37 .-- Front view of shearing tool with test specimen and steel plate in position for testing.] _Preparing the material_: The specimens are usually in the form of small, clear, straight-grained blocks with a projecting tenon or lip to be sheared off.

Two common forms and sizes are shown in Figure 38.

Part of the blocks are cut so that the shearing surface is parallel to the growth rings, or tangential; others at right angles to the growth rings, or radial.

It is important that the upper surface of the tenon or lip be sawed exactly parallel to the base of the block.

When the form with a tenon is used the under cut is extended a short distance horizontally into the block to prevent any compression from below.
[Illustration: FIG.