[Retroplayer]

Here's my situation:

I will be installing my laser cutter in a basement workshop and there are no windows down there, just glass "blocks". So, I have few options for fume extraction without knocking out one of those blocks and limiting where I can install the laser.

Anyway, I bought an ash shop vac to give a whirl. It has an all metal enclosure, airtight canister, carbon filter, and a metal hose. I found it on clearance, so it only set me back $40. The idea would be to just suck the smoke up. I hated the idea of how loud this will be and questioned whether it would really remove the odors. And of course, seems like overkill to me.

But then, an idea occurred to me. I have some experience working with negative Ion generators and ozone generators. These clear up smoke rather well. My thought is to design up a little unit that mounts right at the laser head with a fan that sucks in the smoke, then hits it with a negative ion generator, passes it along a few inches, then hits it with an ozone generator before sending that air down a lightweight corrugated tube to a carbon filter. The whole thing would be contained inside the laser.

The negative ions should dissipate the smoke and the ozone generator should remove the odors. And the carbon filter would catch anything else missed.

I have the laser cutter (it is a "Cheap Chinese 40W cutter") broken down for major upgrades at the moment and haven't actually operated it yet. So my question is - how much smoke does this really generate? I wouldn't think it would be so much that a powerful 12V server fan or blower couldn't suck it up quickly enough, but I don't know. Looking for some input there.

If the idea works, it would be great for those that need to install their cutter in an enclosed space. It should be quieter, and the fact that it is mounted on the head, it should actually be more efficient at removing the smoke. I have the parts lying around, but it should be less than $60 or so in parts to build one.

Oh, there will be an air assist as well that will blow the smoke away from the lens right into the path of the sucker. I have already designed up and 3D printed a little module that I will be able to mount on the head. I already had the parts lying around, so lacking input, I will just give it a try anyway.

Thoughts?

[fixtureman1]

On sawmill creek there is a fellow that built a nice filter for his laser

[Dean448]

My experience is that you need a decent sized fan. If the fan isn't large enough you just smell burning wood. Plastics seem worse. I bought the type of fan that that folk who grow plants in door use. Just over 100cfm I think.

The air on the part is also important. I think that direct air on the cut zone helps burn the wood. Also keeps it off the lens.


Sent from my iPhone using Tapatalk

[buddydog]

My 40 watt cheapie makes lots of smell and smoke. I pump it outside and still it finds ways back in. Others may have other ideas BUT IMHO: Plastic: No way to get rid of the stink without pumping it outside! Even being extracted a lot of it makes it back into the house. I think it is dangerous to even consider somehow keeping it inside. Wood: Same thing but just smell if pure wood. It will be bad enough you will quickly give up the idea of keeping any "used" air in the house. If it's plywood well read the previous on "plastic". What you can "lase" without fume extraction is glass and anodized aluminum.

I'm not a "green guy" at all but I would not suggest exposing your family or pets to the pollution these things make. I just buried a love bird I have had for 20 years yesterday and even though she was very old and it was expected and she wasn't near the machine, my wife pointed out the laser has been in the house for two months and I have been cutting acrylic for the first time this last week and we could always detect when it was cutting throughout the house. Makes me wonder and if I knew for sure I wold not have bought the machine or brought it into my home. I will be adding a second (dust collector type) fan at the far end of a 100 foot 4" drain pipe to get this stuff completely away from the house. It is going to have remote activation. If there is a chance I killed my bird, none of the fun was worth it!

Also the "blue tube" these come with is worthless. Buy an aluminized flexible dryer tube.

The first mod I made was a 3D printed "air assist" head. There are several on thingiverse. Most important mod you can make!You can make the flex hose with the straight hose from a hardware store by filling it with sand, winding it on a 1"pipe and then heating it with a heat gun and letting it take a set while cooling.

I am still changing/testing a pulley system for Z table "even lifting" manual table adjustment I plan on selling on ebay and so far the beta version is working great and I have spent a lot of time refining it for easier installation but all the 3D printed parts take one day for the 20 or so parts to print! I still want to simplify it a bit. I think it is the second most important mod you can make.

I am satisfied with the engrave quality and power of these but I sure need more cutting room!!!

