Laser fume exhaust: vent to attic, outside, or fume extraction?

[Robert Cowan]

OK, so I've been spending the last week reading just about everything I can about fume extraction. It looks like I have 3 options. 1) vent outside 2) vent into attic (and then outside) or 3) make a fume extractor. Each has its pros and cons. I currently have a relatively large exhaust fan, but I'm learning it's not very well sealed so there's a lot of leakage and I get a lot of fumes inside the garage. I also cut a lot of acrylic and ABS, so that's not great. I have a 60W 'desktop' model. Currently, I just run a 4" hose to the exhaust fan and then run another hose out my door (about 10-15' from the door). This isn't a great solution. I need something better.

I've seen a lot about making my own fume extractor, which seems like a good idea, but it takes up a lot of space, costs money, and needs the filters changed periodically. I also looked into putting a fan up in the attic, drawing the exhaust up there and then venting it out from the attic (with gable vents, etc), but my attic is nicely insulated so getting up there and getting things installed will be a huge pain. Then there's just putting a hole in the wall and venting straight outside, but I'd rather not put holes in the wall, and I'm not sure about a permanent location for the laser either...

So all roads kinda keep leading back to building some sort of fume extraction device. Assuming I build it right, should I be able to cut thick acrylic with no smell? I also saw a Hakko soldering fume extraction unit locally for around $100, which is a great deal, I was wondering if that would work. It has 3 stages (pre-filter, HEPA filter, and activated carbon filter). My only concern is that the airflow isn't stated and might not be high enough for a laser. Thoughts on that?

[Bert McMahan]

I can't help a ton but I can offer some advice. First, what type of fan do you have? If it's relatively low power, then your hoses might be killing your flow. Curved hoses and accordian style flexible hose will REALLY eat your flow. Look at something more like a small dust collector fan.

Second, absolutely do NOT vent into the attic. You'll end up making a chamber in your house literally filled with poisonous/toxic particles and possibly carbon monoxide. Fans can help pull it through but you'll basically end up having your whole house smell terrible and making your attic completely inhospitable.

Third, a guy here at work has one of the Hakko fume extractors. It's not even sort of close to being enough oomph for a laser. It's designed to take out a small trickle of smoke from a soldering iron, not a plume of smoke from a laser.

On your exhaust fan, try putting the fan at the end of the line (by the window) not at the front. That way any leaks will suck air in, not blow air out. Also use as much rigid ducting as you can, it helps greatly with flow.

Do you have a window you could vent outside of? I made a wooden panel to sit in my window with a 4" hole for my exhaust fan before I just knocked a hole in the wall.

[Robert Cowan]

My fan is one of these:

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It's not the greatest in the world, but it does push a good amount of air.

Secondly, my attic is detached from the house. The house has no attic, it's all vaulted ceilings and there's a barrier between the attic in the garage and the house. BUT, they're not 100% sealed from eachother, so yeah, that might be an issue.

Good to know about the Hakko fume extractors, that's what I figured. It's a good deal, but I figured it wouldn't have enough airflow. I could modify it to include a much bigger fan, but at that point I might as well build my own.

I might try to get the exhaust fan outside (temporarily, only when I run the laser). Right now it's just underneath on the floor, which probably isn't the best. Running a hose straight from the laser to the fan (outside) and then venting it further away from the house might be a good thing to try. At least I could tell if the fan has enough power to pull the fumes from the laser.

I have a window in the shop, but it's 30' away. I thought about making a baffle for the window, but I don't really have a space for the laser on that side of the shop, so I'm trying to use the door that's right next to the laser (which goes outside).

Good thoughts though, I'll try having the actual fan outside and see how much that helps. Right now, whatever I cut smells up the whole garage for about a day. I never even see smoke, so the airflow is pretty good, I just thing it's leaking out somehow.

[David Somers]

Bert has the right idea. Assuming your fan has good flow, swap out for rigid pipe where you can, put the fan at the far end of the run so that as much of the length of hose/pipe is under negative pressure as possible, then out a window or door using a panel that the door or window can close on, with a hole cut in it for the hose.

