Copy a shape with a contour gauge

What the teeth are really doing

A contour gauge is a row of loose plastic pins in a spine. Push it against a shape and each pin slides back until it stops, so the row ends up holding the outline of whatever it touched. Tighten the lock and the pins stay put while you carry them over to the board and draw around them.

That is the entire idea, and it replaces the job most people do with a tape measure, a calculator and three attempts. Door casings, pipe collars, stair nosings, the curved leg of a radiator. Anything you would otherwise fit by cutting slightly large and shaving down.

Press it square, or the copy lies

The one thing that ruins a reading is coming in at an angle. Held square, each pin stops at the true depth of the shape. Held tilted, every pin stops short or long by a bit, and the outline that comes off the gauge is a shape that never existed.

Push straight in with even pressure across the whole spine, then check the profile against the object before you lock it. Ten seconds of looking beats a cut piece that is close but wrong at one end.

Which length to reach for

We build the gauge in a 5 inch and a 10 inch, and the small one gets underrated. Pipe collars, single moldings and most tile notches live well inside 5 inches, and a shorter spine is easier to press square in a tight corner.

The 10 inch earns its place on wide casings and stair treads. Past that there is a linkable version that joins end to end, so a full doorway or a bullnose step comes off in one reading instead of two that have to be matched up by eye on the board.

Transfer it while it is still locked

The mistake we hear about most is a good reading lost on the walk to the bench. The lock holds the pins, but a gauge dropped in a tool bag or set face down on a stack of offcuts will nudge a few of them, and nobody notices until the cut is already wrong.

Draw the line first, cut second. Pencil the outline onto the material as soon as the gauge comes off the shape, and the reading is now on the board where nothing can shift it. Then the gauge is available for the next opening.

Mark which way round it was

A copied profile looks symmetrical far more often than it is, and a gauge flipped end for end on the way to the board produces a piece that is a perfect mirror of the one you needed. It fits nowhere and the error is invisible until the flooring is down to the last plank.

Put a pencil dot on the end of the spine that faced the wall and draw with that dot in the same orientation. It is a one second habit that has saved us more offcuts than any measuring technique on this page.

Where a gauge beats scribing, and where it does not

The gauge wins where the shape is complicated and the material is easy to cut. Laminate around a door casing, vinyl around a toilet flange, tile against a curved baseboard. All the geometry gets solved in one press, and a jigsaw does the rest.

It is the wrong tool for a long straight run that is simply out of square, because pins only cover their own width and you would be reading the same wall twenty times. Scribing with a compass handles that in one pass. Reach for the gauge when the shape is fussy, not when the wall is merely crooked.