[ssutton]

Just starting to plasma cut material and I have a newbe question regarding zero of the Z axis. Normally (in router mode) I home my Z axis, then home my Y axis and then my X axis. I have homing sensors on all my axis.

What do I do in plasma mode??? In other words I know that I still home Y and X and set a zero position so that my job starts at the right location according to my material position but I am not sure what to do with the Z axis.

My machine is set up with a floating head and when I click "Z home" it goes down until the head switch makes, then it reverses until the switch opens back up. Do I do anything further after that? Do I input a 0 input the Z position? Does SheetCam simply use the switch offset value in the edited post and I do not even have to home the Z axis manually?

Lots of questions and looking for answers.... Thanks in advance

Scott Sutton

[Torchhead]

Z "home" on plasma is the top of the material. You need to make sure the home you use for router (up on the Z) is not defined as a the touch off swtich (home) for plasma. You can wire them in parallel (NO) and in the MACH profile just change the homing direction (up for router and down for plasma) in two separte profiles.

The touch off sequence for plasma is handled by g-code. You call a G28.1 Z## (## is the slowdown distance) and it moves tot he swtich and stops. Then you have to move it UP the switch offset value, and reset the Z to zero in code (G92 Z 0.000) THEN you lift to pierce height.


All of our posts have the auto touch off sequence buitl in and only need you to put in the SwitchOffset value (typically in mm on most posts).

Settign the swtich offset number is covered in detail in the DTHC Setup and Config manual. The connection of the input to Z home is covered in the BladeRunner Manual in the last section. You cannot have two homes at the same time defined in MACH on a single axis. Since plasma cutting is done hovering above the metal a fized distance you have to know where the top of the materials for an accurate piece and initial cut height at the start. After the DTHC takes over *(after DTHC Delay time) it will follow the material up and down and the Z keeps track of all the moves but it is all reality to where it started. The cut HAS to start at the right height every time and if the top of material changes to only way it can do that is to reach out and "feel" for the material BTW there is a setting in the POST called RefDistance that defines (inmm) haw far the XY can travel before it preforms an auto touch off. The concept is that if you are making alot of small close cuts you can control how often the touch off happens to speed things up.