On Woodworking Squares and Working Wood

For more information on the square, see our beginner site Common Woodworking.

What is a Square?
A square is a simple tool used to make marks square to an edge as well as check the squareness of different faces, edges and ends of different materials. Especially is this so in metal and woodworking where rigid materials are formed into fabricated products of an indeterminate range. The square is one of the simplest tools used throughout almost every area of woodworking. A try (also tri) square supposedly derives its name from trying or testing a material part and its accuracy in any 90-degree configuration. We use it throughout a wide range of specific tasks from squaring stock foursquare to laying out and making joints in wood. Though maker’s names may have been established to identify the maker or the type, almost all squares could be referred to as simply a square or a try square end everyone will understand and accept the term in this, its simplest form.

Squares Come in All Shapes and Sizes

Squares come in many shapes and sizes and we can naturally assume always that squares are in fact square; that is that the stock of the square is set to exactly 90-degrees with no inexactness at all. Unfortunately that can often be far from true. In fact, most squares I come across fail to give the levels of accuracy needed for good work or, if they are square to begin with, they often go out of square after a few hours of use. One thing I have learned through my life as a working craftsman in wood and metal is that there can be no acceptance of marginal discrepancies when it comes to whether a square is indeed square or not. If a square is not dead square it is not a square. Of all the tools you have in your workshop you must have the uncompromised certainty of a dead square square no matter what. The square may look almost passive amongst the ‘doing’ tools; in reality, it’s the single most important tool you as a woodworker will ever own.

This tool:

  • Lays out the shoulder lines on every joint we make.
  • Checks our progress planing stock foursquare.
  • Checks our cuts.
  • Checks our accuracy
  • Checks our finished work
  • Confirms many areas of our work

All other tools we use, the plane. the saw, the chisel, those tools that cut wood, take their lead from the square, are regulated by the square in processing the wood and are finally confirmed by that same square.

Parts of the Square

Though squares are available as different types, all squares comprise two basic elements; the beam or blade and the stock or head. The heavier section, whether steel or wood, is commonly known as the stock. Some stocks are moveable along the beam and some are fixed rigidly to the beam.

The stock or head
The heavy stock is the shorter part of the square that, in most cases of use, registers the square to a proven straight edge. Anchored in place by hand pressure, the beam then projects the exact 90-degree aspect to the stock and lines or cuts are made to the squared angle with a pencil, steel scribe or knife. We also register the stock of the square to the adjacent parts of work in progress or completed to check for squareness. These are internal and external corners.

The beam
The beam is the thin or usually thinner blade of plate steel (wood in the case of all-wood squares) extending from the stock of the plane at 90-degrees. Depending on the square type, this beam is either made from hardened or tempered steel and, depending on the thickness of the steel plate used, may also be made from flexible spring steel. The joiners try square usually uses this thinner plate with a wooden stock and brass wear plate running along the inner edge of the stock.

Side note: In general, it might be acknowledged that introducing a moving part allows tolerance that leads to or allows inaccuracies in the assembly whereas fixed components allow no such movement. My experience is different. I have used the same engineer’s combination square six days a week for the past half century and there is no discernible difference since the first day I bought it and it has retained its squareness throughout. On the other hand, I have found many if not most fixed try squares to be inaccurate.

There are many types of different squares manufactured that range in size from 3” to 48” and longer. Size will usually be determined by the type of work they are used for but the most common size used by woodworkers is between 6-12” along the beam, 12” being the most common of all. Depending on the woodworking craft, most woodworkers engaged in general woodworking and furniture making use a square known as an engineer’s combination square. As the name implies, this square was designed for engineering and the term combination is the inclusion of both a 90-degree square aspect and a 45-degree angle in the stock. This combination enables the to be used for square and mitred marking and cuts to be established along the beam.
Most of the squares we woodworkers use are either try squares or engineer’s combination squares because the work we engage in mostly comprises compact and close work surrounding joint making and component parts that build frames and panels etc. There are other squares more specialised and developed for metal working engineering work and carpentry work too. These squares on the one hand are generally more highly engineered on the engineers side and stamped out on the other. Both are designed to suit the different levels and needs of those trades. No matter the differences in tolerances, squares must always be square. A minor discrepancy in a carpenters roof square can translate in major inaccuracy on the roof of a building or a floor layout in a building because, no matter the tools used subsequent to marking and laying out with the square, there will generally be the knock-on effect in inaccurate cuts.

