The humble rule is one of those workshop tools most of us take for granted and I’m no exception.
For many years I’ve used and abused a pair of rather good Rabone Chesterman stainless steel rules but over the course of a few decades the fair wear and tear of workshop use has sadly taken its toll. The edges are now slightly dinged and dented, and both have taken on a patina of fine scratches, notwithstanding that the corners aren’t quite as pristine as they used to be, mainly as they were used as a lever a few times to lift off the lid from the odd tin of varnish.
That said, the rules in the ‘shop have been replaced with a few of the new Axminster Precision range that have been recently introduced. Each is made from Japanese rust resistant stainless steel, finished with an anti-glare, satin chrome finish. My old RC rules had no such finish and as such were quite awkward to read under bright lighting conditions, so that’s a definite advantage.
Each Precision rule is chemically photo-etched and the markings, including the easy-to-read font, are filled with a tough, black pigment and most are supplied with a convenient hanging hole at one end, the exception being the two hook rules.
My old RC rules are accurate to BS 4372 and a couple of extracts from that standard mention that:
‘Maximum permitted departure from nominal for the distance between any two graduation lines on a single scale up to and including 300mm: 0.1mm. Maximum permitted departure from nominal for the position of the 10mm graduation line from its flat end datum: 0.08mm.’
Axminster Precision rules conform to EEC Class 1 Standard (also used for some of our new tape measures) which state that over a 2m length there should be a tolerance of ±0.3mm. If my sums are correct, which is always questionable, they’re accurate to ±0.05mm over 300mm.
Looking at standards is confusing at the best of times, but EEC Class 1 accuracy is without doubt excellent for all normal workshop measuring activities. Comparing my old 300mm CR rule against the Precision Hook Rule it can be seen that for all practical purposes, there’s no discernible difference between the two.
For any users who want to know the precise accuracy of their own new Precision rule, the top of the range Signature rules provide the answer. Each individual rule is accompanied by its own unique calibration certificate, carried out under laboratory conditions at a temperature of 20°C ±2°C. On my particular rule, the top side 0-300mm measurement is actually 300.120mm, an error of 0.04%.
Two unique rules already discussed are the new Hook Rules where an adjustable stainless steel hook is provided at one end. Measuring accurately from an edge is usually always a fraught experience as there’s a distinct possibility of error because it’s difficult to line up both the end of the rule and the edge of the material. It can be done by using a square, but that means you need to use two tools instead of one which is a bit of a faff; the hook rule circumvents that quite neatly.
Two other unusual rules that are well worth having are the Centre Finding Rules. Sometimes it’s very useful to be able to work outwards from the centre point on a board as you’ll be able to see from the picture. It shows the current job in the ‘shop which is a large chest of drawers in oak and English walnut for my wife. The drawers have been fitted and the centre line (arrowed) has been drawn down the middle of each. If I were to decide to fit a pair of handles to each drawer, the Centre Finding Rule could be used to mark the position of a pair of lines, one on each side.
Although not strictly a rule, the last Precision tool to mention is the new D head protractor. Having used a much inferior version last year, this new protractor is simply light years ahead and if you need a protractor, this is unquestionably the one to buy. The only thing missing is a hanging hole in the end but that’s the work of a moment with a sharp twist bit and pillar drill.