime, discuss alternatives that don’t rely on modern mass production, and offer tips on keeping your combination square calibrated and maintained for decades of dependable service.
Why You Need a Combination Square
A combination square consists of a steel ruler blade that slides through an L-shaped head which has surfaces machined precisely at 90 and 45 degree angles. This simple but ingenious design means that with one tool you have:
- A square for checking 90 degree angles and marking perpendicular lines
- A miter square for laying out 45 and 90 degree angles
- An adjustable depth gauge and height gauge
- A center finder for circles
- A straight edge and ruler
This versatility is why the combination square is considered an essential layout tool for any wood or metal shop. Without one, far more single-purpose tools would be required, cluttering up your workbench. Having access to precise 90 and 45 degree references is critical for joinery and machining. And the adjustability of the ruler lets you quickly mark lines, find centers, and measure depths and heights.
Few other tools can match the utility of the combination square. It saves time, cost, and space. For anyone interested in crafting things out of wood or metal by hand, it’s an absolute must-have.
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A Brief History of the Combination Square
While earlier tools like the try square and sliding bevel served some of the same functions, the first true combination square is credited to Laroy S. Starrett in 1879. His original design established the standard L-shaped form with blade, head, shoulder, and anvil that’s still followed to this day.
Starrett founded L.S. Starrett Company in 1880 to manufacture his combination squares, along with other precision measuring tools. Thanks to Starrett’s invention, the company has thrived ever since. They are the most well-respected brand when it comes to layout tools for metalworking.
Over the next few decades, other toolmakers took note and started producing their own combination squares for both machinists and woodworkers. Stanley, Brown & Sharpe, and Union Tool Co. were some of the most prominent. The basic premise remained unchanged even as production methods modernized.
These days companies like Empire, Swanson, and Johnson Level manufacture combination squares at lower price points while still maintaining decent quality. But none have managed to match Starrett’s stellar reputation. As the original inventor of the tool, they set the standard that all others follow.
Selecting a Combination Square to Last a Lifetime
The marks of a well-made combination square that will provide a lifetime of service are:
Precisely Machined Head
The most critical part of a combination square is the head. The anvil and shoulder must join the ruler blade at perfect 90 and 45 degree angles. Even minute deviations quickly compound into accuracy issues. The head should be made from thick cast iron or forged steel that resists warping and deflection. Cheaper squares often use cast zinc or extruded aluminum heads that don’t hold tolerances well under hard use.
Engraved Ruler
The blade should feature engraved markings rather than printed or silkscreened. Printed markings can wear off with heavy use. Engraved markings cut into the metal ensure the graduations are permanent. Durable chrome plating helps prevent corrosion and improves legibility.
Smooth Adjustment
You’ll be sliding the head up and down frequently, so the fit should move smoothly without wobbling. Some play can develop after years of use but an oversized adjustment knob helps maintain rigidity. The knob should also be easy to tighten and loosen by hand.
Level Vial(s)
One or two tubular level vials provide plumb and level references between the head and ruler blade. Better quality combination squares include this useful feature.
When evaluating combination squares, Starrett remains the gold standard even 140 years later. Their tools exemplify all of the qualities to withstand an apocalypse. If that level of investment isn’t feasible, the Empire combination squares manage to emulate much of Starrett’s specifications for a fraction of the cost.
Traditional Alternatives Before Modern Tools
Combination squares are a prime example of a versatile, inexpensive measurement tool that we take for granted in the modern world. Their availability is a luxury arising from mass production. In earlier eras, craftspeople relied on more basic solutions built using traditional techniques.
The Try Square
A simple L-shaped tool made from wood, the try square dates back centuries and consists of a handle with a steel blade attached. While mainly used for checking 90 degree angles, the blade edge can also mark lines. If the blade is sharpened, it can function as a chisel for light duty cutting. Large try squares can reference large surfaces. Making your own try square is straightforward with basic woodworking skills.
The Miter Square
Before combination squares, carpenters and metalworkers used simple miter squares with pre-defined 45 and 90 degree angles. These had to be made precisely and didn’t offer adjustability. Miter squares can be constructed from wood with attention to accuracy.
The Plumb Bob
For determining vertical references, a basic plumb bob hangs from a line centered over a point. A weight on the end keeps the line taught. The same principle applied on a frame provides horizontal leveling. Making an effective plumb bob requires minimal materials.
While combination squares offer enhanced versatility and portability, the basic nature of tools like try squares, miter squares, straight edges, and plumb bobs means they can be fabricated from wood and scrap metal. In a long emergency, being able to construct the tools you need using fundamental techniques could make the difference.
Keeping Your Combination Square Calibrated
To maintain precision and accuracy over decades of hard use, a quality combination square must be cared for properly. Here are some tips for keeping your combination square in peak operating condition:
Protect It When Not In Use
Store your combination square in a padded case or wrapped in a soft cloth when not being used. Keep it in a dry, temperature stable environment away from dust and moisture. Don’t toss it loose into a tool box drawer.
Clean & Lubricate Periodically
Wipe down the surfaces with a lightly oiled cloth avoiding liquid sprays that can get into the head mechanism. Remove any grime, but don’t use abrasives. Ensure the blade moves smoothly in the head slot.
Check Calibration Frequently
Verify the 90 and 45 degree angles against known accurate reference surfaces like machinist squares or a dial indicator. Carefully tweak the head alignment if necessary. Even quality combination squares can get knocked out of calibration with a single hard drop.
Re-true If Necessary
If calibration efforts fail, the head mechanism may be bent or twisted. Carefully re-true the head alignment by securing the blade and tapping the head body with a soft mallet. Take care not to over-stress the parts.
Don’t Improperly Modify
Avoid the temptation to grind or file the precision surfaces to “fix” issues. This will ruin the heat treatment and dimensional accuracy. Proper re-truing is the only acceptable field modification.
With conscientious care and maintenance, a high quality combination square will serve for a lifetime. And maybe your descendants will be using it a century from now as they rebuild a simpler world. When so much is uncertain about the future, having dependable tools you can rely on provides comfort.
In summary, the versatile and enduring combination square is a foundational instrument for precise woodworking and metalworking. The original Starrett design set the standard for an indispensable layout tool that has persevered into the modern age. While cheaper combination squares have proliferated, none surpass Starrett’s quality and longevity. Investing in one made to exacting specifications means it will be ready whenever you need it, even if the power grid fails for good. When other tools quit, you can trust your rugged Starrett combination square to square up that last dovetail by candlelight.
Citations:
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[17] https://toolguyd.com/empire-combination-square-gift-guide-2020/
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