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

  1. #1

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

    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?

  2. #2
    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.

  3. #3
    My fan is one of these:

    s-l1600.jpg
    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.

  4. #4
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    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.
    900x600 80watt EFR Tube laser from Liaocheng Ray Fine Tech LTD. Also a 900x600 2.5kw spindle CNC from Ray Fine. And my main tool, a well used and loved Jet 1642 Woodlathe with an outboard toolrest that helps me work from 36 inch diameters down to reallllllly tiny stuff.

  5. #5
    Quote Originally Posted by David Somers View Post
    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.

  6. #6
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    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.
    Last edited by David Somers; 03-14-2017 at 6:16 PM.
    900x600 80watt EFR Tube laser from Liaocheng Ray Fine Tech LTD. Also a 900x600 2.5kw spindle CNC from Ray Fine. And my main tool, a well used and loved Jet 1642 Woodlathe with an outboard toolrest that helps me work from 36 inch diameters down to reallllllly tiny stuff.

  7. #7
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    Quote Originally Posted by Bert McMahan View Post
    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.



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  8. #8
    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--
    DSC05130.jpg

    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...
    DSC05133.jpgDSC05132.jpgDSC05131.jpg

    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)
    Last edited by Kev Williams; 03-14-2017 at 9:06 PM.
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  9. #9
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    Quote Originally Posted by Robert Cowan View Post
    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.
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  10. #10
    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.

  11. #11
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    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>)
    900x600 80watt EFR Tube laser from Liaocheng Ray Fine Tech LTD. Also a 900x600 2.5kw spindle CNC from Ray Fine. And my main tool, a well used and loved Jet 1642 Woodlathe with an outboard toolrest that helps me work from 36 inch diameters down to reallllllly tiny stuff.

  12. #12
    Quote Originally Posted by David Somers View Post
    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.

  13. #13
    Quote Originally Posted by Robert Cowan View Post
    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...

  14. #14
    Quote Originally Posted by Glen Monaghan View Post
    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...

  15. #15
    I went up into the attic through the ceiling. That's where I installed my blower. From there is exits through a soffit vent.
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