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.

Philosophy does not always have to do with goals, but is often a party to goal-oriented work. All craftspeople over time develop an inner guide regarding the level of accuracy and craftsmanship that are acceptable for their work. Sometimes it is based on the kinds of work they most enjoy, the styles they work in, the level of patience and time they have to give towards their efforts, and if they are working to requirements which are or are not their own.

Materials are often a factor. Consider many different materials, and the methods that render them into a finished product. Casting, molding, rolling, extruding, machining cutting, grinding, all leave behind a surface quality which can affect accuracy, the very accuracy that may be needed to reach a goal. The layout work for a piece of rolled or ground steel may have a smooth surface and take place on a granite surface plate. This smoothness of the surface qualities are enhancements to accuracy.

Wood smoothness is variable, and dependent upon the state of milling it is in. Cutting marks on an 8/4 board from the hardwood dealer can easily be in the +/- .005 to .015 range, and some board surfaces can be found that are coarser than that. Saw tooth marks, planing snipe and other machining factors are the norm. It is up to us to render woods smoother with our own processes, and some woods are rendered smooth from machining processes easier than others.

Moisture content can also play a role. Beyond the limits, which the cellular structure of the wood itself inherently provides, the smoothness from our milling often determines how well we can do with the quality of accuracy we can render upon it. We can mark it for squareness anytime we like, but the quality of squareness we get, no matter how good the tool can be degraded or enhanced by the quality of the surface we are working with. This is why it is a good shop practice to sneak up on the final sizing you need as the board is milled to final dimensions, the process can become more accurate as you go.

Tooling can be a factor. Tooling is available in a number of levels of quality, and accuracy. The higher the quality, of course the higher the cost, and the level of accuracy is commonly better, yet it does not mean that lower quality tools can not be found to be, or made to be highly accurate. It should be evaluated case by case. There are budgets to consider but I’d like to advocate that when it comes to layout tools and approaches to Metrology, it never hurts to do the best you can, and buy the best tool you can afford.

Straightness is a factor, which I touched on, in an earlier article, called The Utility of the Straightedge. Too, squareness benefits from this same straightness, and angular precision is also brought into the mix. Consider a Starrett combination square. It is adjustable, blades are interchangeable on it, commonly to 24 inches, but 36 and 48-inch blades are obtainable. At 24-48 inches away from the squares head, one can begin to realize the value of having straight edges, and precision angular accuracy coming from the tool very easily. If a square with this capability were to contain error, imagine how amplified the error would become at three to four feet from the reference edge.

High accuracy in the tooling pays you. Even when wood surface quality is poor, the layout cannot be more accurate by any tool that is not accurate. The surface quality of the wood can be improved though accurate machine setups, various cutting, planing and machining methods to enhance layout accuracy, if the layout tool can “bring it” to begin with. This means finer accuracy from layout tooling is possible if layout is performed after the surface quality of wood is improved.

Certainly the doghouse we talked about earlier will not be rendered higher quality by using a Starrett precision square, but the jewelry box will suffer if the square used to lay it out was not accurate. If you choose to tool up well, then you are free to work at any level, choosing the level of accuracy you desire, and often even verify the quality of other tools you may own, so you can be aware of the quality of layout they offer, and you can account for, compensate, or restrict the tool for use where it is adequate for the work it is called upon to do.

Wood movement is often at issue, as a reason precision accuracy is not necessary, or desirable for woodworking. Most often, the argument stems from not knowing the ways which wood moves more specifically, therefore ruling out wood altogether as a material capable of high accuracy and precision. Yet those who endeavor to understand wood movement achieve very high quality, stable results from wood in as built conditions.

Here are a few notable thoughts regarding wood movement.

Select grain structure is important. If wood stability for a project is desirable, consider that quartersawn woods are more stable than plainsawn, because the board grain does not cross the pith;

Quartersawn wood orients the growth rings radially, that is, at 45 to 90 degrees to the wide surface. Wood movement is along the rings, and rings are kept short by half or greater in quartersawn boards than that of plainsawn, and the movement from moisture content expected from quartersawn is half that of plainsawn.

Plainsawn lumber deals with growth rings from zero to 45 degrees to the flat side of the board, otherwise called tangentially, it does cross the pith, and movement in these boards can be expected to be twice that of quartersawn.

Vertical, clear grain boards will be most predictable. Avoid boards with interlocked grains, variable grains, reaction woods, tension woods, and mineral deposits, as seasonal movement from moisture content in boards like these is not predictable even at equilibrium moisture. If the figure and beauty these woods can offer is desired, it is up to the woodworker to design with this in mind, and build into their project the compensations needed for these factors.

Once EMC, Equilibrium Moisture Content is achieved, and considering the common ranges of humidity for the area of the country, as well as where the wood will reside in regards to climate control or not, and whether the air handling has air conditioning which is capable of dehumidifying are other factors.

