Sawdust management with a cyclone

[Ole Anderson]

Now that I have had my cyclone for 18 months, I am looking to address a few issues regarding sawdust disposal. First, while I had the filter out to install my ammeter transformer, I opened the bin thinking it probably needs emptying. Good thing as all the room left was just a dimple right under the 35 gallon fiber bin inlet. That brings up the issue of keeping track of the dust level in the bin. And emptying a full bin is a pain, so I am wondering if using a plastic bag liner would help, knowing that you need some type of hold down mechanism or the bag well get sucked into the impeller. Next, the issue of knowing if the filter needs cleaning. And then the smaller issue of dumping the pan under the filter as it has a huge lip. Oh, and while not super thrifty, I will not go for the high buck solution if there is something that will work almost as well.

Starting with the dust pan issue, I think I will just use a piece of poly liner there as the pan is under pressure and it seems like an easy solution.

Regarding the filter, I see that Oneida sells a filter efficiency gauge for $115. They recommend cleaning the filter if it reaches 3" of pressure. 3" of Hg is equivalent to about 1.5 psi. I have an old auto engine vacuum/fuel pressure gauge that looks like it should work, I just need to fab a pitot tube. My manual on the Oneida cyclone shows where to install it. And if I put a tap on the suction side of the cyclone, I can use the same gauge to measure the static suction under various scenarios of blast gate openings and filter cleanliness.

I see now that Oneida only offers a semi rigid plastic bag liner in lieu of the older vacuum bag gripper. $48 for that item. http://www.oneida-air.com/inventoryD.asp?item_no=ABX000035&CatId={E73B4361-F6D4-44D5-A815-E35ECB580382 I used to use a similar device inside my paper lawn bags and it worked well, at least with grass clippings and leaves, not sure how easy it will be to get the bag out of the fiber bin when full of sawdust and then how easy it will be to remove the semi rigid liner from the poly bag, now full of sawdust. Anyone have experience with the new Oneida system? I see also that they sell bags for $2.80 each, seems kind of expensive, but they are 4 mil, far thicker than what you get from HD or Lowe's.

Last, I would like to have an alarm for the bin to prevent stacking my filter with the big stuff. Again Oneida offers several possibilities, this one being the least expensive: http://www.oneida-air.com/inventoryD.asp?item_no=AXB999110A&CatId={4CA9A078-61CB-463F-B843-8C681E38534F} Any better suggestions? I could just go really cheap and install a window in the top of the bin as others have done, but I kind of like the automatic alarm system.

[Brad Sperr]

If you're not in a rush, you may be able to find a good deal on a point level switch on ebay. Search for either "level switch" or "level indicator." I found a really good deal on a bindicator that way. A lot of these switches have internal relays, so hooking them up to a strobe light or using them to cut power to your cyclone wouldn't be difficult.

[John Lanciani]

Hi Ole,

That gauge is pretty coarse for what you want to do, take a look at ebay item #230773236424 (or search for a Dwyer #2005), it is perfect for filter monitoring. As for the bag holder, a piece of formica works just as well and is easy to remove when the time comes.

[Dick Mahany]

+1 to John's suggestion. I put a Dwyer Minihelic 2-5005 and A-302 static pressure tip on mine for about $60. Works great. I also bit the bullet and put Oneida's solid state bin level sensor on my 35 gal drum and it has saved my tail a few times during planer sessions. The flashing red LEDs get noticed quickly.

If you use a drum or wide belt sander, the filter will cake quite rapidly and the Minihelic will let you see the results quickly, plus it will confirm that the filter cleaning was successful afterward.

[Jim Andrew]

Your link to the Oneida site didn't work, but thought I should share with you that I purchased the Oneida dust sentry, and installed it in the top of my lid, and it works occasionally, maybe every 3 or 4 bins full. Normally, the dust runs over and fills my filter, so got tired of that and cut a hole in the wall and installed a window. Have to turn on a trouble light so it shines on the back side of the clear hose so I can tell when it fills up. Mine only takes a few seconds to fill up the hose once the barrel is full, when using my planer, which is the only time mine fills rapidly.

[Ole Anderson]

Hi Ole,

That gauge is pretty coarse for what you want to do, take a look at ebay item #230773236424 (or search for a Dwyer #2005), it is perfect for filter monitoring. As for the bag holder, a piece of formica works just as well and is easy to remove when the time comes.

