Unlocking the Secrets of Bevels: A Tool Guide

Recently, I have been exploring old timber framing structures from Europe, which inspired me to create small models of them. I realized that this endeavor serves as an excellent exercise in geometry. The technical term for what I am attempting is called stereotomy. Stereotomy is the art and science of cutting three-dimensional solids—most commonly stone or wood—into precise shapes that can be assembled into complex architectural structures such as walls, arches, and vaults. The term derives from the Greek words stereós (solid) and tomē (cut). This process involves a complex set of drawings and mathematical calculations, many of which I am not proficient in. However, a crucial tool for achieving the necessary angles is the bevel.

At first glance, the bevel may raise some eyebrows. The initial question is: how is it used? There are no numbers indicating units of measurement or degree angles, so what purpose does it serve?

The bevel tool, specifically the sliding T bevel (also known as a bevel gauge or false square), is an essential instrument in woodworking for setting and transferring angles. While the concept of transferring angles is ancient, and there are various methods to do so, the sliding T bevel as a recognizable, adjustable tool has a more documented history. This tool allows the user to set it at any given angle, providing the primary angle. Since all angles sum to 180 degrees, the bevel also indicates the supplementary angle. Additionally, one can reference the complementary angle, which is 90 degrees minus the primary angle. The two main types of angles when setting the bevel itself are the primary angle and its supplementary angle. To determine the actual degree of an angle, a good protractor is recommended. If the exact angle is required for example, working with plans, I highly recommend the Sawset Pro protractor, which simplifies the use of a miter saw for both single and double miter settings. (click here)

HISTORY

The first sliding “T” bevel appears to have been patented by Isaiah Robinson in 1870, who used a butt-locking method to secure the blade in place. However, (you guessed it) Justus Traut at Stanley obtained a patent in 1871 with a wingnut locking mechanism. Later, in 1897, he improved the design by replacing the wingnut with a thumb lever and an eccentric cam to lock the blade in place. This design is the most common type found in Stanley bevels.

Other companies, such as Nicholas McGrath, Maples and Sons, and St. Johnsbury, also produced bevels, each featuring characteristics that may be beneficial or detrimental depending on your specific application.

Types of Bevels

I have a collection of a dozen bevels, each featuring different mechanisms to lock the blade in place. Here’s a breakdown of their characteristics:

Thumbscrew or Wing Nut

Location: Typically found at the top of the handle.

Mechanism: Tightening the thumbscrew clamps the blade securely in position.

Pros: Simple and reliable; easy to operate with your fingers, providing strong locking power.

Cons: The size of the wing nut can be cumbersome, especially when flipping the bevel over.

Knurled Knob (Brass or Steel)

Location: Often located on one side of the handle.

Mechanism: A threaded knob tightens against a slotted bolt or threaded insert in the blade.

Pros: Classic design that is aesthetically pleasing, especially on high-end or traditional tools. The flat knob does not hinder any application.

Cons: Adjustments can be slower; the knob may loosen over time, making it difficult to achieve good locking pressure.

Lever Lock (Cam Lock)

Location: Mounted on the handle or at the pivot point.

Mechanism: A small lever is flipped to lock or unlock the blade using cam pressure.

Pros: Fast and easy to use; allows for one-handed operation. I particularly like this design, although Veritas used to offer it on their bevels but has since discontinued it.

Cons: More complex and can wear out over time; often more expensive and harder to find.

Thumb Lever with Eccentric Cam

Location: Located on top of the handle or embedded in the side.

Mechanism: Utilizes an off-center cam inside the handle that tightens when turned.

Pros: Provides smooth, tool-less locking; most common on older bevels.

Cons: The cam can wear out over time, and the thumb lever may over-extend, obstructing angle settings.

Screwdriver-Tightened Bolt

Location: Through the body or handle.

Mechanism: Requires a flathead or Phillips screwdriver to tighten.

Pros: Secure and low-profile design.

Cons: Not convenient for quick adjustments; requires a tool, making it a slow process.

Modern Bevels

Today, many companies offer bevels with additional features, including digital readouts and degree angles etched directly onto the tool. I personally own some of these modern bevels, including the 109Tools bevel, and for many years in the field, I used the Starrett angle-finding bevel (click here). It’s important to remember that while digital and etched versions provide highly accurate angles, the accuracy of your saw is crucial. If your saw is off by half a degree, you cannot rely solely on the reading from a digital bevel. That’s why I prefer older bevels without numbers. I take my angle from the bevel and match it to my saw. When making a miter cut, I match the bevel angle to my miter saw and then divide the number on my miter saw in half. For me, this method is more effective. My friend, Jerill Vance, at the Appalachian Heritage Woodshop, would also agree with me on the use of digital bevels, for he experienced the same issues as myself. Plus, he commented that the batteries always seem to be dead when you need them the most. 

If you don’t already own a bevel, I highly encourage you to get one. I have multiple bevels, and they are essential tools when building a chair due to the various angles required.

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To my regular subscribers, thank you for your continued support! If there’s a tool you’d like to learn more about, feel free to reach out to me at [email protected]