Z Axis not correct after multiple tool changes

[WillAdams (William Adams (Carbide 3D))]

See:

New Terms for a Newbie - "Adding Geometry"

I see lots of references to “adding geometry”. I have searched all over the internet for a simple explanation of what that means, and have come up empty.

and

Adding geometry to cut as a pocket with a finishing pass

One technique which is often suggested to avoid slotting is to add geometry around a part which one wishes to cut out and cut as a pocket down to tab depth — here’s one technique for that. In this case, the project is a bevel gauge which will be cut out of 0.0625" (~1.5mm) thick aluminum: [bevelgauge] Due to the narrowness of the angles, an 0.03125" endmill has to be used, so after importing and scaling the file (we will be cutting out one which is 3") we select the perimeter and offset it tw…