Square, Level, True
First Principles of Working With Wood
- 6 chapters
- 17m
- Woodworking
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The book starts with basic sanding techniques and moves through using a jack plane to smooth surfaces. It covers end mills for precise cuts, machinist squares for accurate angles, and Level-5 precision tools for measuring work. Each chapter focuses on one essential tool or technique.
Whether you're setting up your first shop or learning proper hand tool use, this book shows you how to work safely and accurately from the start.
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Overview
A belt sander uses a motor to turn drums with continuous sandpaper loops, making it good for shaping and finishing wood. It can be handheld or stationary, with stationary ones mounted on benches called bench sanders often paired with disc sanders. Belt sanders remove material quickly and are used in early sanding stages or to strip paint. They're also useful for sanding non-ferrous metals like aluminum, which tend to clog other tools. Because grooves in the sandpaper stay open as it moves around the drum, belt sanders don't clog as easily. They range from small handheld units to large industrial models that can sand sheets of plywood. Dust collection systems are common, whether simple cloth bags or powerful vacuums. Some have adjustable idler drums to keep the belt centered. Slack-belt sanding is used in guitar making and other woodworking, where a long belt runs loosely over an object while pressure is applied to specific areas.
Racing
In the early days of power tool racing, belt sanders became one of the first machines to hit the track, pulled by long extension cords through wooden channels. These races took place on tracks that were either fifteen meters or twenty-five meters long, depending on whether the sanders were stock or modified. When the race began—triggered by a shared switch or individual buttons—the machines would shoot down the path, throwing wood dust into the air. Speeds varied greatly, with some reaching as slow as five miles per hour, while others could go much faster. The sport showcased not only the power of different motors but also the skill and creativity involved in building these racing machines.
Wide belt sander
A wide belt sander flattens wood and brings it to precise thicknesses by means of sanding heads, contact drums, and a continuous conveyor belt. Though electrically powered, it depends on air pressure to manage the movement of the abrasive belt. As stock moves through the machine, a rubber belt carries it along while a wide abrasive surface removes material from the top. This tool is often paired with a jointer to produce square and true pieces. It serves woodworking and furniture production, performing fine sanding with rigid and air cushion pads, as well as cross and diagonal techniques and lacquer sanding.
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Overview
A jack plane is a common type of bench plane used to shape wood down to the right size, getting it ready for finishing or joining edges. It’s often the first tool you reach when working with rough lumber, though a scrub plane might come before it for more uneven stock. Because it's so useful in many different tasks, the jack plane is the most widely used kind of bench plane. Sometimes people call it the fore plane, which is a longer name for the same tool.
Description
Jack planes are generally 12 to 18 inches long and about 2½ to 3 inches wide, with some wooden versions slightly wider. The blade itself measures 1¼ to 2¼ inches across. In the United States, traditional wooden jack planes were usually 15 to 18 inches long, with irons that were 1¾ to 2½ inches wide. Under the Stanley Bailey numbering system for metal-bodied planes, the #5 plane, which is 14 inches long, is classified as a jack. However, not every manufacturer used the same numbering scheme. For instance, Millers Fall and Sargent referred to the same plane with different numbers.
Name
The jack plane has been around since at least the 17th century, when it was used to describe tools for rough work. Because “jack” was a common first name, the term came to be used in a dismissive way for both ordinary people and everyday tools. Over time, the jack plane also became linked with the phrase "jack of all trades," since it could do some of the jobs that smoothing and jointer planes handle, especially on smaller pieces of wood.
History
Until the end of the 19th century, jack planes were mostly made of wood, often beech, both in Europe and North America. Then iron-bodied planes began to take over, with some transitional models in between. Leonard Bailey played a key role, patenting several important all-metal designs. Still, wooden planes didn’t disappear entirely—vintage ones are still used today, and new ones are made by a few manufacturers.
Use
The irons on jack planes are often ground with a slight camber, which lets more material be removed without marring the surface. For a finer finish, they can also be ground like a smoothing plane—straight across with just a tiny curve at the edges. The cut is generally set deeper than on most other planes because the jack plane’s purpose is to remove stock quickly rather than produce a smooth finish, which is left to smoothing planes. In the sequence of work, the jack plane follows the scrub plane and precedes either the fore plane or jointer plane, with the smoothing plane coming after. Woodworkers often begin by planing across or diagonal to the grain—traversing—to level the piece roughly, then switch to planing with the grain for a smoother result.