Try Square

At one time the try square would have been the most commonly used of any square ever made. During the 1800’s try squares were manufactured by tool makers using a variety of materials including brass, steel, ebony and rosewood. The two woods were known for their stability, hardness and resistance to wear and change. The best quality try squares were made using these two wood types.

Try squares comprise a wooden stock, a brass wear plate along the inside face of the wooden stock and steel blade or beam made from plate steel stock. The sizes do vary but common sizes along the beam are 3”, 6”, 9”, 12” and 16”. The most commonly used size was the 9”.

Large wooden try squares ere made from dimensionally stable woods such as oak and mahogany. I frequently came across these in my youth when sent to retrieve a tool for one of the joiners in their tool chests. We used these for laying out and checking frames during construction and found it especially useful for sheet materials such as plywood and engineered wood. These were almost always craftsman made tools but I have occasionally come across ones made by known makers.

As a common tool, the try square has stood the test of time and beautifully made examples of manufacture show their revered status a tool of significance and importance. Some very ornate examples made by British craftsmen survive in private collections thankfully. Brass riveting and wear plates contrasted markedly with the ebony and rosewood woods used throughout the Victorian era when these woods were used for fine furniture making and so provided the same quality of materials for tools used by craftsmen.

I restored this Marples square which was a massive half millimetre out of square – I will show you how this was done later

Unfortunately long term use takes its toll on these tools and I have generally found them to be less accurate than is acceptable. It has been difficult to find a modern day manufacturer producing consistent levels of accuracy in these tools and yet there can be no acceptance of anything less than dead square.

Restoring squareness to try squares
Squares get damaged during use and sometimes get dropped or jarred forcing the stock and beam to distort in some way or measure. Restoring the square aspect to a square is not complicated and can usually by accomplished with a flat file provide all of the components are in good condition, solidly fixed and with no movement in the riveting connecting the beam to the stock of the square. Draw-filing the steel plate takes only a few minutes to do with a sharp, single cut 10” file.

The speed square

There are a few squares seen regularly in hardware stores. Four seem to dominate the most and whereas other squares do exist these are often highly specialised squares that exceed the need and requirements of woodworking and furniture making in general.

The speed square was developed for American carpentry building the stud-framed structures the US is famed for. This square was developed to work on conjunction with hand held circular saws to align the flat base of the saw square to the wood being cut, which then guarantees every cross-grain cut is square in both directions or square and angled when combined cuts are needed too. Mainly this square is used on dimensional lumber milled to 2×4, 2×6 sections and comes in two sizes; 7” and 12”. The smaller square is the more common of the two and conveniently fits into the carpenter’s tool pouch.

The aluminum section of the speed square is usually thicker and stockier than other more conventional squares because the saw plate runs along the square throughout the cut. Though these tools bring great accuracy to the hand held circular saws, they generally lack the fineness needed for bench work such as joinery and furniture making and are less suited to this type of work.

The framing or roofing square

This large 1/8” plate steel square has proven popular with carpenters for many decades and the standard size is16” along the tongue and 24” along the blade. Carpenters use this square mainly for laying out cut lines on roof parts such as rafters of different types and also for laying out angles in construction of projects such as stairways and decks. Both this square and its partner the speed square have helpful formulae inscribed or printed into and onto the body of the squares for calculations during use. Whereas the speed square has little use to the furniture maker, the roofing square is very useful for several applications and is especially useful for wide panels and sheet materials such as plywood and MDF.
In this construction industry and to the general carpenter this tool is invaluable for speed and accuracy throughout the building work. Most carpenters could not function well without this tool in their daily-use kit.

The engineer’s combination square

The original engineer’s combination squares used by engineers are fine examples of engineering accuracy and the designs are exceptionally well thought through in terms of functionality and application. Cast iron, weighty stocks and hardened steel beams lock solidly to one another and allow adjustment along the beam that helps to balance the square throughout the many diverse variables in the work in hand. This adaptable versatility permitted a single square to replace multiple sized squares in a single tool and gradually rendered the try square obsolete.

