building a dust trap for media blaster

[Burn1]

Finished building a water bucket dust filter system for the new media blaster cabinet this evening.

Materials included: bucket lid vacuum-home depot special, vacuum hose kit, 2 buckets, 1 lid, 2 rubber hose connectors(1 for blast cabinet to hose, 1 for water trap to vacuume) 2-male 1" PVC fittings, 2-female 1" PVC fittings, 2ft 1" PVC pipe, 1-90deg PVC, PVC glue, 2-o-rings for male connectors, hole saw(1-1/4 32mm).

Construction of the lid was pretty straight forward:
cut 2 1-1/4 holes in lid and installed male PVC fitting with o-ring to seal the connection. Cut a 2 spacer's out of a 1" PVC connector fitting. This takes up extra threads on the inside of lid and mates two fittings between lid. Cut 10-1/4" 1" PVC pipe so it will sit approx 1 inch above water in bottom of bucket. 90deg fitting attached to other side to help keep water from being sucked out of bucket.

Hardest part was gathering up specific vacuum hose fittings. Found a universal rubber hose fitter as well as rubber plumbing connectors which worked out perfectly(1-1/2 x 1-1/4 and 1-1/4 x 1-1/4).

Pictures attached.

 

[Burn1]

Here are few more photos..

 

[PCO6]

That looks similar to the one I built. I like your bucket lid vacuum. I haven't seen one of those before but will check it out. I used a dust bucket lid that I got from Busy Bee Tools for mine. These systems work well.

Busy Bee lid ...
http://www.busybeetools.com/products/DUST-COLLECTION-CYCLONE-COVER-SMALL.html

 

[Burl]

How do these systems work?

 

[stout1]

How do these systems work?

Ditto!

 

[54FordPanel]

Looks good. I'm using just a straight shop vac for mine, and I'm dreading cleaning out the filter. I need to do that.

Burn1 and PC06 should chime in, but I believe it works by filling the bucket 1/2 full with water, and the dust is trapped in the water instead of clogging the shop vac filter.

 

[PCO6]

Without the filter the dust would go straight to the vacuum which is a 4 gal. shop vac in my case (post #2). With the filter a lot of the dust gets trapped in the water. In mine I have about 3" to 4" of water in the bucket. The hose that connects the cabinet to the bucket leads to a straight ridged plastic tube that sits about 2" above the water. A lot of the dust (sand) simply falls into the water. The hose from the vacuum to the bucket connects to a 90 degree ridged plastic elbow on the bottom side of the lid. It creates a vacuum in the bucket above the water line. The dust that doesn't fall into the water makes its way into the shop vac.

 

[James E]

Maybe a dumb question but wouldn't it work better if the tube from the blaster dipped below the waterline and the tube to the vac was above the water line? Then the bucket would act like a water pipe (you might call it a really big bong, not that I would know anything about that) and the air from the cabinet would have to pass through the water. Almost all of the media would then get stuck in the water and the air coming out would be much cleaner.

Just a thought.

 

[Bender78]

Here's another good design for a dust trap.

http://toolguyd.com/shop-tip-5-gallon-bucket-diy-fine-dust-collection-trap/

 

[54FordPanel]

Maybe a dumb question but wouldn't it work better if the tube from the blaster dipped below the waterline and the tube to the vac was above the water line? Then the bucket would act like a water pipe (you might call it a really big bong, not that I would know anything about that) and the air from the cabinet would have to pass through the water. Almost all of the media would then get stuck in the water and the air coming out would be much cleaner.

Just a thought.

James, from the thread Bender posted:

A NOTE FOR BUILDERS: Some people have voiced concerns about their bucket collapsing. To be clear, the reason the bucket collapsed is that the intake tube was below the water lever. In fact the water level should NEVER be higher than the intake tube. This is NOT a “DUST BONG” —

The water simply catches the incoming debris and holds it in suspension. Hence, the water should merely cover the bottom of the bucket, and not rise above the inlet tube. If the water level rises above the inlet tube, the resulting vacuum WILL make the bucket collapse.

Wish I knew what this "Bong" thing is that everybody keeps talking about....

 

[PCO6]

Here's another good design for a dust trap.

http://toolguyd.com/shop-tip-5-gallon-bucket-diy-fine-dust-collection-trap/

That is how mine works. The picture of the underside of the lid shows essential how I built mine.

The amount of sand dust that makes its way into the shop vac is greatly reduced. I clean the water out about once a year. I just throw it on to the grass in my back yard. It is dirty but it never turns to anything close to "mud".

