Running without Air Assist

[Walt Langhans]

Is it ok to run without the air assist on? I've got a cone nozzle and I thought I remembered a discussion somewhere about the heat of the laser running in a cone nozzle could cause a pressure difference and suck smoke up into the assembly and damage the lens.

Thanks!

[Dave Sheldrake]

On a DC based unit you will have flare up and fire issues Walt, low pressure vortexing can happen (crud being sucked back into the cone) but with enough air this can be avoided.

On a Chinese machine I would seriously recommend against running it with the cone attached and no air.

cheers

Dave

[Kev Williams]

I've rarely if ever used air assist. 90% of the time I see no benefit from it. Sometimes with 1/4"+ deep cuts in plex on my LS900 the air helps with preventing wall meltdown. And if I'm cutting thru lamacoid that I've put transfer tape on, sometimes I'll add a bit of air just to blow out the inevitable flameups.

First thing I did with my Triumph is take the cone off. Well, not the first- but close. Never have I seen a lens get caked with soot so fast as running this thing with the cone and air on. And on BOTH SIDES of the lens! With the cone removed the top side of the lens stays clean, and the bottom doesn't need cleaning near as often.

Last month I cut nearly 300 3 x 10" rowmark plates with the triumph, no cone, no air, and nary a flareup. The blower they sent with this machine looks cheesy even by Chinese standards, but man, does it move air! As long as I shut the door, it draws air thru the pass-thru slot at the back of the machine and the airlflow across the material is fast enough to prevent any flareups.

[Walt Langhans]

Fires and flair up are not a concern, I'm just doing some very light rastering of acrylic and I want to keep the vaporized material from spreading any where to reduce the amount of cleanup needed on the piece. Just don't want to mess up yet another lens.

[Dave Sheldrake]

Rastering is fine without air or the cone :)

cheers

Dave

[Mark Ross]

Rastering...meh... cutting without? You are dancing with the devil. We cut all day long and let me tell you, air assist puts out fires.

[Travis Wizniuk]

Rastering...meh... cutting without? You are dancing with the devil. We cut all day long and let me tell you, air assist puts out fires.

Recent experience has taught me that air assist MUST BE OFF for Cermark.. The color comes out kinda grey with your air assist on, but nice and black with air assist off..

[Dave Sheldrake]

heat of the laser running in a cone nozzle

A laser doesn't have any temperature Walt, it causes a temperature to build in whatever it hits but the beam itself has nothing measurable.

Air assist when applied to industrial cutting and lasers is an exact science with quite a lot of reasons behind it, when used on small and mid sized hobby machines it is rarely implemented correctly so can cause other effects as well as benefits.

cheers

Dave

[Kev Williams]

Tip for rastering acrylic: Get some Brillianize, or some Novus #1 plastic polish. Either works fine. Also have some alcohol handy.

Before lasering, polish the acrylic. Don't be afraid to use plenty-- It leaves the surface clean and very slippery, makes the soot come off much easier. And the alcohol helps break down the soot.

[Dan Hintz]

Word to the wise... if you use alcohol (or any wax or solvent) on lasered acrylic, test test test. The wrong solvent at the wrong time will craze a heat-treated edge, and things can go south quickly. The issue can sometimes appear weeks after the fact.

[Walt Langhans]

Thanks guys!

@ Dan, that sounds like the school of OH :eek: experience talking there.

[Jonathan Bowen]

I did extensive testing for a project on what does and does not hurt acrylic. I don't use alcohol. I experienced a lot of stress fractures as it weakens the material slightly. Granted I was soaking it in the stuff if I remember right but it still reacts so might not be a great idea. I use Purple power... I think thats the name. It's an engine degreaser. I was till recently soaking off the paint and glue from acrylic Christmas bulbs with it. I soaked them in it for several days with no ill affects. I use to remove paper from delicate parts with a similar method. Kerosene works as well but you need gloves and it's impossible to find in the pan handle of Florida. No one has space heaters like up north.

I also use my air assist only for cutting. I do my etching without. I get cleaner results without it. However cutting is a must. I have had 2 small fires due to lack of air. One was a compressor failure and the other was me being stupid. Well I should blame Laser Cut for being retarded but I didn't check the setting before hand so I'll take the blame. I actually burned up my proximity sensor for the lame auto focus on the last fire. Now I don't even adjust it. All my materials are the same size or cut out of focus for a reason. Better detail etching thin styrene at the 3mm acrylic level.

[Mike Null]

DNA is my "go to" cleaner for cast acrylic but not for extruded. I do not use air assist for rastering anything.