Upgrading dust collection; could use some help

Discussion in 'Woodturning Health & Safety' started by Mark Hepburn, Dec 31, 2015.

  1. olaf Vogel

    olaf Vogel

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    Hi mark

    Seems like I'm working in parallel, but with slightly different parameters.
    Last weekend I managed to get the blower and motor installed in my new "mechanical room" in the attic. (This is in a workshop, separate from the house, way out in the country )
    It's made by Jos Poitras (sold to General) No 4 blower. All 235lbs of cast iron, with a huge steel impeller. I bought it used with a 7.5 hp motor for a silly price. It's rated at 2500 CFM at 5". Loud as hell - at least it's in the attic!

    Got the electricals going on Sunday, no piping, fired it up. Crap! I didn't want to get near it. Had a small tornado in the room.

    Btw. Amazon has relays with 24v trigger circuits that allow you to remotely turn things on/off. So a small switch will be on the lathe, remotely. Didn't want to run large 3ph wiring back and forth.

    Btw - running the pipes may be a big part of the effort and expense.

    I only plan on using this for sanding on the lathe, since that generates most of the dust in the shop.

    This will have 10" dia steel pipe, from the local hvac store, with about 15' run to the cyclone. For the moment, all air will go back into the shop without filters, post cycle - better than now. Once I find a source for filters, those will be added. They're not cheap. In summer, it will be vented outside - no neighbours.

    All that sits in my insulated "mechanical room". Btw 52F sounds nice and toasty.

    I know this is far from "perfect" but it's much better than now. I've been a software designer and manager for a long time. Often people are looking for perfect. But it's a tough goal. Sometimes just a major improvement is good enough. Heck, it's just a hobby for me.

    I sell my work when I can, but it's a ways from paying the bills....
     
  2. Mark Hepburn

    Mark Hepburn

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    Hey Larry. Actually it's for sure not more than I want to know. I appreciate your knowledge and think that's one of the greatest benefits of this forum; being able to have a person of your technical knowledge willing to freely participate and help. So thanks very much for that.

    My shop is unconditioned space and there are no vents or whatever. It was a porch with two entry doors at opposite ends of a 26'6" space. Those doors were already pretty well sealed against weather but I plan on beefing up the seals, and pulling the casing and blowing in some low expansion foam anyway.

    So the AC system is completely separate from the shop. I tend to go into the shop, close the door and, if I want some air, open the window of a storm door that I placed in the long, exterior wall of the shop. I've attached a somewhat to scale drawing.

    hepburn-shop.jpg

    In an effort to conserve space, I really would like to put the unit outside, but I just got the quote for the ducting and yikes! $2800. Not that it isn't worth it let's say, but really, I'd like to knock that down as much as possible. Re-reading your post, it seems that if I carve out some space for the unit inside, I eliminate the need for some of the duct run and the enclosure (this unit is rated as their quietest collector at 72db at 3 ft). I'd move my grinding station elsewhere (into a "clean" assembly area), which would keep me about par on space if I also move my band saw along the exterior wall and my miter station as well. I also have a shop-built downdraft sanding table that probably just spews more in the air and I could put it outside and sand out there.

    I could build an enclosure around it and put in HEPA filters as you have done so the return air to the shop is filtered again. I understand about loading the filter but not more than a layman's passing awareness. If I were to save a bunch of ducting, I could spend more on the HEPA filters for the enclosure. Having done that, if I were to increase the surface area of the filters would that possibly offset the increase in potential static pressure due to the enclosure?

    It's funny, I started out absolutely certain that I would put the unit outside with auto blast gates. The more I learn the more I learn to be open-minded. It reminds me of a Winston Churchill quote: " A fanatic is one who can't change his mind and won't change the subject."

    Fortunately I'm only halfway there :)

    I just want to get the best clean air I possibly can in my shop and stop having to sweep up after a dust collector. I seriously appreciate your help.

