Neje Max 4 delay Air asist

Hi Guys

I was just wondering if someone could help

I have my air assist connected to m8 and when I start the job the air assist starts immediately

I was wondering if it possible to wait until a the z axis is going into position before it started

I just find that the air can move light weight materials around he bed


I’ve never run across a variable that would alter this.

I use more air assist than most here. I’m at 35psi to achieve 30lpm flow. @jkwilborn is considerably higher than me, but I can’t think of anybody else running quite that much. Maybe @ednisley ? Point being, I’m somewhat familiar with the effects of (perhaps) excessive airflow :slight_smile: .

I secure every single workpiece and often need to use tabs to keep smaller cutouts from dropping partially into the void and leaving a point standing up that can snag the laser nozzle or focus probe. I also use reduced flow on some jobs.

Between those three things, you should be able to get going nicely.

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I’m running 60+ psi and I also secure some things but I make jewellery and currently working with 8-12mm Tassie oak with other timber veneer glued on

I currently create a new layer with 0% power and no air assist and this allows the laser to get into position and lower the z axis before starting air assist

It works but it’s a pain in remembering to put the first layer on the new cut path

I just thought some gcode could be added to when the z offset is starting, that would work for me

Also…if my psi is too high I would love to know the recommended pressure for the type of cuts I’m doing. I bring it down when doing long cuts but most are simple shapes


At 60+, you’re basically blazing a trail of your own. Jack might have some data to share. I can’t really exceed 35 without modification to my laser module. 30lpm was my somewhat arbitrary target (based on some numbers from OPT laser) and I got there. I can’t say if there’s benefit above that or not. Jack must think so… The changes I witnessed going from 9lpm to 30lpm were relatively subtle, but enough that I consider it worth keeping in place.

I got a small speed bump, wider kerf but a bit more depth, too, and the edges are MUCH cleaner.

Regarding the phantom layer, I think you could use sublayers with the parent layer set to no air and 0 power. Save that into the material library and it would be a simple matter to assign that setting to the job.

Edit: No…nevermind. That would still run the whole job. …

Indeed! The piddly pump in my OMTech pushes a dozen-ish liter/min through all that tubing, which suffices for my simple needs.

My flowmeter tops out at 20 l/min from an (extrapolated) 15 psi just upstream of the assist air valves, so I couldn’t check the higher pressures you folks use.

I sympathize with @unstable81, The laser cooling fan downdraft creates a problem sometimes, and nozzle air is worse. On the upside, it also pushes warped ply into the correct focal point when using 100mm x 150mm 1.8mm ply.

I run it out of the compressor at about 60lbs… much more than I need. It seems to cut well with 5mm sub flooring with pools of glue now and then…

Might listen to this guy… it’s about 30 minutes… he seems to simplify it.

This was my stock air pump and ventilation fan, with the top open, cutting 5mm sub flooring


Some great information about pressure but I really just want to know if there is a gcode I can add to change when air assist starts


Sorry to step in.
Maybe you can try with a Custom GCode machine.

Looking for how to delay the other end. I have built a ventilated box and use M8 for both Air assist and 12V fans inside the box. It would be nice to have 30-60 s delay / cooldown after the laser switches off.

A time delay relay may help:

There are many configurations and some have completely programmable triggering, so read the specs carefully!

A simple solution is to put a small microswitch on the top of the Z axis motor. Wire it as normally open, run the wires to the relay attached to M8 and push the switch actuator against the laser module. When the laser module goes down the switch activates and the air turns on. When the laser returns to home position the switch turn the air off. Because the Z axis homes first, the air is not on when X and Y home. I’ve been using this method for months and it works great.
I just have my switch attached to the Z axis motor using “Alligator Tape” (nano tape).
It was supposed to be temporary until I made a proper bracket but laziness won out. If it ever falls off I’ll make a bracket.
I have it set so when the laser goes down more than 5 mm the air turns on.

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