outdoor exhaust dust collection ideas needed

[Nick Crivello]

In order to maximize space in my small workspace I decided on a system that exhausts dust collection directly into my 100gal brown yard waste bin outside.

It's based around a 2hp Jet compressor mounted in the attic space and a 6" line that drops into the shop. The problem is how to best capture dust in the brown bin. The 4" exhaust line is essentially a leaf blower directly into the open can. All the dust does is hit the bottom and back out all over the place. :rolleyes:

I'm considering a few options. Would love to cut 2 holes in the waste bin lid, one for intake and another to vent air out; but I think the city would frown on that. I tried clamping a piece of plywood to the top of the open bin with the same idea of two holes, a 4" hose for the air/fine dust to escape. Works ok but doesn't have a great seal around the bin.

Wondering if a metal cyclone like this would be useful in this application:
https://www.oneida-air.com/dust-deputy/dust-collector-kits/steel-super-dust-deputy-5-inch-cyclone-separator

Make a stand for the cyclone, drop a hose into the bin. The cyclone exhaust would have a flex hose venting in a safe direction.

The idea is to optimize shop space, easy disposal of dust (just roll the bin out to the curb!), keep dust out of workspace, etc.

Suggestions?

[Michael Schuch]

A cyclone on top of a sealed barrel or bin seems like it would be the most promising to me. I think you would still need to have some kind of filter after the cyclone to keep you and the neighbors from being coated with the fine dust that makes it though the cyclone. I would also worry about rain wetting down any filter on the far side of the cyclone. I would guess it would not make a huge difference in efficiency if the cyclone is after the blower instead of before the blower like it is usually configured.

The problem that I have always heard associated with exhausting the dust collector outside is that you loose a lot of conditioned air if you have a shop heater or AC.

I have considered putting my cyclone with top mounted blower and bag/cartridge filter in an outside closet built onto the far side of my shop. Then putting a large area of furnace filters in the closet for extra filtration before the closet empties the air back into my shop through some kind of larger duct. The filter cartridge should catch most of the dust with the furnace filters adding an extra layer of filtration is my thought.

[Nick Crivello]

It's a garage workshop in California that usually has the doors open so climate control or air exchange isn't an issue. The original configuration of the Jet DC had the filter and bag after the compressor so I didn't think having the cyclone after it would matter?

I may just use a cyclone/Rubbermaid (Brute) trash can combo and just dump that into the brown bin when full. That way I can modify the Rubbermaid bin to suit my needs.

[Carl Beckett]

You might get one of those trash can lid swirlers and try it (google cyclone trashcan lid). If it works, then just add it to the lid of your box. A cheap test, it doesnt have to work 'well', just so it doesnt create a dust storm for the surrounding. Getting the air moving in a circular motion seems like a good idea.

I would be wondering how to empty something that is too large (without a tractor). Your idea to try a trash can first is a good one.

[Kevin Jenness]

With an efficient (long cone) cyclone well sealed to a bin you should have very little blowby and might get away without an afterfilter, as long as the neighbors are not too close and and the bin doesn't get overfilled (in which case you will have a chip cannon). When I say well sealed I mean no leaks at all. A cyclone will add some resistance to the system.

You could attach a bag filter like the one that came with your dust collector to a top panel on the bin. It too would need to be well sealed. The filter will add some back pressure, depending on its size.

I don't understand your setup. Normally dust blowers have a discharge at least as big as the intake. A 4" discharge seems unnecessarily restrictive. Why are you using a separate blower to get the chips out of the attic?

You will need some way to empty your bin and removeable liners or a replacement if you want to keep operating when it is full. What do you currently do with your chips?

By the way, the device that provides the suction is usually called the blower or fan. If you are using a compressor all bets are off.

[Michael Schuch]

It's a garage workshop in California that usually has the doors open so climate control or air exchange isn't an issue. The original configuration of the Jet DC had the filter and bag after the compressor so I didn't think having the cyclone after it would matter?

