The two most common reasons which cause the CNC machine to cut above the workpiece surface are the Job setup in V-carve and the Z-axis hitting the bottom travel limit.
Take care when setting up the project in V-carve and when establishing the physical Z origin on the machine. Ensure both match each other. When creating a project in V-carve you are presented with the Job Setup screen. The Z Zero Position you select should match where you are setting the machine’s physical Z zero position. The Machine Bed selection instructs the software to recognize the Z origin position as the deck of the unit. The Material Surface selection instructs the software to recognize the Z origin position as the surface of the workpiece. If Machine Bed is selected and the machine Z zero is set to the Material Surface, this will result in the machine cutting above the material.
To adjust the V-carve project:
- Load the project into V-carve/Aspire (.crv or .crv3d)
- Select Edit, then Job Size and Position
- The Job setup screen will appear
- Change the Z Zero Position to Material Surface
- Then select OK at the bottom
- V-carve/Aspire with prompt you to recalibrate the toolpaths with the new setting.
- Select Yes to recalibrate the settings, then save your .tap Toolpath files again.
- Zero X, Y, and Z on the machine again and the router will cut into your material.
Z-Axis hitting the lower travel limit:
The Z-axis hitting the lower travel limit most commonly occurs when using a V-bit as the tool is typically considerably shorter than an endmill or a ballnose bit. When the Z-axis hits the lower travel limit the machine will still attempt to travel the distance it was instructed resulting in the Z zero position now being higher than it was originally set. (Issue pictured below).
If you are not sure this is the issue you are experiencing, set the project up how you normally would, zeroing X, Y, and Z. Next either move the bit to the edge of the material or move the material off to the side. Then, using the Z minus button, lower the router to the desired depth of the cut and inspect where the bearings on the Z travel are. If it looks like the picture above, the Z-axis bearings have collided with the end of their travel limit.
This can be resolved in several ways.
- Adding another piece of material below the project material being cut will raise it to a position that will allow the machine to reach the desired cut depth.
- Lowering the router/spindle in the cradle.
- For HD CNC machines, installing the gantry at a lower height setting.
If you continue to have issues please contact Technical support.