Measuring and Marking



Measuring and marking are two of the most important aspects of woodworking. As such, one would think that it would be covered more in depth in the how to books and in magazine articles. That does not seem to be the case. There are a lot of fancy measuring devices and gadgets, but not a lot of info on just plane accurate measuring. Ask a question about measuring and you'll generally get answers like, "Be sure to use the same rule or tape for all measuring on a project." Or someone will tell you to get a .5 mm mechanical pencil with which to do your marking. Others will say you need some super accurate new fangled ruler in order to get accurate marks.

All of that is helpful to some extent. But, a lot of it is unneccessary and overkill.

Measure Once, Cut Twice or Thrice

When working from plans realize that the measurements provided are suggestions. In most cases cutting two or more pieces to exactly the same length is much more important than the actual dimension. In other cases what is important is that the piece be cut so that it fits. You must realize that regardless of the accuracy of your measuring device, you are going to have error every time you make a measurement. It might be miniscule, but it can be fatal to a tight joint. One of the most often heard statements in woodworking is to, "Measure twice, cut once." I would much rather measure once and cut twice or thrice or what have you. If you need two or more pieces cut to the same length, say for the opposing sides of a book case, it is more important that those two pieces be cut to the exact same length than it is for them to be the exact dimension from the plan. Use some mechanical means to insure that is the case. A stop block set up on your tablesaw or chop saw. Use two sided tape to attach all of the pieces together for handsawing and planing. Use the same rip fence setting to rip all of the pieces of the same width to final size.

Errors Do Not Cancel Themselves Out, They Add Up

You would think that errors in measuring would be random and that you would have the same odds that the cumulative effect of several small errors would cancel each other out as for them to accumulate to a large visible error. But that is simply not the case. Blame Murphy or whatever, but plan on all those miniscule errors throwing everything off in an amount equal to, at the least, their sum. And some of them multiply and some grow exponentially. Just the way it is.

So, you've got all four pieces cut that make up the overall dimensions of your bookcase. And you cut the dados across the uprights to house your shelves. Everything just to the dimensions in the plan. Now we need to cut some shelves and the plan says 27 3/8" long. Easy enough, right? Well we set up a stop block on our table saw at exactly 27 3/8" and cut our four shelves of that really expensive figured walnut. Everything nice a square because we checked the miter gauge and it was right on the money. We measure and the rule agrees with our 27 3/8" measurement. Cool! Now it is time to assemble everything and, "WHAT THE . . ." The shelves are all 3/16" too short. How can that be? Well, we had a miniscule error measuring and cutting the top, as well as the bottom, then another when we cut the dados. And, of course another when we cut the shelves to length. Each was just a hair, but they were all in just the right direction so that they added up and now we've got the grand canyon sitting next to each shelf in our dados.

Lose Your Rule as Often as You Can



On a construction site you might hear one fella up on a ladder with one end of tape measure calling down measurements to another fella on the ground, "Seven feet, four and a long 3/8 inches." The fella on the ground with another tape then hooks his tape on the end of a 2 X 4 runs it out, bends over his work, and uses a monster pencil to make two marks intersecting each other at a point on the tape. He then grabs up his square and uses the same monster pencil to scribes line across the board. The he grabs up his saw and cuts in the vicinity of the line and hands the board up. The fella on the ladder props one end of the board against another, then uses his hammer to wedge the board in place before nailing. That is fine for framing construction, that "long 3/8 inches" may work there. Like I said, plan dimensions are merely suggestions, even more so when we get to the point of making the parts that need to fit. Fit in between two other pieces. Fit to house another piece of wood. Assemble or at least dry assemble parts that need to have other parts fit into them. Then cut the mating pieces to match the opening they will fill. Mark dados and grooves and the like using the actual piece that they will house. If the shelf material is near our expected dimension, say 3/4", when we read the rule we will not see that it is a scant 3/4" or on the proud side of the 3/4" mark. We will see 3/4" and cut our dado to that width. Lose the rule and use the stick that is the shelf to mark the width of the dado or groove.

Lose your rule when you have your piece assembled to fit those parts that need to fit. Use the actual piece that will be fitted into the space to mark that piece for cutting. Slip one end just barely into the space on one end, then mark the other end where it will touch the opposite end of the housing. Even better is to use a story stick of sorts in the same manner and use that to set up your cut. The picture below shows an instance of this.


Looking at the top piece in the forground you can see a knife mark which is to be transfered to the piece beneath it. Another use for a similar type of story stick is to use it to set the fence or a stop block on a tool as shown in the next photo.


