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Spark trap for shop vac?

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  • Spark trap for shop vac?

    After getting the big belt grinder and every place full of grinding dust I think its time to project some dust control. I'm thinking of connecting my "shop vac" to grinder ports but..

    Anyone got good ideas or links for spark traps?
    I'm thinking of something similar to woodworking cyclones to separate most of the bigger particles and to give time for the sparks to snuff out.
    Location: Helsinki, Finland, Europe

  • #2
    I've never had a problem with my grinder and dust collection system but I have seen where people run a bare copper ground wire through the hose.
    I have got bit before with my shop vac when sucking up a lot of saw dust so I guess it depends on the material and the amount of it your sucking up.
    With my small surface grinder and taking less than .0005 cuts you don't really throw much dust into the vac hose. Unless your taking really heavy cuts??? That may be an issue.

    JL............

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    • #3
      for the grinding sparks, put 1 or 2 in of water in the shop vac. also use a vac. with the intake pointed down into the water.

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      • #4
        Originally posted by JoeLee View Post
        I've never had a problem with my grinder and dust collection system but I have seen where people run a bare copper ground wire through the hose.
        I have got bit before with my shop vac when sucking up a lot of saw dust so I guess it depends on the material and the amount of it your sucking up.
        With my small surface grinder and taking less than .0005 cuts you don't really throw much dust into the vac hose. Unless your taking really heavy cuts??? That may be an issue.

        JL............
        I'm talking about 5.5hp belt grinder on ceramic Cubitron belt. Puts out massive amount of sparks if pushed.. Imagine spark shower from 9" angle grinder and multiply that with three.
        (funny thing with these ceramic belts, they don't produce just "dust" but also long "chips" or slivers of steel, pretty much like steel wool)
        Location: Helsinki, Finland, Europe

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        • #5
          Originally posted by JoeLee View Post
          ... I have seen where people run a bare copper ground wire through the hose...
          This helps only with electrical sparks caused by static due to the moving dust/etc particles.
          The OP’s sparks are from a grinder ... bits of very hot metal and gunk heated by friction & oxidation.

          And I don’t have an answer to the original question ... though I wonder if a screen, like a fireplace screen, would work?

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          • #6
            Originally posted by fjk View Post
            And I don’t have an answer to the original question ... though I wonder if a screen, like a fireplace screen, would work?
            I had bright idea of using those kitchen range hood filters. Typically made of aluminium mesh. Gave it a second thought when I realized that aluminium mesh loaded with iron oxide is a recipe for thermite!
            Location: Helsinki, Finland, Europe

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            • #7
              Grinding sparks don't last very long. What, maybe two feet? It's not like blobs of welding metal. Get a length of that flexible auto exhaust pipe for the first 4-5 feet. After that, it should be cool enough to go through plastic pipe.

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              • #8
                Dust Deputy has a metal version, use a metal 5 gallon can... problem solved.
                Dust Deputy

                Or complete with metal can..

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                • #9
                  Originally posted by JoeLee View Post
                  I've never had a problem with my grinder and dust collection system but I have seen where people run a bare copper ground wire through the hose.
                  In some areas it is a code requirement. Dust collection systems in wood shops are a big fire hazzard and you can get pretty big shocks from the collected charge.

                  This thread has some interesting info on the properties of sparks once inside a collection system, that they stay hot and stay lit much further than you'd think. I didn't know that but it makes sense. You should find out - maybe without asking your insurance company directly - whether you would be covered if sparks from this 'industrial equipment' cause a fire.

                  https://www.bladeforums.com/threads/...ction.1514221/

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                  • #10
                    Originally posted by Glug View Post
                    In some areas it is a code requirement. Dust collection systems in wood shops are a big fire hazzard and you can get pretty big shocks from the collected charge.

                    This thread has some interesting info on the properties of sparks once inside a collection system, that they stay hot and stay lit much further than you'd think. I didn't know that but it makes sense. You should find out - maybe without asking your insurance company directly - whether you would be covered if sparks from this 'industrial equipment' cause a fire.

                    https://www.bladeforums.com/threads/...ction.1514221/
                    I have an un-grounded dust collection system in my wood shop (6" main with 4" drops). Large static buildup does occur and is quite annoying if/when it discharges to you but the subject about them being a fire hazard continues to be debated (at least it was a never ending debate years ago when I was following it over the years). As far as I know, nobody has actually witnessed any type of combustion, fire, etc... The static buildup and potential discharge to person(s) is very real and happens to me a lot but nothing more dangerous than that has ever been reported AFAIK.... ?

