Musings on combination squares and quality

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I had never seen a combination square before we built our house. One of the tradesmen who was helping us had one and I was smitten by it. Not long after in 2009 I popped down to our local hardware shop and bought an Empire 400 mm combination square for about $40, and I felt like a king (partly because it felt like a king’s ransom at the time, being a skint owner builder).

My Empire 400 mm combination square. (Before your OCD runs over and you criticise my having the ruler mounted upside down, we’ll get to that later.)

This square has left its marks on a house, shed, office, fence and a myriad of bits and bobs around our property. It has even lent it’s hand to some finer woodworking.

When I was a Cub Scout and we were learning orienteering at a jamboree I still remember the day our leader pointed to the other end of a field and explained that a bearing error of only a couple of degrees at the start would put us way off the mark at the far tree line where a trail head could be found concealed behind some bushes.

It was this principle that first caused me to realise that there was something amiss with my cherished square when working on my Plain Plane box. In contrast to my other pieces, at 190 mm tall the side panels were far wider than anything else I’d done, plus employing dovetails meant layout errors were very apparent.

Now I know my square was square when I bought it, as I was advised to, and did test with the score-flip-score method. A subsequent thorough examination of the square identified a couple of issues.

Firstly the head material is soft. As in look-at-it-with-piercing-eyes-and-it-will-deform soft. Seriously though, moderate pressure with the awl will leave a deep scratch. I suspect it is cast aluminium (it’s not magnetic either which lends weight to this suspicion). I’m not too concerned with scratch burs and dent crater walls developing with use as these may be removed with a file to restore flatness to the faces. Where the real problem lies in my view is with the raised sliders that are the reference face for the ruler. To show that I’m talking about, they’re really obvious on my 100 mm iGaging double square.

The problem with the Empire square as I see it is that over time the the steel ruler simply wears the sliders down. Here is the Empire’s head, with almost no reference face left. Any wear of those faces will affect accuracy. This is compounded by the fact that the ruler isn’t hardened, so the edges don’t stay smooth for long, which accelerates the wear.

The second issue is that the two edges of the ruler are not parallel. You may recall that the photo at the top of this post has the ruler upside-down (based on the name print). That’s simply because in this orientation it is less out of square than in the other orientation. Inspecting it up against a known straight edge is enlightening!

What you can’t see in the image is that not only is the ruler bowed, but the edge isn’t uniform. There are numerous dips and hollows that have developed over the years.

A new square

With the realisation that my square wasn’t square, and the frustration that comes from not being able to trust your layout, I thought the time had come to buy a higher quality combination square. The price of a Starrett horrified me, at nearly seven times the price of the Empire. Popular opinion by those who use and rely on their squares for their day jobs year after year however is near unanimous; Starrett is accurate and should remain so for your working life. Despite scouring the second hand market for a couple of months, nothing showed up, so finally swallowed the lump in my throat, bit the bullet and bought a new one.

It has now been five or so months and numerous projects later and I am smitten and in hindsight have no regrets spending the money. Why? Because I have a square that I trust both now, and by reputation, into the future. And I guess in the end that’s what it comes down to with measurement tools.


I frequently see online comments where someone bought a cheep square and declared that spending any more would be a waste because the score-flip-score showed the square to be square. I think this misses the point though. I wonder if accuracy of a tool is less about its performance out of the box, and more about its ability to remain so. I learned this the hard way. Not financially, but in wasted time and frequent frustration through layouts that simply wouldn’t line up.

Having said all of that, I still use the Empire when doing carpentry type work where it is accurate enough for the task at hand, or I don’t want to risk damaging my Starrett. If it broke or got lost, I would buy another one for just these tasks. But when working on fine joinery, the Empire is left to hang on a hook next to my claw hammer, and my Starrett is gently removed from its place in my measuring and marking drawer and put to the task.

My Starrett, lovingly stored out of harms way.


March 2020

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