    Mark
     
  3. olaf Vogel

    olaf Vogel

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    Seems like the largest ports are 4". You should be able to get pvc piping from any of the major stores. Very easy to assemble, if you just surface mount them on the walls/ceiling. I just stuck mine together, didn't bother gluing til 6 months later - when I was reasonably sure that machines were in the right spot.

    Ok they create some static buildup, personally I've not found that to be an issue. A hole saw will get you through the walls.

    Auto blast gates are nice. Mine are all of Amazon, with a 24v trigger circuit that powers a relay.

    You may want the HEPA filters in your shop so you have a closed loop system and avoid having route the clean air back in. I'm still looking for a source for those.
     
  4. Mark Hepburn

    Mark Hepburn

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    Olaf,

    Yes, 52 is toasty but you'd be amazed at the people down here bundled up like the ice age is nigh. Thanks for your suggestions. Sounds like you've got quite a setup, by the way.

    I'm hoping Larry will chime in here soon with his thoughts too. I was leaning your way - going wtih 6" PVC. Oneida's design spec is 6" to the machines with reducers at the machine to 4". After reading the quote, I either have to take machines out of the equation and move them somehow, bring the collector into the shop to reduce runs or go with PVC. I don't want to use the snap lock duct at all. Too much hassle for me.

    My reading of the static is that it's more of a nuisance than a hazard in the piping, but the collector bin is something else. I'm good about keeping it pretty empty so no worries there. So now, I'm thinking that if I go PVC, then I can get the auto blast gates with what I'm not spending on duct.

    Sadly, that Gorilla duct seems very very good. Rolled ends, adjustable nipples, clamping rings. No screws, soldering, etc. to assemble (other than hanging straps that is).

    The DC has a hepa filter setup, but Larry's suggestion, like yours, is to put hepa in the enclosure and IF I'm putting the machine in the shop, then I'll do that. I guess one benefit of doing that is that I could actually open the shop doors to the house and not worry about dust infiltration and sucking out all the conditioned air.
     
  5. Bill Boehme

    Bill Boehme Administrator Staff Member

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    Mark, I would encourage you to put everything inside your shop. Otherwise, the difference in pressure between indoors and outdoors even though seemingly small will lead to numerous other annoyances that you will need to address. Some examples are:
    • Air from your living quarters will ba pulled into your shop every time the door is opened and it could make the door hard to open.
    • If you have gas water heaters, the pressure differential will cause the normal updraft of the pilot light will be reversed to cause a downdraft and blow out the pilot light.
    • If your HVAC system uses gas heat the pilot light might get blown out every time the door is opened to your shop.
    • The higher pressure differential would reduce the efficiency of clothes dryers that have outside vents.
    • Water can be sucked out of the P-traps.
    • There would be backwards air flow through bathroom vent fans and kitchen range hoods.

    Of course these situations only exist while the DC is running and the door to the living quarters is open.
     
    Last edited: Jan 7, 2016
  6. Larry Morgan

    Larry Morgan

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    Mark:

    After reviewing your plan layout of the space, I would first consider closing off one or two of the doors (if you don't need them) to allow for more space to have our DC inside.

    Second, I would strongly consider installing metal duct in place of PVC? I understand you had a quote to install metal that was expensive. (I would assume that price most of that was labor) I just purchased 40 feet of 6" pipe, 40 feet of 4" pipe, 8 - 90 degree elbow, 5 "T's" and seam tape for under $260 dollars. Metal ductwork is very easy to work with. Best of all, no static shock to deal with. Place one or two short self tapping sheet metal screws at each joint and place foil tape on the seam to seal all leaks. If you get a chunk of wood inside it will be easy to take apart and clear the blockage. Make sure to pay attention to the how you assemble the duct so your joints and dust flow in the same direction.

    Mains should be be 6" dia. And take offs should be 4" dia. I would make the last take off from the main a 4" to keep velocity up. You can also add one more open vent on the very end of the run that you keep open when you only have one other blast gate open. ( it will also act as an exhaust vent to help clear dust in the room,) This will keep an adequate quantity of air to keep air velocities up where you need them.