Could you describe what improvements you are making to your machine and what type/brand/supplier parts you are using?

[ELaser]

Extraction is a funny thing, you may also need to consider local laws, it may actually be illegal in your area.

4" soil pipe make for nice cheap long runs, if you need to turn a corner used radiused bends, not short 90' elbows as they screw up the flow rate.

dual domestic hidden in the roof space type inline / axial extractor fans, each capable of 350 cfm, are quiet, low power, and do the job, but site them where you can just swap one out if one dies.

HOW you plumb / attach the suction side of this to your laser is a question in itself, in my set-up one draws air though the bottom of the Z table, and one draws air out from the back of the bed, and for me this works excellently.

May I share a cautionary tale........

video - https://vimeo.com/album/3052977/video/112489108
related blog post - How to avoid producing scrap. | Exeter Laser

TLDR version - basically a laser cabinet with extractor fans running can very quickly turn into a forced draught wood burning stove, and even if you have fire and smoke alarms in your workshop, they won't be triggered until the extractor fans burn out or die

Nota Bene this is just extraction, not filtering, filter stages add back pressure, so it gets even more complex... a friend of mine made a wonderfully efficient filter that was basically a big copper water tank filled with layers of foam pellets and auto air filter paper and so on, incredibly efficient as a filter, then one day the whole lot caught fire, so now he had added an intercooler stage, which also needs cleaning, his complete filtration setup is now twice the size of the laser, and about 30% of the cost, but he has no alternative, thanks to legislation applying where his laser is sited.

[buddydog]

Extraction is a funny thing, you may also need to consider local laws, it may actually be illegal in your area.

4" soil pipe make for nice cheap long runs, if you need to turn a corner used radiused bends, not short 90' elbows as they screw up the flow rate.

dual domestic hidden in the roof space type inline / axial extractor fans, each capable of 350 cfm, are quiet, low power, and do the job, but site them where you can just swap one out if one dies.

HOW you plumb / attach the suction side of this to your laser is a question in itself, in my set-up one draws air though the bottom of the Z table, and one draws air out from the back of the bed, and for me this works excellently.

May I share a cautionary tale........

video - https://vimeo.com/album/3052977/video/112489108
related blog post - How to avoid producing scrap. | Exeter Laser

TLDR version - basically a laser cabinet with extractor fans running can very quickly turn into a forced draught wood burning stove, and even if you have fire and smoke alarms in your workshop, they won't be triggered until the extractor fans burn out or die

Nota Bene this is just extraction, not filtering, filter stages add back pressure, so it gets even more complex... a friend of mine made a wonderfully efficient filter that was basically a big copper water tank filled with layers of foam pellets and auto air filter paper and so on, incredibly efficient as a filter, then one day the whole lot caught fire, so now he had added an intercooler stage, which also needs cleaning, his complete filtration setup is now twice the size of the laser, and about 30% of the cost, but he has no alternative, thanks to legislation applying where his laser is sited.

One of the best posts I have seen on here. Thank you. Added new knowledge about thickness/cut distance to my stack.
Because my machine is already low power I am forced to make multiple passes often and so does that figure in any way into the thickness/distance between cuts equation? I have not tried any deep cuts close together. This problem may materialize when attempting "laser hinges"? Also could "skipcuts" help in anyway? is the problem related to heat. The fact that it doesn't work and "don't do it" is good but any good explanation as to the "why"?

[ELaser]

One of the best posts I have seen on here. Thank you. Added new knowledge about thickness/cut distance to my stack.
Because my machine is already low power I am forced to make multiple passes often and so does that figure in any way into the thickness/distance between cuts equation? I have not tried any deep cuts close together. This problem may materialize when attempting "laser hinges"? Also could "skipcuts" help in anyway? is the problem related to heat. The fact that it doesn't work and "don't do it" is good but any good explanation as to the "why"?

I don't know mate, I'm far from a laser expert, and I'm finding by trial and error that many so called laser experts aren't...lol... fwiw my background is real engineering and I also have cnc mill and lathe etc in my shop.