John, yea, my gauge is inches of mercury (Hg), way different from inches of water column (WC). My bad. Now I am going to have to get two of those gauges from Ebay, one 0-5" WC for filter loss, and another 0-15" WC for the total static pressure. Don't know why the links don't work, sorry. I like the formica idea, my scraps are too small, but new material should still be cheaper than Oneida. Looks like conflicting reviews of the dust level sensor though.

[Jay Runde]

Ole,
Alan Schaffter has posted a bin sensor you can make with parts from the BORG that would most likely cost under $50. It is in this thread: http://www.sawmillcreek.org/showthread.php?79451-Ever-wonder-what-happens-if-you-don-t-clean-your-cyclone

[Chris Parks]

Would a cheap video camera from Ebay and an old TV for a monitor be overboard? Put a few LEDs in the bin lid for light might help.

[Ole Anderson]

In my mind, the best bin level indicator would shut off power to the DC when the bin reached 90% full, and it worked all the time, that probably gets back to using a mechanical bindicator with a contactor.

[Jim Neeley]

The McRabbet from ClearVue provides you the ability to wire in automatic DC shutdown or a short delay to allow for duct clearing, or no shutdown at all.

[Michael W. Clark]

Check out the Dwyer Instruments site for the Magnehelic gauges, should be around $60/ea. You can also get the Photohelic and use the relay to shutdown your collector if the filter DP gets too high.

Bindicators work good in the drum. You may need to mount it lower than you think. If you allow the dust to build up to the bottom of the cone, you are re-entraining captured material. The dimple you found was created by the vortex at the bottom of the cone, you were probably already re-entraining depending on what you found in your after filter.

[Ole Anderson]

Check out the Dwyer Instruments site for the Magnehelic gauges, should be around $60/ea.

I found a new Magnehelic 2005 for $32.40 and a new 2015 for $40 on EBay, both with free shipping, they are on their way. Both will be mounted next to my ammeter right on the wall next to my MS. It will be December before I have time to fab a pitot and mount them however. After that I will worry some more about the bin level issue. I am thinking I will just bend a piece of 3/8" tubing and use automotive fittings to make the pitots.

[Robert Payne]

I make and sell a reliable bin level alarm system that uses a pair of garage door safety sensors that monitor the inlet flexible duct on a cyclone bin for a blockage when the bin fills. The control box is equipped with a circuit that trips an onboard relay to actuate a horn/strobe unit and an interface to the users dust collector control relay. The 12V DC powered control box can be located out in the users shop area and low voltage wiring provided with the unit connect to the sensors, up to 50-75 feet away. The user provides a section of 14 gauge wire (NM 14/2 is recommended) to connect his DC control to the bin sensor control for automatic shutdown. A bypass switch is also incorporated to allow the cyclone to continue running when the alarm trip (e.g., while planing a long board to continue collecting chips). In addition, the horn can be switched off for strobe alarm only.

I've included two pictures that show the unit as shipped and a close-up of the control box. I have some SMC customers and sell the unit for $175 plus shipping.

[Brad Sperr]

Bindicators work good in the drum. You may need to mount it lower than you think. If you allow the dust to build up to the bottom of the cone, you are re-entraining captured material. The dimple you found was created by the vortex at the bottom of the cone, you were probably already re-entraining depending on what you found in your after filter.

Can you explain more about this, Michael? I've got a binmaster, very similar to a bindicator, with around a 6" probe and was planning to mount it in the top of a collection drum towards the middle close to where the cyclone discharges. Would it be better to mount it in the side of the drum farther down?

[Michael W. Clark]

It will be December before I have time to fab a pitot and mount them however.

Ole, unless you are trying to read VP (converting to velocity, then translating to CFM based on duct area), you don't need a pitot tube. Plus, not sure how you would make a reliable pitot tube based on the commercially available ones I have seen from Dwyer. These are usually factory calibrated and tested. All you need for the Magnehellics are taps on the duct. A 1/4" coupling and hose barb work well.

[Michael W. Clark]

Can you explain more about this, Michael? I've got a binmaster, very similar to a bindicator, with around a 6" probe and was planning to mount it in the top of a collection drum towards the middle close to where the cyclone discharges. Would it be better to mount it in the side of the drum farther down?