    Do not get wrapped up in all the static pressure calculations as some try to make themselves look good with big tech talk. You pressure drops will not be that much different at the end of the day.

    I am placing all my ductwork on the floor and popping up at each piece of equipment with minimal flex (less than 12") at each station.

    You can install it yourself and I would recommend wearing gloves when installing. I also highly recommend using a 26 gauge metal. Do not use the product on the shelves at the big box stores as they normally stock a thinner gauge material that can collapse under suction pressure.

    Hope this helps
     
    Last edited: Jan 6, 2016
  7. Mark Hepburn

    Mark Hepburn

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    Larry (and Bill too).

    Thanks for checking in. I am persuaded that bringing the unit in is the way to go (I'm a slow learner). I am now drawing up an enclosure that I'll build in the shop.

    Anybody want a homemade downdraft sanding table? :) It makes no sense at all to have that thing in there since it's just a squirrel cage motor sucking air through a top with holes in it and through some filters. At the time I was pretty proud of it but it's gotta go because it defeats the purpose of upgrading my DC. So there's the space I need.

    So, as to the duct, that was Oneida's quote for materials. I would install it. It's nice, heavy, rolled stuff but seriously, I can't spend that on ducts. I've been looking at a PVC run but would prefer the metal. So Larry, are you talking about HVAC duct or the snap lock stuff or what? We actually have an AC / refrigeration tech on our maintenance staff and we shoot together sometimes and are friends. He could a) help me source it and, b) help install or at least give some direct guidance.

    I would like to go with the 6" mains and drops as much as I can, meaning as close to the machine as possible. And I'll be sure to spec the 26 gauge. I do think I'd prefer to hang the stuff. I have a few inches extra height in the shop, no obstructions and I really can't close any of the interior access doors. One goes to my "clean room" where I clamp, assemble, and have a makeshift paint booth (visqueen walls and a couple of filters going inside the space). The other door goes to my kitchen / breakfast room but, as both of these were exterior doors, they're good doors and well cased. I just want to bump up the seals on the threshold, casing and also maybe fill in behind the casing with low-expansion foam.

    So a few questions if you don't mind?


    I'll build the enclosure in the shop, and it'll have to be a double door to access the machine as there's not enough space for a single wide door. No problem, I'll just do them like a full overlay cabinet door with a lip at the center to provide some seal, and the seal everything like crazy. Door gaskets, seal all the joint gaps, etc. Does that sound like a reasonable approach?

    Also, you mentioned filters on the enclosure. What would you suggest I look for in HEPA filters? Could I mount these in the doors for the return?

    This may be a very dumb question. Is there such a thing as a washable HEPA filter that I could service (and are they any good), or will they be an ongoing replacement item?

    As to the duct work, we have tons of fab shops, sheet metal shops, shipbuilding companies and so on. This is basically an industrial town and so there should be no problem getting it. Do you suggest that I go to a HVAC supplier? Should I talk to my friend about this? And I'm assuming that I can get the wyes, long sweep elbows and reducers etc?

    Also, once I go down to 4" at the machine for the hose, can I find the appropriate reducers in metal or do I need to get standard plastic stuff like at Grizzly, Rockler or wherever and fit them for the hoses?

    And I see that you mentioned "T's" Do you use them instead of the Wyes for the drops? If Ts are fine, then that makes it a lot easier to work with for sure.


    Lastly, you're saying that I should add a take off from the main to keep up the velocity. Do you mean essentially a vent that would default to open if only one blast gate is open? If so, then I could set up the floor sweep for that purpose? I am always by myself and only run one machine at a time, so that will be almost a permanent condition.