One thing I have learned, optics (mirrors / lenses / alignment / quality / cleanliness) and air assist (15 psi straight down through the lens nozzle) are vastly under estimated, in a world where everyone talks about tube power, alleged... lol

That video linked is cutting 16 mm thick pine board at 40 watts, so either someone dropped a bollock at the reci factory and despite my tube being 100 watt length and 100 watt nominal rated with 131 peak rating (which is a goooood one, not a "friday" job) someone must have dropped a few grams of unobtanium into the gas mix to double the efficiency and output power, because I see other people saying you *must* have 120 watts to cut 18 mm wood... I also do beautiful (if slow) cuts in 25 mm thick acrylic at 48 watts.




See my latest two vids for more on this, first is 2.5" lens, second is 4" lens, vs 100 mm thick acrylic, top tip, the 4" lens punches all the way through 100 mm of acrylic at 75 watts.. I think the tube is a "good un" and not a friday job, but I think the bulk of the reason I am doing so well is USA and German optics, set up right and cleaned right.

2.5" lens vs 100 mm acrylic -
4" lens vs 100 mm acrylic -

[Retroplayer]

I appreciate the demonstration about not cutting detail smaller than the thickness of the material.


I think it is that any suction system may suck in burning/hot embers. That was why I had chosen an sealed ash vacuum. Another idea was actually to draw the smoke through water in the bottom of a wet/dry vac.

So, depending on the materials, we can create a lot of smoke and possibly even burning embers (mostly a risk with wood, I would think). Plastic may smolder and create a ton of noxious smoke. The smoke may be very hot, which could potentially ignite other things. All things to be very concerned about. But all still a problem with ANY extraction system, even one that shoots the smoke outside.

But, back to my original post - A negative ion generator essentially attaches ions to the smoke particles and makes it heavier than air, so it falls. It also changes the smoke particles and creates an environment not especially friendly to fire.

I did throw together a little benchtop experiment and blew cigarette smoke into the field of the generator. Basically what happens is that the smoke just dissipates. It disappears almost as quickly as you can supply it. With this fixed near the head of the laser, it *should* kill the smoke right at the source. This air is then sucked into the system and the fumes are introduced to an ozone generator. An ozone generator is very similar to a negative ion generator, but it has the added bonus of removing odors. In large scale, these are used in a burned out building to completely eradicate the burnt smell. Apartment complexes also use them to get rid of stinky tenant odors after they move out. It creates a smell like a fresh thunderstorm (the generator is actually like tiny lightning by creating an arc across a ceramic plate.)

Anyway, in my little benchtop experiment, you blow cigarette smoke into one end of the thing and no smoke comes out the other end. That's the gist of it. The parts I used were fairly small scale and the laser looks like it can produce much more smoke than a cigarette can, so that is why I was wondering about the volume of smoke in order to size the components correctly. I guess I will just have to browse some youtube videos to get an idea.

The concept (I am not promising that it will work) would have this system right at the head of the laser following the laser around. This would prevent the smoke from accumulating.

I do understand the thinking that plastic fumes are bad. This is because the burning platic is vaporized and airborne. You breath in these vapors and then they settle in your lungs. This is why they are bad. By using an anion and ozone generator, you are making the particles heavy. They are no longer airborne. They fall out of the air and into your filter. The air that comes out is safe especially if you use an activated carbon filter at the output. It is safer than any gas mask.

I apologize for the long post. I wasn't looking to try to convince anyone that this will work. I am not 100% certain that it will only because I am not certain the system can keep up with the amount of smoke generated. That is my only concern. I will create a better experiment and put together a video if anyone is interested.

Thanks for the responses.

[buddydog]

Yes very interested even if very skeptical. A reasonably priced unit could be very marketable.

[Retroplayer]

I will keep you posted, then. My parts I have in my junkbin are old and heavily used, so I ordered new parts for a proper experiment and to ensure that whatever I design will fit current available parts. Once I get them and wire it all up, I will post a video to show what I have been talking about. In the meantime, there are some youtube videos of experiments with anion and what it does to smoke. Like this one for example: https://www.youtube.com/watch?v=0GNCd9cgZTg

This one is a bit more dramatic: https://www.youtube.com/watch?v=ZeHoQ2M-1Uo

[ELaser]

ummmm, if you are basing your experimental starting point on that, I have news for you, and it's not good

using a figurative example, the proof of concept in those videos is a 25 buck toy RC aircraft, now you have to make a commercial jumbo.

