Dust collection question for Alan in Little Washington...

[scsmith42]

Alan:

Doug and I were kicking around an idea this morning, and your name cropped up as someone good to bounce it off of (amongst others...)

I have a 16" jointer/planer which I use for personal woodworking, and it's plumbed into an Oneida 3 hp SDG (the Oliver 25" is on a separate DC system).

Even though I only have to take about 4 steps to empty the drum on the Oneida into the back of a dump truck, it's still a pain (and it fills up rather quickly when I'm joint/planing a lot of boards). What I'd like to do is to suspend the SDG from the ceiling over my dump truck, and come up with a way to auto-dump it into the DT when it's full.

Cyclones work as a "closed" system, so I can't just leave the bottom open. What I'm wondering about is putting a "Y" adaptor underneath the cyclone so that it could dump into one of two different large diameter tubes, and have ports at the top and bottom of the tubes that would automatically open and dump one, alternating the dust flow to the other tube when one is being emptied.

Do you (or anybody else for that matter) have any ideas as to how this can be done efficiently, effectively, and economically?

I figure that you would enjoy the intellectual challenge that accompanies this topic! Thanks much.

Scott

[MIKE NOAH]

Not quite sure about diverting from one drum to another but, I can envision hinging the bottom of the barrel, welding an arm on it and putting a double acting cylinder/solenoid on the side of the barrel to open and close the bottom lid. A sensor such as Alan's could trigger an open close cycle and shut the system down for the 30 seconds or so it takes to empty. You would need a couple limit switches to tell the system to shut down when the lid was open and one to start a small time delay when the lid was fully open before closing the lid...just random thoughts. Seems like a neat project and I'm sure you will get plenty of ideas in this thread.
Mike

[gdoebs]

Didn't David Marks have a cyclone that was outside his shop and it just dumped on the ground? I think The Wood Whisperer had his cyclone direct the chips through the wall of his shop too. I could be wrong though...

Could you get an auger system that pushes the chips from the barrel out to the dump truck? Not sure if that would be sealed enough.

[Bas]

How about a see-saw, two drums, two blast gates, a Wye, and some string. A little ingenuity and it should be possible for drum #1 to close its own blast gate as it fills up with chips and shavings, and open the other. But it would be difficult to tune, since the density of the material varies.

You could just duplicate Alan's system, by combining actuated blast gates and a full-bin sensor. But, instead of shutting off the cyclone when the bin is full, the sensor would close gate #1 and open gate #2. Simple in principle, lots of parts to get it to work. And not exactly a Scott Smith solution.

Can you suspend the bin above the ground (~ 6 ft) and put in some kind of valve you can use to dump out the chips via the bottom? Then just use the skid steer when the pile gets too high.

[TV]

Here's a thought. If you have some sheet metal, fabricate a cone shaped drum (minimum 70 degree hopper to help with flow) with the top being the largest diameter. The bottom of the cone would have a 8 or 10 inch opening with an actuated slide gate. Using Alan's high level sensor, the bottom slide gate would open allowing material to flow. Of course, you might have a problem with ratholing or bridging (bridging being the worst case). To prevent or minimize bridging, attached an electric or pneumatic vibrator to the side of the cone. When the slide gate opens the vibrator turns on and makes sure the accumulated dusts exits the cone. You can use a timer for how long the slidegate and vibrator stays on.

tv

[ptt49er]

Maybe I'm under thinking this....

Why not set up the blower from the cyclone to directly deposit the shavings into the dump truck like you did with the big one? I know it negates the purpose of the cyclone, but you'd never have to worry about emptying it or cleaning the filter.

Or could you run a line from your huge DC to the collection bin of the cyclone. Put a blast gate that is actuated by the full bin sensor. When that blast gate is opened, cut on the huge DC to evacuate the shavings from the cyclone.

Big toys make even bigger messes huh Scott

[Mike Davis]

Right, why do you need a cyclone or a filter if you can dump directly into a truck bed?

Seems to me you are over engineering for no gain.

UNLESS the filter is inside the building and helps retain conditioned air.

[JimmyC]

I have to kind of agree with Mike here, I've seen Alan's home system and it's a push through cyclone set up. So if you used the blower to push through into a collector, or straight into the truck, then I don't see much of a problem. I think that you would only need a closed system if the cyclone is before the blower.

I am waiting for Alan's response though because he is the man, to me, on this subject.

[Glennbear]

I do not know if this is any help but here goes.............way back in ancient times when I worked in the PVC compounding industry we used a weight sensitive sensor (load cell) to switch blower discharge of PVC pellets when filling boxes (gaylords). You might consider that instead of photocell controls JMTCW.