 

[Burn1]

That looks similar to the one I built. I like your bucket lid vacuum. I haven't seen one of those before but will check it out. I used a dust bucket lid that I got from Busy Bee Tools for mine. These systems work well.

Busy Bee lid ...
http://www.busybeetools.com/products/DUST-COLLECTION-CYCLONE-COVER-SMALL.html

Nice, had no idea someone offered a plastic injected lid like that. That is a great off the shelf solution. Regarding the home depot vacuum/lid. Its pretty cool and a great little 2nd shop solution for a dedicated power tool such as a miter saw,etc. The jury is still out if the bucket lid vac it has enough suction vs. blast cabinet rate. I'll get a chance to use this weekend and find out. If not, I have a full size shop vac as a plan B. Initial thought is to build a two bucket wood box w/ casters. When the blaster is not in use, I can roll away the collection system under my workbench and out of the way. My blasting area is small, but specifically placed blast cabinet in front so I can open garage door, place the vacuum cart in the driveway and start blasting away.

If the bucket vacuum system works well, next on the list is building a rolling cart setup.

 

[rwhite692]

Design improvements that really make these separators work:

http://www.evenfallstudios.com/woodworks/2008/06/27/building-the-5_gallon-thien-separator/#.Tx79EoHDBZ4

This approach is interesting as well:

http://shopngarage.com/2010/07/blast-cabinet-dust-filter/

 

[Stephenw]

This approach is interesting as well:

http://shopngarage.com/2010/07/blast-cabinet-dust-filter/

That's my "super complicated" approach.

 

[jrsulo]

Kinda like the cheap system the sell for sanding sheetrock.

 

[rwhite692]

Based on StephenW's design, and some others, It would seem that it is indeed possible (preferable?) to have the air inlet pipe (dirty air coming from the blaster) be beneath water level, and then that would allow that air to "percolate" through the water, therefore making that air much cleaner before it heads to the shop vac.

I would think that there would only be an issue with the bucket / lid "collapsing" if for some reason new dirty air supply from the cabinet was choked off...

Obviously, water level would be critical, you would need to have the water level be **just** a bit above the inlet tube, so that when vacuum is turned on, a "break" in the water surface can be formed at that point.

Have not built one of these yet, just thinking about it.

 

[James E]

Again, I don't get the physics of this but why would the bucket collapse? Wouldn't air just be pulled in through the inlet tube through the water?

School me, please.

 

[Stephenw]

In addition to the dust outlet on the cabinet, there must be a fresh air inlet. A lower pressure area will develop inside the bucket, but not low enough to collapse the bucket.

 

[rwhite692]

In addition to the dust outlet on the cabinet, there must be a fresh air inlet. A lower pressure area will develop inside the bucket, but not low enough to collapse the bucket.

Exactly what I was thinking. On my old cabinet, I had added an adjustable port to let fresh air into the cabinet, and the ability of the vacuum system to "clear the air" was greatly improved. Particularly, when the port was at just the right size adjustment to get the most velocity.

 

[PCO6]

Design improvements that really make these separators work:

http://www.evenfallstudios.com/woodworks/2008/06/27/building-the-5_gallon-thien-separator/#.Tx79EoHDBZ4[/URL]

If you cut through all of the construction details, the article in the link basically says that the lid doesn't work well as it comes and it's good to add a baffle plate of some sort to slow down the air before it leaves the bucket and enters the shop vac.

I agree on the first point. The inlet and outlet on the lid as manufactured are too close together (only 3" or 4" apart). In mine (post #3) I simply added a straight length of ABS like Burn1 the OP did. I wouldn't go through the effort of adding the angled port to the top of the lid as described in the above link.

On the second point, I guess a baffle would be helpful but with mine very little sand makes its way in to my shop vac so I don't think I would bother.

 

[RMR&C]

Mine is a simple plastic bucket and some pvc fittings. I run the inlet just UNDER the water level.....all of the dust gets trapped in the water. I just drilled some 3/8 holes in the lid to equalize the pressure (vacuum?). Shop vac stays nice and clean....

 

[SGKent]

my experience is that no more dust gets trapped than a good shop vac with bag and hepa filter. I've even tried a 33 gallon waste can full of water and you can see fine particles of dust rising out of the water. It only works if the bubbles dissolve before reaching the surface. Big bubbles still have fine dust trapped in them when they break the surface.

 

[theoldwizard1]

Again, I don't get the physics of this but why would the bucket collapse? Wouldn't air just be pulled in through the inlet tube through the water?

School me, please.

Your statement is correct. The air in the bucket is under a vacuum (less than the 14.7 psi atmospheric pressure).