the amount of "smoke" liberated even by just 50 watts raster engraving wood (some woods more than others) has to be seen to be believed, after some testing when designing my quieter extraction system I estimated it at the high side of 10 cubic feet of smoke per second., yes, that is not a typo, 600 cfm of smoke

[Retroplayer]

This is a homemade (and dangerous looking) ozone generator: https://www.youtube.com/watch?v=GlCSwjq8CmY

In a professional unit, that plasma is contained across the surface of a ceramic plate and it just glows purple. No crazy looking lightning bolts. I chose that video only because it more clearly shows what is happening. In my experiment video, all you would see is a ceramic plate glowing purple.

Ozone generators also increases the weight of smoke particles like the anion generator, but it is not as efficient. What it is more efficient at is removing odors.

Any good industrial air purifier system uses a combination of anion, ozone, and HEPA filtering. Again these are used to remove the burning smell from buildings after a fire, they kill black mold, etc....

[Retroplayer]

Elaser,

Thanks for your opinion.

I don't want to come across as rude, but your responses are only tangentially on-topic and rarely decipherable as to your point (WTH does an RC toy have to do with any of this?)

It is clear that:

A. You don't understand the technology I am discussing
B. Have some unknown vested interest in this beyond just curiosity. Do you sell fume extraction systems or something?
C. Don't seem to understand what an "experiment" is
D. If you KNEW the volume of smoke in the first place, which is what I asked in the first place, why didn't you just say it rather than going off on some tangent about cutting wood details smaller than the thickness of the material which I never once implied that I was doing or even that I will ever cut wood at all? A laser cutter can create fire. Yes. It cuts by burning. Burning can cause fire. Fire is bad. Fire hurts. I would hope everyone beyond the age of 5 understands this. How it fits into this discussion, though, is beyond me. We are talking about smoke and it's extraction. Did you know that drilling and cutting wood can cause a fire, too? Not the point.

Have a good day.

[ELaser]

Elaser,

Thanks for your opinion.

I don't want to come across as rude, but your responses are only tangentially on-topic and rarely decipherable as to your point (WTH does an RC toy have to do with any of this?)

It is clear that:

A. You don't understand the technology I am discussing
B. Have some unknown vested interest in this beyond just curiosity. Do you sell fume extraction systems or something?
C. Don't seem to understand what an "experiment" is
D. If you KNEW the volume of smoke in the first place, which is what I asked in the first place, why didn't you just say it rather than going off on some tangent about cutting wood details smaller than the thickness of the material which I never once implied that I was doing or even that I will ever cut wood at all? A laser cutter can create fire. Yes. It cuts by burning. Burning can cause fire. Fire is bad. Fire hurts. I would hope everyone beyond the age of 5 understands this. How it fits into this discussion, though, is beyond me. We are talking about smoke and it's extraction. Did you know that drilling and cutting wood can cause a fire, too? Not the point.

Have a good day.

I'm sorry that you feel that I am attacking you, or your project, or attempting to hi-kack the thread... none of these was my intention, but since that is just more of my words I don't suppose you'll give it much credence.

Some points in response to you though.

1/ laser "smoke" != cigarette smoke, joss stick smoke etc, eg it is not a by product of combustion, it is a combustible product, think fuel air mix

2/ I do not "know" the volumes, I guesstimated the volumes based on experiments with MY kit and the woods *I* used, 360 CFM fan didn't even begin to match laser smoke output at 50 watts, 500 CFM looked like it was getting close, 720 CFM did the business, and was a lot quieter and used a loss less power than the 3,000 CFM extractor

3/ I do not, never have, never will, sell anything even remotely related to fume extraction, hint, there is a clue from the vids what business I am in and where money might influence my thoughts and opinions

4/ I'm a time served marine and hydraulic engineer by trade, and tinkered with *tons* of stuff in my spare time over the years, from tesla coils through home made masers all the way down, I could go on and on, but I won't, suffice to say I was playing with electrophoresis and electrostatic precipitation after seeing the first ***commercial / industrial *** installation I'd ever seen or heard on in the late seventies, it was a century old then, but that was the first I personally had ever heard of this stuff, as in it was brand new and exciting to me because I had never heard of it before.... my point being, to make an outright statement that I do not understand the technology you are discussing... well, how would you know?