The good news is, wood movement in a climate-controlled area, such as indoors, often has very predictable movement in select, uniform grained boards. A great deal of research and observation has been conducted over the last century, dealing with the many species of woods that are used as building materials, and the data is freely available for use to the builder. Please see Wood As an Engineering Material, written by the US Department of Agriculture, Forest Products Laboratory as one of the foremost writings on this subject. There is a copy available in the Woodworks Library.

The details can be accurately worked out. Properly sawn, select lumber is also helpful when future predictability is desirable, and most boards will not shrink more than 0.2% longitudinally from green to kiln dry, so most any angle cut on the end of a board will remain accurate, as originally cut over the service life of the piece, meaning the accuracy of squareness, can be made highly precise, and can be counted on to remain that way.

Learn to familiarize yourself with the various appearances of grain in wood, and know where and when to put it to the best use. While they can be very, very beautiful, boards of any variety containing interlocked grains, variable grains, reaction woods, tension woods, and mineral deposits will not move consistently when the seasonal moisture in these boards swings. Cupping, twist, warp and wind are all plausible factors, which will affect dimensional accuracy in any direction and the best way to deal with this is to bring these boards to EMC and let them move all they want as they acclimatize.

Begin final milling difficult boards by starting a bit bigger than the intended final size. Work your way in, so as to relieve any of the stresses these boards may have, correcting as you go, so that when you have them at the final dimension, and in the realm of the target EMC, you have the best chance of knowing the future outcomes, and then design around the seasonal movement they will still require.

Once the boards have been milled to the flatness, squareness, and dimensions needed, the next step often includes joinery, and adhesives. Joinery inherently enjoys flatness, straightness and squareness as components of it’s fit and finish. The need for close tolerances is relatively high. Glues commonly call for joinery tolerances for squareness and parallelism of .002-.005 inch, for optimum adhesion, and clamping forces will not help you achieve better results from improper milling.

If the factors affecting wood movement and surface smoothness are observed, wood should be able to be worked and milled easily to accuracy approaching .001 inch, and certainly .001-.003 inch, depending on grain smoothness. As previously discussed, not every project will require this precision in every way, and it will be up to the builder to decide what works best for the project. However if the tooling you own cannot bring .001 inch accuracy, cutting tools cannot mill to accurate lines, and the bets for precision are off, whether the project would benefit from fine looking accuracy or not.

…Or: How I Learned to Stop Worrying and Love the Honing. (Dr. Strangelove has nothing on us.)

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.

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.

A little about flattening the back. Many people take this as meaning they must flatten the entire back of a chisel or plane iron to properly complete this step. Nothing could be further from the truth, but you can be happy if you’ve the mind to. Try thinking of how a knife has a bevel on each side of an edge. Remember how we hone both sides to make a knife sharp? We are simply trying to hone both sides of a chisel or plane iron too, but we want to keep the flat side in plane with itself for the most part.

Flattening the back really only means that you only need a planar surface near the location where the bevel is, and the width of flatness on the back, or in other words how far away from the edge on the backside need be no wider than the bevel is, but you are welcome to flatten more of the back if you like, because sometimes it is easier to hold the tool on a wider surface.

Flattening doesn’t have to kill you or be drudgery, just buy a Kanaban plate and some silicon carbide grit or diamond paste and get it over with. There are a number of places that sell those items, so in all fairness to them, please use a search engine for pricing. That is the fast track to flat backs. It is more important for backs to be a planar surface, flat, than it is to have a mirror finish, but the mirror finish is what we often wind up with eventually anyway.

The bevel side too, the bevel’s actual surface, is a narrow flattened plane. It is the intersection of these two planes where the angle forms. The flatness of these two planes are what help them succeed at being very sharp, at the angle point. In fact it is difficult, maybe impossible to achieve a high degree of sharpness if this planar-flat surface isn’t present on each surface that makes up the bevel.

It is geometric, and has to respond to a couple different things all at once to be most effective. Just like you would hone both sides of a knife to restore its edge, It just happens that on edge tools, the back makes up half of the beveled edge. It is the straightness of these two planes which form a line along the intersection of these flattened and honed surfaces, and that makes this edge. It is also often helpful if this honed edge is square to the side of the blade, unless skew (an angle that is not 90 to the edge) is desired.

Guides are useful for grinding specific angles. Please feel free to use them for the heavy work. Honing and polishing are something often done quicker, which is more useful and easy if you can learn to do it free hand. Free handed, the side sharpening method is likely the easiest to learn and use. The steel does not care, the wood does not either. If you cannot do this well enough, please, feel free too use the honing guide.

Remember, forming a wire or feather only means you have ground, honed or polished past the dullness, depending on how long you allowed things to dull. It means you can now stop grinding and start honing and polishing.

Honing up through the finer grits is how we remove the wire edge created by honing past the dullness. If you hone and do not create this wire or feather, then you have not honed past the dullness. The dullness is the wear on the edge that you want to remove. The wire edge is what you want. It is the indicator that you have abraded the steel enough to have ground away the dull parts. Once you have achieved this all the way across the edge, you can then begin working both sides of the bevel with the grits appropriate to the level they are currently polished, alternately, to hone the edge to working fineness.

