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Starrett Combination Squares - Tool Review

by Jeffrey Fleisher
New Market, VA

Click on any picture to see a larger version.

Most woodworkers have a combination square in their shop but don't really think about the importance of this tool for fine craftsmanship. You cannot build a quality piece if your measurements are not accurate or layouts are not square. The Starrett Combination Square is the gold standard by which all other squares are measured.

Starrett Combination Squares have hardened and tempered satin chrome blades which are graduated in 64ths and 32nds on one side and 16ths and 8ths on the other. Blades can be reversed to read whichever scale is most convenient for a given job. The lines are etched into the blade so they will not fade with time but more importantly, you can set your marking tools, eg. the knife on your marking gauge, into the etched line and get a very accurate setting.

Heads are precision-milled cast iron with black wrinkle finish. They have a level built into the base and a removable scratch awl for marking on your wood.

The blades come in a variety of lengths such as 4 inch, 6 inch, 12 inch and 24 inch. The 4 inch and 6 inch combination squares are the perfect size to carry in your apron pocket. Having it in your apron pocket makes it available immediately for a quick measurement or marking at the bench or at a tool prior to a cut. The 12 inch size is the most common and has the most uses around the shop. We will explore some of these uses later in this review. Finally, the 24 inch blade size is the perfect size for measuring large panels and is an excellent straightedge when used without the handle. There are optional accessories which can convert the combination square into a center finder for round or square stock, or into a large precise 180 degree satin chrome reversible protractor for determining or laying out uncommon angles.

The Starrett Combination Square is an extremely flexible device. I classify its functionality into three categories...measuring with the ruler, measuring a distance but without using the scale and measuring for square. The most common use for the combination square is to measure a distance from the edge of the board and draw a line. I find the most accurate way to draw a line is to set the blade in the head at the desired distance, place the head against the edge of the board and scribe the line. When cutting remember that a line does have a thickness so it is important to determine if you are going to split the line or cut on one side of the line or the other.

Obviously, this works for both with the grain and across the grain. When making small marks on the edge of the board or wrapping a line around the edge, the 4 inch combination square is very useful.

The main use for my combination square is using it to record or transfer a measurement that I need without actually recording a numerical number. I like to think of this as "what it is supposed to be" versus "what it actually is". Here are a couple of examples of what I mean. If I'm trying to match the thickness of a board coming off of my planer to an existing board I can either measure the first board with a ruler or record the size with my combination square. In the first case, the board is supposed to be 13/16 inches thick.

However, what it is supposed to be doesn't mean that is what it actually is! In this case, it is a 'smidgen' (yes, that is a technical term) oversize. That is very hard to measure and then compare to another board. But, if I set my combination square to this thickness, as shown in the previous picture, I can now compare that setting to the board being planned.

I can easily see that the board is still too thick and will keep planning it down until I feel that the edge of the board matches the edge of the combination square. I don't really need to know what the actual thickness is in this case.

Another example came up last week when I was building a top for a buffet. I was trying to determine the size of the top, which included a profiled edge, so that I could eventually use an existing piece of glass on it for protection. I needed a way to measure the size of the profile plus a 1/8" flat for both ends of the top and then add this to the size of the glass to get my final top dimension.

As shown in the photograph, this was very easy using the combination square. I just set the flat surface of the head against the profiled edge, set a 1/8" flat distance on the surface and tightened down the screw. This gave me the exact size I needed to add for both ends of the top.

The final category, measuring for square, takes advantage of the extreme accuracy of the Starrett combination square. This is one of those times where the old saying, "you get what you pay for", is really true. The one criticism that most people have when you tell them to purchase a Starrett square is the price. This is one of those times where you just need to accept the fact that you are purchasing a quality tool and it is well worth the price in order to achieve fine craftsmanship.

The most common use for the combination square is to set the blade of a tool square to the table. Here are a couple examples of this for the tablesaw and the bandsaw.

Not only can you use it to set a cutting blade but you can also use it to set the tables of your belt sander and other similar tools.

I also use the combination square during assembly to make sure that my parts are going together square. I used the combination square on my buffet to make sure the door and drawer openings are square.

I could go on about the various uses of the combination square. You can use it to set the height of your tablesaw blade or your router blade. You can determine if your tablesaw blade is square to the miter slot...and so on. The important thing to remember is that accuracy is extremely important and the Starrett Combination Square is extremely accurate right out of the box. Yes, the cost may be double what you might pay for one from a big-box store but the improvement to the quality of your work is immeasurable. I have been using my Starrett Square for the past 20 years and am very pleased with how it improves my woodworking on a daily basis.

Find out more about the Starrett Combination Square

Jeffrey Fleisher has been a woodworker for approximately 20 years and a professional woodworker for the past 6 years. He is the president of his local woodturning club, the Woodturners of the Virginias and past president of the Northern Virginia Carvers. You can see some of the furniture he has made at He can be reached by email at

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