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Picture of Marking Gauge for a Perfect Circular Saw Rip Cut

This easy to make tool is used to perfectly position a straightedge guide for a circular saw rip cut.
When I rip a long plank I usually use a straightedge clamped on both ends and slide along it with my circular saw. The problem is the accuracy of the position of the straightedge. Positioning the straightedge is a multi step process with some math first :

  • measure the gap between the saw blade and the edge of the saw shoe
  • add it to the size of the expected cut
  • mark the result on both end of the plank
  • position your straightedge and clamp it

Each of those steps may introduce errors or inaccuracy and you may end up with a cut that is not perfectly parallel to the reference border and has not the exact width you were expecting.

With this marking gauge, you:

  • eliminate the math part
  • make sure both ends are perfectly positionned
  • can easily verify the position once the straightedge is clamped
  • see exactly where the cut will be

optionally use it as a "regular" mortise and tenon marking gauge.

Step 1: Tools and Materials

Picture of Tools and Materials

Materials:

  • left over pieces of wood. (I used oak for mine)
  • one 5mm screw
  • one metal washer and small wood screw (optionnal)
  • some glue

tools:

  • saw (mitre saw is perfect)
  • drill
  • circular saw
  • straightedge guide (I use a cheap aluminum masonry straightedge for those long edge rip cut)