The Importance of Being Square - Tool Guide

Welcome to this week's Hand Tools Blog.

Can anyone explain to me why so many woodworkers who have all the machines and tools, do not own absolutely accurate basic layout tools such as Squares?

One assumes (woodworking swear word #324) that any Square that you buy is square: NEVER ASSUME!

Get a bunch of us woodworkers together, and we will happily pontificate on the subject of everything needing to be square, flat and straight, but we most often don't actually know if our Woodworking Squares are telling us the truth or not. 

The above image shows an English Layout Square. The history of the tool goes much further back to Roman times. (this version apparently speaks English).

These squares are great fun to make, are dead easy to tune, you can make them in any size you wish and if you add a plumb bob and a piece of string to it, you have an amazingly versatile tool for life. Not bad for some scrap wood and a couple of hours in the workshop. I have made a few over the years, all are half lap jointed and I usually make them from hard straight grained Maple, and have also made them from Bubinga, Sycamore, Mahogany, Pau Marfim and other scraps. On some of them, I have added a registration lip as well. My preferred finish for Layout Squares is BLO (Boiled Linseed Oil, applied warm).

Woodpeckers 1281 Precision Try Square. CNC Milled from a single billet of aircraft grade aluminium.

"Square Means Square", 90º is square, anything else is not! If you build your furniture with inaccurate layout tools, or for that matter a thick carpenter's pencil, you will waste wood, raise your blood pressure and dramatically enhance your naughty word vocabulary.

A range of Engineers' Squares

Squares are basic precision tools that every woodworker needs to achieve good work. If your Squares are under a pile of tools on the bench, get frequently dropped and have even tiny spots of adhesive or rust on the referencing surfaces, you are guaranteed to not do accurate work. 

L.S. Starrett 150mm & 300mm Combination Squares

My strongest advice with regard to Woodworking Squares is as follows:

• Buy the best quality brands you can afford.
• Make wooden boxes for them (Like the one your Vernier Gauge came with) or keep them safely in a dedicated rack or drawer.
• Always keep them very clean.
• Test them for squareness from time to time.
• Your squares are precision instruments, treat them as such.
• Have a few sizes and types available.
• Have one reference square that you test all your others by. Do not use this square for work, only use it to check others.

In woodworking, we make use of a variety of Squares. I suggest that a basic "Square Kit" should consist at least, of the following instruments:

• 1 x Precision 200mm Calibrated Engineers Square for reference.
• 1 x Precision 100mm Double Square
• 1 x High Quality 150mm or 300mm Combination Square
• 1 x Large English Layout Square (Make it yourself)
• 1 x High Quality Speed Square
• 1 x High Quality 150mm Try Square
• 1 x High Quality 300mm Try Square
• 1 x High Quality Mitre Square or Japanese Combination Square
• 1 x Precision 600mm or longer "T" Square
• 1 x Precision Setup Square (with 90º & 45º) for calibrating machines
• 1 x High Quality Framer's Square
• 1 x Pair of Gauges for Framer's Squares

A beautiful set of craftsman made traditional Layout Squares

It is important to bear in mind that buying a Square from any company or brand that does not truly specialise in this type of precision instrument, will result in money down the drain. You would not use a R29.95 plastic Vernier Caliper to do precision metal work, so why on earth would you use cheap, unreliable Squares to do your best woodwork?

With the development of absolutely precise CNC milling, Try Squares that are milled from a single billet of aircraft grade aluminium are fast becoming the "go to" standard for fine woodworkers all over the world. As soon as the instrument is made from two parts that are riveted together, or has moving parts, such as in a Combination Square, the potential margin for error rears it's ugly head. Not only is is quite possible that the Try Square is not true from the start, but if you accidentally drop it, it is guaranteed to then be out of true. With a single part Try Square, dropping it from bench height for example, it will still be true, although it might have a dinged end!

Woodpeckers Mini Square, 641 Try Square and Carpenter's Square Set

When you invest in a Square of a specific size and type, buy once and buy well, you with thank yourself over and over again. (If you look after it properly).

