laser Surveillance

[Martin Boekers]

After seeing Dean's dillema I got to thinking.
Yes, I do my best to keep an eye on my laser as much as possible but as Dean's experience shows serious damage can happen in minutes.

I my shop I have 2 lasers and heat presses they are in an adjacent room for temp & humidity control. I have my work area, then the store area.

Being a small shop it's hard to be everywhere at once.

I was wondering if any one has set up a web cam or security camera that is focused on the laser so you can keep an eye on it while working on files are dealing with customers?

Just a thought, maybe good insurance with a small investment.


Marty

[Scott Shepherd]

I have a webcam that I sit on the top of the glass on the lid, pointing in. I open a window with it and leave the small window open while working on the computer. If I need to do non computer work, I open it up larger, so I can see it across the room, and I always point myself in that direction when I'm working.

[AL Ursich]

I think at some point I will setup a Smoke Detector with the output relay that is hard wired into the Cover Switch and able to shut off the blower.

I plan to do the same with my CarveWright cover switch.

You would need to use a relay and power supply like a wall wart through the smoke detector. Use the Normally closed contacts on the relay so when the relay in the smoke detector activates it activates the external relay opening the normally closed contacts opening the Laser Door circuit.

AL

[David Fairfield]

I like that camera idea, my shop is divided with the laser behind a partition. I'd just be leery of getting into a habit of not really paying a lot of attention to the picture on the screen. It gets boring, and boring things are easily ignored.

I do simple tasks in the laser area when the machine is running. Stuff like packing small parcels. So I'm watching, but not wasting time either.

Anyway, I'm not turning my back on it when I'm doing acrylic, that stuff is just not stable.

Dave

[Kim Vellore]

I think at some point I will setup a Smoke Detector with the output relay that is hard wired into the Cover Switch and able to shut off the blower.


AL

Al,

A smoke detector will not be a good choice because it will be going off all the time. A heat detector will be too late and you may be able to save from additional damage outside the laser, what you need is a flame detector, Flame detectors are smart devices that actually look for flame radiation at different wave lengths and looks for the flame flickering pattern, compensated for ambient stray wavelength etc.... they are a little expensive too but one mounted on the top can cover your full shop. You can even hook up a co2 extinguishing system to it or a $5 halon extinguisher if you hook it up yourself just for the inside of the laser. Just read all instructions regarding Halon if you plan to use it.

Kim

[Dan Hintz]

Kim beat me to the punch... I'd go with an IR flame detector. If a smoke detector is not going off all of the time due to too much smoke in the area, it will be at the other end of the spectrum and not going off until it's too late (as your vacuum system pulls the smoke out right up to the point where the entire system goes up in flames).

If you do install a fire extinguisher system, use a Class C dry powder system (though not a standard home ABC system... that powder can be highly corrosive to electronics) or Halon. Don't use a CO2 system as those can make water condense on electronics.

[Keith Outten]

I have a camera mounted high on the back wall of my workshop that allows me to watch my CNC router from my upstairs shop office. It connects to the TV, it isn't a web cam.

This works well for my CNC router but it probably wouldn't work for a laser engraver. By the time I got to the laser if something happened the damage would be done. I expect you would have to be right on top of the machine in order to have any chance of preventing serious damage. FWIW the guy who owns LaserBits told me years ago that if you have a fire inside a laser engraver the machine will be ruined, the only thing you can do is prevent the fire from spreading outside of the cabinet.
.

[Randy Digby]

I noticed in Sam's the other day, a wireless camera / receiver set. The camera was about the size of a deck of cards and the receiver was about twice that size. Info stated that software was provided to view/record on PC if you like. Receiver can look at up to four cams. Price for a set was $149.00. They had a demo set out running and the pic was very good for the money. The cam and receiver both have batteries on-board and will operate for several hours on battery - normal operation is plugged-in power supply. Cam had decent mounting bracket.

[Keith Outten]

I wish I knew the answer to why acrylic tends to flame.

I have never seen a flame in my Epilog Legend 24 in the seven or eight years I have owned it and I have cut a truckload of acrylic.

In the shop at CNU we have a Xenetech laser engraver and I am fighting a flame problem that only seems to happen on the extreme right side of the table.

The Xenetech machine has a totally different air assist system then my Epilog. The Xenetech has a fixed bar that runs the length of the X axis, the Epilog has an air tube that is fixed over the lense and points directly over the cutting area.

The second condition that I am considering is dust collection. The dust collection on my Epilog is more powerful and more efficient than the one we use on the Xenetech.

One or both of these conditions has to be the reason that one machine never experiences a flame and the other does.
.

[Mike Null]

With my Trotec the flaming tends to be related to speed and power settings. The lower speed, higher power invariably will cause flaming.

I have taken to doing the cuts in more than one pass rather than take a chance with the flaming. Fortunately, my business doesn't require cutting a lot of thick acrylic.

[Dan Hintz]

Keith,

If the entire bar is pressurized and you only get flaming on the far right-hand side, is the bar pressurized from the left-hand side? If so, I'm willing to bet your pressure on the right side is significantly lower than on the left.

[Kim Vellore]

I have had fire when I was warming up the laser. I usually cut a square at 100% power, 1% speed and 5000DPI. I do that to avoid the start up no fire issues and once I put my acrylic part in to cut and remembered that I did not do my start up so I moved the part to the side and sent the square to be cut, unfortunately the moved acrylic part tip was inside the square and I saw orange light from the laser and I dont remember what I did but I managed to blow it out, there was not much damage there is slight heat damage on the top acrylic cover of the laser but I guess I was lucky... the next thing to burn up would have been the acrylic lid of the engraver. I am extra careful now with cutting acrylic.
Kim

[Marc Myer]

I've noticed the air nozzle on my Epilog is not aimed precisely at the focal point.
Is that intentional? I do get regular flaming with acrylic, even at 45 psi. Would like to figure how to reduce that.