Features of the engineer’s combination square comprise:

  • Cast iron head
  • Hardened steel beam
  • Marking pin
  • Easy hand holding
  • Imperial and metric markings
  • Adjustable beam
  • Lockable mechanism
  • Use for distance marking
  • Use as depth gauge

Unfortunately not all engineer’s combination squares are created as equal as we would like. As with most tools, many squares found in hardware stores have declined in quality with most hardware stores trying to compete more on price and failing to offer the quality tools needed for good work. Aluminium versions (shown here) of the good quality engineer’s squares seldom maintain the accuracy we need and the inaccuracy becomes projected into our work. A good quality square will last for a lifetime’s accurate service and use and this alone will always be worth paying premium prices for.


  1. without a doubt the a good quality square in making anything in wood is essential, as i have found out to my cost, both in disappointment and frustration . i now am a proud owner of a starrett combination square and the peace of mind it brings is worth every penny

  2. It seems like Starrett is the undisputed best, but can be pretty expensive. From what I’ve heard, PEC, Products Engineering Corp, are also very high quality. I found that you can get “blemished” PEC squares here, for a very reasonable price: http://store.harryepstein.com/c/ProductsEngineering.html These squares are in perfect working order, but have the name of the maker ground out. From what I can tell, they are very solid and high quality. Eventually, I’ll spring for a Starrett, but I’m very happy with the PEC I have for now.

    1. Unfortunately, Starrett puts out its share of junk too. Their tools for measuring angles are the best example. You can find several reviews of them on Amazon, including mine, stating they are all at least a half degree off. Of course, this is an intolerable flaw for those trying, for example, to cut dead on picture frame miters.

  3. I love my speed square, I imported the metric version from the US as we don’t sell them at all over here. I love the design and idea of it more than the implementation perhaps, if only it was more finely graduated and machined after casting, then for me it would truly be the king of squares.

    1. I use a Rabone Chesterman X two of them. I also have a Browne and Sharpe and a Starrett.

  4. I don’t understand the meaning (I understand the words) of the following sentence. I suppose “like” should be replaced with “lack”… but as English language is not my mother tongue, it is not so easy to correct typos…

    >they generally like the fineness needed for bench work such as joinery and furniture making and >are less suited to this type of work.

    About the square Paul use, I can remember he said “somewhere” that it is a Rabone square.
    I’m not sure Rabone still exists as a company as Stanley is selling a “Rabone’ comb square.

    Stanley sells many comb square. I suggest to buy a steel cast one, Aluminium alloy ones are cheaper but are often slightly out of square after a while.

    I’ve bought a “Stanley 1912 Comb Square 300MM/12In 0 46 151” (I think, once again, Paul talks about it “somewhere”).


    1. Stanley still makes the cast iron head model and we use these in the woodworking school here at Penrhyn Castle. On the package it says Stanley Chesterman and all of the ones we’ve bought they were always square and have stayed so.

      1. Hi Paul. First of all I want to let you know I really like your way of teaching the craft. Based on your recommendation I bought the Stanley 1912 Comb Square. It’s unfortunately not square at all. Is there a way to fix this or is the only right thing to do to throw it in the bin? Thanks in advance, Alexander

    2. You were right. it was lack and not the auto correct ‘like’. So thanks for this.

  5. I bought many years ago a 4″ and 12″ Starrett and have been very pleased with them. I also have heard Pec makes a good square, I did by the 4″ double Square from Lee Valley which also is very good.


  6. A full “Engineer’s Combination Square” has two normal additional pieces (that may or may not be -that- useful in woodworking).

    There’s the ‘center finder’ piece, and there’s the protractor/360-level. (And the occasional “What in the heck do you use -that- for? piece.)

    Starrett is the go-to name for metalworking measuring/marking bits.

    Enco Catalog Page


  7. Thanks for the article Paul. How would you recommend we test that a square is actually square

  8. thanks again Paul for a great and frankly very entertaining article. Being new to the craft the amount of tools necessary and available can get a little overwhelming. I am quickly learning not all of these are created equal and perhaps in this field more than some others I found I am getting what I pay for.

  9. My husband does a lot of woodworking. He makes wooden models from blueprints from the company TOYSandJOYS.com The projects he builds have a lot of thin wood pieces and he finds it hard to use the regular square and it has a thicker handle and does not give a flush against the wood he is trying to mark. Is there a square that is available for purchase that has this thinner handle for thinner wood use?

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