Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: rabso on October 31, 2022, 08:52:10 AM
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Hi everyone,
This is my first post in this forum but I have been around reading and learning, thanks to all
I have built my diy CNC and everything is fine using Mach3 with USB control board. Recently, I decided to add a laser to my machine, and I managed to make it working ok, but I have issue with early laser turning off.
Let me explain the wiring, I had to use relay as the laser needs 12v, and it's controlled by an output pin (M3/M5).
I have connected PWM pin with the laser to control its power (using S command).
As relay has some delays, I couldn't use command M11/M10. Instead, I used M3 command to turn on relay (laser is powered now) with S0 command to make no beam firing, then I used PWM to turn on/off the laser beam; S0 to cut it off and S10~S100 (depends on power I need) to turn on.
I have created a test G-code that make 4 lines with different feed rate each (start from left slowest) as follow:
(1001)
G90
G64
G54
G43 H65
M3 S0
G4 P2
G0 X-5. Y-10.
S100
G1 Y10. F100
S0
G0 X0. Y-10.
S100
G1 Y10. F200
S0
G0 X5. Y-10.
S100
G1 Y10. F300
S0
G0 X10. Y-10.
S100
G1 Y10. F400
S0
M5
G0 G53 Z0.
G0 X0. Y0.
M30
The result is that the higher feed rate I use the earlier laser will turn off as per attached photo, is this delay a limitation with mach3 same as M3/M5 as well? I have tried to write some text, but it will not connect lines as it's cutting off early.
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IMHO you will have no luck with using M3 and S commands to control your laser properly
because these commands are not syncronized with motion commands.
the only two possibilities i know are:
- use M10/M11
- use the direction pin of a virtual axis (A/B/C) to switc laser on/off
there are o lot threads about this problem here on the board.
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So, S command is behaving similar to M3.
I read several topics about M3 delays and possible solution. Unfortunately, I can't use M10/M11 commands as I am using a relay for laser power and relays have delays.
I am thinking of an idea to play with PWM signal; it's to use an output pin and connect it to laser PWM input, then activate it by M10/M11 commands. So, M11 = 5V mean 100% duty cycle (max power) and M10 = 0V mean zero duty cycle and beam will cut off. But I will not be able to control laser power level, so I will buy PWM Controller Module (same this https://www.aliexpress.com/item/1005003293196150.html (https://www.aliexpress.com/item/1005003293196150.html)) to control laser power manually. Hopefully it will work ok.
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here:
https://www.machsupport.com/forum/index.php?topic=12444.msg265104#msg265104
Tweakie explained how to control this with a small pcb board.
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I saw his post and as am civil engineer so really nothing I understood, D
I sent it to my brother maybe he will help. Moreover, I purchased the PWM module to try it and will post my result.
thank you
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It is possible to use a relay and use M10/M11. You need to figure out your ports and pins setting. I use it this way and it works well.