L.S. Starrett 100mm Double Square 

The number of times that I have witnessed woodworkers using cheap Combination Squares featuring rust and dried adhesive for added value, for setting up their jointers, table saws and for laying out joints is astounding. Why do woodworkers do this? Your Squares are precision instruments and deserve to be treated as such.

The excellent Shinwa Japanese Combination Square. 

As much as I love traditional Rosewood, Brass and Blued Steel Try Squares, I am fully aware that unless these instruments are made by specialists, they are more than likely to be unreliable. Today, we have some really excellent squares from the likes of Woodpeckers, Veritas, Incra, Shinwa, Nobex, Swanson, Crown Tools and L.S. Starrett available in South Africa. 

Swanson Speed Square and Nobex Octo Precision Locking Multi Angle Square

For my Double Square and Combination Square I choose Starrett. In Try Squares, I would most definitely choose either Woodpeckers or Incra. For Speed Squares, Swanson rules the game. Reference quality "T" Squares are Woodpeckers' exclusive domain. For small adjustable Try Squares, Crown is excellent and phenomenal value for money and for accurate folding squares that will lock at all the important angles (and 90º!) Nobex has held the podium for many years.

Even an extremely tiny variation off 90º in a Try Square will compound throughout a furniture project. For example, a 0.5º error in your Square will add up to 2º error when carrying a pencil line or scribe line around four sides of a planed component! This error will multiply with each furniture part and jointing procedure that you do and will lead very quickly to badly fitting joints, extreme frustration and quite often having to remake parts. (the process is also likely to be littered with many choice naughty words).

Woodpeckers 600mm T Square

The easiest way to check your squares for accuracy is to take a piece of flat hardboard (I use the flat white 3mm stuff that kitchen installers use). Plane one edge true, either by hand or on your jointer. Place your square with the short thick part (the Stock) registering on your planed edge. Now scribe a line with a sharp marking knife along the long edge (the Arm) of the square. Next, flip the square over so that the stock is on the opposite side. Move the square inwards so that the arm is about 1mm away from the initial scribe line. Repeat the scribe line. You will easily be able to see any error in parallelism between the two lines, due to the compounding effect of any error.

If the square appears out of true, don't use it for important and accurate work. For laying and marking out rough cross cuts, it will still be fine, but definitely do not use that Try Square for anything that requires accuracy.

Interestingly, all squares that are manufactured in Britain must conform to British Standard.

Under this standard, Try Squares are permitted a tolerance of only 0.01 mm per 1 cm of steel blade under BRITISH STANDARD 3322 - i.e. no more than 0.3 mm on a 305 mm try square. The measurements given relate to the inside edge of the steel blade.  

There is no international standard specifically for woodworking Try Squares that I know of, but you should observe a very logical rule here: The accuracy usually varies with the amount that you are willing to pay for your Try Square.

Brass & Ebony Try Square dated 1840

In my opinion, Crown Tools (made in Britain) offer the best inexpensive Try Squares, Mitre Squares & Dovetail Squares, if you are starting out. I base this evaluation entirely on the Crown Squares that I own, some for over 20 years. 

The cheapest Engineer's Squares of decent quality and accuracy in South Africa are made by Groz. 

For a great Setup Square for your table saw blade, jointer fence and other machines, Veritas Tools from Canada make an excellent, absolutely true Setup Square specifically for the purpose.

Above is the excellent, value for money Veritas Blade Gauge

In closing, the general advice based on my own experience and many mistakes remains steadfast:

• Buy well and buy once.
• Single part CNC milled squares remain accurate and reliable.
• Proper care and maintenance is paramount, as with any tool.
• Test your squares before you start a new build, it only takes a few minutes and will save you hours of frustration and wasted timber.

Next week on my Hand Tools Blog, I hope to delve into the nitty gritty of marking gauges.

Until then, let's make shavings, not dust.