I may just use a cyclone/Rubbermaid (Brute) trash can combo and just dump that into the brown bin when full. That way I can modify the Rubbermaid bin to suit my needs.


I paid $20 for a plastic 55 gallon food grade barrel with a clamp on top. I also have a 30 gallon one that I paid $30 for (The 30g ones are less common so go for more $). I think they would work MUCH better for you than a Rubbermaid trash can since the food grade drums seal very easily but very tight.

There are usually a half dozen places selling once used food grade drums on Craigslist in my neck of the woods.

473732

I do not believe that having the cyclone before or after the blower (compressor) will make any difference.

[Keith Outten]

I use an exterior chip box.

The first pic is the shipping box for the ShopBot CNC router that I converted to a chip box at CNU. I cut a hole in this box and placed a baby diaper over the hole as a filter and installed the dryer vent as a cover. Just to the right side of the truck bumper you can see an asphalt walkway, students walked within twelve feet of the chip box all day long.

The second pic is a 3000 gallon tank behind my current workshop. This tank has no top, its not necessary when the size of the receptacle is very large.
The DC line goes from the shop dust collector through the wall into the tank or box.

My first chip box was a 4' by 4' by 8' long plywood box I built for my previous workshop.

[William Hodge]

In order to maximize space in my small workspace I decided on a system that exhausts dust collection directly into my 100gal brown yard waste bin outside.

It's based around a 2hp Jet compressor mounted in the attic space and a 6" line that drops into the shop. The problem is how to best capture dust in the brown bin. The 4" exhaust line is essentially a leaf blower directly into the open can. All the dust does is hit the bottom and back out all over the place. :rolleyes:



Do you have neighbors?

I have my blowers shoot into a trailer. The air circulates, and I have baffles on the walls and ceiling. The air has to do a U torn to get out. The big stuff stays in the trailer, the fine dust blows out into the meadow behind the shop. I like this, because the animals using the sawdust as bedding have less fine dust. My nearest neighbor is 1/4 mile away.

[Chris Parks]

With an efficient (long cone) cyclone well sealed to a bin you should have very little blowby and might get away without an afterfilter, as long as the neighbors are not too close and and the bin doesn't get overfilled (in which case you will have a chip cannon). When I say well sealed I mean no leaks at all. A cyclone will add some resistance to the system.

No Clearvue in Australia (read hundreds) uses filters unless there is a site specific reason (maybe 10?) and the dust can't be seen or detected by any other means. I installed a short cone Taiwanese machine about a year ago and it also has no filters and no one complains. The biggest problem exhausting to atmosphere is the noise, in the Clearvue case around 90db and that needs dealing with.

[Patrick Curry]

I’ve got a cyclone (XL Dust deputy) sitting on top a 55 gallon drum and exhaust out a garage window. The exhaust is aimed toward the ground by using a dryer vent. Im in a residential neighborhood so I had some concerns but there are so signs of sawdust on the ground dust ‘clouds’ out the window while I’m working.
Since I don’t heat or cool the garage this was the ideal setup for reasons of cost, airflow, and noise.

[Nick Crivello]

Thanks for all the feedback. Haven't decided on what approach to take yet.

I'm kicking around the idea of switching to a used 3hp 3ph Dustvent DC with integrated cyclone I found for sale. Concerned that the Jet blower is slightly underpowered and suction seems to drop off where it hits my Felder slider. This unit is more powerful and has a metal cyclone for what I was potentially going to have to spend on just a metal dust deputy from Onieda. I'll also run 6" lines throughout. It would need noise abatement/sound control measures since it'd be outside...

[Alan Lightstone]

I use an exterior chip box.

The first pic is the shipping box for the ShopBot CNC router that I converted to a chip box at CNU. I cut a hole in this box and placed a baby diaper over the hole as a filter and installed the dryer vent as a cover. Just to the right side of the truck bumper you can see an asphalt walkway, students walked within twelve feet of the chip box all day long.