When honing off the wire, always hone the backs of the tool with the finest grit you have previously honed the back with. It often means alternating stones from the bevel to the back, but why scratch up the back if it is already polished?

If you examine your backs and bevels after honing to a mirror finish and see a glint of light right at the angle point, that is a flaw in your work. It should be a complete surface with no glints of light sparkling at you, especially from the bevel angle point. Glints of light indicate dullness.

In most steels, once you have honed through the grits to the 8000 grit stone, you have honed finely enough to pare end grain pine. End grain pine is the most difficult wood to pare without crushing; it really is the toughest task an edge tool for use in wood will ever see. **(Japanese tools often use finer steels and traditionally were used in softer woods, so there may be some benefit in honing good Japanese steels slightly finer if for use in soft woods)**

There are no recognized tests of, or charts with “scales of sharpness”. The time honored test for sharpness has been and always been; if the edge is sharp enough to do the required work in the material required, to the level of result desired, then sharp was sharp enough. I personally contend that with the wide ranges of tooling, sharpening media, and woods to use them on, this test for the woodworker is still good enough to be true.

The only major corollary to this adage is concerning edge-wear. Can the sharpness last a reasonable quantity of time, so as to bolster productivity? That would depend on the environment. Is it one of production or for that of the hobbiest? Harder tooling is wonderful in a production setting where the sharpening media can match the task of maintaining it, but can the hobby woodworker go toe to toe with the price tag needed to buy in? For most of us, common tooling is just fine, and the results of adequate sharpening as shown in the work have always sufficed, once learning what is needed so as to make results repeatable has been established.

You do not have to shave off your hair! Many people contend hair popping sharpness is an adequate test for sharpness. The truth is, it isn’t. Hair is not wood, and shaving a hair from the surface of skin is is a completely different set of circumstances and dynamics happening, that actually do not require the sharpness required to take a shaving from wood.

The sharpness required for shaving is not as sharp as required for paring wood and as such is not an adequate test for pairing wood. I can shave hair with knives coming off 1000 grit abrasives. Since this is true, what if you can shave hair, should you stop honing well before you are sharp enough to do the work you need to? I was able to accomplish hair popping sharpness with spit on carborundum stones as a young kid, so I am not personally impressed with hair popping sharpness.

For woodworking, shaving hair is the equivalent of a neat card trick. Good for show, not much go. This is a long way from the sharpness we need to push a blade through end grain pine with least effort, so as to pare it. I am saying, we are aiming for and achieving a much higher level of sharpness. If you have sharpened to 8000, you are well past the sharpness needed to shave hair. (Read this as, being able to shave hair can fool you, I hope I have made that clear.)

If you visually examine the edge and see no glints of light reflecting from your edge, and you have polished to the 8000 grit level, no tests are necessary. At 8000 and after a little stropping on leather, the tool is as sharp as you will ever need, I assure you. Honing beyond here is a lot of work spent honing with a diminished work time in wood. In other word, the honing takes longer than the dulling does in this range. You can strop on leather with a little honing compound if you like for a slightly finer edge, which is sometimes temporarily helpful in softwoods. Again, if you feel the need to test, the pine is fine.

Much has been and continues to be written about sharpening, and I encourage you to study this subject, and pay attention to your own realizations as you sharpen. This here is at the heart of what you really need to know. It isn’t rocket surgery. Once you get the heavy work done, (flattening and bevel shaping) it is done forever, and “maintaining” sharpness should generally take no more than 30 strokes on most any stone as you hone up through the grits. This means, If it is taking more that 30, you chose to hone with a stone to fine for the work you need done.

Don’t let your tools get too dull before you touch them up. You can easily maintenance hone as you work. It can take less time to keep your edges in working condition if you become a fastidious maintainer. If you have to rebuild edges every time you sharpen, then you have likely waited too long, and that is a lot more work than 30 strokes of maintainence sharpening.

I need to touch on one last thing here. Bevel angles. Commonly, woodworkers like to bevel their tools so as to be easiest to push through the work. I feel there are some hard fast rules that need to be understood.I am going to touch on a common for instances.

In a nutshell, not all steels are created equal. There are trade-offs we have to learn to live with. Here are a couple.

A-2 like any Steel, has a particular molecular structure. In A-2, the hardening process forms carbide particles in the steel which has a high wear resistance. It will stay sharp longer than that of other steels, but it will require you to sharpen it at usually no less than a 35 degree bevel angle in order to maintain an edge that won’t fail. In other words, If you attempt bevels of 30 degrees or less with A-2, the effect will often result in the edge failing and crumbling. This is due to the very carbides that form to make it wear resistant. It also takes longer to sharpen than High Carbon, or O-1 Steel. As such, this steel is not the best choice for low bevel angles where paring is desired. A-2 is far better lasting where the tooling will be struck with a hammer like in mortising, or for people who prefer a lot of chopping with their bench chisels, or when used to plane in abrasive woods like many tropical hardwoods.

