Contour Gauges, Scribers, Calipers and Wood Moisture Meters

A tape measure tells you how long. These tools handle the jobs a tape can’t: copying a shape, fitting something to a wall that isn’t straight, matching one part to another, and telling whether the wood is ready to build with. WBC carries a set of General Tools layout tools for each of those, plus scratch pads for keeping the numbers.

Copying a shape: the contour gauge

A contour gauge is a row of thin pins in a holder. Press it against a shape, a door casing, a baseboard profile, a pipe coming out of the floor, and the pins slide to take its exact outline and hold it. Lift it off carefully, lay it on your flooring or trim, and trace.

That’s the tool for cutting flooring or tile around a door casing, matching a piece of old trim you need to patch in, or notching a board around anything curved. The General Tools 837 contour gauge does it without guessing and recutting.

Fitting to a crooked wall: the compass and scriber

Walls are never straight, and a cabinet, a countertop or a shelf pushed against one shows the gap. Scribing fixes it. Set the cabinet in place, open the scriber to the widest gap, and run the point along the wall while the pencil traces the same wavy line onto the cabinet edge. Cut to the line and it fits the wall.

• General Tools 843 compass and scriber: a compass with a pencil opposite a sharp point, for scribing and for drawing circles and arcs.
• General Tools 842 compass, divider and scriber: adds two-point divider use. A divider walks off equal spaces, so you can split a board into equal sections for spacing balusters, shelf pins or a row of holes, or transfer a measurement exactly without reading a ruler.

A sharp scribe point marks with very little pressure, so keep a light touch.

Matching parts: outside calipers

The General Tools 452 6-inch outside caliper has curved legs that close around the outside of a part. Set it to one piece and check the next against the same setting, no numbers needed. That’s how turners match the legs of a stool or the spindles of a railing, and it’s handy for checking a dowel against a hole or a pin against a bit.

Checking wood before you build: the moisture meter

Wood that’s too wet moves after you build with it: it shrinks, cups, cracks, opens joints, and can grow mold. The General Tools MMD4E digital moisture meter tells you the moisture content of a board before you put work into it.

This matters around here. In Libby, January humidity reaches 94 percent, and lumber stored outside or in an unheated shed takes on moisture. Bring that wood into a heated house to build cabinets, trim or flooring, and it dries and moves. So:

• Check it, then let it acclimate. Bring the wood into the room where it’ll live and let it sit until the meter readings settle, before you cut.
• Take several readings across the width and down the length of each board. One reading is one spot.
• Read dry wood, not a wet surface. Surface water from snow or rain gives a false reading.
• Know the target. Flooring and furniture often call for 6 to 8 percent; framing lumber runs higher. The product you’re installing will say what it wants.

A pin meter pushes two small pins into the wood, which leaves two tiny holes, so test on a face that won’t show, like the back side, away from the ends, which dry faster than the rest of the board. And a display that shows tenths of a percent doesn’t mean the reading is that exact.

Keeping the numbers: scratch pads

WBC carries carpenter scratch pads and a 4-pack of tape measure scratch pads made to ride on your tape measure. Write the measurement where you took it, and it’s there when you get to the saw.

The Pick

For flooring and trim cuts around casings, the contour gauge. For fitting cabinets and counters to the wall, the 843 compass and scriber, or the 842 if you also lay out equal spacing. For matching turned parts, the 6-inch outside caliper. For any wood that’s been sitting outside or in an unheated building, the MMD4E moisture meter before you cut.

Frequently Asked Questions

What is a contour gauge used for?

Copying an exact shape, like a door casing or a pipe, so you can trace it onto flooring, tile or trim and cut it to fit the first time.

How do you scribe a cabinet to a wall?

Set the cabinet in place, open a scriber to the widest gap, and run the point along the wall so the pencil copies the wall’s line onto the cabinet. Cut to the line.

What moisture content should wood be before building?

It depends on the job. Flooring and furniture often call for 6 to 8 percent; check what the product or the job requires, and let the wood acclimate to the room until the readings settle.

What’s the difference between a compass and a divider?

A compass has a pencil opposite a sharp point, for drawing and scribing. A divider has two sharp points, for transferring distances and stepping off equal spaces.