    Here's a drawing that shows the general idea.

    hepburn-shop-03.jpg


    Many thanks,

    Mark
     
  8. Larry Morgan

    Larry Morgan

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    Mark:

    I will try to answer all your questions:

    If you received a quote from Oneida, I understand the high number now. They typically provide a top line product for industrial purposes. A very good product, but you are going to pay for it. They are not for the hobby shop user. Regular HVAC 26 gauge duct with snap lock seams would be optimum for our use. The ends will be a slip fit connection. Two screws and metallic duct tape will be sufficient.

    1. Your door solution appears to one the right track. Make sure to provide for a tight seal.

    2. Filters could be mounted in the door...do not install in the return. HEPA Filters (1") can be found at most building supply big box store. No, they are not washable. You could take them outside periodically and blow them out with an air hose...I do not recommend doing this. You health is more important than a saving a few bucks. I don't expect you would change this but every two to three years depending on use.

    3. I would get your duct work from an HVAC supplier. I would get the 45 degree offset wye if you can, otherwise get the Tees. You should be able to purchase your straight runs in lengths of 60 inches. You can cut them to exact length later with tin snips or other power tools if you have them. They will provide the straight duct to you flat. You will need to roll it and snap the seam together. (Thus the term "snap lock")...it's not difficult. Long sweep elbows are best but don't get too worried if you can't get them.

    4. I have found the Rocker and Wood Craft fittings are standard in size to fit HVAC nominal duct sizes. I would not worry about the fittings. Occasionally you may need to use a short section (less than 6") of flex duct to make a final connection.

    5. I would keep your takeoff from the 6" main at a 4" size to keep the velocity up and moving he dust or wood chips. Otherwise you run the risk of dust falling down due to an overhead DC system. There needs to be velocity/quantity to move the dust particles. I would highly recommend that two ports are open at all times for a 6" duct. These ports will need to be the one your using and one that is upstream of that port. This could be a floor sweep. That is the reason for my recommendation to have one extra port beyond your last piece of equipment.

    Maybe I need to write a book on this topic.
     
    Last edited: Jan 6, 2016
  9. Bernie Hrytzak

    Bernie Hrytzak

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    Dust collection

    Hi Mark,
    I have attached pics showing my set-up.
    I put my dust collector outside for noise control when I had a bag type unit, so created an insulated lean to structure outside to house it. When I upgraded to Oneida, I barely had enough room to fit it. Luckily the outside door provided an additional 2 inches of clearance where I needed it!
    The first pic shows the pipe going thru the wall connected to the Oneida, can see the return air from the Oneida Hepa filter going thru furnace filters before coming back into the workshop. Also you can see the remote, and the manometer that indicates when to clean the filter.
    The next picture shows the addition and the DC in place, note the air hose (accessible) to simplify cleaning.
    Next is a shot of the return air opening to the inside
    Next is the pipe, shown with pop rivets, 2 at each joint to hold together, and aluminum adhesive tape at all joints to prevent air leakage.
    Lastly, with the 6" steel pipe, I also used 6" clear flex pipe as much as possible stepping down to 4" only at the very end if req'd to meet machine fittings, the overhead table saw pickup is shown.

    Bernie
     

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  10. Mark Hepburn

    Mark Hepburn

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    Hi Bernie. Thanks for the pics. That's a nice setup you have there. So the return filters are mounted on your interior wall, which is similar to what I want to do. So how much clearance space do you have around the filter and do you find it's enough? I was going to go sort of tight - the machine footprint is 30 x 50 and I was going to do a 34 x 60 enclosure (inside dimensions). A couple of questions if you don't mind....

    You're using 6" blast gates at the machine just before you reduce down to 4" flex?

    What is the purpose of the small air hose above the filter?
     
