What is a sliding bevel?

A sliding bevel, also called a bevel gauge or T-bevel (in Dutch zweihaak or zwaaihaak), is an adjustable square used to copy any angle and transfer it to another workpiece. An ordinary try square only gives 90 degrees. On a sliding bevel the blade pivots relative to the stock and can be locked in any position with a screw or lever.

Construction

• Stock: the thicker part that you hold against the edge of the workpiece.
• Blade: a slotted metal blade that can pivot and slide.
• Lock: a wing nut, screw or lever that fixes the blade at the chosen angle.

How to use it

1. Copy the angle: hold the stock against one surface and swing the blade against the other, for example a sloping wall, roof pitch or stair string. Lock the blade.
2. Transfer the angle: place the stock against the edge of your board and mark a line along the blade.
3. The other way round: to mark a known angle, set the bevel with a protractor or angle template.

Typical jobs include marking out roof boarding and rafters, fitting skirting and mouldings in corners that are not square, and copying the pitch of a staircase.

Digital versions

There are also digital bevels with a display that shows the set angle in degrees. A separate digital angle finder or inclinometer can also help, for example to check the tilt of a saw blade.

Tips and common mistakes

• Lock it firmly: a blade that slips while marking is the most common mistake.
• Use a sharp pencil or marking knife and always keep to the same side of the blade.
• Halve it for mitres: for a mitre in a corner that is not square, copy the angle and halve it for the cut.
• Test on an offcut before cutting expensive material.

Related terms

• Spirit level
• Mitre joint
• Mitre saw
• Inclinometer
• Roof pitch

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