What should you do after you suspect the metal is at the solder's melting point and have placed the flame at the center?

When you suspect that the metal is at the solder's melting point and have directed the flame to the center of the joint, the correct action is to touch the solder to the bottom of the joint. This approach allows the solder to flow into the joint effectively. The heat from the joint, which has reached the solder's melting point, helps the solder to melt and fill any gaps, ensuring a good bond between the components.

Positioning the solder at the bottom allows it to be drawn into the joint by capillary action as it melts, promoting better adhesion and continuity of the connection. This is a key step in the soldering process as it ensures the integrity and strength of the joint once it cools and solidifies.

In contrast, moving the flame to the side can disrupt the heating process, potentially preventing the solder from melting evenly. Removing the flame immediately may not give enough time for the solder to flow properly, while increasing heat may risk overheating and damaging the components or the solder, rather than facilitating a proper join.