Cutting Straight with a Circular Saw or Jig Saw

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• Filed under: Furniture Building Tips

Building furniture plans, or doing any woodworking, means at some point you need to cut straight edges. My rule for choosing the right tool to cut with depends on the length and type of cut. If the cut is to be a straight cut for more than a few inches on an edge, the circular saw is the only way to go. It cuts far faster than a jigsaw, and doesn’t change angle very quick as you’re pushing it along. If the cut is curved or only a few inches, I’d go for the jigsaw because it is easy to maneuver and gives a clean edge. I would mention table saws here, but they are quite expensive for the occasional woodworker.

This post deals with cutting straight edges using a circular saw. In my experience, I would much rather cut really long pieces (like over 3 feet) with a circular saw rather than a table saw - its much easier to handle a small circular saw rather than a huge piece of board! The choice of buying a circular saw is outside the scope of this post, but many resources are available online.

The easiest way to cut straight is to clamp on a straight edge of some sort. I like to use extruded aluminum from some door framing (I found some in my basement), or use the machined edge of a piece of plywood, or even a piece of dimensioned lumber like a 2×4. The key of using anything is how straight the piece is, and where it is clamped to the workpiece. How straight the piece is depends on what you’re using. Where you clamp it is what the rest of this post will discuss.

For either a circular saw or a jigsaw, the critical measurement is the distance between the edge of the base plate and the end of the cut from the blade (see fig 1 and 2 below). This is the distance you need to clamp the inside edge of your straight guide. The fastest and most accurate way to measure this distance is to take a piece of scrap wood and cut it with the circular saw, and measuring where the edge of the base plate is to the edge of the cut. Take your time here.

Now using the same piece of scrap wood, try clamping on your guide, measured off a line you want to cut to. Take a cut and see how accurate you were. That’s it!

There are quite a few different guides on the market, but this way is far cheaper and great if you’re just getting into woodworking, or don’t have much coin. The main point to remember is that clamping wrongly will cost you in extra materials in the end.