The second pic is a 3000 gallon tank behind my current workshop. This tank has no top, its not necessary when the size of the receptacle is very large.
The DC line goes from the shop dust collector through the wall into the tank or box.

My first chip box was a 4' by 4' by 8' long plywood box I built for my previous workshop.

Keith, how in the world do you empty that thing? :eek:

[Nick Crivello]

Keith, how in the world do you empty that thing? :eek:

Had the same question; how does that work out?? :confused:

[Keith Outten]

Keith, how in the world do you empty that thing? :eek:

The first plywood chip box I built when I lived in a neighborhood in 1985. I used 30 gallon trash cans and hauled the chips to a local horse barn a half mile away that would pay me 5 bucks per can.

The small chip box I used to use at CNU I emptied periodically by shoveling the chips into 30 gallon trash cans and taking them to the dumpster. The university still uses this box today.

The big 3000 gallon steel tank I am using now is so big it has never filled up. Every time we have a major storm the contents of the tank are emptied by mother nature :) If I had to manually remove the chips for some reason I have a tractor with a front end loader, I would have to lower the bucket into the tank and then get inside and shovel the chips into the bucket.

Since my first chip box I have never once have had to use, clean or purchase a filter and my 2hp dust collector performs like it is 4 hp because there are no line restrictions.

[Alan Lightstone]

OK. Retire the trophy. Keith wins. Hands down. We're not worthy. We're not worthy. We're not worthy. :D

[Bill Dufour]

Open the trash bin lid and let it flop down all the way. Set a piece of plywood ov r the top and drill holes in that as needed. Remember to remove the plywood and close the lid before pickup day.
That is the basic way it was done at the lab with a 30 yard dumpster Boss called for a pickup when needed so we could disconnect before hand. We actuallu used. a compactor bin. loaded from one end. They left the vented top on and had to bring back the same bin each time. I think it went to the botanical garden.
Bill D

[Michael Fink]

My DC is outside (under an eve). No filter on it. Works well; but stuff near it outside does get a coating of fine dust on it. I don't find the loss of heated/cooled air is that significant; I'm sure it is a lot of air being sucked out, but there's a whole lot of air in the shop to start with, so doesn't appear to have as much impact as I initially thought it might.

6in pipe going through the wall to the DC; then piped around the shop to all the tools. I'm very glad I did it this way, one less filter to maintain, and honestly, it's noisy. It's even noisy outside, so I'm REAL happy it's not next to me when I'm trying to use a tool/think.

[Nick Crivello]

Update for all those who replied:

Swapped in a 3ph 5hp blower with 14.5" impeller, increased exhaust sizing to 6", and dumping into two 55-gallon drums outside. Much better, ~67db outside and 70db inside shop while running. :)

Big dilemma is that the 6" mains are choking the new blower out. Already spent a fortune on 6" piping. Might start another thread on what to do on that front.

[Chris Parks]

Update for all those who replied:
Big dilemma is that the 6" mains are choking the new blower out. Already spent a fortune on 6" piping. Might start another thread on what to do on that front.

Unlikely as 6" will flow 1200cfm and will handle a 15" impeller (just). I run a 15" impeller at 70hz with no issues. It must be 6" end to end including a 6" or better port on the machine.

[Nick Crivello]

Unlikely as 6" will flow 1200cfm and will handle a 15" impeller (just). I run a 15" impeller at 70hz with no issues. It must be 6" end to end including a 6" or better port on the machine.

I tested the 5hp blower with open exhaust. It was 2400cfm at the 7" inlet. Dropped to ~1900cfm with a 6" reducer.

Through the system I have in place it's a max of 1250cfm at the ceiling port which is a 5' straight shot forward and 90 degrees down from the blower. Getting 800cfm from the 5" line under the saw and 600cfm from the 4" hose over the saw (at the same time).

The 6" lines are choking it big time.

[Chris Parks]

I tested the 5hp blower with open exhaust. It was 2400cfm at the 7" inlet. Dropped to ~1900cfm with a 6" reducer.

