How to avoid z axis exeeded?

So today I faced my spoilboard I put another one on top faced that as well.

I wanted to cut an edge and keep getting z axis exeeded …I had the spoilboard dig in feature at 0.125"

I disabled it …again getting z exceeded.

I enabled it again now with 0.5" and now it cuts…so I disable it should it not avoid the z axis msg?

Tnx!