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Thread: Help me with an exhaust question.

  1. #1
    Join Date
    May 2015
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    FL
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    Help me with an exhaust question.

    I know it's been discussed lot.
    I've been searching like crazy. I've read everything from how much 90* bends hurt flow to super long runs. Most of the posts I've been reading have been out of my budget range.

    I believe I have a sh-350 laser. I have a 6" outlet for the exhaust that goes right out the window that's next to it. It's maybe 4'-5' of hose from the exit to the window with 2 90* bends.
    I noticed that the smoke wasn't being evacuated very fast while I was engraving and cutting so I bought this 6" inline booster that runs along with the stock blower. It's suppose to be rated at 240 cfm.

    http://www.amazon.com/gp/product/B00...?ie=UTF8&psc=1

    Measuring the speed of air coming out with this new addiction I notices a small increase in flow but I'm still not satisfied. I still have a chamber that seems to allow smoke to linger.

    So i want to upgrade. Personal I'd like to see the smoke shoot straight back and get exhausted (no floating around). Currently funds are limited since I just bought the laser. I'm looking to see what I can buy or build for around $100.

    Here's where my questions comes in. I've been comparing specs on 2 items from harbor freight.
    1 is a 8" portable ventilator fan with specs of 1.4amp draw and 1590 CFM on the high setting and 8" intake and exhaust. I would have to figure out a way to adapt the 6" hose to the 8" opening.

    http://www.harborfreight.com/8-inch-...tor-97762.html

    The other option I'm looking at is the common dust collector. It's specs are 7 amp draw but only 660CFM with 4" intake and exhaust.
    This setup I'd have to figure out a way to adapt my 6" hose down to 4".

    http://www.harborfreight.com/13-gall...tor-31810.html

    Here's where I'm getting confused. Wouldn't I want to go with the higher CFM blower? Something that didn't restrict the airflow through a 4" opening?

    Should I be removing the stock exhaust fan from the system when I add my own blower?


    I'm also open to any other suggestions. I'm good at most fabricating and electrical work. I have had the thought of a whole house blower but I'm afraid it might be too loud. And finding one hasn't been very easy.

    I would love some advice.
    Jeff Body
    Go-C Graphics

    China 50W Laser
    Model # SH-350
    Controller RDC6442
    Vinyl Plotter Graphtec CE600-60
    Software used
    Inkscape, FlexiStarter, VinylMaster 4, RDWorksV8

  2. #2
    Join Date
    Oct 2013
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    That inline stuff is never going to work if you're going any distance at all especially if you ever cut, exactly what you are experiencing now will happen even with another inline. I have the harbor freight 2hp, does very well 1 laser, borderline on 2. That 1 hp should be fine one laser going that short of a distance.

    As for the pipe, go 6" all the hard pipe you can then reduce at the very end. We made the mistake of going 4" and had to rip it all out recently. About a 25% gain for us going all hard pipe and 6" vs 4" even though we reduced to 4" when it hit the laser.
    Last edited by Keith Winter; 05-13-2015 at 3:50 PM.
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  3. #3
    Join Date
    Mar 2011
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    Olalla, WA
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    Quite a few people, including myself use the little green dust collector from HF with good results.

    http://www.harborfreight.com/13-gall...tor-31810.html
    Shenhui 1440x850, 130 Watt Reci Z6
    Gerber Sabre 408

  4. #4
    Join Date
    Nov 2011
    Location
    Los Angeles
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    That is the one I have and it works great. I vent about 10 feet through the wall into a "dryer exhaust", through the wall and then onto the outside. Purchase the extra warranty. I have gone through two in three years that shattered impeller blades, the third is still running strong.


    Robert
    Robert Tepper
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  5. #5
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    Quote Originally Posted by Jeff Body View Post
    Here's where I'm getting confused. Wouldn't I want to go with the higher CFM blower? Something that didn't restrict the airflow through a 4" opening?

    Should I be removing the stock exhaust fan from the system when I add my own blower?
    The reason the 8" ventilator has higher cfm is because it is meant to operate in free air - no restrictions, just like a house fan. The dust collectors are meant to move air under pressure.

    With only a few feet to go the HF Green dust collector should work very well for you. It's what I use in a machine four times the size of yours - and I nearly always operate with the lid open. The only time I have an issue is when I am cutting something that makes a lot of smoke near the front of the machine. Then I simply close the lid and it clears just fine.
    Shenhui 1440x850, 130 Watt Reci Z6
    Gerber Sabre 408

  6. #6
    Join Date
    May 2015
    Location
    FL
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    Sounds good.
    I'm liking the responses.
    So a whole house furnace blow wouldn't perform as well as the HF blower?

    So..... Should I remove the stock fan that's mounted to the laser? or should I just leave it?
    Jeff Body
    Go-C Graphics

    China 50W Laser
    Model # SH-350
    Controller RDC6442
    Vinyl Plotter Graphtec CE600-60
    Software used
    Inkscape, FlexiStarter, VinylMaster 4, RDWorksV8

  7. #7
    Join Date
    Mar 2011
    Location
    Olalla, WA
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    Quote Originally Posted by Jeff Body View Post
    So a whole house furnace blow wouldn't perform as well as the HF blower?
    Might work okay - seems like a lot of trouble when there are much easier ways.

