DIY $12 air assist

For anyone interested here’s some details on a $12 DIY air assist to automatically power on the air pump and exhaust fan once a file is begun and shut them off when complete. On my RD3445G controller, the 6 pin CN1 is the air assist module. During operation pin 6 (+24V) and pin 4 (Status) output 24vdc. I had expected to use pin 5 (Wind) but found it outputs 24vdc only when the laser is firing ie between every raster line engraving it would briefly shut off then back on. Pretty sure the equipment would hate that. Luckily pin 4 outputs continuously until the file is complete.

Once I figured this out all I needed was a $12 relay from Amazon. I got a 10a relay with 24v coil, and spliced it into the red (neg) 120v wire of one of the integral 120v outlets on my laser. Wired the coil to pin 4 and 6 of CN1 and tested- total success. The wiring of the built-in 120v jacks are a pitiful 18awg, but my pump and fan together pull 3a so its sufficient. I also wired a rocker switch ($2) directly to that outlet so that I could have manual control of the equipment if I needed it.

The only difference between this and the much more expensive and labor intensive “Ultimate Air Assist” is that it apparently automatically decreases the air flow during engrave and maxes it during cuts. Anyways- thought I would share as it took a bit of head scratching but ultimately worked out perfectly.

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Hi … Thank You for sharing your findings … I have ordered the Cloudray Ultimate air Assist and was hoping to find a way to turn a separate Air Solenoid on and off that is hooked up to my Shop Air … would you happen to have any insight how I could accomplish that ? … The Solenoid is 24v

I was thinking that there is a setup to start an Aquarium Pump … could I use the same wiring setup ?

Any help would be most appreciated


The Ultimate air assist kit comes with a 7A 24vdc relay as I recall, which means you can power 7A of equipment from that relay (safely 5.6A using the 80% continuous rule). I can’t see any reason for a second relay. If it is wired to the air assist output of your controller it will fire at the exact same time so a second relay would be redundant. There are multiple wire paths on the relay if you want to split the signal. Just be sure all components are properly sized for the current draw of your equipment.

Do you happen to have pictures of your modifications?

Here’s shots of the relay and linked outlets, control wires from RDC6445G, and manual switch. On the relay the yellow pair go to the controller pins 4 and 6 (+24V and Status). The blue wires go to a manual switch by the control panel of my laser. The red wires show the relay spliced into the 120V neg (hot) wire of the topmost 120v outlet on my machine. Hope this is clarifying.

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Thank You for the pics … I’m hoping my Ultimate air assist kit comes in soon … I’ll do a dry setup and ask if it looks good before I fire it up … I’d really rather not burn up my Controller !!! :slight_smile:

Take Care


Keep in mind software (LB) and controller settings play a role. Ie green “air assist” button in LB cut settings editor as well as controller settings such as “if blowing: YES”.

Thank you for the images!
It does clarify a lot for me :slight_smile:

Hi Mike … thank you … I have an air solenoid working on my shop air now … I just wanted something to control low air … after doing some more research it looks like the Relay on the Cloudray Utlimate Air Kit is to control the air pump … it’s 24v so I’m thinking I can us that to control the Solenoid on my Shop air Line ?


Brian check out this video of the inventor of the Ultimate Air Assist describing the wiring of his original build.

As he describes it- full air is sent for cutting processes but a second relay closes most of the air flow during engraving processes. From my tests I don’t see how this could be done as I didn’t notice a difference in the output to the various terminals under cutting vs engraving but my tests were not exhaustive as I was not trying to enable that feature.

also here’s another helpful youtuber who recorded his process of installing the UAA

Hi Mike … yes I’ve seen both those videos … really good ones … the last one was where I got the idea that the Relay could control the Air Solenoid on my Shop Air.


@rythmik thank you for the video Links. Russ is the man! this man has done so much for the advancement of Chinese lasers into the main stream along with his numerous inventions that have come out of it.

Not sure the super expensive laser machine manufacturers… like Russ very much. : I am certain they are not happy :frowning_face: that they have lost the dominance :money_with_wings: : they once enjoyed during the 80’s and 90’s.

I appreciate seeing individuals like yourself that share their knowledge with others.
We all bring something to the table I appreciate all members in our forum.

Cheers :beers:



My laser always use this function. laser out exhaust fan work + air pupm work . or laser stop all stop. no more noise.
and I add air pressure regulator on the laser, it is easy to contorl the air for cutting or engraving.

Kind of you to say Mr. Snowman, thank you. Yes Russ is a joy to watch- brilliant hacker, zero hype. And I appreciate your tip in another thread about the unsharp mask for photos- huge difference. Cheers.

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