Part of Lesson Plan: How to square a board using machine tools.
Activity Overview / Details
Now it's time to take the students into the lab and demonstrate the four steps.
First, gather the students around the jointer and explain to the class the reason why the process begins at the jointer. Tell the class that they must first start by straightening one edge just as they did when making the oval paper square earlier. Demonstrate how to joint one edge of the board while reviewing safe practices. Instruct students to check for accuracy by measuring the angle of the face in comparison to the edge and looking to make sure the edge is straight by placing it along a straight metal surface and sighting along its edge while looking for gaps.
Second, gather students around the table saw and explain why ripping to width is the next step. Take a moment and explain to the class that they simply cannot joint the other edge. It would not be parallel to the first edge. Demonstrate how to place the joint edge against the rip fence and set the fence to the desired width to be cut. Rip the board to width while reviewing safe practices. Reinforce the idea that ripping makes the two edges parallel. Check for accuracy as you did with the jointer above.
Third, gather the students around the power miter box or radial arm saw and explain how this machine is used to square one end similar to when they cut the oval paper earlier. Demonstrate how to trim a small amount off one end of the board while reviewing safe practices. Check the end with a tri square to see if the end is square to the face and the edge. Mark this end with an X.
Finally, explain how this fourth step is like the final step when cutting the paper. Measure from the trimmed end to the desired length and make a mark. Square the mark with a tri square and demonstrate cutting the board to length at the power miter box while reviewing safe practices. Reinforce the idea of cutting on the waste side of the squared line and to check for accuracy using the measuring tools.
Check for understanding by having students review the above four steps and why they must be done in correct order.