Is there an air assist output on a GRBL CNC3018 board that can be picked up, as currently using the spindle output through digital delay relay board to fire/ activate a solenoid valve, as that picks up low voltage at low laser output levels. The delay is to have continuous air rather than create relay chatter on the solenoid, any help appreciated the board is a Cronos maker 3018 v3 or is this solution not available to use on the board, with selecting the air assist on/off in the cutting strategy selected
I have a Woodpecker control board on my 3018. There is no hardware output that is available when the machine is in the ‘run’ mode that I’m aware of. I don’t know if there are any free ‘pins’ that could be repurposed. Since it’s open source the only possibility would be a software change. You would need an unused pin to access. When the software is updated, say to grbl 1.2, you would have to ‘hack’ the new code to make it run on your machine.
The problem with the spindle is it’s actually driven by the PWM output that drives your laser. Using that would turn off the air every time the laser was off, even when moving to a different burn spot. That ‘infernal clicking’.
I’m afraid with that level of a machine the manual method will probably be it. If you come up with something make sure and post it.
Good luck 
Many thanks for your reply and conformation, I will just have to keep using the timer off delay relay, I have connected to the PWM output, of the spindle, difficult to find due to it needing to react to as little as in some cases less than 3 volt but seems to be ok , with power levels lower it is unlikely that not activating the relay that triggers the air solenoid would be an issue, fairly new to laser engraving, but getting into it, if it becomes a problem I could add a simple 2 way override switch. thanks again for you input
There’s lots of those machines out there. But they are pretty limited in where you can go, as far as expanding the machine. I have a 30 watt SS laser I mount up on mine, but it’s too smoky and smelly. Mostly just use it for CNC PCB construction. Have the China blue in the garage. Not as convenient, but easier to deal with in many ways…
Why don’t you just turn it on before you run the job, then turn it off? Seems like a simple option, in comparison?
Mine runs low pressure anytime it’s running and when I ask for air assist it bypasses the restriction and I get full pressure air for cutting. The little machines don’t have the control outputs needed to automate it. 
Take care, good luck 
I would if i had a garage or place to use it outside the house, not be to bothered , but as its build mainly for the GF to use i had to make it fully enclosed and as automated as possible extraction filter and simple ways to adjust pressure, hi/lo options, and none, as it was found that with very fine detailing the carbon would distort around the line if to high, but needed when defocusing for fill burns.
It has been made so its easily useable, with jigs also standard size parts etc, for part/s placement, it has been quite a project, camera as to avoid opening the door and negate the need for eye protection, the focus is set via a probe so it it always consistent via a conductive print nozzle, that has I found been very useful with different apertures for different levels of details, easily changed. and de focused via z axis movement , for larger fill cutting down cycle times. As many Diode lasers are sold open frame, and pretty much not spare room friendly unless in an enclosure.
I really did not want her to go down the road of using a CO2 laser as for use with craft the users are not so technical aware of the dangers of something that is invisible. but after this I see a lot of 2nd hand open frame lasers on the market , due to people buying them thinking its going to be as easy as a paper printer to use, then the smell hits them and the reality becomes apparent
Luckily all the effort was not totally for a one off as a few of her friends. are asking for one to be built.
And thank you for the reply.
I have both a 30 watt ssd laser and a co2 laser. I admit I spend more time fiddling with it than actually doing anything. But realistically that’s what I purchased it for.
Sounds like you have a nice design with the enclosure and especially your jigs. Many people ask about setting up repeatable systems. You should post some of your efforts. This is helpful to many.
I really enjoy my co2 machine, but it’s top is open most of the time or at least cracked about an inch to allow good air flow towards the vent.
Take care, good luck 
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