Your accuracy will be a function of the tools you use, and how well you use them. Two of the most popular measurement tools are the tape measure and the straight ruler.
Essentially there are two kinds of tape measures – carpenters’ tapes and woodworkers’ tapes. A 25 foot carpenters’ tape with a 1 inch wide blade and a durable belt clip is just what you need when framing that addition to your house. These tapes need super sturdy cases and stiff blades that will withstand the rigors of a construction site. The scales are usually clearly laid out and easy to read, though the blades tend to be heavily bowed (which makes the blades much stiffer). While tapes are available with both imperial and metric scales, those with just one scale printed across the entire width of the blade are easier to use and read, particularly in less than ideal lighting. The Irwin Straight Line tapes have the scale printed on both sides of the tape, a very handy feature, while Stanley’s Fat Max Extreme have a 13 foot stand-out with a 1 1/8 inch wide blade. In the woodworking shop a carpenters’ tape comes in handy for quick measuring of rough lumber prior to milling, or for laying out the cut lines on sheet stock.
A carpenters’ tape is, however, much too bulky to use for precise measurements on most woodworking projects, and it’s darn heavy to carry around in your apron pocket all day. When making cabinets and furniture, it is very unlikely you’ll be called upon to measure parts longer than 10 feet. You’ll also find it much more convenient to be able to press the blade almost flat on the piece you are measuring. A tape with a shorter and flatter blade is far more appropriate to the task. Shorter tapes have narrower blades and this translates into a light compact package that you can carry in your apron all day without discomfort. Woodworkers’ tapes are also available with tapes that read from right to left making it easier for right handed people to hold the tape in their left hand while accurately marking the length with a pencil in the right hand.
For a tape measure to be accurate in use, it must have a hook on the end that automatically adjusts for inside and outside measurements. This is accomplished by anchoring the hook to the tape using rivets in a hole that has been elongated enough to compensate for the thickness of the hook. Do not let a tape retract completely into the housing at full speed, this will stress these holes and the tape will lose its accuracy. To check for hook accuracy, cut a piece of wood around 10″ long, hook the tape over the edge of the board, and note the exact length. Then place the board on your table saw against the rip fence and butt the tape hook against the fence. Measure the board again – it should be the same as your initial measurement. If it isn’t, time for a new tape.
In our shop, tape measures are only used for pieces longer than three feet and for laying out rough stock. For everything else the ruler is king. They are available in various lengths and configurations, and in stainless steel, aluminum, plastic and wood. We prefer stainless steel for durability. They also tend to be a bit thicker with sharper edges, which means they do double duty as small straight edges. You can run a marking knife along the edge without fear of damaging a steel ruler.
When choosing a ruler, avoid any that have the graduations printed on them; these will wear off in time and the graduations are too wide to be truly accurate. Instead, select one that has the graduations laser engraved or etched. These allow for much more precise marking and are also easier to read.
When using a ruler, it is always best to use one that is just long enough to measure your item. Trying to measure something five inches long with a 24″ long ruler is awkward. While you are concentrating on the short end of the ruler, the other end can easily dent and ding other parts, resulting in damage you will have to repair. We have found that a set of four rulers, 6″, 12″, 18″ and 24″, will cover the majority of your shop measuring needs.
Woodworkers’ rulers, also known as 4R rulers, have four scales marked on them. On one side they are graduated in 1/8″ and 1/16″ increments, and the other side in 1/32″ and 1/64″. Hook rulers have a single or double hook on one end of the blade, and are used when the piece you are measuring has a profiled edge. Sliding the hook into place allows you to reference the edge of a board accurately and transfer a measurement to the surface of the piece.
To find the center of a piece easily, use one of the specialty rulers made for the purpose. These come in one of two types. One type has a zero mark in the center with graduations increasing outwards to either edge. To find the center, lay the ruler on the piece so the same number falls on the edge on both ends and mark the center at the ‘0’ point. The other style has a regular scale on one edge that is used to measure the piece normally. The other edge of the ruler is printed at half scale and you simply need to locate the first measurement on the other side to mark the center.
A new type of ruler, made by Incra, incorporates a series of 1/32″ perforations along the face of the ruler. Insert the tip of a .5 mm mechanical pencil to make precise measurements. These rulers come in a straight and a corner format.
Folding wooden rulers, usually in six foot or eight foot lengths, have been around for a long time, but we’ve never found them to be as convenient or accurate as a steel straight ruler – but they sure look good on a workbench.
Everything you build starts with a measurement. Invest in a good set of rulers and take care of them, they will be a pleasure to use and serve you well for many years.
Over time, as furniture design has evolved, objects whose dimensions follow the 1:1.618 relationship (the Golden Ratio) between the length and width of a piece have been found to be most pleasing to the human eye. This ratio can be applied to portions of a project such as the arrangement and sizing of doors and drawers as well as to the overall project itself. Designing a project using these ratios usually involves determining the length of one side and then calculating the length of the other using the ratio. To avoid the need to use any math, Lee Valley has introduced a set of Phi Rulers ranging in length from 6″ to 24″. These two-sided rulers have scales printed on both sides. Use one side if you know the length of the short side and the other if you have a known long side. Using the ruler is simplicity itself. It functions very much like a center finding ruler; use the ruler to measure the known length using the full size scale and then find that measurement on the adjusted scale on the opposite edge of the ruler to mark the length at the correct ratio. A set of these rulers will quickly allow you to explore various design options based on the Golden Ratio. They also function as handy general purpose rulers.
If you’ve ever tried to use a tape measure to check the diagonals of a cabinet during assembly you will realize how hard it can be to get into and around corners accurately, and above all, repeatedly. The new Lee Valley Tape Tip is an ingenious little device that solves this problem. It is a plastic tip fitted with grooves and magnets that attaches to the hook on a tape measure and provides you with a pointed tip that easily fits into a tight corner. On the underside is another set of notches for measuring inside and outside diagonals. The tip is reversible as well and in this position it provides a notch that centers a pencil point 1″ from the end of the tape allowing it to be used to draw lines. An integrated screw hole in the tip also allows it to be used as the center point with a tape measure to draw arcs or complete circles.
A fence can improve the utility of a tool dramatically. The Veritas Ruler Stop is a fence that fits steel rulers from 7/8″ to 1 1/8″ wide and up to .05″ thick. It converts the ruler into a handy marking gauge allowing it to be used as an accurate, repeatable layout tool. We find it to be almost indispensible in the shop.