5/ I believe you discussed eliminating the smoke at source, at the laser head, that means, considering the volumes of smoke produced, a very considerable power EHT supply INSIDE a laser, mounted somehow on the flying XY laser head itself, you effectively can't add any mass greater than 100 grams to the head or you'll start putting adverse loads on the system, and nobody is going to upgrade their steppers / servos and drive systems *just* to mount some new system ion the flying head, yet it has to carry considerable power EHT and has to have a 100% cast iron guarantee that none of that trickles away into anything else, like, the operator, the work, or the electronics in the laser itself, and I'm not even scratching the surface here.

6/ if you're not doing it inside the laser then we are talking a separate cabinet in the exhaust system, but it is still not chicken feed, and any system powerful enough to do this for a laser pumping 50 watts into wood is also powerful enough to generate toxic levels of ozone if designed badly and fatal levels of electrical hazard even if designed well.

Nota Bene, I'm NOT having a go at you, or your project, or saying it is impossible or anything else, much less come buy my whizzo acme widget instead, I'm just old enough and experienced enough to be *extremely* sceptical...........

Tell you what though, if you can make one that meets all my concerns, you van put me down for your first order and sale, and that isn't a joke.

[Retroplayer]

Elaser,

Thanks for the polite response and I apologize for being a bit gruff. It did appear to me that you were presenting more than just skepticism. I now understand your position much better.

I do understand that cigarette smoke is not exactly the same as the smoke created by the laser, but for the purpose of an experiment it is the same. At the very least, it does support an experiment which is simply a small and controlled demonstration in which to take measurements and make observations. I could just as easily set wood on fire as well as smolder it (which would be more similar to laser cutting). But then the experiment itself must be bigger. Not the point of a first experiment.

Regarding adding weight to the system. There is no significant weight, really. The anion generator and fan is all that would be installed at the head. And the bulk of the components would be mounted on the flat part of the carriage, not extended out over the laser head. The business end of an anion generator is two carbon brushes with high voltage/low current wire attached. The business end of an ozone generator is a thin ceramic plate about 2x1.5cm also with high voltage/low current wire attached. The inverters themselves (which are light also) would be mounted remotely mostly due to their size.

So, the bulk of the head portion would be the anion generator end, the ozone ceramic plate, a 40MM high output server fan (only the first stage just to lift up the smoke) and a small plastic housing to hold these components in position. The scoop would come down the side of the head and be positioned near the business end of the laser.

Attached to the module would be a 1.5 inch hose, so there would be some dragging of the hose, but it is just a thin walled corrugated hose. No significant weight. It can be supported and suspended from the chassis.

So the smoke is lifted up from the work piece using negative air pressure (smoke will follow the path of least resistance), sucked up into the module which passes it over the anion generator and then the ozone generator. This would continue down the hose with the assistance of a second fan pulling it. It would then reach the final stage filter which will be an activated carbon filter. And this scrubbed air will be released out into the open air.

I am concerned about the volume, especially when working with wood. I don't personally expect to work a great deal with wood, but based on our conversations here, I think that is the best measure to use because it appears to generate the largest amount of smoke, especially plywood which contains binders.

I understand the skepticism, and as I said, I am not 100% positive that it will work yet. I can defend the technology, but I cannot yet defend how well it will work for this application. My prior experience with the technology tells me that it worth exploring at least. I also understand that I am trying to describe a system with just words and really that leads to much mis-understanding. I am a visual person. I promise that I will post a video of my experiments once I have something proper set up, whether it succeeds or fails. Then the discussion would likely be more productive. I even have gas sensors on the way to take measurements of the air at the output so that I can have actual data and not just rely on what I "see." These will measure solvents, carbon monoxide, etc... basically an electronic 'nose.'

This probably doesn't help a great deal, but this is the prototype assembly that I used for my preliminary experiment and would be mounted on the carriage:

Attachment 262832

On this thread of discussion, what smoke source would you suggest for an experiment that would most closely resemble what the system will deal with?