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Overview
An end mill is a cutting tool used in industrial milling, and it's distinct from a drill bit in how it works and is made. While a drill can only cut straight down, most end mills can cut sideways as well. They come in different end shapes—round, tapered, or straight—and are used in machines that move the material against the mill to cut away pieces and shape it. These tools are used in several kinds of milling, like profile milling, face milling, and plunging. Not every milling tool cuts tangentially, but those that do are called end mills.
Types
End mills vary by plunge capability, flute count, helix angle, material, and coating. Common metal cutting helix angles are 30 degrees, while finish cuts use 45 or 60 degrees. Straight flute mills (0-degree angle) serve plastics and composites, though Carl A. Bergstrom introduced helical flutes in 1918 for metal. Modern end mills feature variable or pseudo-random helix angles and discontinuous flutes to improve chip removal and reduce jamming, often including corner chamfers and chipbreakers for better durability and high-speed machining, though at higher cost. Solid end mills increasingly yield to inserted tools allowing easier edge replacement and greater material flexibility, especially in larger diameters. Inserted tools typically handle roughing while traditional solid end mills remain preferred for finishing and tighter tolerances. End mills sell in both imperial and metric sizes, with metric standard in Asia and Europe, widely available but not universal in the U.S. and Canada.
Geometry
When working with wood, you can create grooves, slots, and pockets using tool bits like those with square, ball, T-shaped, or shell-cutting edges. Each tool has four important angles that affect cutting performance. Material type determines which tool and design are best—aluminum might call for a tool with deep, polished flutes and sharp edge, while stainless steel requires shallow flutes and squared-off cutting edge. Materials used include carbide, high speed steel, ceramics, and diamond. In the early 1990s, coatings became common, offering wear resistance and heat protection. Some end mills use a vein of polycrystalline diamond, formed under high temperature and pressure, which makes them very durable but costly. Coatings can be colored differently for branding, even if that color doesn't affect performance. End mills are made on CNC grinders using high-pressure lubricants, with wheels made from materials like industrial diamond or cubic boron nitride depending on what's being ground.
Operations
When working with wood using an end mill, the first step is usually roughing, where you remove most of the material to get close to the final shape and size. This initial cut is followed by semi-finish and/or finish cuts. You might also contour or profile different surfaces—flat or irregular ones—during either the roughing or finishing stages. Facing is another operation, used to flatten a part down to a specific dimension, and can be done with an end mill or a special face mill. If you need to create a pocket inside the part, that’s called pocketing or slotting, and it can be shallow or deep depending on the requirements.
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Overview
A machinist square, also known as an engineer's square, is a tool used by metalworkers that works like a try square does for woodworkers. It has a steel blade set into a thicker piece of metal at a perfect 90-degree angle. The two parts are either welded or pinned together. There’s usually a small notch at the inside corner to keep dust and debris from getting trapped, which could throw off the square’s accuracy.
Use
When using a machinist square, you align the body against one edge of the object you're working with, and then present the blade to either the end or the main body of that piece. If you're checking the end of something, shining a strong light behind the square helps reveal any misalignment between the blade and the edge of the workpiece. This method lets you verify whether the piece is square—or to mark out a line along the body of the wood itself.
Accuracy grades and standards
Engineer's squares are made to meet specific international standards, with two main ones being BS 939, the British standard, and DIN 875-1, the German or Euro standard. Both set out requirements for blade and body dimensions, including how they're constructed—like whether the blade is inserted into a solid body or if the blade and body are one piece with an attached plate for a true square edge. These standards also define accuracy grades, usually labeled A or B. B grade squares are good enough for most workshop tasks where some precision is needed, while A grade ones are used in toolrooms or for checking other squares, making jigs and fixtures that demand higher accuracy.
Accuracy checking and calibration
To check a low-grade square for accuracy, draw a line on a board using the flat face and straight edge, then flip the square 180 degrees and see if the blade aligns with that line. Any error shows up as a wedge or taper, doubled in effect. For ultimate calibration, a cylindrical master square is placed on a flat granite or cast iron surface plate; because of its shape, it sits perfectly at 90 degrees to the surface. A square being tested can be held against it, and feeler gauges with light behind the gap can detect deviation. Done properly, this method finds errors down to 0.01 mm, which is as precise as practical accuracy gets due to thermal expansion from finger contact distorting the blade by about that much. Other methods use modern tools like a CMM or a vertical machining center with a dial indicator.
