Marking Tools: Gauges

MARKING GAUGES

The beam and fence may be made of wood or metal. Wood marking gauges are more common and may or may not have brass strips inlaid to reduce wear. Some beams have scales, but these are best used only to set the fence to an approximate distance.

Basic use

To use a marking gauge, loosen the thumbscrew and slide the fence the desired distance from the pin. Tighten the thumbscrew and make a test mark; readjust as necessary. Place the fence of the gauge up against the edge of the workpiece and angle it so the pin tilts away from the direction you’ll move the square. Although most woodworkers feel they have better control pushing the gauge, there’s no reason not to pull it if this feels better to you.

Steady, even pressure

A marking gauge will accurately scribe parallel lines as long as you use steady, even pressure to hold the fence firmly against the edge of the workpiece. If you don’t, the pin can and will wander. Pressing firmly will also keep the beam parallel to the surface, which will prevent the pin from scribing at an angle.

CUTTING GAUGE

A cutting gauge is very similar to a marking gauge except that instead of using a pin to mark the work-piece, it uses a knife. The advantage to this is that the knife cleanly cuts through the wood fibers instead of tearing them, as a pin does. This makes a cutting gauge the tool of choice whenever you need to mark lines across grain.

You might then think, why not throw out my marking gauge and just use the cutting gauge? Because since the knife of a cutting gauge leaves such a thin, crisp line, it virtually disappears when you use it to scribe a line along the grain. Shop-Tip: To create a “universal” marking gauge, some woodworkers file the point of their marking gauge to a finer point. This does an adequate job of marking both with and against the grain, but is still inferior to results from the individual gauges.

Basic use

The technique for using a cutting gauge is virtually identical to that of the marking gauge, with one exception: Take care to use very light pressure. If the knife is sharp (a few licks with a diamond hone will bring it to a crisp point), it’s easy to cut deeply into the wood, leaving cross-grain scratches that can be a hassle to remove.

MORTISE GAUGES

A mortise gauge has two pins instead of one to simultaneously mark out two parallel lines. It’s designed specifically to lay out the cheeks of mortises and tenons. One of the pins is fixed, while the other is independently adjustable.

In some cases, this pin adjusts via a simple pull slide; on others there’s a thumbscrew or knurled knob mounted to the end of the beam. Many mortise gauges also feature a third pin on the beam opposite the two mortise pins. This allows the mortise gauge to also function as a marking gauge.

Setting the pins

The first step in using a mortise gauge is to set the pins. To do this, hold the mortise chisel up to the pins, adjust the traveling pin over to match the width of the chisel and lock it in place. Then slide the fence over so the pins are set the desired distance from the edge of the workpiece. Try the setup on a scrap piece first and check the layout with a rule. Readjust as necessary.

Basic use

Just as with the marking gauge or the cutting gauge, the critical thing here is to firmly press the stock up against the edge of the workpiece. All you’re looking for here is steady even pressure. Popeye-like strength will only cause problems – most commonly, excess pressure will shift the position of the traveling pin or the beam. Use a light, firm grip, and tilt the gauge away from the direction of movement.

PANEL GAUGES

A panel gauge is basically a wood marking gauge that’s designed to handle big panels. The difference is the beam is much longer (typically 15″ to 30″) than a standard gauge and the fence is much wider. In the past, panel gauges were often made of mahogany with brass wear fittings. You can also regularly find antique panel gauges on the Internet at various sites, running anywhere from $20 to $40 for a gauge in good condition.

Two hands

Using a panel gauge is definitely a two-handed operation. After you’ve loosened the thumbscrew (older versions often use a wedge to lock the beam in position) and adjusted the pin or knife the desired distance from the edge, lock the beam in place. Then press the fence firmly against the edge of the workpiece with one hand while you apply light downward pressure to the pin or knife with your other hand. Move the gauge slowly with steady even pressure.

Cutting disc

Instead of a pin or knife, the Bridge City panel gauge shown here uses a cutting disc. The disc is made of hardened steel and is beveled to help pull the fence into the work-piece as you move the gauge along the edge of the workpiece. This leaves razor-sharp lines with no tear-out, even when your cutting across the grain.

DOVETAIL GAUGES

A dovetail gauge (or dovetail marker) is a single-use tool that’s designed to lay out the pins and tails for dovetail joints. Quality dovetail gauges will offer the two most common angles for dovetails: a 1:8 slope for hardwoods and a 1:6 slope for softwoods. If you generally use these two slopes, a dovetail gauge or set of markers like those shown in the top photo will serve you well (the gold marker is for hardwoods, the dark marker for softwoods). If you prefer to set your own angles, a bevel gauge is a better choice.

Tails

To use a dovetail marker, first use a marking or cutting gauge to set the depth of the tails to match the thickness of the wood. Then carefully lay out the tail spacing. Position the dovetail marker so it aligns with one of the marks and so the slope is in the correct direction. Then use a pencil or marking knife to mark the side of the tail. Flip the marker over and mark the opposite side. Continue like this until all the tails have been marked. Depending on how you cut your dovetails (I always cut the tails first and then use them to locate the pins), you may or may not want to mark the pins at the same time you lay out the tails. Whichever method you choose, align the marker with the layout marks that you made on the end of the work-piece and mark their location with a pencil or marking knife.

BEVEL GAUGES

A bevel gauge (or sliding T-bevel) is an invaluable layout tool in the shop. You can use it to verify angles, set tools to match angles, and lay out virtually any angle. Most bevel gauges feature a metal slotted blade and a stock or body made of wood, plastic, or metal, available in a variety of sizes. The blade conveniently slips into the slot in the body for storage. The blade is locked in place by tightening a thumbscrew, wing nut, lever, or knob at the base of the stock.

Duplicating an angle

A common use of the bevel gauge is to duplicate an angle so that you can reproduce it. To do this, loosen the thumbscrew or wing nut so it’s friction-tight, and press the stock of the gauge up against the edge of the workpiece. Then angle the blade until it rests on the angled end of the workpiece. Tighten the wing nut, and then use the gauge to duplicate this angle on another workpiece.

Setting with a protractor

In many cases you’ll want to set the bevel gauge to an exact angle, or read the angle you’ve just set (such as when you’re duplicating an angle). The most accurate way to do this is to use a protractor. The critical point here is to make sure that the blade of the bevel gauge intersects the base of the protractor exactly on center. Then either adjust the blade to the desired angle, or read the angle of the blade.