O-1 and high carbon steels are considered finer grained and do not form these carbides in them in the same way A-2 does. As such, these steels are able to hold a shallower bevel angle than A-2 commonly can without edge failure, they sharpen faster, some feel they sharpen finer, and lend themselves well to shallower bevel angles that works well with paring and lighter impact work that is common with many american hardwoods.

in any case, watch your edges. If you find them failing it is usually some combination of the steel type and wood hardness coming to loggerheads with the style of work you are performing and the bevel angles you have. Prepare to adjust the bevel angles accordingly.

My overall sense of this as well as my recommendation to you is this. A-2 Steel really prefers most usually to have a 35 degree bevel ground on it for best outcomes. To go shallower than 35 degrees with your bevels is something you may find works, but please don’t have high expectations. While these angles are not good for paring, they are great for rough service, so mindfully purchase O-1 or high carbon steels for the paring tools. O-1 Is not going to hold a lasting edge is really rough service. Steepening the bevel angles will help, but it still preforms better for finer work. Asking one steel to be all things to the various woodworking tasks is not going to happen. The same is also true of the tooling itself, some things simply find it difficult to interchange. Generally Speaking, Rough service bevels are in the 35 degree range, General purpose bevel angles are in the 30 degree range, and light service or paring bevel angles will be ion the 25 degree range. The steel you have may require slight adjustments, just realize your steels can not be all things to all situations and you will be well serve when reaching for the right tool for the job.

I hope these tips help get you on the path to maintaining your tooling with the least effort possible!

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.

It may not seem relevant, but here is an analogy for higher accuracy. A surveyor will set up an optical instrument, and first, sight their back sight. What they are establishing is a couple of different things, but what is important for us to know for this discussion is that the further away the back sight is from the instrument, the higher the precision of accuracy will be when the surveyor makes other measurements that are shorter than the distance between the instrument and the back sight. The practice is sometimes referred to as going long, and is meant to create higher precision.

One of the common things I have heard over the years, is that in woodwork, a high degree of accuracy is not needed, and then there is the ever ubiquitous, “wood moves anyway”. The understanding being overlooked here is that a lot of assumed accuracy is inherent in the process, because it has been manufactured into the tools we buy, as well as a lot of the lumber we purchase, and we take for granted that it is already “there”. Even wood movement is understood and can be compensated for with relatively high accuracy. None of these assumptions fully get us off the hook.

Consider the ruler. Sure, the ruler has the increments we need, the 1/32nd, and the 1/64th… But we rely on the very same precision accuracy at the fractional level to be consistent to the thousandth of an inch, to assure each of those graduations are where they’re supposed to be. Someone in some lab and factory put all that accuracy into our tools. If we want our precision to maintain 1/64th accuracy, it has to be consistently maintained to 1/64th, plus or minus .001-.002, otherwise the eye will be drawn to errors. After the tool has done its part, the rest is up to us.

Unfortunately, not all levels of woodworking accuracy can be assumed. There are some levels that each of us working the tradecrafts are personally responsible for, and things go better when we are mindful of them.

Take for instance, straightness. The layout of lines is many things, but few things in the layout of lines are required to have the precision of accuracy we have come to expect from straightness. From precision straightness, we can evolve precision flatness, and also use precision straightness as a construct of precision squareness. Parallelism is yet another important derivative of straightness. How straight, straight is, is a pretty important matter. It is always best to start from the best we can do, as it will surely be degraded from there.

Think about the tooling we use to create straightness and flatness. It is inherent in the tooling and machinery. It had to get there somehow. We have to accept that the industrial designers, engineers and machinists did their part, and many woodworkers rely on the good graces of a millwright they never met for a lot of built in accuracy, but there is another part, which they left to us.

One of the more important tools a woodworker can own is a good straightedge. You can have them short or long and there are a number of makers offering them, but if you choose only one, a two-foot straight edge offers a lot of well-rounded utility to the Woodworker. Once you have one, what I want to encourage is; the use of it. Sure they are high accuracy, but it isn’t just for hanging on a peg and looking at.

Straightedges in the woodworking shop have a lot of application. They are available in both steel and aluminum, however they all have more utility if they are made from flat bar stock. Steel straightedges are generally made from stress relieved, 01 steel and are hardened. They are precision milled straight and parallel, and often offer accuracy generally to .001 over the length of the tool. The manufacturer will state the accuracy of their tool, sometimes offering a letter of certification as well. They lay flat on their backs for scribing or drawing lines, and stand on their edges for the comparison of surfaces. They are available with or without beveled edges, and with or without graduations for measurement, but these upgrades are not a necessary requirement, and usually add cost. If you can only afford one, it is better to leave measuring to steel rulers and tape measures.

