Hi all,
Until another board arrives, I have some UNO CNCshield v3 lying around. Is there any good setup to beef up a K40 with that? Also, any schematic to do a middleman adapter.
I’ve lost an while searching out there but I only find “chitchat videos” of how cool is this or that but no a good old blog with connections and schematics.
Thanks!
@donkjr is the man for that
@Jorge_Robles here is an index:
Thanks @donkjr I will take a look 
Seems you are using smoothie, any chance where to get info on cncshield? Seems it uses inverted pwm signal
If I’m not mistaken the Z endstop will fire the laser. I need to do it myself
@Jorge_Robles if you point me to a schematic and code I can see if I can advise you on wiring PWM
You can invert the pwm signal in grbl. You need to change the code spindle.c where you can initialise the pwm timer register. Also atmel has a datasheet on how to do that on their website
@Jorge_Robles Here is a good link about interfacing that board;
http://diy3dtech.com/?s=cnc+sheild
Also when you say “invert the PWM” are you referring to interfacing with the “L” input? If you control the laser with the “in” input (where the pot is) you do not need to invert the PWM signal but will need to invert the laser “on” signal to trigger the power supply “L” input. You can use Peter’s inverter or if you are comfortable with programming, this can be done in the GRBL config.h file. Also be aware that the signal pins have changed from GRBL v0.8 so if you are going to use the newer GRBL then you will need to adjust the board’s pin out accordingly.
Thanks @HalfNormal , yes “Inverting PWM” was about the L input. I think will use the inverter, but have to get the model of transistor and resistance values. Anyway, I’m doing this all on my head. I’m sure I will have a bunch of questions when unit arrives.
When you say interfacing with “in” input, I guess L controls Enable (M3), and IN is the PWM (Sxxx) real signal?
Yes on interfacing.
And a so noob question. The pot limits the voltage delivered to the laser. Do I have to connect the PWM signal to the pot and then to the IN?
Best to remove the pot.
ok, remove, but keeping the mA meter? So you have a reference o maximum mA (tube lifespan). I’m going offtopic, sorry 
Yes keep the meter
hmm I’ve seen Smoothie boards use 3.3v PWM and arduino Uno GRBL 5v, should it be a problem? Should I have a level shifter?
“In” uses 5 vdc
I mean if I ever get a Smoothie one, is needed a Level shifter to take in account isn’t it? (sorry the confusion)
@Jorge_Robles i use a switch so i can choose between the pwm and pot which is useful when cutting. However most cnc software let you tune the pwm output in steps of 10% increase on the fly
@HalfNormal grbl1.1e works really nice in laser mode.