Or....go a step further. Same idea, but move the blower so it is outside the door or window. Build a box to contain it to protect it from weather and to sound proof it a bit for your neighbors sake, (remember it needs air to keep cool or you can overheat it) and now your entire run of hose/pipe inside the garage space is under negative pressure and leaks should not be an issue.

[Robert Cowan]

Bert has the right idea. Assuming your fan has good flow, swap out for rigid pipe where you can, put the fan at the far end of the run so that as much of the length of hose/pipe is under negative pressure as possible, then out a window or door using a panel that the door or window can close on, with a hole cut in it for the hose.

Or....go a step further. Same idea, but move the blower so it is outside the door or window. Build a box to contain it to protect it from weather and to sound proof it a bit for your neighbors sake, (remember it needs air to keep cool or you can overheat it) and now your entire run of hose/pipe inside the garage space is under negative pressure and leaks should not be an issue.

I really wish I could have the unit outside, but the back of the garage is somewhat visible from some angles, so I can't really have an 'eyesore' out back. I don't even like how my mini-split looks. I'm fine moving the fan in and out when I use it though. I think a bit problem is that once I get it out the door, I need to move it much further away from the house, or else the fumes just come back in through the door.

[David Somers]

Like Bert suggested with the window.....use a board to create a filler panel. Cut the board to run the length of the door from the sill to the top of the frame. Put a hole in it the size of your hose. Or....get sneaky and put a hose fitting in it with the right size "nipple" on both sides of the board that will fit your hose and leave the hose inside the garage attached to the board all the time. Put that board into the door, attach a short length of hose to the blower and the outside of the boards hose fitting, put the board in place in the door and pull it shut on the board and you have a reasonably snug opening. You can still go in and out the door as needed. Just make sure when you close it that you close it snugly on that board again.

In my case I had the option of going from the garage through the crawl space under my house and out the side of that. My blower is in that space just before the hose goes out the wall of the crawl space to the outside. The crawl space is insulated so I cant hear the fan in the house. Almost the entire length of hose/pipe is under negative pressure so I get no odors in the crawl space. And my garage is reasonably odor free and nice and quiet with the blower so far out of the way. In your case, you will achieve the same thing in terms of negative pressure and quiet by going out the door like this.

[Joe Pelonio]

I can't help a ton but I can offer some advice. First, what type of fan do you have? If it's relatively low power, then your hoses might be killing your flow. Curved hoses and accordian style flexible hose will REALLY eat your flow. Look at something more like a small dust collector fan.

Second, absolutely do NOT vent into the attic. You'll end up making a chamber in your house literally filled with poisonous/toxic particles and possibly carbon monoxide. Fans can help pull it through but you'll basically end up having your whole house smell terrible and making your attic completely inhospitable.

Third, a guy here at work has one of the Hakko fume extractors. It's not even sort of close to being enough oomph for a laser. It's designed to take out a small trickle of smoke from a soldering iron, not a plume of smoke from a laser.

On your exhaust fan, try putting the fan at the end of the line (by the window) not at the front. That way any leaks will suck air in, not blow air out. Also use as much rigid ducting as you can, it helps greatly with flow.

Do you have a window you could vent outside of? I made a wooden panel to sit in my window with a 4" hole for my exhaust fan before I just knocked a hole in the wall.
My setup is similar, but I used 1/4" clear acrylic rather than wood so I can still see through the window. Whatever you do, you will still have to put up with some smell cutting acrylic, and many other materials. The aroma lingers in the machine and on the material when removed. Acrylic smells a lot better than ABS, rubber, leather or even ADA material, but I kind of like the smell from cutting wood.

[Kev Williams]

You can always add some flue pipe and a rain cap to the roof and connect the vent line to that-

