To scratch a line at an angle of 25° to the edge of a bar of metal, you can follow these steps:
1. Select the location where you want to scratch the line on the metal bar. This will determine the starting point of the line.
2. Place a ruler or straight edge along the edge of the metal bar. Make sure it aligns with the starting point of the line.
3. Use a pencil or a scribe tool to make a small mark on the metal bar at the desired angle of 25°. You can measure this angle using a protractor or refer to a guide that indicates the angle measurement.
4. Hold the ruler or straight edge firmly in place, ensuring it aligns with the mark you made in the previous step.
5. Take a sharp object, such as a metal scribe or a scratch awl, and carefully scratch along the ruler's edge or straight edge, following the desired angle of 25°. Apply gentle pressure to create a visible line on the metal surface.
6. Continue scratching along the ruler or straight edge until you reach the desired length of the line.
Remember to be cautious while scratching the line to avoid damaging the metal bar or injuring yourself. Also, ensure that the ruler or straight edge is securely held in place to maintain the accuracy of the angle.