At the bottom of the cone, the vortex does some weird stuff when it drops the dust and turns to head back up the cyclone to the outlet. If you allow the dust to fill to the bottom of the cone, some will certainly be re-entrained. A rule of thumb is to keep the dust about three discharge (or duct diameters) below the cone bottom. This much length may not be necessary in home shop cyclones, but some distance would certainly be desired.

Regarding mounting the indicator, If you mount it in the side, you have to take into accound the angle of repose of the material. This sounds complicated, but if you have a pile of dust it will be highest in the middle and lowest on the sides. If your level indicator does not reach the middle, then it would need to be lower so it can detect the level on the side such that the high spot in the middle does not get too close to the cone.

If you have a 6" cone outlet, and your hose is 18" long, then you would be fine to allow the material to build up to the top of the drum. Otherwise, the top of the material may need to be kept lower, depending on your cyclone's characteristics.

Mike

[Ole Anderson]

Ole, unless you are trying to read VP (converting to velocity, then translating to CFM based on duct area), you don't need a pitot tube. Plus, not sure how you would make a reliable pitot tube based on the commercially available ones I have seen from Dwyer. These are usually factory calibrated and tested. All you need for the Magnehellics are taps on the duct. A 1/4" coupling and hose barb work well.

I was wondering about that, as all you are doing is measuring suction or pressure at a given point in the system. But the filter gauge installation instructions from Oneida includes a pitot tube which confused me.

[Michael W. Clark]

I was wondering about that, as all you are doing is measuring suction or pressure at a given point in the system. But the filter gauge installation instructions from Oneida includes a pitot tube which confused me.

There are SP tips that resemble a pitot tube. They insert into the duct and are bent at a right angle. They usually only have holes on the side, perpendicular to the flow direction. A pitot tube will have a hole on the tip and holes on the side. It is a tube within a tube with two pressure connections outside the duct. One port is total pressure (TP, holes located on the tip of the tube), and the other port is static pressure (SP, the holes on the side of the tube). When you subtract these two pressures via a DP gauge such as the magnehellic or manometer, you get velocity pressure (VP). The duct velocity is mathematically calculated from the velocity pressure and correcting for density. Once you know the velocity, multiply it by the duct area to get the flow.

Mike

[Bill McDermott]

Ole,

My experience with the Onieda sensor has been perfect.

As I bought some 1" x 1/8" flat aluminum bar and bent it into a ring that fit inside a plastic bag, inside the drum. I took another piece and screwed it to the ring so that it comes up the inside of the barrel to the top. That's the handle that allows me to remove the ring. Even though the bag folds over and is held tight by the lid; when empty, the bag wants to collapse near the top until chips and dust hold it in place. That's not a problem, but it did set off the sensor once. It was cheap and easy and works great.

The first time I filled a lawn and leaf bag. Carrying it up from the shop and out through the house was a bit nerve wracking. Now, I use the heavy plastic bags made for construction site clean up. Peace of mind.

[Ole Anderson]

Well, I have the two Dyer gauges installed. Sorry I don't have pics, will be a month before I am able to post those as I am now out of town. I have the Oneida 2 hp Super Dust Gorilla. The filter was recently cleaned having only cut a few boards since, but it is well seasoned, having emptied the cyclone barrel about a half dozen times so far. The 0-5" WC filter pressure gauge taps into the elbow about 2/3 of the way down as suggested by Oneida. I just used an 1/8" pipe tap directly into the plastic elbow, with no pitot or other pressure tube as used with the more expensive Oneida gauge. With both TS blast gates open I am reading about 1.7 inches of pressure, with all gates closed I am still reading 0.3 inches, which I attribute to system leakage, mostly from the blast gates as virtually all duct seams are taped or sealed with silicone. Thinking it might be leakage through the corrugations of the main 7" aluminum flex, I tried wrapping it in saran wrap, but it didn't seem to suck down at all, so I don't believe it is occuring there. Oneida recommends cleaning the filter at 3" of pressure or damage could occur. It will be interesting to see how the filter pressure gauge reacts when I get to some serious dust making operations.

