Aug
19
2008
For the average user of a retractable tape, there can be some usages of a tape measure that unwittingly reduce its accuracy. Basically, many people are not even aware of these details. I did say usages, but there are also problems inherent with the way a tape measure is made, that for fine work, render it a tool which is not always the best tool for the job. When we ask a tool to wear too many hats, it fails to do as well by us as we may think it should. It is good to know what some of the weaknesses are so we can learn to accept what are and are not good practices for the tape measure.
When you are buying a tape measure, there are several available features that you can consider. For shop use, furniture making and cabinet making, you will rarely need a long tape, but the long tapes have features that enhance accuracy. They come with 1-inch wide tapes, which are easier to read for eye relief, harder to distort and are more rigid. Often the 1-inch tapes include more rivets on the hook, which lend themselves to resistance to wear and stretch. Unless you need a shorter tape for handy reasons, I recommend the bigger tape just for its added stability. Continue Reading »
May
03
2008
Yup. The Challenges to Squareness.
You didn’t actually think this was going to be easy did you? Well, it isn’t always, but I think the endeavor of overcoming some of these challenges can make things better, especially if you like taking good to great. Knowing what some of the issues can be, and how to overcome them when and if they arise, can help our results better match our desires.
We learned in The Constructs of Squareness article that geometrically speaking, a right angle is 90 degrees, and if it isn’t 90, then it isn’t a right angle. Everything can be represented perfectly on paper, in CAD drawings and in theory, but in building, milling, and manufacturing there are a number of factors, which can affect the quality of accuracy. Some we have to accept, some we can learn to work with, and knowing the difference is how we approach closer to fine, if fine is the goal.
Things that affect the accuracy we use to build do vary. Goals, philosophy, materials and tooling all play a part.
Goals affecting accuracy are often production oriented, cost oriented, or what the intended use of a final product is. If the Goal is to build a doghouse, it needs done quickly, and the price of materials and labor needs kept low, then, the accuracy of squareness need only be relative. If the goal is to make a jewelry box, where scale is small and appearances will be highly scrutinized, then the accuracy of squareness becomes much more important, because the philosophy behind jewelry boxes is seeing how far craftsmanship can be taken. Close tolerance fit and finish is a very large part of how this type of work will be evaluated. Continue Reading »
Apr
29
2008
The prevalence of the right angle in engineered structure is probably second only to the straight line in order of importance. Engineered structures in wood are often using plane geometry to help describe and document what they are and how to build them.
Much of the way we think about civil engineering, architecture, woodworking, and even some metalworking, call it flat work if you like, is based on previously understood, maybe even taken for granted, notions about geometry.
Every line that goes in a given direction without variance to that direction is straight, all points that lie upon a line, line segment, or ray can be thought of as congruent. At any point on a line, another line, line segment or ray can intersect, begin sharing a common end point, and create an angle.
There are four ways we look at angles… The most basic angle is the right angle, the angle of 90 degrees, which when measured, corresponds to a quarter of the 360 degrees in a circle, or some thing other than a circle that circuitously begins and ends at the same point. The other ways we describe angles are of angles smaller than 90 degrees which are “acute” and angles larger than 90 yet smaller than 180 degrees, which we call obtuse. If the angle is greater than 180 and less than 360 degrees we call it a reflex angle. When working in terms of squareness, we are only concerned with the 90 degree, or right angle. Continue Reading »
Apr
06
2008
Precision refers to the amount of dimensional accuracy or incremental refinement used when something is made, and can be attributed to the quality of the layout, workmanship, or machine set up.
Accuracy refers to the confirmation of dimensional tolerances.
Dimensional tolerances differ with the various types of projects a woodworker will commonly undertake. The set up of shop machines and precision hand tools often requires the precision of accuracy to be at the thousandth of an inch level, however most woodworking projects require accuracy at a level which is commonly referred to by fractions, and is often referred to in the 1/32nd (.031) to 1/64th (.016) range.
The quality in our craftsmanship is inherent in our understanding of these constructs, and our personal stake in setting for ourselves, a level of tolerances. These tolerances are the differences between woodworking, and fine woodworking. Continue Reading »
Mar
31
2008
I want to have that little talk with you about, Fractions. Yeah. But the plan is, if all goes well, that it won’t hurt – as much as it did last time. Working in sub inch territory usually involves the use of little buggers. The problem many people have when working with fractions, is that they relate the use of the common fraction to their math education experience when they were in school as children.
Our school systems scared the bejeezus out of everyone by forcing us all to learn a series of mathematical exercises, which evolved around fractions that we would never use again in our entire lifetimes. For many, this often created mental blocks to the entire notion of fractions, even the simple useful ones, because after that harrowing experience, it seemed that nothing pleasant could possibly come from the manipulation of fractions at all. In fact, when people are faced with dealing with fractions, they generally feel some panic along with it. A panic that rates up there with the sound of high speed dental drills and root canals, and it is most likely from their harrowing experience in math class. Folks remember what all the wonky practice of solving mismatched fractions was really like, and relate that it was way, way too similar, and maybe even the diabolical preparation, for diagramming English sentences later on during their high school education.
I hope I can help make this a lot more user friendly! Continue Reading »
Mar
24
2008
The way measurement is handled in the United States, and to some degree the UK and Canada, depending on the person’s age, is the foot. The foot has an interesting history, and there are a couple different accounts you can go with, but it has its beginnings in the Roman Empire.
Before the world was very big and there was not so much need to measure great distances, measurements were based on what a man had, er, handy! Sure there was mans foot, which is the foot’s namesake, but it didn’t keep a consistent length, so three hands, four palms and twelve thumbs worked better to more consistently derive it. So the Foot became the distance of 12 thumbs, and the width of the thumb became the inch. Welcome to base 12 measurement. Continue Reading »
Mar
18
2008
Metrology is defined as the science of measurement. More particularly for the woodworker or the home shop machinist/toolmaker, one of the divisions of metrology, which is of particular interest, is applied or industrial metrology. This is about the application of measurement, the suitability of measuring instruments, their calibration, and the quality of the measurements they produce.
So the accurate instrument is applied to create a needed measurement. The quality of the measurements becomes the layout that evolves into successful production. The gist of it is that the woodworker is trying to produce a thing, and the thing is often rendered from a drawing and plans which include materials and cut list. The go between that takes the project off the prints and puts it on the materials being used are the tools of metrology. The measurement and layout tools. Continue Reading »
Mar
15
2008
Layout work is a tedious and exacting part of woodworking. We select boards for size and grain orientation. We hope this is in part, the “art” of our work that separates our project from that which is good, to that of greatness.
We sharpen our tools and skills, we buy accurate measuring and marking tools all with the hope of accurately conveying our vision. We go to work and accurately lay out the work, checking, and double-checking everything as we go to assure we have everything right. Continue Reading »
