What is the recommended material for checking the countersink tool?

The recommended material for checking the countersink tool is a piece of scrap material. Using scrap material allows the mechanic to evaluate the effectiveness and accuracy of the countersink tool without risking damage to any finished components or assemblies. This practice can also help in ensuring that the countersink depth is appropriate for the specific application, such as allowing for proper rivet head seating or providing adequate clearance for screws. Scrap material is typically inexpensive and easily accessible, making it an ideal choice for this kind of testing. Additionally, testing on scrap reduces the chance of wasting critical materials or incurring costs due to imperfections that could arise during use on an actual part. This method also allows for adjustments to be made safely if the countersink tool does not perform as expected.