    Quote Originally Posted by Jeff Body View Post
    So..... Should I remove the stock fan that's mounted to the laser? or should I just leave it?
    I would remove it.
    Shenhui 1440x850, 130 Watt Reci Z6
    Gerber Sabre 408

  8. #8
    Join Date
    Mar 2014
    Location
    Iowa USA
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    What Rich said. Propeller fans don't like ductwork, get the HF small green dust collector its set up for what you need.
    Retired Guy- Central Iowa.HVAC/R , Cloudray Galvo Fiber , -Windows 10

  9. #9
    I have the HF Blower with 4" pipe/ flex hose. The suction side is about 20 feet long, the discharge side is about 4 feet. I also put in a gate valve on the suction side attached very close to the blower. I actually have the gate valve closed about 20% to cut down on heat/ac loss. Since the laser is in my basement, I always keep a small window open to equalize pressure so not draw any carbon monoxide fumes from my furnace and hot water tank. I primarily cut 1/4" BB
    GWeike LC6090 130 Watt 24" x 36" Table
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  10. #10
    Hi Jeff

    In my opinion you want a blower that has 8 inch connections and the blower should be rated 1.5 hp minimum. The blower should be a centrifugal type (it turns the air 90 degrees). I think a variable speed drive is valuable as some jobs you want extra flow and other jobs you only need small flow with less noise. See My extraction system set up, it sounds it would work well for you.

    Cheers
    Keith
    Universal Laser VLS6.60, Tantillus 3D printer, Electronic design
    edns Group, Mairangi Bay, Auckland, New Zealand

  11. #11
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    May 2015
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    FL
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    Quote Originally Posted by Keith Colson View Post
    Hi Jeff

    In my opinion you want a blower that has 8 inch connections and the blower should be rated 1.5 hp minimum. The blower should be a centrifugal type (it turns the air 90 degrees). I think a variable speed drive is valuable as some jobs you want extra flow and other jobs you only need small flow with less noise. See My extraction system set up, it sounds it would work well for you.

    Cheers
    Keith
    Yea that seems just alittle extreme for my application.

  12. #12
    Join Date
    May 2015
    Location
    FL
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    295
    Well.............
    I purchased the HF blower yesterday and unboxed it last night.
    This thing is loud which really throws a wrench into my plans. It's way to loud to be in the house. My fiance would not be happy.
    I'm looking at a few options.
    1 Build a box and line it with egg crate foam and see if I can get the noise down. I'm alittle worried about heat with this option and I really don't have any space to put this box around my laser.

    The other option is moving everything to the garage. This presents a few problems. I have block walls so I don't know how I should route the exhaust. Unless someone has some better ideas I'm thinking the only thing I could do is to route it through the ceiling with a 180* bend into the soffit.
    The other problem with this idea is I'll have to do I complete redesign of the garage because currently I don't have extra space in the garage.
    I'm also not excited to be working in a non air conditioned garage.

    What have I gotten myself into?
    Jeff Body
    Go-C Graphics

    China 50W Laser
    Model # SH-350
    Controller RDC6442
    Vinyl Plotter Graphtec CE600-60
    Software used
    Inkscape, FlexiStarter, VinylMaster 4, RDWorksV8

  13. #13
    Join Date
    Mar 2014
    Location
    Iowa USA
    Posts
    4,441
    You never said your going to be operating in your house in that case you need the re circulating air filter system that Dan H. has designed or another just like it.
    Retired Guy- Central Iowa.HVAC/R , Cloudray Galvo Fiber , -Windows 10

  14. #14
    Join Date
    May 2015
    Location
    FL
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    Quote Originally Posted by Bill George View Post
    You never said your going to be operating in your house in that case you need the re circulating air filter system that Dan H. has designed or another just like it.
    Yep.
    It's in the house and I build a spacer that slides into the open window and then the window closes on it The spacer seals the opening and has a 6" vent that the exhaust connects too.
    The window is right next to the cutter.
    Jeff Body
    Go-C Graphics

    China 50W Laser
    Model # SH-350
    Controller RDC6442
    Vinyl Plotter Graphtec CE600-60
    Software used
    Inkscape, FlexiStarter, VinylMaster 4, RDWorksV8

  15. #15
    Quote Originally Posted by Jeff Body View Post
    Well.............
    I purchased the HF blower yesterday and unboxed it last night.
    This thing is loud which really throws a wrench into my plans. It's way to loud to be in the house. My fiance would not be happy.
    I'm looking at a few options.
    1 Build a box and line it with egg crate foam and see if I can get the noise down. I'm alittle worried about heat with this option and I really don't have any space to put this box around my laser.

    The other option is moving everything to the garage. This presents a few problems. I have block walls so I don't know how I should route the exhaust. Unless someone has some better ideas I'm thinking the only thing I could do is to route it through the ceiling with a 180* bend into the soffit.
    The other problem with this idea is I'll have to do I complete redesign of the garage because currently I don't have extra space in the garage.
    I'm also not excited to be working in a non air conditioned garage.

    What have I gotten myself into?
    Most blowers that effectively move a lot of air will make shop-level noise that will probably be too loud for most living spaces, in my opinion. Not only from the motor, but also from the air rushing through and especially exiting the pipe/hose.

    If you intend to build a box, the egg crate won't do much. Noise isolation, damping of mechanical vibrations, and ventilation without letting sound escape will require some research and careful planning to get the most bang for your buck. It is also not cheap to do this.

    A short-run with recirculating exhaust/filtration and a quiet inline fan might work, but you will have to run some numbers. Dan H.'s DIY scrubber is clever, easy, and cheap. A good overall solution or start, depending on your time and budget.

    The garage set-up could be a little more forgiving and less expensive to run.

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