I tapped the other 1-15" WC static pressure gauge into the inlet on the cyclone about 2" from where the flex duct attached to the duct system. Again I just tapped the heavy steel 7" inlet directly with the 1/8"pipe tap and used the barbed brass connection supplied with the gauge. Both gauges are set up for differential pressure, I simply left the secondary connection open to atmospheric pressure. With all blast gates closed I am reading 9.4" WC. The fan curve from Oneida indicates the suction at no flow should be about 10.5" WC. Per the curve, at 9.4" the system should be passing about 500 cfm. I can't imagine the leakage is that high so there are some errors in either the fan curve, the gauge (spec at +/-3%) or in my gauge tap point. I will take some more readings when I return as well as post some pics.

I am thinking I should install a small filter, like a paint gun pre-filter, before the gauges to protect them.

Regarding the bag, I will try a heavy contractor trash bag with a ring of formica inside to keep it from being sucked into the impeller. As for the bin full indicator, I am still leary of a system that allows the drop tube to begin filling before alarming. I would rather have an alarm at 80% bin full.

[Michael W. Clark]

Ole,
Before you get the filter much dirtier, I would record the pressure readings with different branches open to get baseline readings. Once the filter gets dirtier, repeat. You may not know the exact flow in CFM, but the difference in SP will tell you the flow difference in % flow. The SP will vary with the square of the flow change. You may decide to clean the filter before 3" of DP due to the flow loss. You will also be able to tell how effective your filter cleanings are. As the filter gets older, the "clean" DP will get higher (unless the filter gets torn). Cyclone DP can also be used to indicate flow, but it may be difficult to get that with Oneida's fan/cyclone arrangement.

You don't need the paint gun filters, especially on the inlet SP, the system is pulling air out of the gauge (negative pressure). The air is relatively clean after the cyclone so I wouldn't put one there either. The magnehelics are very robust and are installed in conditions much more challenging than yours in industry.

I agree with your take on the dust drum level. Unless you have a lengthy pipe/hose between the cone and dust bin, you are already re-entraining particulate if it gets into the hose before detected.

Mike

[Kerry Wright]

I made something very similar to what Alan Schaffter (suggested earlier) did. The one thing I would caution about. Don't use any device that shuts down your DC! Any large burst of chips could cause a brief false alarm and if that happens while your in the middle of planing that one of a kind piece, the results could be less than desirable. The other thing I did was to extend my piping about 10 inches into the collection drum. This way when the dust gets to that point the pipe fills up much quicker and triggers the alarm (two high intensity 50 LED alternately flashing) lights before the drum itself is overfilled. Cuts down on the mess when emptying the drum.

[eugene thomas]

I am thinking my filter needs some monitoring, can any body that has put the dwyer gage on their filter setup post some pics. Thanks eugene

[Jim Neeley]

For any who may be interested, Dwyer makes a version of the gauge that also has a set of contacts that close when a certain pressure drop is reached. Some may wish to add a filter cleaning indicating light.

Jim

[Ole Anderson]

I am thinking my filter needs some monitoring, can any body that has put the dwyer gage on their filter setup post some pics. Thanks eugene

Sorry I am out of town so I can't post pics for a while, but it is so simple pics aren't needed. Get a 0-5"WC Magnehelic gauge made by Dwyer. Ebay has some real deals. I paid $32.50 with free shipping. http://www.ebay.com/sch/i.html?_trksid=p2047675.m570.l1313&_nkw=DWYER+MAGNEHELIC+DIFFERENTIAL+PRESSURE+GAGE+&_sacat=0&_from=R40

It comes with 4 pressure ports, 2 plugs and 2 barbed hose connectors. You plug off the ones you don't need, in my case I plugged off the redundant ones on the side of the gauge and used just the low pressure port on the back, and left the high pressure port on the back open to atmospheric pressure. One barbed fitting goes in the low pressure port, the other barbed fitting goes in the side of your elbow just upstream of the filter (after the cyclone). Connect the 2 fittings with 1/4" rubber hose and you are done (after of course mounting the gauge, I put mine above the door to my cyclone closet).

[Robert Payne]

I made something very similar to what Alan Schaffter (suggested earlier) did. The one thing I would caution about. Don't use any device that shuts down your DC! Any large burst of chips could cause a brief false alarm and if that happens while your in the middle of planing that one of a kind piece, the results could be less than desirable...
Kerry,

Your concern about automated shutdown is valid for any system that detects a short blockage. The system I mentioned in an earlier post in this thread has a 10-12 second full blockage requirement before a full bin condition trips the alarm and the DC is shut down. The user can bypass the auto shutdown with a simple switch while performing operations (like planing a long board) where he wants chips/sawdust to continue being collected, yet he'll know that the bin is filled as the alarm has been triggered. Once the planer pass is completed, the user can flip the switch and the DC will shut down. I have dozens of units working on ClearVue and Oneida cyclones where the users are pleased with this feature and I have gotten no complaints.