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                    • #11
                      Run your spark collector through a huge bong

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                      • #12
                        I have a Rainbow vacuum cleaner that uses a water-bath filtration.
                        Location: Saskatoon, Saskatchewan, Canada

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                        • #13
                          Originally posted by MattiJ View Post
                          I'm talking about 5.5hp belt grinder on ceramic Cubitron belt. Puts out massive amount of sparks if pushed.. Imagine spark shower from 9" angle grinder and multiply that with three.
                          (funny thing with these ceramic belts, they don't produce just "dust" but also long "chips" or slivers of steel, pretty much like steel wool)
                          OK, I wasn't aware of the massive amount of material removal, particle size and spark shower produced from your grinder. With that I would say forget the plastic hose or pipe. Any accumulation of steel wool like swarf in the pipe is sure to catch fire. If I were to use a grinder like that inside my shop I would put a basin of water under it for a collection system. That would not only collect the grinding swarf but also put out any sparks. Either that or take it out side when you have to use it.

                          JL..............

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                          • #14
                            On one of our bench grinders,the guards have rear ports that,if you squeeze'm,3" cheapchit duct fits perfectly.I thought it funny? to use an old,labled gas can.....half filled with sand,as the arrestor.The sparks mostly get snuffed making the one or two 90's.....but get completely lost once hitting the sand trap.I thought about water,and just chose sand because it was more worthwhile as an emergency fire retardant.....meaning,we already had/have water close at hand....a little sand goes a long way.

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                            • #15
                              What about a sheet metal gathering hood "funnel" into a length of sheet metal ducting long enough to allow the sparks to burn out? Then a short hose to the chip separator and on to the vacuum? Or perhaps even a fabricated metal separator and collection can so it's all metal right up to where it exits the separator where it's a flex hose to the vac? by the time it finishes with that there should be no sparks left to reach the vacuum.

                              You'll need a good turn of speed in the duct to pull the bigger chips. So no larger than 3" ID for the metal duct. But you don't want to choke down the air movement with too small a duct either. For a shop vac that "sweet spot" seems to be in the 2 1/4 to 2 1/2" size range. If the 3" home heating duct proves to be too big and you're getting a build up in the tube then some sort of thin wall steel tubing in that smaller but still nonrestrictive size range?

                              The darn thing though is that you still need a good air movement in the mouth of the hood/funnel. Or you need an open enough funnel that pretty much the whole spray is collected and shot down into the tapered opening to be sucked away. A shop vac simply does not move enough air to provide the suction for that so you'll need to make a long tapered collector hood so it picks up the whole spray without relying on suction. The long taper will direct the spray down to a smaller cross section where the air movement is stronger and can then carry away the particles.

                              At least that's how I'd go until proven that there's a downside to it all. That's a lot of sheet metal fabrication to do. But I think you're stuck with doing your own since the long tapered collector will have to be custom made anyway to suit your grinder and mounting options. And for a smaller cyclone separator such as you'll need for this scale of collection using a shop vac are all plastic and you'll be wanting a metal version.

                              Another option that could work in this case since even the longer pieces are not "bird's nest" sized clumps is a Thien baffle separator that could probably be built into a small or mid size metal trash can with some modifications. Of course following along in line with the red hot embers you'd want to use sheet steel for the baffle instead of the wood commonly found in the examples found online for wood shops.

                              Although the water version would certainly work I'd wonder about the need to clean it out after each use. If it wasn't cleaned out promptly then the steel bits in the collection water would make for a right ugly rusty soup in only a day or two. I know that even the plastic dipping pot of water I keep by my own grinders gets pretty brown in short order and the water off the steel that sprays down into the collected particles below the wheel turns brown and crusty really fast. So my own thoughts are that I'd want to run all this "dry" other than any slight residual water that is on the metal after dipping to cool it down. And even then I tend to shake away the excess.
                              Last edited by BCRider; 02-09-2018, 05:40 PM.
                              Chilliwack BC, Canada

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