But the deeper the water (or the further below the water level that the inlet is located) the more vacuum (less pressure) is needed to **** the air out of the submerged inlet. This puts a lot of strain on the bucket/lid.

Running the vacuum with this type of pre-filter puts additional load on the vacuum motor. The motor is used used to drawing from atmospheric pressure and now has to draw from below atmospheric pressure.

Someone stated that they burned out a vacuum motor after running for an extended period. I would probably limit the run time to less than 30 minutes with a 60 minute cool down.

 

[iron_worker]

Why not use a cyclone type design? They use them a lot in industry.

Air comes into the top of a cone tangentially (kind of following the interior profile). The air thus gets spun around. The dust particles have mass and thus are forced against the outside wall. The friction of the dust particles rubbing against the wall slows them down and they slowly drop down the slope of the cone. There is another container beneath the cone to trap particles. The cleaned air then has to travel up and out the center of the top of the cone.

That's how a dyson works! lol

Some reading: http://www.dustcollectorexperts.com/cyclone/

IW

 

[shoot summ]

I used to use a bucket and shop vac, didn't use water, just created my own cyclone effect with elbows. It did work, but was a lot of hose and took up a lot of space.

I installed this instead and have been very happy.

http://www.harborfreight.com/blast-cabinet-reclaimer-kit-94275.html

 

[porphyre]

On the second point, I guess a baffle would be helpful but with mine very little sand makes its way in to my shop vac so I don't think I would bother.

The baffle is nearly magic. "Very little sand" gets to your vac? Think none. My buddy has a 30 gallon trash can dust collector w/ a Thien baffle lid. He cleans his vac filter when the trash can is full. That's 30 gallons of sawdust and chips.

Why not use a cyclone type design? They use them a lot in industry.

Cyclones definitely work well, but they're big and tall. You need more room than with a "cyclone in the lid" design.

 

[PCO6]

The baffle is nearly magic. "Very little sand" gets to your vac? Think none. My buddy has a 30 gallon trash can dust collector w/ a Thien baffle lid. He cleans his vac filter when the trash can is full. That's 30 gallons of sawdust and chips.

That's correct ... "Very little sand" gets in to my shop vac and I am OK with what does. I've used this set up for about 4 years. It would take me about 40 more to fill my 4 gal. shop vac with sand. I have thrown the dirty water from the bucket out at least 3 times and that's where most (90%?) of the exhausted sand ends up.

 

[T.Hadley]

Here the one I just made.


I went and bought a bucket vac from Lowes for my blast cabinet, it works very well for a 20.00 vac, the only issue I have it the filter plugging up to fast, so I thought I would build me a Cyclone separator,

I watched a few vids on YOU TUBE, and then got to building the type I made is called a top hat design.

clogged filter.

Took some scrap I had laying around and made a circle cutter for my router.

The slot is where the debris will fall through.

Top and bottom

Got the tin put in.

A look inside

hose fittings installed

Started with a clean bucket.

as a test I vacuumed up all the saw dust from making it, it works awesome, all the saw dust was in the separator and only some fine dust was in the vac.

 

[54FordPanel]

Nice work, Hadley! Thanks for posting.

 

[Darkbreeze]

(Yes, I realize this is an old thread, but I came across it, so others will too. I also posted this in another thread until I realized it was even older than this one, so hopefully I might get some suggestions from one or the other of these threads. Appologies for dual posting. If I get some decent feedback I'll delete my post in the other thread.)

There is a separate issue for those of us who are using a cyclonic OR Thien OR Semi-Thien clone type setup for dust collection connected to a sandblast cabinet. Pre-media separation, to help reduce the amount of unspent media that gets caught up with the spent media and ends up in the scavenge cannister. Just wondering if anybody has come up with a configuration inside the cabinet that minimizes unspent media loss without creating a pressure loss like an "inside the cabinet" pre-filter configuration does.

I'm thinking I might try running PVC from the exhaust vent hole INSIDE the cabinet, up to the furthest inside topmost point so the actual intake for the exhaust port is as far from speeding media as possible, but I'm unsure this will actually resolve the issue so I'm open to other confirmed ideas.

Also, sorry for necro-mongering this old thread, but it was even more relevant than the other thread I posted in. Thanks.

 

[Craptain]

(Yes, I realize this is an old thread, but I came across it, so others will too. I also posted this in another thread until I realized it was even older than this one, so hopefully I might get some suggestions from one or the other of these threads. Appologies for dual posting. If I get some decent feedback I'll delete my post in the other thread.)