  11. Bernie Hrytzak

    Bernie Hrytzak

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    dust collector

    Hi Mark, Thanks,
    Yes, I mounted furnace filters on a "collector box" to increase the filter without increasing the hole in the wall as much. (This helps muffle the sound)
    You should be fine with the area you are considering, my enclosure is 24" x 52" x 100" high
    I believe the Oneida filter capacity (because of the folds) is equivalent to a 10 ft x 10 ft straight sheet, so the actual air flow per inch of filter is quite small and so your enclosure (or mine) will not impede air flow.
    I am using 6" blast gates at the lathe and table saw overhead pick-up. The lathe has a collection box with a 6"flexible hose going directly to the box with no reduction to 4". The saw overhead pick-up is a 6" flexible pipe going to a 4" fitting on the pick-up box. ( this was done to keep the chip shutte narrow.) The preferred blast gates are aluminum purchased from Lee Valley, plastic ones clog up with chips at the sliding grooves and will not close properly and it is difficult to clean them. The router table, planner, thickness planer, drill press , band saw and floor sweep all have 4" flexible pipe going to them.
    The small hose next to filter is for sensing the back-pressure in the air stream and is connected to the water manometer shown in the first pic I posted earlier. When the filter gets plugged, the air will not be able to escape as easily and a higher pressure will be created just before the filter. A new system should be run before any dust is captured to establish a baseline for a clean filter. I would run this with one or 2 gates open ( want to pull maximum amount of air) record your reading between the 2 columns.
    You can observe values in the future and decide at what point in the readings it is time to clean the filter.
    Hope this helps.
    Bernie
     
  12. Mark Hepburn

    Mark Hepburn

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    Bernie, thanks.

    So I pulled the trigger, ordered the Oneida 3 HP V-series and a bunch of metal duct. 6" to the drops, 4" to the machines; minimal flex hose but as Larry said, I'm not going to sweat the minor points. And not gonna run a bunch of engineering studies on my 9 x 26 shop :D

    Raul posed a good question, which was why would I not simply open a gate as I approach the tool, and he's right. So instead of paying nearly $200 per tool for an automated system, I've ordered the 220v Long Ranger blast gate controller and micro switches, for about $120 for the entire system.

    Note to Bill Boehme from a different thread: my "Savings" will allow me to buy that Powermatic drill press I've been eyeing! :D


    A few questions to you and others who may be following this thread and may have some helpful thoughts.

    I'm going to make a manometer also and mount it on the outside of my enclosure. Because of the narrow size of my shop, I've put the collector in a corner enclosure (shown) and am going with a removable panel instead of a door. I can seal the edges with window sealer - flexible rubber - and will use jig through knobs with 1/4" Tee - nuts epoxied from the inside of the enclosure. Easy to remove and I won't be doing it too often any way. I'll check every week for the first few weeks and then see where it goes from there.

    I like the idea of an access panel that can be easily removed and seals well, so does that sound reasonable?

    Also, I bought some 20 x 25 filters and plan on putting 2 of them side-by-side in the access panel at a good height. My reasoning is that this will blow the exhaust into a "neutral" area where I'm not working and there's only the band saw opposite and I don't use it a lot. So there's a crude sketch included.

    Is there a reason not to place the filters as shown? Also, their combined surface area is about 6.9 sq ft. Meaning that about 200 CFM per square foot will be moving across them when in use. Is this enough surface area? They're high efficiency (99.7 @ .3 mu). Do I need more filters or is this enough? Bernie, I see that you use two. I like the way you've set yours up but I can't do that in my shop. Not shown is that the miter station bumps against the enclosure on the long wall at right.

    So again, thanks to everyone who's offered their thoughts; much appreciated.

    Mark

    View attachment 9178
     
  13. olaf Vogel

    olaf Vogel

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    Having spent the weekend wrestling with that metal tubing, I was seriously reconsidering my desire for DIY.
    That stuff is PITA (or just haven;t figured it out.

    That 2800 you were quoted is starting to sound like a good deal!
    Congrats and I;m sure you will love it. With less hassle than I.

    BTW - I've got a Delta 17-600 drill press I'll be selling in spring.
    Theres the small issue of shipping a 400 lbs beast :)
     
  14. Mark Hepburn

    Mark Hepburn

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    Thanks Olaf. Please let me know about that drill press this spring. Is it the Rockwell-Delta?

    Road trip perhaps!
     

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