Again a knife mark darkened with a pencil for clarity can be used to set up for the cut. Realize that the story stick would set much straighter than appears in the photo. I'm not much of a multitasker, and snapping the pic while holding the story stick in place proved more difficult than I could handle.

Some Tools of the Trade



The Marking Knife



The marking knife comes in a number of configurations, from a thin bladed flexible knife to the old fashioned striking knife. Pictured below are two home made marking knives. The top one is my version of an old fashioned striking knife, the bottom is a spearpoint marking knife. I made the striking knife from an old farrier's rasp, while the marking knife blade is an old cutter from my tailed jointer.



The striking knife combines a knife blade at one end for marking across the grain with an awl for marking along the grain as well as for end grain use. The awl does not have the tendency of following that grain that the knife edge does. A light touch at a fairly acute angle with the awl makes a very nice visible line.

For marking across the grain, I prefer the spearpoint knife over the striking knife as the spearpoint can be used on either side of a straightedge simply by flipping the knife, where-as one has to either move the straightedge to the other side of the intended mark, or flip the workpiece in cases near an end where there is no edge on which to index the square.

I also have a store bought marking knife made by Crown (shown below). This knife has a thin flexible blade which some prefer. I don't.



The use of the thicker stiff bladed marking knife is fairly straight forward. While some of the "experts" recommend holding the beveled edge against the guide being used to make the mark, others say to set the non-beveled edge against it. I've tried both and find it easier and more natural for me to index the knife with the non-beveled edge against the straight edge.

At times one wants to carry a cut line from the initial face being marked onto an adjacent edge, or even all of the way around a workpiece. I find this useful when preparing to make a cross cut on the table saw or to assist me in obtaining a square cut using a handsaw. While a mark on the face of a piece can be lined up with the edge of the table saw blade, a paralax error can occur. Continueing the line onto the edge of the piece which faces the blade when setting up for a crosscut on the table saw allows you to put a tooth of the blade right onto the exact location on the edge of the piece, eliminating the chance of paralax error. The knife scored line also helps to prevent tearout since it slices through the fibers on the surface.

The thicker stiff beveled edge is particularly useful in carrying cut lines onto adjacent edges. The picture below shows the face of a workpiece being measured and marked near an edge of a workpiece. I find it easiest to get an accurate measurement by running the rule close to an edge since it is easier to see that the rule is parallel to the edge, and thus gaining an accurate measurement as opposed to running the rule closer to the center of the face where one could be out of parallel with the edge and thus making the measurement at an angle.



The line can then be scored using one or another square by sliding the square up to the flat edge of the knife inserted into the mark made from the rule. The beveled edge of the knife should be on the waste side of the cut. Once the guide has been located, move the knife to the top edge of the board with the knife edge straddling the corner. Prior to striking across the board, push the knife slightly into the corner creating a wedge shaped indentation. Then strike across the face of the board keeping the flat edge of the knife against the guide. At the end of the cut, force the blade into the bottom corner of the the board creating another wedge shaped indentation on that corner. You should now have a line on the face of the board with two small wedge shaped indentations as can be seen in the picture below.



Now you can flip one or the other edge of the piece up and set the knife into the indentation on the corner as shown below.



Now you can slide your square up next to the flat edge of the knife and score the line on the edge, again creating a small indentation with the knife at the end of that cut. Continue around the board in the same manner until all four sides of the board are marked.

Another benefit of this method is that the indentations can be used to index your handsaw if you wish to make the cut in that manner. This method remedies one of the most difficult aspects of using a handsaw to cut to a line, getting the cut started accurately. Just set the blade of the saw into the intentation as shown in the photo below.

The Marking Gauge


While everyone has their favorite rule as well as some of the other tools needed for laying out and doing whatever they need to do on a project, some of the tried and true tools of the past, as well as some which are more modern derivations of older tools are not as well known. Marking gauges have been around for a long time, the early ones simple shop made devices with a pin for marking attached to a stick of wood and a fence held in place by a wedge. More recent ones still maintained the marking pin but relied upon a thumb screw for locking down the fence. For marking along the grain one has to be mindful of the pin trying to follow the grain, and in cross grain use the pin has a tendency to scratch leaving a pretty ragged line. So some had the pin replaced with a knife-like device which cuts a much nicer line across the grain, though has a greater tendency to follow the grain in long grain applications. The most modern equivalent is the Wheel Gauge as seen in the picture below.