I find the non-beveled, non-graduated types are less expensive and if it is less specialized, then it usually will offer more utility. Another rational is, that the less it costs the more likely a craftsperson will own it, and if you don’t have one, you can’t put it to good use. There is a lot of good use to be had. Longer than the average ruler and better quality ones are thick enough most generally to stand on edge.

For layout work, the straight edge is a heavy, wide tool, which stays where you put it and has a tall side, which is great for the marking of your work. It is very comfortable for use with any pencil, and it really shines while a marking knife is registered against it. It is an excellent way to connect all the straight lines after you have laid them out. It is also a very nice extension for use with the squares you have and will extend the reach of shorter tools when more reach is needed.

To the hand tool user, the straightedge brings a lot of utility. It can be used to verify the soles of hand planes. After you see where the work needs done, you can then lap the soles to correct the issues and verify as you go. Feel free to verify the flatness of your honing equipment. Flattening the workbench with the use of feeler gauges, a straightedge, and marking is a great use of the tool, because the high spots can be found and removed. The flatness of the workbench is a frame of reference for all future work that comes off it.

Is your board, especially when prepped by hand ready to accept the joinery profiles you intend to put in them? The flatness and trueness of boards is crucial for the fit and finish of dovetails. The plowing of slots and grooves such as dados and sliding dovetails, as well as the treatment provided by hollows and rounds are always made to look a lot better on boards that have been properly evaluated as ready by a straightedge. Handwork is a challenging process; why not evaluate the needed quality before moving to the next part of the process? Besides, the evaluation of a freshly jointed board edge, is just a quick quality assurance check, and a savior before you find an error in mid glue up.

The straightedge is also useful when evaluating the cup, twist, and wind in boards as well as evaluating the flatness of panel surfaces. A pair can even be used as winding sticks. Another good use is for establishing the straightness of the chute edge and fences on a shooting board as well as the overall flatness of its surfaces. While you are at it, evaluate your other shop built jigs from time to time as well.

For machine setups, routine adjustments and maintenance, the straightedge is a great tool. It is invaluable for evaluating the surfaces of the jointer beds for parallel and coplanarity as well as the proper calibration of its vernier settings.

The table saw can be evaluated for table flatness, which is not uncommonly found to be less than perfect yet in some cases correctable. There is also the adjustment of side tables, out feed tables and the trueness of miter slots. It is also valuable to know what the relative flatness and straightness the fence faces have. If there are anomalies, you can then compensate or adjust for them.

Miter saws can use the straightedge for evaluating the trueness of the fence, and are also aided by the straightedge when side wings, when used, are leveled with the main surface of the saw.

A straightedge can also be used for the routine set up of roller stands when used as an in feed or out feed support on any shop machine.

The router table is a high precision shop machine which is commonly shop made. There are many uses for the straightedge with this tool. Evaluation of the tabletop is a constant need with some designs due to the weight the tabletop supports. Many designs are under built and table sag is an error inducing issue. The plates often used to fit the router to the table can be ill fitting in their mortise, and require fine adjustments be made, in order to be brought flush with the table surface.

The router table fence is often in need of straightedge evaluation as well. It needs to be flat and straight, if split, it also has a need for coplanarity. It also must be evaluated to determine if it has any tendency for deflection. The router fence is also a candidate for using a straightedge along with 1-2-3 blocks, gauge blocks and feeler gauges for the settings of the fence and router bit height. With these tools in use, on a well-made table, one can expect fully repeatable accuracy from a router table to be in the .001 range.

The evaluation of any wood, which has been prepared for milling, is important as well. Any cup, twist, warp or wind is something that will throw off the fit and finish of the simplest joinery, and even make edge treatments like bevels, round-overs and more sophisticated profiles look awful. Further, these evaluations can make a lot of difference as to how safe a milling process may be. Knowing ahead of time saves a lot of needless frustration. There are few tools available to the woodworker which can assure things go right, and evaluate why things go wrong, with more power than a straightedge.

If I thought about it, there is probably much more which could be said about such a simple tool, but this is a reasonable well-rounded look at it. It may seem to be a cost prohibitive tool to some, but after thinking outside the box with me awhile, you see it has so much application, and with its evaluatory prowess, how much money could it save you in error free or error caught woodworking, even over the short run? In my shop, it has more than earned its keep and continues to, as I find that wood is costly, even more so than tools. In fact, around my shop, the straight edge offers more value than many other needed tools, and if you can get your mind around that, one will serve you just as well. It can touch so many aspects of your woodworking, that is, if you give it a chance!

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.

With all things old becoming new again with the resurgence of interest in woodworking as well as some of its somewhat forgotten ways, many libraries as well as groups like Project Gutenberg and companies like Google and Microsoft have taken on the mammoth task of digitizing many of these old texts, of which there were few left in access to the public, before father time could claim them. Fortunately many of these books are now available in the public domain and can be used quite freely by anyone as long as their purposes are not commercial.

