No excuse for wrong measurements

Measurements can make or break your woodworking project.

Digital calipers give exact readings in three different measurements

Measurements can make or break your woodworking project. Not only must your measurement be accurate, if you are making multiple parts, it must be repeatable with the same accuracy.

The most familiar measuring tool is the tape measure. There are many different types and some are decidedly better than others. My favourite is an Irwin 25-foot-by-1-inch that has black writing on a white background, but what sets this tape apart is that the graduations are on both sides of the tape. I find it all but impossible to get an acceptable degree of accuracy with a tape measure that has both metric and imperial graduations on the same tape; half the time, the wrong scale is against the workpiece.

When working in the shop I use digital measuring almost exclusively and I leave my tape measure to the lumber room where I use it to select rough boards.

Like everything else in life, electronics have revolutionized the way we do things. Digital measuring makes it possible to measure parts down to a resolution of 1/1000 of an inch but woodworkers have been slow to adopt these precision measuring tools.

However, with new woodworking jigs and tools promising accuracy in the range of thousands of an inch and the advent of inexpensive, easy to use electronic tools, it only makes sense to step up your game with more accurate measurements.

A good quality electronic caliper can be one of the best investments you can make. This multifunction tool can make inside measurements, outside measurements and depth measurements. It really shines when used to lay out your joinery and do your machine setups; the days of guesstimating will be over.

Digital calipers will display the values in three different formats, fractional inches, decimal inches and mm.

Using the calipers for most woodworking tasks is simple and straightforward since adding and subtracting whole numbers is easier than working with fractions. This is especially true when you dress your own lumber to non-standard thicknesses and are then adding and subtracting the measurements.

When woodworking, the natural tendency is to think of fractional values when using inches but the change from fractions to decimals is an easy one to make.

Most quality digital calipers are made of hardened stainless steel for long-term accuracy. It stands to reason that as the price goes up, the quality of the tool increases as well, and with calipers holds true. My six-inch King caliper cost a fraction of what my eight-inch Mitutoyo did.

The caliper can be used for simple comparisons as well, even without the display. If you mill your own lumber using a thickness planer and need to match the specific thickness of some existing part, then just measure the part and use the caliper as a simple ‘go/no-go’ gauge or transfer the measurements directly to your thickness planer.

Wixey makes a digital retrofit kit that will adapt to most thickness planers.

Machine setup and adjustment is a breeze with the right digital tools. Measuring and marking your pieces accurately is only half the battle; you still have to set up your tools to make the cut. There are several tools I use all the time to achieve this level of accuracy.

When using a variable spacing dovetail jig, like the Leigh D4r or the Super Jig, a caliper makes symmetrical and custom spacing of the pins and tails a breeze. Using the caliper to set the cutter projection makes it unnecessary to rout test pieces to check the fit.

The router table is one of the most used tools in my shop and a digital height gauge makes setting  the depth of cut to an accuracy of 1/1000th of an inch possible. I have my main router mounted in a bench dog lift which allows me to accurately adjust it to any setting I choose with these measuring tools.

My other two router tables rely on the adjustment mechanisms that are incorporated in the base of the router and while these are not as fine, using these tools is still more precise than any other method.

If you use plywood then you will be aware that plywood is never as thick as they indicate. For example, when using ¼-inch plywood for door panels you will have to cut an undersized groove or it will rattle in the groove left by a ¼-inch cutter. To achieve a tight fit, measure the thickness of the plywood with the calipers and then make two passes with an undersized cutter for an exact fit.

Distance is just one item that you can now measure digitally. Another measurement that will affect the accuracy of your work is measuring and setting angles. If you have not set up your jointer fence to be 90 degrees to the table then your material will never be square.

Using a digital angle gauge to set the jointer fence will allow you to dial into the accuracy to 1/10th of a degree. This is far more accurate than you could achieve with an engineers square and a flashlight. Using an engineers square limits you to only setting the fence to 90 degrees while the digital angle gauge will allow any measurement between 0 and 90 degrees with a resolution of 1/10th of a degree.

If you have to measure an angle, my tool of choice is the Digital Protractor. Fit it to any existing angle and it will display it down to 1/10th of a degree. Setting your jointer fence to this angle is then very easy using the digital angle gauge.

Using the new digital tools when measuring and laying out your joinery will bring a new level of accuracy and precision to your work. Instead of complicating the process it will actually simplify and speed up your work.

When using these tools to lay out your joinery, I recommend using a Veritas striking knife rather than a pencil as the line left by the pencil is simply too wide to be accurate.

 

Michael Kampen runs the CNC shop and is the resident woodworker at Westcoast Home Hardware.