I did notice the air assist path can become clogged. As a quick fix, I'll send air through it backwards.

[Dan Hintz]

I've noticed the air nozzle on my Epilog is not aimed precisely at the focal point.
Wouldn't this depend upon the lens you're using? A 2" lens will have the tube aimed at a different spot than, say, a 4" lens.

[Marc Myer]

You're right.
In my case, it's the stock 2" lens, and the air assist is as it came from the factory. It doesn't seem to be easily adjusted.

[Tom Bull]

X10 dot com has amazing camera package deals. Never used them, so can't recommend, just know prices are cheap. I have seen their stuff and it looks OK, one person I have talked to said their system was great in their beauty shop.

[Keith Outten]

Keith,

If the entire bar is pressurized and you only get flaming on the far right-hand side, is the bar pressurized from the left-hand side? If so, I'm willing to bet your pressure on the right side is significantly lower than on the left.

Dan,

I believe the air supply is in fact connected to the left side of the bar.
Knowing that, I tried increasing the air pressure so more air would be available to the right end of the bar but it hasn't made any difference even at 60 psi.

Mike,

I have tried every combination of speed and power settings possible to stop the flaming on the Xenetech. The problem isn't just thick acrylic, it flames when I cut any type of thin engravers plastic as well but only on the right side on the table. This would seem to eliminate speed and power from the equation.

It just seems strange to me that I have never seen a flame on my Epilog Legend no matter what material I have cut or what thickness.

[Dan Hintz]

I believe the air supply is in fact connected to the left side of the bar. Knowing that, I tried increasing the air pressure so more air would be available to the right end of the bar but it hasn't made any difference even at 60 psi.
Can you block off the left half of the bar, forcing the air to exit only on the right side, maybe using tape? It's too coincidental that it's powered on the left and the right-hand side is the problem area.

Air knives (essentially what you have) are notorious for this exact problem, particularly the ones designed without this problem in mind. The cheapest air knife is a series of holes drilled into a tube, and it also shows the worst characteristics. There is no laminar airflow on this type and very little directionality.

[Mike Null]

Keith

I am fairly sure that has to do with the variance of the exhaust air flow from one side to the other. (just a guess)

Mine flames worse in the front cutting x axis; cutting to the back in the x axis the flame is about half and side to side it's minimal. I think this is caused by the direction of the air from the air assist nozzle in conjunction with the exhaust air flow.

[Rodne Gold]

IMO one should never have flaming , even cutting thick stuff if you got enough pressure and flow in respect of air assist.
In 10+ years with 3 models of laser currently running 6 , we have had flaming one time and that was when our main compressor broke and we used an inadequate one.

The exhaust system itself , whether working or not has never a factor in our setup , I could however forsee that perhaps a very strong one could concievably "fan the flames".

I have no idea of our air assist pressures or flow
however they are either concentric with the lens or a directed nozzle and they all "hiss angrily" and push out a lot of air. I use a big 3 phase compressor for all shop air . An added benefit is that the high flow ejects the melt from the kerf well , providing its not too high so that it doesnt overcool the edges and make em frosty.

Is it not possible to retrofit a small directable nozzle type air assist connected with aquarium tubing to a good source of air - it doesnt even have to be dry if you bypass the lens. If you loop the tubing right , you should have minimal drag on the head and at any rate , you cut at slow speed so enfoulment or stiffish tubing shouldnt be an issue.

Im sure something better in the assist has to solve the problem.

As an aside , cast needs a higher temp to start burning , it will burn with a crackly smoking flame , but wont drip molten flaming balls that silent burning extruded would.

[Marc Myer]

I just realized that my flaming problem is primarily with Rowmark metal finish acrylic. But given the info you've provided, I'll begin a tweaking process and see how it can be improved.
There may be air flow impedance in the system that reduces pressure at the workpiece. A pinch in a hose, a piece of debris or buildup of goop from the compressor? Time to dig deeper.

[Roy Brewer]

I've noticed the air nozzle on my Epilog is not aimed precisely at the focal point.
Is that intentional?Marc,

The design of your (standard) Epilog air assist is to strike the surface barely(~1/8") in front of where the laser strikes the surface. This forces vapors toward the exhaust. It is very common to find that, sometime during the learning curve, the operator allowed the product to strike and bend the AA nozzle while focusing. One set screw (not easily seen) allows the nozzle to be properly redirected if it is not bent. If it is bent remove and with a couple pair of vise grips, reform to where it strikes at the above mentioned location. Do not try to reform the AA nozzle while its mounted to the X-Axis assembly.

[Bill Cunningham]

Roy; When you say 1/8" in 'front' of where the laser strikes the surface..
Which 'in front" do you mean? The laser can travel in four directions, but the air direction from the nozzle is fixed.. Or, do you mean 'in front' meaning towards the front of the machine and not in front of the beam/kerf direction.
Is there a tech sheet to explain the correct position?

[Roy Brewer]

Roy; When you say 1/8" in 'front' of where the laser strikes the surface.. Which 'in front" do you mean? Bill,

Sorry for the confusion. The air assist should blow vapors from the front of the machine toward the "sucker"(back of machine)hitting the surface ~1/8" closer to the operator who is always religiously watching the laser do it's thing, JIC! ;)