The daunting thing I have learned is that it is hard to know what all has been digitized to the public domain, and where exactly to find a particular kind of knowledge, because each place has a bunch of books but none of them has all of them. Harder still the books are not categorized for easy access to the woodworker with a need for specific information. My desire was one amongst others I am sure, to help people find and have access to this old but still completely relevant information. By the time I finished hunting (for now) I came up with over 100 books and nearly 1 gigabyte of collected works.

This collection became The Woodworks Library. My criteria for the library was to only have complete books which were fully clear in the United States as existing freely as public domain. The original copyright holder has not renewed their claims and the book is no longer of commercial value to publishers, this means you can have it, I can have it, and as long as we do not use it for commercial use in any way, then the priceless information within is available to help us all be better at the things we hope to achieve.

The Woodworks Library is organized in a somewhat comfortable fashion. I did not bother with over-categorization of it, because many of the books in it cover a wide range of subject matter. After evaluating each book, I placed it in the list according to what seemed to be the biggest theme of the book. You will find that many of the books will cover many of the same things, topically, but once you wade in, you will see that the books were written at different times and or each author came from a different school of thought, and so the cross comparisons of information will be very interesting.

Read with an open mind and remember the era for which they were written as well as the audience the author was writing to. While it is great to feel a certain book speaks to you more than another, there is something in all of the books and the differing methods and understanding are of note, because it affords us all a chance to walk in that author or editor’s shoes. Wood, and the crafts that are supportive to it, are a many faceted knowledge, and you never know when a knowledge you discount or disagree with today may become your saving grace tomorrow. So just do your best and absorb all you can. Trust me, there is a lot to read and many of these authors clearly made sharing it with future generations it their life’s work.

Is there something in here for everyone? Perhaps a little, maybe not. I’ll leave that up to you to decide for you. That which is here, I’ve tried to organize by listing books and writings in categories which were most directly related yet not overly topical, and as a descending list in an order, which mainly attempted to group like with like without being too constraining.

By topic, we have; Understanding Wood, Furniture and Design, Woodworking, Carpentry, Turning, Carving, Finishing, Patternmaking, Shop Mathematics and Calculation, Blueprint Reading, Hand Tools, Machine Tools, Shop Machinery, and finally, Blacksmithing Welding and Metalwork. Remember, There are over 100 full-length books, and the occasional technical paper, just waiting for whomever to have a look and learn something new.

Feel free to bookmark the Library, and remember there is always a link to it directly on every page here at the Woodworks, so help yourself, and learn what was known about working wood long ago. It is here for everyone to use as a resource that helps us all become better woodworkers. All the information is as valid and applicable today as ever. If you know of any books in the digital realm, which are in the public domain as complete works, and seem like they are a good fit for the Woodworks Library, please fell free to contact me about them and we’ll see what we can do to add them. After all, it’s all for anyone practicing the crafts.

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!

Fractional arithmetic for measurements within the sub inch territory is much simpler than the nightmare a lot of people conceive it to be, because there is a fixed set of fractions that are in use, and memory tricks which you can learn to make well practiced calculations that you can do in your head. This is the reason why the trades have been slow to discard the use of the inch. The fractions are just too handy for halving, quartering and doubling.

There are just some basic constructs we need to know about fractions. A quick few definitions of terms, and memory tricks for using them quickly, and we can be off and running with this for most linear measurement purposes.

Basically put, a fraction is a division problem, which is meant to deal with components of a unit that are smaller than the unit of one. Within the realm of linear measurement, the constructs used are expressing the halving of the unit from the whole on one end, to what is commonly considered usable with common tools on the other. The tools are made to fit the fractional intervals.

Commonly, the scale by incremental division looks like this:
1, 1/2. 1/4, 1/8, 1/16, 1/32, 1/64, 1/128.

In descending order you have a process of halving, and in ascending order you have a process of doubling. Divide or multiply by 2. So there is a memory trick. Get used to doubling and halving units less than one.

Though the numbers in the fractional divisions seem to become larger, it does not indicate the size of the unit, but rather, the quantity of units, which will fit within an inch, so it is best to think of it inversely. The larger the number gets, the smaller the unit is.

The parts of a fraction are worth touching on for a moment.

1 (the numerator) It is the first number or the above number as written.
– Then there is this dividing line, which signifies the division problem.
2 (the denominator) It is the second number or the below number as written.

The dividing line has a name and the name is different depending on how the fraction is written, but the names of the separator do not help you work with fractions easier. So don’t worry about what to call it. For us, “Slash” and “Dash” are fine.

The denominator signifies the sizes that the divisions of one (1 inch in our discussion) are. The numerator signifies the quantity of those denominated divisions we have.

For most of our purposes in linear measurements, these fractions when used strictly as fractions of an inch, will only be added and subtracted to and from each other.

It is important to accept that 1-inch can be expressed as a fraction. No matter what the denominator may say, if you have any quantity of numerators equal to the denominator, the quantity is equal also to one. Such as 4/4ths, 8/8ths, 32/32nds.