[ELaser]

First how pleasant it is to deal with fellow adults, may not make sense, unless you've been on other forums... lol

Speaking as someone who has spent much of his life developing and designing stuff one way or another, indulge me for a minute.

One of my favourite sayings is "The differences between theory and practice, are greater in practice, than in theory."

One of the biggest problems by far faced by people in your position is they substitute X for Y in the development stage, because X is easier to do, they then spend a lot of time and money perfecting their widget to work with X, and it does, really well, and they then try it with Y, and the results are a disaster.

My biggest by far concern here is not so much the volumes of "smoke" you are using for your prototype, but they "type" of smoke.

Lasers sublimate (solid > gas) and by definition if they are sublimating a combustible material then they are producing a fuel / air mix.

You can make a gasoline engine run on wood smoke with a gasifier, which is a device to convert wood to sublimated smoke, a fuel / air mix.

HT/EHT + fuel/air mix - source of ignition

small scale you could probably use something like a big pond smoker (the ultrasonic ones) and a bowl of liquid paraffin as your smoke source, it's not violently combustible, eg closer to diesel than gasoline, but if you can run that and get no ignition even when other parts of the system fail, eg arc detection and prevention, you should be on the right track.

Once you get that sorted then it really is just a matter of scaling it up.

Watch out for that ozone though, it is a killer, literally.

I think of necessity you'll be using automotive oxygen / mixture sensors or some equivalent to guess the smoke load / mixture, maybe an arduino to control it all, which would also give you a status / output that customers would want.

My 2c, don't try and build it down to a price, build it so it works, kickstarter / open source hardware may be your friend,... IF you can build it to handle a laser chucking 50 watts into wood, then it is a piece of piss to scale it down and wrap it in an A/C style package and you will sell one to every house in the country wanting clean air inside the home, every RV and boat too, everyone with a kid with asthma, you get the idea.

[Retroplayer]

I suppose I should have made this clear up front. I am only concerned about solving my particular problem. I'm not really looking to develop anything to sell. In fact, if it works for me, I would just post up the details and files to build your own. I am far too busy in my engineering day job to go into manufacturing, marketing, distribution, and sales. This is a hobby for me.

Also, I have already upgraded my steppers to more powerful steppers with a 0.9 degree step angle (I am putting in a ramps 1.4 based system with 1/32 microstepper drivers.) I did this for more resolution, repeatability and a quieter system. At any rate, that may mean whatever experience I have attaching this system might vary from a stock system. So, again, I was only looking to solve my own particular problem but it may prove useful to others if it works.

I bought the K40 "cheap chinese laser" system for the sole purpose that I wanted to upgrade the hell out of it and make it exactly what I need. Starting with the cheapest barebones system made sense to me. Plus I got it on a holiday special for $400 shipped and I could barely buy just the laser and power supply to build my own for that! I intend to etch mostly glass and cut mostly acrylic. And perhaps experiment with thin metals and possibly thin plywood (not detailed work at all), but I don't expect too much out of a 40W system. The goal is learn some useful things from it and eventually use that information to build my own.

With that out of the way...

It seems that your main concern is that the gas in the smoke may be a fuel-air mixture meaning "combustible". Is that correct? I am not entirely sure I understand how it would be. I am not saying you are wrong, but the laser beam itself should burn up whatever gasses are in the air and once you burn up the gas, it is no longer combustible. It is just carbon soot. This is how an ICE deals with gas vapor getting into the exhaust. You just burn up the excess in a safe environment. Hmm... I wonder if anyone ever tried strapping a catalytic converter to one of these?

Well, perhaps interestingly if any combustible gasses do make it into the system they would be consumed in the presence of the plasma from the negative ion generator. As long as the system does not pressurize this gas, no explosions should result. You are simply burning up the fuel and outputting inert gasses.

Am I understanding your concern?

BTW, this entire system is just an air-purifier system. These are already commercially available to every home, RV, kid with asthma. In fact, the parts I used in my mini experiment were removed from an air purifier system with an unknown amount of hours on it. I am not inventing anything new, just possibly a new application to an existing technology. You would find these components in just about air purifier on the market. I am simply repackaging it into a point-of-source system specific to laser cutting.

And as far as the danger of ozone. Honestly, the debate is hot and heavy about that. It is not settled in the least. There is no scientifically proven danger to it. If it was as dangerous as some would have you believe, we would die every time there was a thunderstorm.