Most important if you're gassing yourself out is to get the blower outside--

That said, you might give this some thought: Home Depot has these patio boxes for about $50, it's the cheapest one they had--
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The nifty thing is, a HF green blower will fit inside in ANY direction, and only take up about 1/3 the space. There's plenty of room inside for TWO of them if need be...
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While any way is possible, the ideal way (imo) would be like the first pic... you can cut a hole (or drill holes) next to the end of the motor, this will supply the motor with the cooling air it needs.
Depending on other plumbing, bore a few holes in the sides somewhere for the motor cooling air to exit the box.
A hole on the opposite side of the motor will be needed for the intake from the laser. For simplicity, you can move the blower to the other end, and cut a hole for the exhaust outlet and just poke the outlet out the hole...
From there you can just leave it be, or add vent pipe and rout it where you want.
_OR_
you can leave the blower as shown and get creative with all the open space you have left...
Like build some screened dividers- you can put a furnace filter in front of the first divider, a second divider could be placed 8" or so from the first one- that space you could fill with charcoal briquettes...
Ok, so they might not work quite as well as activated charcoal, but briquettes WILL help, and they're dirt cheap and easy to change out.
After the second chamber you'll still have space for more furnace filters or whatever. Bore some exhaust holes at the far end and screen them...
If you set the blower on a thick layer of fiberglass insulation, and pack more insulation around the blower and into any unused air space inside the box
(just be sure to allow for motor air ventilation), it should work great and be quiet as a mouse!

I got this one to do exactly the above with my Triumph/GCC blower, but I haven't gotten around to it yet (plus, the wife's using it at the moment)

[Rich Harman]

Good to know about the Hakko fume extractors, that's what I figured. It's a good deal, but I figured it wouldn't have enough airflow. I could modify it to include a much bigger fan, but at that point I might as well build my own.
Increasing the airflow without increasing the surface area of the filter media would be pointless.

[Robert Cowan]

Thanks for the ideas everyone.

Kev, I really like your solution. Unfortunately, the bottom half of my garage/workshop is brick, so I can't really just pop through the wall.

I'm toying with either just venting out the door (but with a better air path and better exhaust fan) or building a charcoal/carbon filter box for inside. They each have pros and cons. There really isn't a window nearby (it's 25-30' away, and I don't really want to move the laser right now). So venting out the door, or keeping it inside are really my only two options right now.

[David Somers]

Robert,

I may be wrong, but I dont believe 30 foot is a problem with that blower. I have the same green Chinese blower and my distance is more like 40 feet. Using solid ducting I have tons of suction inside the laser. Lots of airflow. My dog has to fight to keep from being sucked in as he walks by!!!!! (OK....maybe a bit hyberbolic....but you get the idea <grin>)

[Robert Cowan]

Robert,

I may be wrong, but I dont believe 30 foot is a problem with that blower. I have the same green Chinese blower and my distance is more like 40 feet. Using solid ducting I have tons of suction inside the laser. Lots of airflow. My dog has to fight to keep from being sucked in as he walks by!!!!! (OK....maybe a bit hyberbolic....but you get the idea <grin>)
I don't feel like it would be a problem for the blower either, it's more of a location issue. I'd have to run a 30 foot hose across the length of the shop. I could run it up to the ceiling, but that adds another 20 feet and 2 90 degree bends. It's just a matter of location. The near side of the shop (where the laser currently lives) is where my tool storage and workbenches are. The far side of the shop (by the window) is material storage and my woodworking tools. So, it's just a matter of layout really.

[Glen Monaghan]

Unfortunately, the bottom half of my garage/workshop is brick, so I can't really just pop through the wall.

It's not _that_ hard to punch a hole through a brick wall...

[Robert Cowan]

It's not _that_ hard to punch a hole through a brick wall...

OK, I was a bit vague. I wasn't saying I couldn't, I was saying I didn't want to. I'm not going to knock a 4-6" hole in my brick just to exhaust fumes from my laser. I'd sooner move it over to the window or knock a hole higher up where it's not brick. I'm not going to decrease my home value for this...

[Jeff Body]

I went up into the attic through the ceiling. That's where I installed my blower. From there is exits through a soffit vent.

[David Somers]

Jeffs approach is similar to what I described, with the exception I am under my house and Jeff is above it. Same idea though. One suggestion if you did this. Consider putting a smoke detector in whatever space you put the fan in. And mark your calendar to change its battery annually. You might also put a camera of some sort down there that you can access remotely.

Can't blame you for not wanting to go out a brick wall. I wouldnt want to do that either. But adding extra hose/pipe to get over to the window shouldnt be an issue in terms of the overall length if that helps. Especially if you are using smooth walled pipe, the distance you describe should be fine. For what that is worth!

[Kev Williams]

What you really should shoot for (IMO) is to get the blower OUTSIDE. As long as it's INside you're smoke & soot & stink into your house. My garage blower is still in the garage and engraving leather sucks in there! My basement lasers's blower is outside, and the air down here is nice & clean.

