Trotec Air Assist questions Also job settings questions

[Mayo Pardo]

Being new to lasers, I don't want to start off on the wrong path due to my assumptions or ignorance, both of which I have plenty.

From reading numerous posts I determined it's best to have air assist on when cutting.
Is this pretty much true for all materials or not so much for paper or light weight material?

Should it also be on during engraving to prevent flare up or scorching, or does it just depend on the material being engraved?

I read a post which mentioned removing the cone - is it advisable to do that on a Trotec Speedy 300? If so, when would you want to do that?

Job Control
I understand the Trotec job control has settings numbers built in for common materials. Are these to be considered "starting points" regardless of laser wattage or does the software adjust the material settings based on the wattage entered when initially setting up the software?

Am I correct in thinking the job settings can be saved for each job without altering the default settings in the database?

Thanks in advance for any info

[Mike Null]

Mayo

I find that air assist is essential for most cutting operations. I don't cut much paper or card stock so I can't give you a good answer but I would check it without air assist to see the results.

I don't use air for engraving.

Steve Shepherd has jobs where he removes the nose cone. I leave mine on all the time unless I need to remove it to solve a height issue.

Preset material settings in JC are a starting point. Almost all machines perform differently even if the same brand and wattage. You can adjust your material settings in JC and you can add or delete new ones as needed. Rather than saving settings for each job I save settings for each material.

I suspect that you may find yourself tweaking settings for as long as you have your machine trying to find the optimum for each material.

Practice is the best teacher so call all the suppliers and request samples of their materials and have at it.

[Scott Shepherd]

My rule of thumb is "Air On- Nose Cone On", "Air Off- Nose Cone Off". If I violate that rule on either of our lasers, within a minute or two, it will begin to accumulate large amounts of debris directly on the lens, which is a really bad thing. Once that happens, it goes from bad to worse quickly, and within a short period of time, you will have ruined your lens.

We do engrave without the air on, and cut with the air on. That does mean you need to stop and put the cone on. I suspect part of the issue is that we are always using the nose cone with the small hole in it. If I were using the one with the large hole, I'd probably just leave the air on all the time, engraving and cutting, but I like that cone with the small hole in it.

Just last week we were engraving something and I walked by the machine and immediately noticed the nose cone on while it was engraving. I stopped, said "The air isn't on". It was within a few strokes of finishing at that point, and when it stopped, I took the lens out and it was totally hazed over with plastic debris. Not a good thing.

You have to religious about it. If you're not, you'll be buying lens often and they are quite expensive.

[Mike Null]

I should have mentioned that I use the cone with the small opening as the air assist is more efficient with that cone. I also check my lens frequently and that means sometimes every hour or two.

[Mike Audleman]

Well, wanting to learn here too...


Why would you not use air assist? Does it not keep the smoke and debris away from the lens? I mean what problems does it cause by having it on?

I have also seen reference to changing the air assist volume. Under what circumstances would you turn it down from full on? I haven't acquired a valve to adjust the power yet. Not sure what to buy, a pin or ball or gate type valve.

I was considering making an air capacitor chamber (likely to be a piece of 2-1/2 PVC with end caps and nipples on each end) to take out the pulsing from the air pump. Worth the effort?

[Kevin Gregerson]

Being new to lasers, I don't want to start off on the wrong path due to my assumptions or ignorance, both of which I have plenty.

From reading numerous posts I determined it's best to have air assist on when cutting.
Is this pretty much true for all materials or not so much for paper or light weight material?

Should it also be on during engraving to prevent flare up or scorching, or does it just depend on the material being engraved?

I read a post which mentioned removing the cone - is it advisable to do that on a Trotec Speedy 300? If so, when would you want to do that?

Job Control
I understand the Trotec job control has settings numbers built in for common materials. Are these to be considered "starting points" regardless of laser wattage or does the software adjust the material settings based on the wattage entered when initially setting up the software?

Am I correct in thinking the job settings can be saved for each job without altering the default settings in the database?

Thanks in advance for any info

Job control should maintain the settings you last used.

If you are really a material converter such as VHB, 3m tapes, etc. then never remove the air assist and it should be on with every job. As for settings, trotec will get you close on that stuff but typically you have to adjust with things like temperature etc.

[Scott Shepherd]

Well, wanting to learn here too...


Why would you not use air assist? Does it not keep the smoke and debris away from the lens? I mean what problems does it cause by having it on?

On some materials, like engraving plastics, it can blow the debris back into the engraving, where it sticks into the newly engraved area, leaving a mess to clean up. On things like clear acrylics, it can blow a haze around the engraving area, which again, sticks to the surface, and can be a pain to remove.

About the only time I might leave the air on when engraving is on wood, where it doesn't seem to change much.

[Kev Williams]

I hardly ever use air. But then, I hardly ever cut anything thicker than 1/8" rowmark or plex. And these stupid nose cones, who thought those up? My LS900 has no nose cone, for air it has a copper tube that swivels down or (like usual) up out of the way. Guck on my lens has never been a problem, sometimes it's weeks before I need to clean it. I was test cutting thru 3/4" thick mahogany on the Triumph not long ago, with the cone on I was never able to cut thru it. With the cone OFF it made it thru in one pass. This tells me the beam is hitting or otherwise being absorbed by the cone, even tho a tape test shows the beam passes thru the cone as dead center as you could ask for. I made a wire holder to position my air hose if and when I use air.