[scsmith42]

WOW - LOTS of great advice thus far. Here is some more background info:

The ceiling height above the dump truck is probably 17' or thereabouts, so I have ample room to suspend the entire SDG above the dump truck. There is a catwalk along one side of the ceiling (for servicing the filters for the return air), and I could situate the filter for the SDG near the catwalk for ease of service.

Mike Noah - good idea re the DA cylinder. My reasoning for splitting the shavings across two different barrels is that way I could alternate between them, dumping one from the bottom when the other was receiving the dust from the top. It is probably better not to be constantly cycling the system; Oneida recommends leaving it on as much as possible versus frequent power cycling.

GDEBS: The system is contained inside, so as to minimize the loss of conditioned air. I have a recessed garage adjacent to the SDG and the blower where the dump truck is parked, and this is all part of the conditioned space. A wall of filters is in-between the dump truck garage and the main shop, preventing dust from entering the shop with all of the return air.

BAS - I'll have to look at Alan's system a little more closely - it sounds like he has already solved part of the problems that I face (which is probably why Doug encouraged me to contact him!). Since I already have the dump truck garage for capturing the shavings from the big system, it seems logical to me to use the same dump truck to capture the shavings from the small one, thus eliminating an additional step of having to handle the shavings with the skid steer. The see saw idea is interesting....

Todd - I like your "cone shaped" barrel concept - this should minimize a lot of problems. Now, envision two of those side by side, with a valve at the top that could direct shavings into Cone A when cone B was being dumped, and vice versa. The "thumper" is a good idea too if I used some type of straight barrel, instead of a cone shaped one.

PTT49R, Mike Davis and JimmyC: The wide belt sander is plumbed to the SDG, so in addition to course planer shavings it also captures some extremely fine dust. That's one big reason why I don't want to bypass the cyclone and discharge directly into the dump truck - with all of the fines in the air I'll have a real mess (and a potential explosive environment). Simply dumping straight down a chute via gravity should produce less airborne particles.

In addition, in order to use the large system to empty the small one, I would have to crank up the 400 hp diesel generator in order to operate the large blower (its 25 hp 480V 3 phase), and I'd prefer not to do that every fifteen minutes or so if I'm doing a lot of planing with my small system.

Glen: The interesting thing about the dust collected by the SDG is that the weight of the material in the drum seems to vary depending upon what it is. If there is a lot of sanding dusts mixed in with the other shavings, it is much heavier than if it is just shavings. Thus, triggering the dump by an optical sensor may be more desirable solution. Don Patterson's design could also work well for this.

All: Please keep the ideas coming!

[Bas]

Originally Posted by TV

You can use a timer for how long the slidegate and vibrator stays on.

You know, a timer might be the way to go on this.

Why not build what's essentially a big blastgate that replaces the bottom of a 55 gallon drum, with some sort of motor attachted to it. The drum hangs over the dump truck. When the SDG is running, power is fed to a timer that goes off every 15 minutes. When the timer goes off, the blast gate opens. After 5 seconds, when the chips have all fallen out, the gate closes. And the cycle repeats. No dust sensors needed. During this cleaning interval, you may have some pressure loss, but I don't think this would be a big problem provided you can open/ close the blast gate quickly. Perhaps a sliding gate is a poor design, a butterfly valve would be better.

Of course, the gate may be opening even though the barrel is empty. We all know how Scott loves to talk when he should be woodworking! Then again, the SDG is also running for nothing when that happens, so by comparison we're not wasting a lot of power.

[Alan in Little Washington]

I'm here, I'm here- out on the left coast so on a different time schedule!

A lot of good thoughts here so far, but here is how I would do it automatically.

First, as someone mentioned a cyclone is only good in a semi-closed system- if you remove the drum (pull through) or bag (push-through) you lose cyclonic separation and the ability to return clean air via the filters back to the shop, so you might as well do away with the cyclone- plus the discharge may be really messy, especially in high wind conditions.

One solution, similar to what others have suggested is a blast gate (or two if used with a wye) at the bottom of the cyclone and a means to dump the container- BOTH the blast gate(s) and the dump gate/trap door, etc. must seal very well however, and is really critical in a pull through system to prevent dust getting through to the filters.

A push through system would need to be sealed to keep dust under control around the cyclone, but I don't think it is critical to the filters.

Some commercial systems use a rotary hopper valve, kind of like a big turnstile revolving door to dump the drum while maintaining a seal, but frankly I think it would be too hard to manufacture and operate.

