Woodworker's Journal 2004-28-6, страница 18

Ian's Must-have Measuring Tools

By Ian Kirby

The range and variety of measuring tools has exploded since the days of wooden, shop-made versions. The author simplifies your choices by dividing them into four categories and assessing their pros and cons.

The walls of one shop in which I worked were covered in sayings. One of them declared, "If it looks right — it is right." Another goes back to my early days in an English chairmaking shop where they measured things by "a skeg of the eee." Especially on Chippendale style chairs, if you measured carefully, the left and right sides are not exactly alike — same as your face. But if it looked (skeg) right to the eye (eee), then it was complete. Nevertheless, we make things with the aid of measuring tools, but then again, they all rely on the "eee" to determine right or wrong!

As woodworkers we need to be able to measure four things:

• alignment — straightness

• planar accuracy — twist

• angular accuracy — angles

• linear dimension — length

Of the tools we use for our measurements, only the dimension

measures are calibrated so that we can say the measurement is too small or too large and by how much. 'Hie rest tell us right or wrong but not by how much. In other words, we rely on our eyes to gauge a given measurement. For instance, if you want to check that an edge is square to a face, you plant a try square on the face of the board and look to see if light is showing through between the edge and the tool. In real terms, that's a lot of leaps of faith:

• is the try square actually square?

• is the face on which you put the stock of the square flat?

• are you holding the square in contact with the face of the board?

• could you actually detect an inaccuracy of a degree or so? Valid questions all, but how much

does it matter? The answer lies in what you are making.

What Are You Making?

If it's an Adirondack chair nailed together from scrap softwood, as the originals were, you are likely applying a different set of standards than if your goal is a chest of drawers in quartersawn oak. 'Hie absence of square edges on the boards of the chair will make little difference to the final outcome. Unsquare edges on the parts of a chest of drawers could be of consequence since unsquare edges are a prelude to inaccurate joints. In any case, it's your decision in the end, and it's your assessment of what is square.

To gauge the planar accuracy of a piece of stock ... to see if it is twisted, the author uses winding strips. Winding strips are simple, eiegant and dead accurate.