For expressing results when two fractions added together create a numerator, whose quantity exceeds the value set by the denominator, then a whole number, such as 1, 2, or what have you, is generated, and the fractional remainder is then expressed with the whole number. This expression is called a mixed number, and is the final expression of your result. As an example you would express 3/4 + 3/8 as 1-1/8, instead of 9/8.

When expressing fractions, they are best expressed in the reduced or simplest form possible. If the numerator is able to be added to another numerator which will derive an even number, the denominator level you are working with may not need to be referred to as a smaller unit, in fact, when numerators added together resulting in an even number, the denominator can likely be expressed as a reduced or simpler unit. As an example: 1/4 + 1/4 = 2/4 = 1/2, and 3/8 + 3/8 = 6/8 = 3/4. It is considered best practice to express the fraction in its simplest form.

A useful property of numbers, which creates a memory trick that we can use, is that if one of two numbers to be added together is an odd number, it will always result in the sum of the numbers being added together to be an odd number. Interestingly, even numbers when added together will result in an even number, and when any two odd numbers are added together they will also result in an even number. Learning to notice this trick will alert you to when the numerator will result in an odd number. When the fractions numerator is an odd number, the denominator cannot be expressed more simply than the finest size being used amongst the mixed fractions, and you will not likely be able to simplify it beyond that resultant fraction. As an example: 7/32 + 1/8 = 11/32. The trick here is that 1/8 has to be converted to its 32nd equivalent, 4/32, and then you can easily add it to the 7/32. The result is as simple as it can be made, because the numerator is an odd number, and cannot be reduced.

Halving all fractions, which are not part of a mixed number is a pretty simple process. Halve the denominator, (multiply the denominator by 2 as this doubles the fractional division making them smaller by half) the numerator remains the same. The result is always half. For example: 3/4 halved is 3/8. 5/16 halved is 5/32. 7/8 halved is 7/16, and so on.

For mixed numbers it is almost as easy. Convert the mixed number into a pure fraction and multiply the denominator by 2. When finished, convert the fraction back to its simplest form, which includes reverting back to a mixed number if that is the simplest form. For example: 1-7/8 = 15/8ths. 15/8 halved is 15/16ths. This is its simplest expression. 2-9/16 = 41/16ths. 41/16 halved is 41/32nds, which is not a simple fraction, so converted back to a mixed number it becomes 1-9/32nds. Please note again, the numerator numbers in simplest expression form did not change from the original expression. Remember when you see the numerator, the trick is that it will still remain the same but the denominator changes by half, leaving little to think about once you remember the trick.

Fractions by the 128th, from 1/128th to 1/4th, as expressed in simplest form. Observe the patterns: 1/128, 1/64, 3/128, 1/32, 5/128, 3/64, 7/128, 1/16, 9/128, 5/64, 11/128, 3/32, 13/128, 7/64, 15/128, 1/8, 17/128, 9/64, 19/128, 5/32, 21/128, 11/64, 23/128, 3/16, 25/128, 13/64, 27/128, 7/32, 29/128, 15/64, 31/128, 1/4. See the interchangeability of denominators?

And finally the last biggie is that fractions only hit specific decimal locations, so sometimes, in order to get to an increment near the fraction you have, you need to convert to a decimal and work it from there. It is simple. Divide the denominator into the numerator for the decimal equivalent. For instance 7/64ths would be converted by dividing 7 by 64, and the result would be .1094, 3/4 would be .750, and 3/32nds would be .0937. How fine is markup to the 128th of an inch? It is .0078 of an inch. Call that about the width of two whiskers.

Why is the fractional to decimal relationship important? Say you are working on adding a shelf to a cabinet project in 3/4 Baltic Birch. This is nice plywood, commonly available, but the thickness is actually metric. 3/4 is close to 18mm but there is a catch. The decimal equivalents are not exact. 3/4 = .750 and 18mm = .709. This is a 41 thousandth of an inch difference, which will need compensation. Usually the compensation is made by working to the fraction nearest to the metric equivalent, which in this case is 23/32nds, but there is a .010 of an inch remainder. This can be an unacceptable gap in some work, so this too is good to know.

Another workaround which creates a better looking fit, could be to disregard the metric size for joinery altogether, and create a 1/2 inch tongue and groove, but in order to center the .500’s of an inch tongue on the .708 inch thick board, you are going to have to subtract .500 from .708, and halve that result of .208 to make it .104, so you know what the shoulders for the tongue will need to measure, in order to center it on the metric board. The nearest fractional increment to the proper size of this shoulder is 7/64 and as you see by dividing 64 into 7 that .109 will make the shoulder too large. The shoulder too large will make the tongue too small. If you cut to the nearest fractional increment here, the tongue will be centered but only .490 wide, and this is a sloppy fit in a .500 groove for very fine work. In fact the same quantity of slop you had working 18mm into 23/32nds. Now you can dial in the necessary compensation.