There is a separate issue for those of us who are using a cyclonic OR Thien OR Semi-Thien clone type setup for dust collection connected to a sandblast cabinet. Pre-media separation, to help reduce the amount of unspent media that gets caught up with the spent media and ends up in the scavenge cannister. Just wondering if anybody has come up with a configuration inside the cabinet that minimizes unspent media loss without creating a pressure loss like an "inside the cabinet" pre-filter configuration does.

I'm thinking I might try running PVC from the exhaust vent hole INSIDE the cabinet, up to the furthest inside topmost point so the actual intake for the exhaust port is as far from speeding media as possible, but I'm unsure this will actually resolve the issue so I'm open to other confirmed ideas.

Also, sorry for necro-mongering this old thread, but it was even more relevant than the other thread I posted in. Thanks.

I use a cyclonic dust collector powered by my shopvac. The media is Glass beads, and so far I am not seeing any media loss. It would be easy to see in the bucket as the dust is dry (rather than the OP's wet system). No special separation, just air in at top right back of cabinet, and suction out at lower left front. It stopped all the leaks too. I guess the big factor is not blasting towards the outlet as that is not where I position the work.

 

[Darkbreeze]

Nice. I can see that too using glass bead, since it's probably at least marginally heavier than the aluminum oxide I use. I'd actually prefer to use glass bead but there are sources to get glass bead in the town I live in and having it shipped seems to be incredibly expensive. I haven't found ANY suppliers yet that have free shipping on Ebay or Amazon and the **** HF sells is NOT glass bead, it's crushed glass, and the results using that in the past were piss poor at best.

The finish with that junk was about the same as the finish using aluminum oxide, except it was almost instantly spent as soon as it had been cycled once so aluminum oxide has been what I've used and it works really well, leaving a finish that's just about perfect for priming and painting or prepping small automotive parts like thermostat housings and exhaust manifolds, for installation.

We ARE getting a Tractor supply here soon, it's being built right now, and they sell glass bead, so that might resolve the issue once that happens but the glass bead finish might not be suitable for all my blasting projects so I still probably need to figure out how to minimize some of the unspent media loss. I'm thinking that my latest change might help that, with the exhaust port intake run up to the top of the inside as close as possible without constricting the airflow too badly. That puts it as far as possible from the path of speeding media so hopefully that's an improvement, but I was just thinking that I've come across some incredibly astute solutions here and other similar forums, that I probably would never have thought of in a million years, that after seeing them I'm always baffled how it never occurred to me in the first place.

Hard to tell from this picture I just took, but there's about 3/16" gap between the end of the PVC and the inside of the cabinet lid which I think should be enough to not drastically restrict the airflow.

 

[James-W]

I finally broke down and bought a sand-blast cabinet. I just take it outside to use and it hasn't been a big deal, at least so far it hasn't. I have a squirrel cage fan I could connect to it and just blow the dust right outside, but unless I do quite a bit of sandblasting with it I really don't think I need it. I mostly use it to clean up mower blades before I sharpen them. Some of the blades have a lot off caked up grass on them from mowing when the grass was wet. I clean the blades up and then I sharpen them and when finished they look like a brand new blade.

 

[Darkbreeze]

Hey James. Still probably be a good idea to trap the dust. Glass, aluminum oxide, soda, and silica or "play" sand (Hopefully nobody is using this as it creates a severe probability of silicosis) are all incredibly bad for you if you breathe them in. Even in small doses. Even outside if you are not wearing a respirator there is a good chance of breathing in the spent media whether it's actively vented or simply escaping the enclosure.

I understand about the lawnmower blades. I use my cabinet so much more since I've done many of the modifications to it. It's just impossible to imagine not having one now. I've even eliminated the etching of the viewport glass by installing a framed screen about a quarter inch below the glass to deflect the media. I've had the same piece in there for about six months now and I use the cabinet at least several times a week. VERY little etching so far. It's still probably 98% clear.

 

[James-W]

Hey James. Still probably be a good idea to trap the dust. Glass, aluminum oxide, soda, and silica or "play" sand (Hopefully nobody is using this as it creates a severe probability of silicosis) are all incredibly bad for you if you breathe them in. Even in small doses. Even outside if you are not wearing a respirator there is a good chance of breathing in the spent media whether it's actively vented or simply escaping the enclosure.

I understand about the lawnmower blades. I use my cabinet so much more since I've done many of the modifications to it. It's just impossible to imagine not having one now. I've even eliminated the etching of the viewport glass by installing a framed screen about a quarter inch below the glass to deflect the media. I've had the same piece in there for about six months now and I use the cabinet at least several times a week. VERY little etching so far. It's still probably 98% clear.