I will see what I can do about the paraffin wax source you mentioned. Thank you for the suggestion. Also, I ordered the MQ series of sensors. Specifically the MQ-2 and MQ-7. I had not thought about using an O2 sensor. Good idea, actually. And yes, an Arduino would be collecting the data. The Ramps1.4 system is based on Arduino, so it wouldn't be too difficult to put this into a final system for continuous monitoring. The original purpose of ordering the gas sensors was actually going to be part of the interlock loop which would shut off the system if it detected a fire or especially noxious fumes. I already have a pyro-electric sensor installed in the cabinet (just a firstalert ANT tiny smoke detector.) I put it in a place that shouldn't see a ton of smoke (way towards the back.) So, if it does, something is going very wrong and smoke is filling the cabinet. The pyro-electric alarms are designed for smoldering fires and are less sensitive to smoke created by cooking for example. So, it shouldn't go off unless something is seriously wrong. And of course, I don't plan to do any cutting unattended. Burning down the home is not part of the goal.

Anyway, sounds like you might have a decent visual of the system I am proposing. Alright, enough talk. Back to the workshop! I need to show something.

[ELaser]

That's kinda why I linked to those videos

1/ if the material being lasered is combustible, the gases given off when lasering are *very* combustible.

2/ I know of *no* laser cutting or engraving process where the combustion is desired or an improvement over the same process without combustion.*****

***** laser cutting steel is of course done with oxygen so in many ways the same as a gas axe cutting steel, arguably this is combustion of a sort, but steel is a metal... and so outside the scope of what you were discussing.

getting back to that video I linked to, you can HEAR it when the gases ignite, it sounds like a blowtorch cut, and it totally screws up the work being cut.

Speaking personally, I do *NOT* want my gases combusted *anywhere*, as the un-combusted gases are a lot "cleaner" and safer than the combusted ones, because the free air combustion temperatures are way way way too low to break everything down.

You can *easily* create copious and lethal quantities of cyanide if you ignite the gases produced by laser cutting some materials.

There are no circumstances whatsoever where I want laser produced "smoke" being ignited anywhere in or near my laser or workshop.

[buddydog]

I like reading both of y++ou and I'm no Pollyanna. Retro if you want an idea about what El is talking about, build a wood fire outside and stick a 3/4 inch metal water pipe into the center of the fire near the wood. Now bring a lit match to the other end of the pipe and you will lite a gas flame. The laser cut is the "fire" and the smoke tube is the pipe so you have to hope the fuel air mixture is not close to "stoiciometric" (probably spelled wrong) and that there is no spark or other ignition anywhere in the pipe! I think the laser especially with the air assist on is prime to create combustible gas as the flame is immediately blown out by the air assist leaving what has to be a high amount of combustible gas.

As long as were taking "flyers":
I think I will patent this idea before you guys beat me to it!: Laser beam hits wood in a closed vessel, gas is created, gas is moved to combustion area, power is made! hmmm.

Retro I'll need your machine to clean up what's left over in the exhaust stream.

The mixture from the laser must be extremely on the lean side of stoiciometric because the exhaust fan is pulling so much gas through the machine and that is why we have so few (anyone know of any?) laser explosions like in sawmills or flour mills. I wonder how the mixture would change over time if the "smokefan" stops during a cut and you had a continuous spark inside the case! I want some one else to be there, not me!

[Retroplayer]

Alright, let's leave this until I can come back with an experimental setup. I am more than happy to test any suggestions that you have as I believe that will make it as robust as possible. Your skepticism is exceedingly valuable in that sense.


I also appreciate your over-abundance of caution (when you see all the safety features I am fitting into my cutter, I think you will understand that I am also quite cautious.) I can't say I agree to the level that you take it, but let's experiment and find out. There are ways to verify vs. educated guessing. But for one, I disagree that free roaming combustible gasses floating around my workshop (especially a basement where my furnace and water heater are ignition sources) is better than burning it up safely and then filtering it. I can't think of any system in which it is a safe practice to pump combustible gases into an enclosed and occupied area. All systems I am aware of intentionally burn up this gas before releasing it to the air.