Knowing how to manipulate the fractions and knowing where the fractions lie amongst the decimals will help you build higher quality into your fine woodworking or machine work, where fit and finish is everything.

Hopefully these memory tricks and conventions will help you to work with fractions faster, easier, and more proficiently with more confidence. The understanding of fractions for use in linear measurements is conquerable, and for the most part is kept pretty simple and doable by the constructs involved with them. One could only hope that much of the rest of fractional manipulation could work as easily.

Going forward, feel free to practice these memory tricks, and if you like, add both a fractional and decimal dial caliper to your metrology tool arsenal, they will help you a ton. For further reference, feel free to use the Decimal Equivilents chart I have provided, as well as the other tools available in the Woodworks Reference Library. They are all printable and ready for use in the shop.

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.

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.

While this article is about what it takes to install cross dowels, due to popular demand I have researched and included links to what I feel are the best sources for this hardware in it’s various sizes out there. The links are included at the end of this article.

It is notable that bench building is enjoying a renaissance right now. some great new designs, vises and hardware packages have recently become available.

Amongst these offerings, a top of the line All Steel Cross Dowel Package has been made available by Benchcrafted. They are marketed as Benchcrafted Barrel Nuts, and they are the best product available to the bench builder. Unlike any other cross dowel meant for use with benches, these are all steel for heavy duty applications and the design allows the installer to align them with fingers during assembly. These are top quality, a great value and installation doesn’t get simpler.

Ok, if you already have your hardware in hand, then layout for cross dowels in knock down bench legs works like this. If you have not obtained the parts you need, please consider waiting until you have it in hand.

Lay your two legs and cross piece on the bench, Inside face facing up, already milled, mortised and tenoned, and dry fit them. Clamp them top and bottom to hold the unit together with enough force so that things will not move while you perform the layout, and check them for square. Make sure you have them square.

If you have a Veritas saddle square, or equivalent, that would be handy, but if you don’t, no matter, here is a work around:

Position the leg assembly by allowing it to hang over the edge of your bench and support it with a something like a telescopic roller stand. Take a six-foot length of string line and tie a nut or a heavy washer on each end for weight, and drape it over the leg assembly, along the centerline of the crosspiece. This string line forms somewhat of a double-ended plumb bob, which will indicate the centerline of your layout work and will project these lines around corners. You can eyeball centerline of your work piece or measure. Once the string is located, go ahead and put a piece of blue painters tape on each end near the corners where it drapes over the edge.

The best position for the cross dowel on the bolt is at the end of the bolt with all the threads in the nut fully engaged. The formula for figuring cross dowel hole location from any combination of length and diameter hardware is to take the working length of the bolt (which differs if the cap screw is hex head, allen head, button head or flat head) and subtract half the diameter of the cross dowel from that length to find hole centerline for the cross dowel. The length of the bolt, when you are choosing the length optionally, is best determined by the thickness of what it has to pass through on the bolt head side, plus 1-1/4 inches minimum into the adjoining board for cross dowel centerline.

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.

The heavy hitter in the woodworker’s and home shop machinist’s shop then becomes not only the quality of the layout tools, but the knowledge of how to apply them, and the quality of the results rendered by them, and that trifecta is the system of dimensional metrology.

One of the things I have enjoyed down through the years is the process of laying out the work. It is something I have enjoyed professionally, and something I enjoy as a hobby, because the challenge, which comes from, it is always new. I am sure that for some, the problem-solving component of woodworking is what keeps their hand in it. It is not as much the end for some, as it is the means.

In any case, the subject of metrology, most specifically ‘dimensional metrology’, the tools and the layout strategies that they help employ are something of a fun puzzle for me, and will be a part of what I’ll write about here. It has it’s own category, and I’d like to extend the invite to click into the subject from time to time, just to see if there is something there for you.

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.

We cut our wood, taking care to get every cut right and of course they are perfect, except for the fact that the face of the board we loved so much is now going to be the back, because we got turned around while we were trying to be so careful. We did not mark our boards properly to affirm their proper orientations in the project above all else.

Can you imagine being half way through with some half blinds when you discover the orientation error?

Oh Man…

A bummer, but it is avoidable.

Buy yourself some chalk and mark your boards as to the intended orientation. Chalk is a buck for a box and it could save you thousands of dollars in layout errors over time. Wipes off, leaves no trace, keeps you on the intended track

Blue painter’s masking tape and a Sharpie marker is a great adhesive notepad for on board paper brain purposes as well.

As an upgrade to plain chalk, consider getting a chalk holder for your piece of chalk. It keeps you cleaner and helps keep the chalk from breaking and rolling off onto the floor. Keep it in the pocket of your apron really nice, you know, where you may find it and maybe remember to use it!

You can also use the blackboard chalk as a release agent on files so that hardwoods, brass and aluminum do not so easily clog the grooves of the file, and this helps make the files work better, last longer and dull more slowly.