I can hook up the squirrel cage fan to **** the dust out of the cabinet and blow it away, but do you think I should have a "dust trap" to collect the dust as well?

 

[valiant100SM]

(Yes, I realize this is an old thread, but I came across it, so others will too. I also posted this in another thread until I realized it was even older than this one, so hopefully I might get some suggestions from one or the other of these threads. Appologies for dual posting. If I get some decent feedback I'll delete my post in the other thread.)

There is a separate issue for those of us who are using a cyclonic OR Thien OR Semi-Thien clone type setup for dust collection connected to a sandblast cabinet. Pre-media separation, to help reduce the amount of unspent media that gets caught up with the spent media and ends up in the scavenge cannister. Just wondering if anybody has come up with a configuration inside the cabinet that minimizes unspent media loss without creating a pressure loss like an "inside the cabinet" pre-filter configuration does.

I'm thinking I might try running PVC from the exhaust vent hole INSIDE the cabinet, up to the furthest inside topmost point so the actual intake for the exhaust port is as far from speeding media as possible, but I'm unsure this will actually resolve the issue so I'm open to other confirmed ideas.

Also, sorry for necro-mongering this old thread, but it was even more relevant than the other thread I posted in. Thanks.

I think you're on the right track keeping the vent away from where the media will be - my HF floor-mounted cabinet is set up that way more or less, with inlet in the back right and outlet generally upper left. At least that's how I interpret how the box works. If you run PVC inside the cabinet, I would run relatively large pipe (2" or so) to minimize the velocity of the air entering the pipe. That will reduce the chances of the heavier particles being drawn in to the pipe in the first place.

I also like the idea of using screen over the window into the cabinet, and that reminds me that I used window screen material to make a "filter" for the gas furnace exhaust through the roof. Lots of leaves and other tree debris that could get in that pipe, so I used about an 18" square of screen to make a "sock" over the end of the exhaust. Could do something similar on the inlet for the vacuum pipe in the cabinet to keep out the larger media.

 

[astroracer]

A blast cabinet should be equipped with a dust collector. That is the best way to ensure you will have very little issues with breathing it in or it getting all over stuff in the shop. The dust collector also improves visibility inside the cabinet while blasting as it will draw all of the dust out while you are blasting.
I wear a dust mask when using mine but it's not really necessary as my collector works very well and I have no dust issues outside the cabinet.
I couldn't see spending 600 bucks or so on a canister vac so I built one. I used a couple of kitty litter buckets, a shop vac filter and a Harbor Freight dust collector vac.

I use one of my shop vac hoses to hook the cabinet up to the top bucket of the collection stack.

The hose simply plugs into a close fitting hole I cut in the bucket.

The upper bucket has a shop vac filter bolted into it.

The air is drawn through the filter out of the bucket through the big flex pipe. Any dust is collected on the filter and doesn't get through to the vac.
This setup works very well to keep dust down in the cabinet. Well worth the 120 dollars I have into it.
Plus, it all breaks down and stores inside the cabinet when not in use.
Mark

 

[Darkbreeze]

For anybody interested, this is the pre-shopvac setup I'm using. I tried the regular DIY water trap setup similar to the one this thread is based on but it didn't work like I wanted.

Next I tried the Thien baffle setup as seen at this link, which worked pretty good:

And currently I'm using the semi-Thien baffle clone setup, which works better than anything else I've tried so far. I'm using the "long outflow" arrangement and as far as I can tell it works as well as my neighbors dust deputy that cost him 75 bucks for the dust deputy and another twenty five for the sump bin.

Mine cost 15 bucks total.

Video:

Page: http://familyweb.us/TinkerT/default.asp?Post=178-Step_By_Step_-_How_to_Build_my_Semi-Thein-Clone

 

[Falcon67]

I skipped all that and just bought a $20 vacuum that is hooked directly to the exhaust vent. When it croaks, I'll buy another. Takes up less space too.

 

[Darkbreeze]

I skipped all that and just bought a $20 vacuum that is hooked directly to the exhaust vent. When it croaks, I'll buy another. Takes up less space too.

That was the FIRST method I tried, when I first purchased the HF stand up cabinet for 50 bucks because the guy who had it couldn't make his gun work right. So, it worked, somewhat, but using aluminum oxide it died within the first two hours of blasting. Motor caught on fire. Guess the particulates made their way into the motor. That was the last time I tried using a vacuum and is exactly why I didn't use my shop vac without at least some kind of pre-filtration.

It also didn't keep the cabinet very clear. Shop vac keeps it crystal clear inside. But whatever works for each person, is the right way to go I suppose.