A fixed base router locks the bit at a set height or position. Many units include small dials that allow the user to make fine adjustments. Once set in place, the bit does not move, meaning the user can set the bit at the exact depth needed. They differ from plunge base routers, which feature spring-loaded arms that lift the motor and bit off the piece you’re working on. In order to work, the user must push the router down onto the material. Releasing the pressure allows the router and bit to lift back up. This type of router allows you to adjust the depth of the cut without needing to turn off the motor. Fixed base routers offer more accuracy than a plunge router base. Because you set the depth beforehand, it allows for little human error. This means they work well for projects that require edging. However, plunge base routers offer more versatility. They allow you to adjust the depth as you work. They can also start a cut from the top or middle of the piece, which a fixed base cannot accomplish. Plunge based routers work well for projects that require a cut from above.