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Overview
In October 1998, Akihiro Hino started a video game company in Fukuoka, Japan, after leaving Riverhillsoft. That company is called Level-5 Inc., and it has made several well-known game series. Some of those include Ni no Kuni, Snack World, Megaton Musashi, Inazuma Eleven, Yo-kai Watch, and Professor Layton.
History
Level-5 began in October 1998 when Akihiro Hino and his team from Riverhillsoft formed the company after OverBlood 2. Sony Computer Entertainment helped them start up, letting them make games for the PlayStation 2 on the condition they created their own firm. The name came from Japanese report cards, where "Level-5" means the top score. The company had eleven people when it started. Their first big project was Dark Cloud, made under contract with Sony, delayed until December 2000 in Japan and 2001 worldwide. They followed up with Dark Cloud 2, and worked on an MMORPG for Xbox called True Fantasy Live Online, which was cancelled in 2004. In 2011, Yasumi Matsuno joined briefly and finished Crimson Shroud before leaving. By the early 2010s, Level-5 was one of Japan's ten largest game makers, with a 3.2% market share. In 2015, they opened a new company in Santa Monica called Level-5 Abby. But in October 2020, North American operations including Level-5 Abby closed due to poor sales. That same month, Level-5 launched a manga publishing platform named Manga 5.
Roid service
In 2009, Level-5 introduced a service called Roid, short for Revolutionary Original Ideas Discovery, which was a mobile app for i-mode users in Japan. It offered access to exclusive games and social features through a monthly subscription. The platform launched with six titles, including Mystery Story by Paul Sloane and Des MacHale, Professor Layton and the Mansion of the Mirror of Death Remix, and Chara Jo P, all developed by Level-5. The other three games—*Yuuenchi wo Tsukurō Revolution*, Treasure Island, and *Elf the Dragon*—were made by external developers.
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Overview
In digital audio, dBFS measures how loud a signal is compared to the highest level possible in the system. Zero dBFS is the absolute peak, so anything below it is a negative number. For example, a signal at 50% of that maximum would be −6 dBFS. This scale applies to PCM systems and is related to other units like dBov and dBO. Because digital signals are reconstructed into analog form, they can still clip even if no sample reaches 0 dBFS—this happens when the process interpolates between samples. The issue can be avoided with careful converter design. True peak levels, which account for these inter-sample peaks, are labeled dBTP or dB TP.
RMS levels
When assessing audio performance, peak measurements alone don't capture the full picture, so engineers often rely on RMS levels instead. However, ambiguity arises because some follow the strict mathematical definition where the RMS of a sine wave sits 3 dB below its peak, while others align the reference so that sine waves read the same whether measured as RMS or peak. The ITU-T G.100.1 standard defines dBov such that a full-scale square wave is 0 dBov, with all values negative and sine waves never exceeding −3 dBov without clipping. This unit applies to both analog and digital systems and underpins the LUFS loudness standard used in tools like Sound Forge and Euphonix meters. Meanwhile, specs from companies like Wolfson and Cirrus Logic adopt a different convention where the RMS of a full-scale sine wave is 0 dB FS, making a square wave read +3 dB FS. Even Analog Devices uses this same dBov-based approach in their digital microphone specs—but refer to it as "dBFS."
Dynamic range
The dynamic range of a digital system reflects how much stronger a full-scale sine wave can be compared to the quietest signal it can reliably reproduce. This weakest signal is limited by quantization noise, which is often treated as a uniform fluctuation across the least significant bit. Because this measurement compares against a full-scale sine wave, the same formula estimates both the system’s dynamic range and its noise floor in decibels relative to full scale: DR = SNR = 20 log₁₀ (2ⁿ√(3/2)) ≈ 6.0206n + 1.761. For a 16-bit system, that calculates to around 98.09 dB. In actual converters, dither is introduced before sampling to reduce distortions from non-uniform quantization, though it raises the noise floor slightly.
History
The term "dBFS," which stands for "decibels below full scale," has been used in technical writing since 1977, though the broader concept of decibels appeared in print as early as the 1950s. While the decibel itself is allowed for use with SI units, dBFS is not recognized as such. The CD-DA Red Book standard, published in 1980, established that the maximum loudness level should be set at 0 dBFS.
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