After setting zero, when I start a job, the Z ganty rises all the way to the top and hits the gantry then stops and hums for a few seconds while the numbers change. After that happens all my Z moves are off and the bit plunges deep into the wood. How can I stop this from happening?
@Ismael Z does not really rise all the way to the top. It rises by a preset amount and if that takes it to the top, then, as you say, Z gets messed up. This will frequently happen when the material is thick, so your Z travel is already limited. The key to moderating this is to make sure that your router is held in the clamp to give you the most travel possible. That will mean that the router is high in the clamp for thick material and low in the clamp for thin material.