dust collectiors and spark arrestors

J

Jimbo670

Member
So I have done some checking through old threads about dust collection and spark arrests. I believe I will use a water trap before my craftsman dust collector for the sanding of handles and materials and finishing. For steel grinding I am thinking and a shop vac with water in it.

I am in a garage at a condo association so I am limited to what I can do.

Thoughts and input wound be great.
 
In your situation, my first advice would be a 5 gallon bucket of soapy water hung under your grinder. If you need more then that, make yourself a 5 gal bucket with a lid....and inlet and outlet that fits your shop vac hose.....and put about an inch of water in the bucket.....the bucket is a "catch". Whatever you do, DO NOT PUT WATER IN THE SHOP VAC! The suction goes to the filter in a shop vac.....any sparks/hot bits of steel will be sucked to the filter, and the draft will cause it burn.

At one time I had a full dust collection system in my finish shop.....and a moment of not thinking (I had ground some handle material, then started grinding some Ti) almost burned the place down. I pulled ALL the dust collector hardware, and go with the buckets when grinding steel/ti, or anything that sparks, and have a single shop vac with the 5 gal bucket/filter between the grinder and the shop vac for non sparking materials.
 
I made knives for several years while also living in a condo with a tight association. I never had any issues.

My advice is this: you NEED a dust collector system. I tried the water bucket route. My entire garage and everything in it was coated in a layer of black dust in no time flat. If your garage is typical, meaning it is also your storage area then that black dust will be on top of, and inside of, everything.

Installing a dust collector setup from Harbor Freight made an immediate improvement. In fact, it solve the problem entirely. The mistake I made was trying to save fifty bucks by going with the smaller unit. That little dust collector is LOUD and it also uses a motor with brushes. It ran great for about a year and by the time I knew the brushes needed replacing the commutator was chewed up inside. Long story short, I fought that unit for a couple of months and then bit the bullet and bought the unit I should have purchased to begin with. It is only fifty bucks more than the cheap one, but it is light years better and maintenance free.

https://www.harborfreight.com/2-hp-industrial-5-micron-dust-collector-97869.html

Your Craftsman unit should work fine, lots of guys run a big shop vac.

You are also correct that you need a water trap. I made a water trap from a bucket I had on hand. (kitty litter bucket) I plumbed my dust collection hose through the bucket and it works like a champ. I got about a year from the first bucket before sparks burned holes through the sides (not checking the water level before I used it).

I grind AEB-L stainless almost exclusively. That stuff smolders and burns. Please do not EVER grind AEB-L on a dust collection system that does not have a water trap. It doesn't take much imagination to foresee what would happen if you were blowing smouldering dust into a bag full of wood dust and then going inside for the night while it sits there.
 
John,
In your water trap setup, is the air exhausting onto the surface of the water or is it submerged and forcing the air/dust through the water?
 
WY_Not said:
John,
In your water trap setup, is the air exhausting onto the surface of the water or is it submerged and forcing the air/dust through the water?
Click to expand...

It blows onto the surface, then the airflow has to bend several times to escape. I'll explain. *Keep in mind that my water trap is a 1ft-cube-shaped bucket with a lid. So I'll describe it from the perspective of the water trap bucket.

The inlet comes in the front side of the bucket at about the middle center of the front panel. I cut the openening as a square, still attached at the top. This makes a flap, which when pulled inward makes a deflector that directs the incoming debris downward to the water's surface.

The outlet of the water trap bucket is on the top of the bucket, which is also cut like a square, attached on one side to make a deflector. The deflector is angled downward into the bucket. I screwed a heavy block of wood to it so that the dust vac can't pull it up and close off the air flow. I don't know if the top deflector makes any difference, but the idea was to make the air flow through the bucket have to make several turns. I was hoping for a vortex of sorts to give the debris more times to fall out of the airflow and into the water below.

It works very well. I have very little dust of any kind on my dust collector's collection bag. My water trap collects a lot of debris. The metal solidifies into the bottom like a big, nasty brick that I have to dump out of there every couple of months because it gets so thick that my water trap doesn't hold much water before it starts to spill out of the inlet in the middle of the front panel.
 
I'm sure there are many ways that will work. This is the way I set mine up, figuring I would improve on it as time went. It just so happened that it worked so well I never had to fool with it anymore.
 