Through the system I have in place it's a max of 1250cfm at the ceiling port which is a 5' straight shot forward and 90 degrees down from the blower. Getting 800cfm from the 5" line under the saw and 600cfm from the 4" hose over the saw (at the same time).

The 6" lines are choking it big time.

You can't measure the airflow without dedicated expensive equipment you can only say it seems less or more. Forget impeller driven gadgets to measure air flow, they don't work nor do other common devices. They will give a result but you can't put that result into numbers.

[Nick Crivello]

You can't measure the airflow without dedicated expensive equipment you can only say it seems less or more. Forget impeller driven gadgets to measure air flow, they don't work nor do other common devices. They will give a result but you can't put that result into numbers.

Yes I don't have the fancy doodads, but if the same anemometer reads 1900cfm at a 6" inlet with open exhaust then 1250cfm through the same size hole with everything installed does that invalidate the reading?

In other words I don't really care what the 'true' scientific number/cfm is... just that the same device at the same size hole measured in the same fashion at two different points is showing a marked reduction. That's all I need to know.

Edit: call it 'relative' measurements if you like.

[Chris Parks]

Yes I don't have the fancy doodads, but if the same anemometer reads 1900cfm at a 6" inlet with open exhaust then 1250cfm through the same size hole with everything installed does that invalidate the reading?

In other words I don't really care what the 'true' scientific number/cfm is... just that the same device at the same size hole measured in the same fashion at two different points is showing a marked reduction. That's all I need to know.

Edit: call it 'relative' measurements if you like.

Forget the air flow and measure the current the motor is using, more flow = higher current draw.

[Nick Crivello]

Forget the air flow and measure the current the motor is using, more flow = higher current draw.

Hi Chris,

Just checked with an ammeter, about 5.5-6.5amps across each of the three wires. It's supposed to be a 5hp/14a blower. What does that tell us?

Edit: my thought is that low current = reduced load/efficiency and thus lower flow.

[Carl Beckett]

Another instrument that was eye opening to me, was a particle size meter. I bought one recommended by another member here (bangood?) - was about $50 and allows me to measure effectiveness of the overall system.

Similar to your philosophy but one step further; I dont care about air flow, I just care if is collecting dust and fine particles...

[Alan Lightstone]

Another instrument that was eye opening to me, was a particle size meter. I bought one recommended by another member here (bangood?) - was about $50 and allows me to measure effectiveness of the overall system.

Similar to your philosophy but one step further; I dont care about air flow, I just care if is collecting dust and fine particles...

I care about both, but Carl brings up a very good point regarding the real risks/hazards.

[Jason puckering]

Do you happen to have pictures of the inside of the box? I am doing the same thing.


Do you have neighbors?

I have my blowers shoot into a trailer. The air circulates, and I have baffles on the walls and ceiling. The air has to do a U torn to get out. The big stuff stays in the trailer, the fine dust blows out into the meadow behind the shop. I like this, because the animals using the sawdust as bedding have less fine dust. My nearest neighbor is 1/4 mile away.

[Chris Parks]

Hi Chris,

Just checked with an ammeter, about 5.5-6.5amps across each of the three wires. It's supposed to be a 5hp/14a blower. What does that tell us?

Edit: my thought is that low current = reduced load/efficiency and thus lower flow.

My apologies for missing this post, the higher the amps the greater the air flow. There are some really nifty digital read outs available that can be installed to monitor the motor load and they are very cheap.

[William Hodge]

Do you happen to have pictures of the inside of the box? I am doing the same thing.

The baffles are 2 X 4 studs on both walls and the ceiling, set on edge, every 2'. The studs also provide structure for the trailer box. Hardly any chips blow out. I have removable gate boards at the back.

I ran a 2 X 4 along the floor inside the studs so that the farmer's shovel doesn't catch on the studding. He comes with a truck, hooks up the trailer, hauls it away, and returns the empty trailer.

The trailer has a metal roof. It's real important to keep the sawdust dry.