Here is what I would try:

1. Configure cyclone as a push-through
2. Connect a large discharge tube/pipe (8" - 12" in diam.) to the bottom of the cone that is as long as you can fit above the dump truck- this is now your dust bin.
3. Add a blast gate (one of my electro-pneumatic ones since the actuator power using safe shop air is much stronger than any other method ) to the bottom of tube/bin that is as large as the tube. As someone mentioned this tube could have a tapered/conical bottom so it would work with a smaller blast gate, though it might cause a backup if working with wet wood, etc.
4. Use a 110V solenoid air valve to operate the blast gate actuating cylinder. Control it with one of my high dust alarms and a delay relay (or other circuit using two sensors- one at the top and one at the bottom). I have some of 110V solenoids left from my shop project.
5. Testing will determine if two (upper and lower) or just one blast gate are needed.

In operation, when the tube is full, the blast gate opens and allows dust to drain into the truck. The time delay (or preferably a simple circuit using top and bottom sensors and a relay) prevents the blast gate from closing too quickly as dust empties.

The only thing I would worry about is dust hanging up in the bin/tube, however the circuit that controls the gates or the pneumatics could power a simple vibrator.

[ErnieM]

Originally Posted by Alan in Little Washington

I'm here, I'm here- out on the left coast so on a different time schedule!

A lot of good thoughts here so far, but here is how I would do it automatically.

First, as someone mentioned a cyclone is only good in a semi-closed system- if you remove the drum (pull throught) or bag (push-through) you lose cyclonic separation and the ability to return clean air via the filters back to the shop, so you might as well do away with the cyclone- plus the discharge may be really messy, especially in high wind conditions.

One solution, similar to what others have suggested is a blast gate (or two if using with a wye) at the bottom of the cyclone and a means to dump the container- BOTH the blast gate(s) and the dump gate/trap door, etc. must seal very well however, and is really critical in a pull through system to prevent dust getting through to the filters.

A push through system would need to be sealed to keep dust under control around the cyclone, but I don't think it is critical to the filters.

Some commercial systems use a rotary hopper valve, kind of like a big turnstile door to dump the drum while maintaining a seal, but frankly I think is would be too hard to manufacture and operate.

Here is what I would try:

1. Configure cyclone as a push-through
2. Connect a large discharge tube/pipe (8" - 12" in diam.) to the bottom of the cone that is as long as you can fit above the dump truck- this is now your dust bin.
3. Add a blast gate (one of my electro-pneumatic ones since the actuator power is much stronger than any other method using safe shop air) to the bottom that is as large as the tube. As someone mentioned this tube could have a tapered/conical bottom so it would work with a smaller blast gate, though a .
4. Use a 110V solenoid air valve to operate the blast gate actuating cylinder. Control it with one of my high dust alarms and a delay relay (or other circuit using two sensors- one at the top and one at the bottom). I have some of 110V solenoids left from my shop project.
5. Testing will determine if two (upper and lower) blast gates are needed.

In operation, when the tube is full, the blast gate opens and allows dust to drain into the truck. The time delay (or preferably a simple circuit using top and bottom sensors and a relay) prevents the blast gate from closing too quickly as dust empties.

The only thing I would worry about is dust hanging up in the bin/tube, however the circuit that controls the gates or the pneumatics could power a simple vibrator.

It seems to me that the true consequences of the pre-determined analogy might undermine any attempt to further obfuscate the penultimate query. It is possible, however, that the conical underlayment may well circumvent the solenoidal associations that would likely occur given the parameters previously extrapolated. On the other hand, as I fail to comprehend any of the utterances emanating from the writing implement belonging to Alan in Little Washington, you may, without guilt or fear of consequences, ignore the gibberish I just wrote.

Bottom line: If Alan says it will work - it will work.
Ernie (with apologies to Prof. Irwin Corey)

[scsmith42]

Originally Posted by ErnieM

It seems to me that the true consequences of the pre-determined analogy might undermine any attempt to further obfuscate the penultimate query. It is possible, however, that the conical underlayment may well circumvent the solenoidal associations that would likely occur given the parameters previously extrapolated. On the other hand, as I fail to comprehend any of the utterances emanating from the writing implement belonging to Alan in Little Washington, you may, without guilt or fear of consequences, ignore the gibberish I just wrote.

Ernie (with apologies to Prof. Irwin Corey)

Gee Ernie, it appears that you are well qualified to get a job drafting legislation up in Washington DC....

[scsmith42]

Alan, thanks for the feedback all the way from the left coast!

Maybe we can bounce some ideas once you return. I'd like to learn more about your system and various nuances with it.

Thanks.

Scott