May 03 2008

The Challenges to Squareness

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.

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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 »

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Apr 29 2008

The Constructs of Squareness

Published by under Layout Strategy,Metrology

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.

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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 »

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Apr 22 2008

Edge Tool Sharpness and Flatness, The Fast Track.

…Or: How I Learned to Stop Worrying and Love the Honing. 😀

Ok, this is a little longish, but there is no substantial way to provide a sharpening primer in a sound bite. I’ve tried to write about what will work well overall, without getting too focused on too many particulars in any sharpening media. No matter which way you choose to go ahead with sharpening, this advice should be helpful to you overall. It’s a reasonable primer that will put you on the road with usable sharpening skills. So grab a snack and a drink, and settle in for a bit. If you really want to learn to sharpen, reading this will likely be worth your time. Your Questions and Comments are invited as always!

When it comes to sharpening, abrasives are abrasives the world around. They may have particular idiosyncrasies you need to pay attention to, but they all abrade metal. Once you choose the abrasives you feel will work best for you, you will establish your own routine for working with them. All paths are means that will lead to a similar end. Waterstones, oilstones, ceramics, particulates, sandpaper, various styles of machine sharpening etc. The steel does not care; the abrasives don’t care either, as long as the grit equivilents of abrasiveness are appropriate to the goal. Sharpness.

For the sake of this discussion, I am referring to the abrasive grits, as they correspond to the grits common to waterstones. I do this simply for the reason that waterstones are very popular, but I am in no way advocating that waterstones are the best abrasive. Most all abrasives will sharpen, and it is up to the end user to investigate the pros and cons of the various abrasives to determine the best paths for themselves. For cross-reference please refer to this cross reference chart to derive the equivilent grit for the media you choose.

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It is important to keep in mind that the goal of sharpness has stages.

Coarse grits are for grinding, heavy material removal, bevel forming, flattening. Initial flattening and bevel angle forming are the biggest jobs and to aid getting the job over with, the coarsest grits should be used to get the bulk of these tasks done.

Fine grits are for honing and polishing. Once you have established bevels and flatness on the backs, you will want to polish it. Removing coarse scratches in steel with finer ones is what creates finer sharpness. Sharpness actually is where the intersection of the two planes formed by the bevel and the back meet. The finer they are polished, the sharper they will be. the act of creating the wire or feather edge happens when the bevel side of the iron or blade is abraded until the dullness has been honed away. This is required to establish a fresh edge on the tool, and can be done with any number of the different honing or grinding grits.

It is up to the sharpener to determine how dull the tool is, and select the coarseness or fineness of abrasive grit needed to restore the edge to sharpness the fastest way. This means, it comes down to how much steel needs to be removed on the bevel side to form the wire, or feather. You must determine the condition of the edge, and the fastest way to restore it. If only a lttle honing is needed to restore the edge, don’t select coarse abrasives when you begin. If a lot of honing is needed, don’t select fine abrasives when you begin, but realize you will have to polish all the way up through the grits to the fine abrasives to restore the sharpness.

It is important to get a feel for the finish your honing equipment will give you as a finish result at each stage of the work. It will aid you to learn to evaluate what is needed, where to start, how long to hone, and when you have reached what was needed. Knowing this simplifies the task and helps you save time. This is experiential– it is learned by using the sharpening tools you have on your edge tools. It is getting to know one another. Call it sharpening intimacy if you will. Continue Reading »

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Apr 13 2008

Improve your Sharpening with a Portable Sharpening Station

Lets face it, sharpening can be a big undertaking. Many edge tools we bring in our shops will benefit from having a flattened back and the optimum bevel angle for the task it is meant to do. Streamlining the process is possible, and most of that comes from organizing the honing gear so it can work the best with your applications.

Sure, That is a very large amount of application options. There are variables such as steel types. Cast steel, hand forged, high carbon, O1, A2, and D2. There are sharpening options. You have scary sharp, water stones, oilstones, and diamond stones amongst your choices for abrasives. There are a number of different sharpening methodologies, various jigs, freehand, even machines.

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I use a portable sharpening station designed for use with stones, with both jigs and freehand manner. This helps facilitate the process, contain the mess, protect other shop furniture from damage and helps keep the honing tools organized. It can be used in a couple configurations, and can be moved out of the way when necessary. It is simply stored when not in use. Continue Reading »

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Apr 06 2008

The Utility of the Straightedge

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.

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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 »

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Apr 02 2008

The Woodworks Library

Amongst the many dilemmas facing the woodworker, just a few are what to build and how to build it, but even as those questions seem like early ones in the process, the earlier ones considered are even more elementary.

The nature and ways of wood, joinery, adhesives, and style are all things that need to be dealt with in the “what” to build and “how” to build it. Is it furniture, casework, cabinetry? Will it involve carpentry, as a built in as many elements of Arts and Crafts styling will? will it include some metal work or upholstery? Other leading questions like, will I have the appropriate tools, and can I properly fixture the work for all the different elements of construction? What finishes are most appropriate, and how best to apply them?

You see, it is a lot of questions. Fortunately there are a lot of answers. The art and craft of woodworking is age old, in fact, even our great grandparents and grandparents knew a lot about it, and lucky for us, even as much of an undertaking it was to publish books back in the day, the understandings of the woodworking trades, the methods and the how to with hand and power tools was something they authors of that period wrote about quite articulately. There was a want for future generations to know these things, and there was a lot they understood. Continue Reading »

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Mar 31 2008

Understanding Fractions, The Key to High Accuracy When Measuring.

Published by under Metrology,Skill Development

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.

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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 »

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Mar 24 2008

John Barleycorn Must Die. The History of Modern Measurement.

Published by under Metrology,Thoughts & Musings

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.

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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 »

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Mar 23 2008

Using Cross Dowels for Knockdown Joinery

The big thing about using steel cross dowels for knock down construction is that your layout must be absolutely meticulous. I have, and continue to use these a lot in jig construction, but there are a lot of other great applications. cross_dowels.jpg

While a lot can be done with these, a common application is for use in workbench base construction. Real life happens. People move, circumstances change. Sometimes the dream shop in the basement relocates to a garage or an outbuilding. Many of us cannot build a bench with the certainty of knowing it will never need to be easily transported to elsewhere at some future point. This makes the use of steel or brass cross dowels a wonderful option. Continue Reading »

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Mar 18 2008

Metrology, The study of accurate measurement.

Published by under Design,Metrology,Skill Development

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.

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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 »

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