‘Z’ Zero – Top of the Material or Bottom?

This is quick walkthrough on how to not cut through your spoil board

When first getting set up on your machine you may find that even after touching off your tool you are cutting above your material or through your spoil board.  This is often caused by choosing the inappropriate setting in your CAM program.

In nearly every CAM program you will decide where to set your origin, and specific to the Z, you will need to decide whether you are referencing the top or bottom of your stock material. Which is the better choice? Generally speaking, if you have a fixed tool touch-off point with a vacuum table and/or if you are cutting through the material, you want to reference the bottom of your material (top of the spoil board).  If you are doing detailed engravings you may want to reference the top of your material. What does this mean when I run a file on my machine? When you attempt to run the file on your CNC machine you need to remember whether you’ve used top or bottom, and when setting your Z Zero on the machine you should match those settings. If you choose to reference the bottom of the material in your CAM software you should set your Z Zero to the bottom of the stock material on your machine (top of the spoil board). Conversely, if you choose the top of the material as your reference point you should touch your tool off to the top of the material.  This will require either a movable touch-off puck or manually touching off the tool.