Laser tool paths

[CNCadmin]

I see that sheetcam allows for plasma, but how would I integrate that in to Laser use? I need to be able to set a % of power and simply turn on and off the laser, all the other feature for a plasma I would not be using.

[locost_cam]

How is the power specified? I assume you use M03/M05 to turn the laser on/off. If you give me the details I am sure I could write a post to suit.

Les

[CNCadmin]

The laser uses TTL for control, I guess mach would treat that as a Z ?

[locost_cam]

I would use spindle to turn the laser on and off. You can use Z direction but you must be careful as it is possible to turn on the laser by accident.

When you say the laser uses TTL, do you mean that it uses PWM to control the power? If so you can use the spindle speed for power control.

[CNCadmin]

Yes it uses PWM to control the power.

[locost_cam]

OK, you can use the Mach2 PWM spindle output to control the laser. If the spindle is turned on the PWM pulse width is set depending on the current pulley selected and the spindle speed selected. For instance if the pulley speed is set to 5000rpm and you specify 3000rpm spindle speed then the PWM would be 60%.

I believe Mach2 has a laser specific feature that turns down the power when the machine slows down for a corner. You will have to look in the manual to find out how to use it though.

If you don't mind setting the spindle speed(power) manually then you can use the plasma THC1 post. This post does not use the Z axis so it is ideal for your purposes. Before you run the code simply set the spindle speed(power) in Mach2. You can then run the code and it will cut at that power.


If this works and you want to be able to specify the power in SheetCam then let me know and I will see if I can tweak the post to suit.

Do you want to be able to take cuts at different depths in one go? If so I may be able to tweak a mill/router post to set the laser power dependent on the feed rate and selected cut depth. I will need to think on that one. Try the plasma post first and we can take it from there.

[CNCadmin]

Well I tried to use that post but so far I can't very the power, still trying to work it out.

[locost_cam]

Have you got any control of the laser power at the moment? You should be able to turn the laser on/off using the spindle on/off button and you should be able to vary the power by changing the spindle speed.

In Mach2, go into Config->Logic and check the PWM base freq is set to whatever your laser needs. If you laser will accept a range of frequencies then use the lowest the laser will accept. This will improve the resolution. If you have an oscilloscope then it would be a good idea to have a look at the PWM output and watch the changes with different spindle speeds.