Many DIY laser builders come from a CNC background. They have built a CNC mill or router and gained the confidence to try a laser build. They love Mach3 for the CNC, so they want to use it for their laser cutting. There are some inherent problems, but in most cases it will work fine for laser cutting.
The method I am going to describe here uses the E1P0/E1P1 method of laser control. This allows fast turn on/off of the beam without the delays Mach3 adds with spindle based beam control. I have tried many other methods, but this is my favorite for laser cutting. I use manual control of the beam power using a potentiometer with this method.
When Mach3 sees E1P1 in G-Code, it immediately turns output #1 on and will immediately turn it off when it sees E1P0. Therefore, you just need to have a E1P1 before your first feed move and an E1P0 after your last feed move. There is one catch. It appears there must be some actual movement after each E1Px command. If your last feed move ends at your “home”, you won’t be able to turn off the beam unless you move away from home then back. You should be able to setup a post processor for your favorite CAM software to do this. I will detail that in a later blog post.
Before we get started….
Any control system, especially a PC based Mach3 system is not fail safe. Be sure you have an easily accessible e-stop button that will directly stop the beam (not through Mach3). This button should always be in the stop position when you are not cutting. Never leave the cutter alone and always pay attention to it while it is running. An error in any of the multiple circuits and processes could cause a dangerous situation.
Mach3 should always be running when the laser is enabled. The parallel port pins should always be under Mach3 control or they may change to an undesirable state. Like This: Start Mach3, Power up laser, Power down laser, Stop Mach3.
Mach3 allows you to setup multiple profiles. You should use this feature to setup a new profile for this so it does not mess up any others you might have. It stores these profiles in XML files. I named my configuration LaserE1P1. You can get it here (LaserE1P1.xml).
Mach3 setup should have created a shortcut called “Mach3 loader”. The shortcut is just Mach3.exe without any added command line arguments. This lets you setup new profiles. If you already have a profile with all your motors tuned, clone the profile when creating it to make your new one. This will save time . This is the form you should see.
Under the Config…Ports and Pins menu
Select the Motor Outut TAB. Be sure your Spindle is disabled.
Next go to the Output Signals TAB. Enable Output#1 and set the correct Port # and Pin Number.
Next go to the Spindle Setup TAB. Be sure all of the spindle features are disabled.
That is it. You should now be able to try it out. Be sure to do some simple test cuts first, with your hand on the e-stop button.