I have the big HF blower outside in a shed next to the house. I got tired of burning up shop vacs that I was using- and their noise- as chip extraction vacuums and have been using this blower for 13 years. No, it doesn't have anywhere near the suction of a a good vacuum cleaner, but it's dead silent, and even funneled down to the 1/2" hose that's connected to my machine's depth gauges, there's plenty of draw to suck up the engraving cuttings. I rarely have the end cap off but I do take it off occasionally so the heavier chips that just sit in the vent will suck back to the vacuum. I have two 25' dryer vents connected together, and there's still GOBS enough airflow to suck 2 laser's worth of smoke out if needed...

Proving again that I'm the king of underkill, here's the vent run, it starts with the black hose that connects to Don's C2000,
from there it runs along the ceiling, 38' to the side of the house and out into the shed and the blower...
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The dryer vent is also 13 years old and still in good condition.

In the first pic above, you can see the LS900 vent run up the wall, across the ceiling, and down the door jamb, where a Y pipe connects a second vent (hard flex aluminum) that sucks the smoke from my fiber.
That's nearly a 25' run with an against-the-wall 90, plus 3 more 90's once out the door, plus a second wide-open pipe...

To show how well it pulls smoke even with all that cheap pipe and bends, in this pic I'm running the LS900, door wide open, and hard- engraving wood 16" down,
pretty much out in the middle of nowhere, AND with the fiber's blast gate open (look close)-
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While there is smoke drifting up around the back of the cabinet, you can see the smoke being
pulled to the back of the cabinet, and NO smoke leaves the cabinet.
(this also speaks of Gravograph's way of exhausting, it simply works great)

This is the smoke exhausting with the other blast gate closed,
notice the smoke is going straight back...
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So, just my 2c but I wouldn't about long runs or what pipe to use. We don't need a 100% efficient hospital-grade air ventilation systems, we're sucking smoke out of laser engravers! ;)
A 30 or 40 CFM airflow loss out of 4 or 5 hundred CFM doesn't add up to a hill of beans as far as extracting smoke from your laser. That little bit of air loss is well worth the clean air you'll enjoy.

[Bill George]

Be very aware like most Chinese imports I am sure they "stuck" a UL label on that fan. I would bet a lot of money it means nothing, as UL means it was tested and approved and that means time and money. My just the UL label (if it has one) perhaps means the cord is approved!
I would consider any Import from China or India to be a fire hazard. Sticking it (your fan) in an attic or un-attended area is just asking for a fire.

[Keith Winter]

For what it's worth I've tossed a number of those green Chinese blowers, utter junk. The $80 harbor freight would be well worth your money to upgrade. With a coupon you can get it even cheaper some weeks.

[Kev Williams]

The blower that came with the Triumph is pretty much identical to the one in Robert's pic, but 220 volt. I was impressed at the amount of air it blew. But one day it simply wouldn't kick on. I tested the power outlet, it was fine, fan freely spun, just no worky. Wasn't worth digging in farther when a new Harbor Freight unit was $138. I have nothing but good to say about these- The one connected to the lasers I got in 2004 when I got the LS900. The one before it I got in 2002, last year a motor bearing started a high pitched squeal. I could've spent my time (which I have very little to spare) to change it, or pay the motor shop $80 to do it. At 14 years old it served me well. I didn't even replace it as the second one does fine by itself. The big one in the shed I got shortly after small one so it's nearly 13 years old. The one in the garage is going on 3 years old. Fact is, I have good luck with most HF products.

[Matt McCoy]

If you're cutting a lot of acrylic and ABS, the sticky residue left on the cutting surface, as well as the inside of your cabinet will continue to off-gas and linger. The current collector you're using is a beast and will move a lot of air. The CFM is about the same as the HF 1 hp dust collector and both are made in China, so my opinion is that location of the extractor will make the most impact. If your compromises won't allow you to place it in the optimal locations that have already been suggested, then some concessions will probably have to be made in regards to smell and noise. Everything else might just be rearranging deck chairs.

P.S. Dave's solutions are always the coolest! So much thought goes into everything. Your shop must be almost like the Batcave.