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Walt Langhans
08-17-2015, 12:06 PM
Hi All,

I need to do some fine engraving on acrylic so I got a lens with a shorter focal distance. The problem is that the tip of the nozzle is only a few millimeters from the acrylic and on my first attempt to engrave without air it so much junk got on the lens it almost ruined it.

So for my second attempt I tried with minimal air pressure but that caused the acrylic dust to spread and cause a haze on the piece.

Now I'm thinking why not just get a second nozzle for this kind of work and cut off the tip of it so I have proper clearance from the material? Good idea / bad idea?

Oh and my lens is held in the nozzle which is why I can't just remove it.

Thanks!

John Noell
08-17-2015, 1:19 PM
... on my first attempt to engrave without air...
Personally, I would never engrave acrylic without air. The air removes the material in the path and gives a cleaner engraving or cut. It also, critically, greatly decreases the chance of fire.

Kev Williams
08-17-2015, 5:12 PM
My first 2 lasers (Uni and LS900) never had cones. The Uni doesn't have air.

I never engrave anything WITH air. Always found it counter-productive for raster work, always have more mess to clean up. Air plus Romark red/white = waste of time & material. I only rarely use air when cutting.

My eastern Triumph is the only machine I have that has a cone. Took it off after the first week. Everyone says you need the cone and air to keep the lens cool. The only time I've found the lens warm is if the cone is on. I've also found the cone inhibits cutting. IMO part of the beam hits the cone, takes away work energy and just heats up the whole lens assembly. And finally, doing anything with the cone on seems to dirty up the lens 5x faster.

Mark Sipes
08-17-2015, 6:21 PM
My Trotec is pre-cone era. My air has an adjustable direction nozzle that points to the surface of the material My focal length is 1.5" and I have no problems with lens heating, dust collection, flare-ups, etc..

.

Rich Harman
08-17-2015, 7:05 PM
IMO part of the beam hits the cone, takes away work energy and just heats up the whole lens assembly. And finally, doing anything with the cone on seems to dirty up the lens 5x faster.

If part of the beam is hitting the cone then it isn't aligned correctly - removing the cone wouldn't help because the part of the beam hitting it wasn't aimed towards the right place anyhow.

I use a cone all the time but there is no air going through it. I rerouted the air assist outside the cone similar to how Epilog does it. I clean the lens every couple months, if it needs it.

Dave Sheldrake
08-17-2015, 10:26 PM
Hi All,

I need to do some fine engraving on acrylic so I got a lens with a shorter focal distance. The problem is that the tip of the nozzle is only a few millimeters from the acrylic and on my first attempt to engrave without air it so much junk got on the lens it almost ruined it.

So for my second attempt I tried with minimal air pressure but that caused the acrylic dust to spread and cause a haze on the piece.

Now I'm thinking why not just get a second nozzle for this kind of work and cut off the tip of it so I have proper clearance from the material? Good idea / bad idea?

Oh and my lens is held in the nozzle which is why I can't just remove it.

Thanks!

To be honest if you do mostly engraving then cutting the nozzle will be the easiest way round it. Be aware though you will mess up the airflow if you later want to do a lot of cutting.

For cutting you want as close to a laminar flow into the cutting kerf as possible.

For engraving a cross flow rather than aligned flow of air will be better, lower pressure than cutting with a very slight upwards tilt to blow acrylic / wood dust away but upwards from the job as well.

On one of my variable job machines I have 2 air fittings in the nozzle, one provides cross flow with a larger bore(lower pressure) assist for engraving switchable over to a hard co-axial higher pressure / smaller nozzle end, through flow for cutting work.

Air for cutting and engraving requirements are often two very different things.

Walt Langhans
08-19-2015, 1:04 PM
Thanks Guys!