Woodshop Wednesday: 5 Ways to Cut a Straight Line

Wouldn’t it be great if you could buy your construction materials already the right size? Studs and sill plates and headers all cut perfectly for your job, exactly the right number of 22½-inch blocks, plywood pre-cut to fit around windows and partial shingles to cover your roof precisely? I’m sure you could actually do this, assuming you found the right supplier and paid the right price… but that solution is not only expensive but also impractical because field conditions require new dimensions all the time. Fortunately, carpenters have lots of ways to cut straight lines in the field and create the sizes they need. Here are five methods I’ve found useful while building this house.

The chop saw.

The chop saw.

1. Use a chop saw. This blade cuts through all types of lumber, plywood, PVC, foam… pretty much anything on site except metal and masonry. It’s very fast and precise, but it only works for long skinny materials, with a maximum cross section of about 12 inches by 4 inches. Just mark a point at the desired cut length and set the blade angle to 0 degrees; the cut comes out perfectly straight all on its own.

Uncut foam, ready for a trip through the table saw.

Uncut foam, ready for a trip through the table saw.

2. Use a table saw. If the chop saw cuts across the street, then the table saw cuts down the road. You can set the depth of the cut and the desired width of the cut piece, up to about 12 inches. Then, feed your material through, ideally with a partner to catch on the other side. Like the chop saw, this blade cuts straight automatically and works great for anything softer than a rock.

Colin follows the straightedge on a framing square to cut shingles.

Colin follows the straightedge on a framing square to cut shingles.

3. Draw a line with a straightedge. When you’re cutting something that’s too wide for a stationary saw, or immobile, you’ll need to draw your own straight line. The simplest way to attain a straight line is with a carpenter’s square or a larger version called a framing square – both tools have a right angle you can hook on the edge of the piece you’d like to cut. Use a pencil to draw a line, then cut along it with the most appropriate blade… a utility knife for shingles, a circular saw for plywood or large lumber, a masonry blade for concrete.

Terry and Colin snap a chalk line.

Terry and Colin snap a chalk line.

4. Snap a chalk line. Sometimes even a framing square is too short to make a consistent straight line. In this case, measure the location of the cut line and mark a few points on it. Then get a chalk box, hook one end of the string on your material, and pull the string taut over the cut line. Snap the string to leave a beautiful chalk line. Finally, cut along the line, again using whichever blade makes the most sense.

Tracing one piece of plywood onto another.

Tracing one piece of plywood onto another.

5. Trace a pattern piece. If you need to cut lots of materials the same size, you can save time if you measure and cut just the first time. Then, align your cut piece above the next piece and trace it. Repeat as often as you need. No need to use your framing square or chalk box every time – just keep your pattern handy!

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