The contour gauge may be the best kept secret in carpentry. When you need to cut a piece of flooring to fit around a piece of trim, or copy a piece of trim that you can’t buy anymore, a contour gauge lets you do it. Here’s how to use a contour gauge.
What is a contour gauge?
A contour gauge is a profiling tool that just consists of a bunch of sliding plastic or metal probes that conform to a surface when you press up against it. Using it, you can duplicate any outline, no matter how intricate or complex.
There are kids’ toys that operate on the same principle, saving the profile of your handprint or faceprint. Most stores that carry tools have them. Home Depot sells a reasonably good one for around $9. Harbor Freight also carries one, and it’s a good deal if you can use a coupon on it.
For a lot of people, the trick is knowing what to ask for. A contour gauge makes laying flooring or tile much easier, though it has other applications too.
Putting it to use
Press the contour gauge up against the piece you need to duplicate. Double check your placement, and if you’re not happy with it, repeat until you’re happy with the placement.
Then place the gauge up against the edge of your workpiece, check your placement to make sure it’s flush and square, and trace its outline with a pencil or a permanent marker. Then cut out the outline in your material with a saw or knife, as appropriate. For thinner materials, a utility knife may be most appropriate. For thicker materials, a jigsaw may be most appropriate. For metals, you’ll want to use a metal shear.
If you need to trace onto the underside of your material, you can do that. Simply flip the gauge over to invert it, then trace onto the material. I prefer using the underside, because then any stray marks aren’t noticeable. It’s also generally better to saw from the underside than from the top. You get a smoother cut that way. But if you want to mark on the front, here’s how.
After you cut out the profile you copied, place your workpiece into place. You’ll find it fits very well. If not, typically it will fit with some very minor filing. The tool will pick up those slight imperfections where the piece isn’t quite as straight or square as it appears to be. Picking up those imperfections is key to gettting a really good fit.
If this is your first time using a contour gauge, you may want to test on a scrap piece first until you get the hang of it. That way you can avoid wasting material.
I’ve written before about how to improvise without a contour gauge using paper. But using a contour gauge is faster and more appropriate for thicker materials.