[Jeff Heil]

Look online at Uline and some of the other vendors of heavy duty plastic bags. I bought a case of 4 mil clear bags from Uline that has lasted for several years for my Jet Canister DC. The Jet bags were much more expensive.

[William Payer]

Ole,

As to holding a plastic bag in place in the cyclones dust bin I have a cheap solution I've used. Get a reminant of formica ( any plastic laminate). Cut it so it is just an nice or so shy of the bins height. and about 1 foot longer than the circumference of the bin. Round the corners to make sure they are not sharp enough to tear the plastic bag. I used duct tape on all edges . Place bag in bin and "roll" the laminate so it is smaller than the bag, insert and release. The laminate will expand, holding the bag open. When emptying, you need to grab the laminate and ease it out before removing the bag. Easy, and inexpensive and, unlike the vacuum bag holders, nothing to ever fail!

[Ole Anderson]

Ole,

As to holding a plastic bag in place in the cyclones dust bin I have a cheap solution I've used. Get a reminant of formica ( any plastic laminate). Cut it so it is just an nice or so shy of the bins height. and about 1 foot longer than the circumference of the bin. Round the corners to make sure they are not sharp enough to tear the plastic bag. I used duct tape on all edges . Place bag in bin and "roll" the laminate so it is smaller than the bag, insert and release. The laminate will expand, holding the bag open. When emptying, you need to grab the laminate and ease it out before removing the bag. Easy, and inexpensive and, unlike the vacuum bag holders, nothing to ever fail!

William, that is my plan, except that I plan on fixing the laminate cylinder slightly smaller in diameter than the drum using pop rivets, and cutting some hand holes to help ease it out of the bag when it is full, after lifting the bag out of the drum. I know that the sawdust can get tightly packed in the drum and I am afraid that trying to lift the bag out of the drum after removing the laminate cylinder could be difficult. Am I missing something?

[William Payer]

William, that is my plan, except that I plan on fixing the laminate cylinder slightly smaller in diameter than the drum using pop rivets, and cutting some hand holes to help ease it out of the bag when it is full, after lifting the bag out of the drum. I know that the sawdust can get tightly packed in the drum and I am afraid that trying to lift the bag out of the drum after removing the laminate cylinder could be difficult. Am I missing something?

I think making the kaminate a fixed cylinder using pop rivets may very well be a good idea. THe holes for grabbing the laminate for removal from the drum are definitely a good idea. On mine, the laminate fits tightly to the bag/outer drum and I have to lift one end of the laminate a little and then work the laminate up about an inch before I can remove it.

AS far a the bag od sawdust clinging to the outer drum making removal difficult, I have not had any problems getting the bag out once the laminate is removed. I suppose if you used very thin plastic bags, there could be problems. I tend to use the larger trash bags from either HD or Costco as they are quite strong and long enough to get a good grip to put everything out of the bin.

[Ole Anderson]

I ran across this today while on the Grizzly website, the part he is gripping looks just like the one I am going to fab up, although I think the bag would fold over the outside of the bin when you close it up under the cyclone unless it is tall enough and sturdy enough to compress against the gasket. They sell this for $70 for the 35 gallon size:
http://cdn0.grizzly.com/pics/jpeg500/h/h8173.jpg

[Howard Acheson]

>>>> AS far a the bag od sawdust clinging to the outer drum making removal difficult, I have not had any problems getting the bag out once the laminate is removed.

Here is the way I did it. I drilled a couple of pairs of 1/4" holes in my formica expander and inserted a length of 1/4" rope or cord into the pair of holes. The holes are about an inch and a half from the top of my formica expander. I tied a knot in the end of each cord to keep the rope from pulling through the holes. So I now can get my hand into the rope handle and easily slide the expander up and out of the barrel. Make a pair of holes for each handle positioning the two handles approximately opposite each other.

[eugene thomas]

A little feed back, few weeks ago seen this thread and ordered the dwyer gage. Well worth effort. Now know when time to clean the filter on the collector