This is the deluxe model from Lee Valley Veritas. It is micro adjustable and has a built in rule. The cutting wheel is replaceable (to my mind easier and faster than trying to sharpen, although it is sharpenable). Very simple to use, simply set it, hold the fence against the edge of the piece and scribe the vicinity that needs to be marked. My deluxe model has a built in rule which I never use. Since the fence has a slight recess at the center where the rod feeds through, it is difficult to judge exactly where the measurement lines should be in reference to it. But the real reason I dont't use it is that no two rules are ever exactly the same and, even with this, I prefer to take the setting from the workpiece.

If I am marking for a rabbet or for the base line for dovetails, I use the piece that will be joined to the piece being marked to set the gauge. If I'm setting it to a specific measurement, rather than using a rule to set the gauge, I find it easier to measurement on one of the workpieces, making the mark parallel to the edge on which the fence will ride using a marking knife. I then slide the fence back wider than the measurement will be, set the cutting wheel into the knife mark, then slide the fence against the edge of the workpiece and lock it down.



A close cousin to the marking gauge is the mortice gauge. As seen in the picture, it has two pins for marking the edges of a mortice. This one is a nice older model (Stanley I think, or a patent infringement of one made by Stanley). One of the pins is stationary, while the other is adjustable using the thumb screw at the opposite end of the rod to set it for different widths of mortices. The mortice width is best set using the chisel that will cut the mortice as a gauge. Then the distance for the edge is adjusted by moving the fence.

Squaring Things Up


Making things square seems to be a constant battle when it comes to woodworking. There are tons of devices out there to help get the job done, from little engineering squares, to great big rafter squares. But just because "square" is in their names doesn't mean that they are. Grab a handful of different ones and you'll be lucky to find even one or two of them that are truly square. To test one, set one leg against a straight edge of a table or other similar surface and mark a line across the surface using the other leg. Flip the square left to right so that it is now upside down from its previous position and the leg against the straight edge is now pointing opposite from the way it was. Now slide it up next to the line you drew and see if it is parallel. Chances are it is not and 1/2 the angle of difference is how far out of square it is. There are methods of adjusting most "squares" but I won't go into them here.

For most marking in my shop, I generally rely on the small engineer's square pictured below. Very similar to the old fashioned carpenter's Trisquare, this one proved to be accurate on both sides of the blade. This is not always true of any square.



Another go-to for me is this "Speed Square".



This usually hangs out at my table saw as I don't trust the gauges showing the bevel angle or on the miter gauge. The wide base makes it easy to set onto the table for adjusting the bevel and for some reason most of these that I've seen have been pretty true.

One of my two rafter squares are true and I use it for help in squaring up large assemblies.



While on the subject of assembling projects, the bar gauge pictured above is a very nice tool to have. Made from two pieces of scrap and a pair of bar gauge heads from Lee Valley, it is great for transfering measurements or for spanning diagonals for comparison to insure a large assembly is square.



You'll also want a couple combination squares. In addition to these, I have one which has several heads, the regular one as shown, a center-finding head (I do a bit of turning and that comes in handy) as well as a protactor head. The small one shown seems to check out as being square, as does one of the other large ones I have, but I don't use these for marking square unless I'm out of the shop and these are all I have with me. The are very good at tranfering measurements and for marking lines parallel to an edge. They also make nice depth measurements.


Other Angles


On occassion one will be called upon to mark an angle other than 90 degrees. While a nice drafting protractor is nice to have for these cases, they are a bit fragile and getting banged around on a job site or on top of the bench can quickly destroy them. And it would be nice to have a method where-by one can duplicate existing angles or set a particular angle to mark several workpieces. The sliding T-bevel is the weapon of choice. Again, I have several of these as I tried a couple new ones, some different designs of older ones and, after I found the design I liked best, I obtained others in different sizes.



The style in the picture above is my personal favorite. Stanley made these and put their name on it as well as the names of a couple other companies with whom they did business.

These can be set to an existing angle, either on a workpiece, or from a drawing in a plan. They can also be set using a protractor as well as using a known slope drawn on some scrap as one might do to lay out the tail angles for dovetails knowing the ratio needed for the application.

Other items that are nice to have in the shop for layout are a protractor and compass as well as an assortment of dividers. A couple or three different sizes of compasses are nice. In addition to drawing circles and arcs, they are nice for bisecting angles if one can remember their old High School Geometry (or if you can't, check the bottom of this page for a refresher course).

Of course this page is by no means a complete listing of tools, nor all there is to know about marking and measuring, but it is a good start. And please don't take my word as being final on any of the methods described here. I am not an expert, just a hobbiest, but these are some things that I have found to work well for me. It is both a condensation of a lot of what I have read on the subject, as well as what I have found to work better for me than what I may have read in a book, magazine or on one of the myriad of other web sites dedicated to woodworking.