Hey John, after we talked about this a few months ago, I went and got one of the big HF dust collectors. Unfortunately, it's still sitting there the box, keeping getting sidetracked! On the setup I'm planning, the collector will be on the other side of the wall from my grinder, with about 10' of metal pipe in between. I am planning on routing mine where I can choose to either vent directly outside, or route it into a metal trash can through a metal cyclone. I was sort of thinking that a spark would cool within the 10' of metal pipe and cyclone and not be an issue. Like when you use an angle grinder, the sparks fly out there and cool down before hitting the ground. Might still be a risk, not so sure.
 
Hi Anthony, I think you are correct about the sparks cooling with that much distance. The only concern I'd have is when the dust forms clumps. I know I talk a lot about AEB-L, but what happens with that stuff is worth repeating. The dust clumps very quickly into a thick, clingy pad. It looks like steel wool. The sparks that get into this pad will smoulder and will outright burn for a long time. I'd be afraid of steel dust collecting inside of that pipe and having spark lodge in it, causing fires after you've turned everything off and left the shop.

If I vented directly through the wall into a rock pit or something I'd probably not worry so much. That was my original plan, I just never got around to it because the water trap works.
 
Yeah, you've got me wondering now. I was going to route my knife grinder, surface grinder, and sandblaster all on the same trunk line. It would be a PIA to get the spark bucket on the surface grinder, at least how I have it now. The only actual flammable material entering would be from knife scales. I tend to trim my scale material pretty close to final before shaping, so there wouldn't even be that much of it going in there really. I'm curious how many guys have actually found a smoking/burning clump in their dust collectors that could have been bad if not checked. In my shop, I do all kinds of sparky work, welders, cutting torch, plasma cutter, angle grinders, etc, and haven't ever had a close call with fire. I'm just not sure how much I should worry about the dust collector.
 
Well, the good news is that the only thing that should be throwing enough sparks to burn anything is your belt grinder. I can't see a surface grinder removing enough material (vs the proportionality of air flow) to ever be an issue. A water trap at the belt grinder inlet would keep the belt grinder from clogging the air duct with debris, anyway. The belt grinder is going to be your major culprit. As you said, that length of duct ought to be enough to cool any sparks from just about any other source.

Again, running all of that outside to a rock pit or rain barrel would be the ultimate idea, anyway. With the water trap, I honestly don't get much of anything in my collection bag. It takes six months to accumulate about a half gallon of dust at the rate I work. The water trap fills up a lot faster, and being metal dust and wet wood dust it settles to bottom and makes a hard brick.
 
SO would you have one system with a water separator for both wood working (handle finishing) and for grinding steel? OR would you have two systems one for the wood and the other for the steel. Keeping in mind the handles may get the occasional spark from pins and guards etc?
 
I would have one system and just add a water separator at the grinding point that needs one. My 2x72 debris goes into a suction line which leads immediately into the water bucket. Of course I grind everything under the sun on this grinder. It all goes to the bucket. A few feet away is my disc grinder with its own suction line. This suction line feeds into a "T" on the front of the same water trap that the 2x72 uses. I have slide gates that cut off the air flow to the grinder I'm not using so that I don't lose suction where I'm grinding. The bigger dust collector from HF has two inlets. I have considered running the second inlet over to my wood cutting bandsaw. I would not put a water trap there because nothing there throws sparks. But it would be easy enough to add a water trap anywhere along the way that is easy to get to. For that matter, I could run the vacuum line through the same water trap as the others. My water trap is about 1 foot away from the dust collector blower, as shown in the drawing I posted.
 
I got a small shop in my basement no windows I am going to get that air filter from Grizzly that hangs from the ceiling and use buckets under my grinder.
 
Rick Otts said:
I got a small shop in my basement no windows I am going to get that air filter from Grizzly that hangs from the ceiling and use buckets under my grinder.
Click to expand...
You will eventually have dust everywhere. I have a 20x30inch filter box 5 filters deep, air changes 12 times per hour I still get dust still wear a mask (a must)
I started wet grinding with a kool mist system for the big hogging, then dry for 220 and above I just use water and air. Its not full proof but cuts down on dust considerably.
 
Rick Otts said:
Oh I agree I will always wear a mask and I will always vacum my shop no way around it.
Click to expand...

Vacuum wont trap the tiny debris (most dangerous) to your lungs. I exhaust and replace air, filter air, wet grind kool mist with a water bucket under the platen or wheel.
Keep in mind when you vacuum without a water separator, you are second coating your lungs ( after you remove your mask) and the work space. To be honest I didnt take metal dust serious until I had an outlet fire. I was able to hear it crackle and see it ignite, its no joke. Good luck.
 
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