And to add to what Steve said, the LAST thing you want is air blowing sticky plastic soot into your engraved letters. No air ever while rastering... :)

[Dan Hintz]

And these stupid nose cones, who thought those up? My LS900 has no nose cone, for air it has a copper tube that swivels down or (like usual) up out of the way.

Co-axial air (cones) is on every high-powered laser system out there... you will not find a high-power laser with side-sweep tubes. Co-axial guarantees the lens remains free of substrate material, something that can't be guaranteed by side-sweep (despite any run of good someone has), particularly if your extraction system fails or is too weak for the job at hand.

If your beam is not aligned and hits the cone, or the cone is not properly sized for your machine, it seems unfair to blame co-axial systems.

[Mayo Pardo]

Lots of good responses - thanks everyone!

It seems some people have success with air assist on, some prefer it off, sometimes it just depends on the materials, so "your mileage may vary" seems to be the answer... all points of view mentioned seemed valid.

I'm wondering if Trotec has specifically recommended keeping the air assist cone on at all times or taking it off for certain situations. (On with air on, off with air off? as mentioned above)

My thoughts about air assist blowing plastic gunk back into engraved areas -
wouldn't the right amount of air psi blow the debris out of the engraving? Or does the air assist air combine with the vaporized plastic and deposit it before the exhaust can get it out? Someone in a lab somewhere has probably made tests and taken measurements at the microscopic level...

All the variables with laser cutting or engraving reminds me of learning kitchen design with five different catalogs of cabinets and accessories to choose from.

[Mike Null]

Job Control allows you to determine whether you want air assist for either cutting or engraving--your option.

[Scott Shepherd]

I'm wondering if Trotec has specifically recommended keeping the air assist cone on at all times or taking it off for certain situations. (On with air on, off with air off? as mentioned above)

My thoughts about air assist blowing plastic gunk back into engraved areas -
wouldn't the right amount of air psi blow the debris out of the engraving? Or does the air assist air combine with the vaporized plastic and deposit it before the exhaust can get it out? Someone in a lab somewhere has probably made tests and taken measurements at the microscopic level...

I've had tech support people (not Trotec) tell me under no circumstances could leaving the nose cone on with the air off do any damage to a lens. I've also seen the results of what happens without the air on and the nose cone on. The only machine I really care about is ours. I know, for 100% certainty what happens when I run the machine with the air off and the nose cone on. That's not a Trotec issue, that's a co-axial air issue. We have the exact same problem on the Universal, which is how I know about it. We've been dealing with it for 6-7 years. Knowing what happens means I don't do it because I know the end results, which is a ruined lens and possibly one mirror. I also know that I'm not going to ruin the lens by engraving something for 10 seconds with the cone on and air off.

Our basic rule is, cutting- air on, engraving - air off.

And you are correct, the air assist combines with the vaporized material and it sticks to the area just engraved. That's why we don't engrave with the air on.

[Mike Null]

As I have said, I leave the cone on for all operations but there is no question that it gets contaminated fairly fast when the air isn't on. I may give Steve's method a try though my habit of cleaning the lens and mirrors frequently will be hard to break.

I am now using the cone with the small opening and my lens gets dirty faster with this cone when engraving than with the larger cone. The trade off is better air assist when cutting.

[Scott Shepherd]

Mike, I hate what we have to do with the co-axial air assist. The fact that I have to stop, put the cone on, change something in job control (skip or don't skip), irritates me. If I worked in the engineering department at a laser manufacturer, I'd design a little solenoid activated nose cone that would swing in and out based on the setting in Job Control. It seems so simple and so basic.

My problem with the vast majority of applications labs and their advice is that they are running in lab conditions. It's very easy to do something once or do a sheet of them, but now let's run 1000's of them. Your lens might not get dirty with one piece, but when it goes into production, it's a nightmare.

My guess is that my lens stays clean for weeks at a time by switching the nose cone in and out. I check it frequently, but it's probably a solid 2 weeks before I clean it. On the Universal, it's probably less often than that.

[Mike Null]

Steve
I'm sure you're right but with the kind of work I do removing the cone seems more of a problem than cleaning the lens.

[Scott Shepherd]

Steve
I'm sure you're right but with the kind of work I do removing the cone seems more of a problem than cleaning the lens.

No, Mike, you might be right :) It might be easier to clean the lens frequently than deal with all we deal with. I'm just terrified of cracking a lens. Those babies aren't cheap and if I ran the machine all the time, I'd be comfortable with it, but when we put other people in front of it, I can't say that their attention to detail is always where I'd like it to be.

You might be right, it might just be easier to deal with a dirty lens.

[Paul Phillips]

FWIW, I've found that I can keep the nose cone on for most engraving, at least on a small run or when I'm having to switch back and forth frequently, I just turn the air pressure down to about 2-3 psi which seems to be enough to keep the lens from getting any build-up, but not enough to splatter molten acrylic, then I turn it up to 20+ psi for cutting, works well for me on small runs but if I have a lot of acrylic to deep engrave then I remove it.

[Kev Williams]

My cone has to be removed TO clean the lens, which is another reason it's hardly ever on.