preliminary test of DC-- man is it noisy!

[James Baker SD]

I have just about finished installing the metal ducting for my Oneida Pro 2000 cyclone. I keep the ducting at 7" diameter until the last instant when I stop down with reducers and/or reducing branches to the size of flex hose I will use to connect the various machines. I plan on running one machine at a time with all other branches shut down with metal, manual blast gates. Many machines have multiple connection ports that share a single 7" blast gate. As of now there is no flex in the system, just the metal ducting, no machines actually connected. I thought I would give it a test to feel the suction at each port to get a very qualitative feel for the losses as I move further from the cyclone.

Opening one gate at a time and checking, the system is incredibly noisy--painfully noisy even with hearing protection; vibrations somewhere. I suspect it is the metal plate of the various closed blast gates vibrating, but not sure if that is only source. I felt for vibrations along the ducting itself, and could not feel it, nor deaden the noise any.

The level of noise will be a real distraction to an enjoyable hobby. Any ideas how I can get the noise levels back to what I had when the Oneida was "mobile" and I connected one machine at a time solely with flex hose and reducers? Thanks.

James

[richard poitras]

James I just finished installing my Pro 2000 with metal 26 snap lock pipe and metal blast gates. I have no vibrations in my system. I was putting the flex pipe on today. No sure way you have vibrations in your system but you shouldn’t? None of my blast gates rattled when I had then on with just a friction fit or the now permanent fit? How did you attach it to your ceiling? It could be a loose ceiling or wall mount?

Good luck Richard

[James Baker SD]

Richard,

Seems we are installing similar systems. I have a variety of attachment methods, mainly metal rings around the duct with eye bolts instead of regular bolts holding the two halves of the ring together. Then turnbuckles from the eyebolts to screw hooks into the 2x4s in the ceiling. Other method between the metal rings, is an eye-screw into the ceiling and a 36" nylon tie (the kind that locks itself at the smallest loop you make) around the duct and thru the eye.

I cannot feel the main ducts vibrating if I climb up the ladder and touch them. I know the blast gates are part of the problem (maybe all the problem) because I can silence any particular one of them by opening it or by pressing against it with my hand, but that still leaves the others singing away.

If I open multiple gates, the noise level gets reasonable (vibrations seem gone) but I have reduced suction at any given open port.

James

[Ole Anderson]

Like Richard, my system with the 2 hp SDG is steel snap lock with aluminum blast gates and it is not noisy at all, except for the rumble of the blower. Are your blast gates cast aluminum? How do they stay open, with a friction fit or like mine, with a thumbscrew? Are your joints taped and your wyes and bend joints sealed to contain leakage and rattling? From your post it appears that the objectionable noise is from vibration of the duct and not from the blower itself. On my system I have 7" aluminum flex (it was an in-stock item at HD) between the cyclone and my main run due to lots of odd angles. Maybe for me it is acting as a vibration isolator, I don't know for sure. I was able to contain the noise of the blower in a closet, here is a video of the noise measurement: http://www.youtube.com/watch?v=8X8qwMqm3Ek

[ian maybury]

Speaking in general because i'm not familiar with the Oneida. There's two basic sources of significant noise on a dust system: (a) impeller noise caused by the air being very energetically churned in the fan, and (b) vibration from the motor and impeller being transmitted into structures that by vibrating create noise.

Don't know how often this happens (rare as it's not come up recently) and it's only a possibility, but good balancing and accurate machining of the impeller is important in the case of the second - a well balanced impeller is smooth running. If it feels like there's a lot of vibration it should be possible to check the impeller balance by slipping a piece of bright round mild steel bar of the same diameter as the bore into it (it should be a close sliding fit), and setting the whole assembly up so that 'shaft' rests on a pair of carefully levelled, parallel and vertically set knife edges. If the impeller is badly out of balance the shaft will roll on the knife edges so that the heavy point ends low. If it's obviously off (the same section of the disc always ends up low) then it's probably a return to maker deal. I guess aerodynamic issues could arise too if the impeller was not made accurately - different sized vanes, not flat based, bored crooked etc. Maybe run the motor on its own too just to cover the unlikely possibility that vibration is coming from it.

The transmission of the vibration that inevitably does occur even on a well balanced fan into either ducting, or the cyclone, the building structure - or whatever - can produce a lot of noise. It's generally a good idea to soft mount the motor and cyclone assembly on flexible pads (machine soft mounts are fairly easily bought - select to match the weight) so that vibration isn't transmitted into other stuff. A strongly built stud wall or floor, or even masonry can generate an awful lot of noise if vibration is fed into it.

A second related step that's well worth doing is to make sure that there is a short flexible hose (a gap of a few inches is plenty) in the connection from the cyclone inlet to the ducting - that way the vibration can't be transmitted into the ducting.

Another step that can pay off handsomely (it relates to (a) above) is to fit an HVAC silencer in the exhaust of the fan - although the Oneida presumably exhausts directly into a filter cartridge which will do that job anyway.

Make sure that stuff like the blades in metal blast gates or anything else metal to metal is not loose. (plastic or wood is inherently quieter, and the cast aluminium variety often have poor fits and can anyway leak a lot of air)

Check just in case (the design should avoid this) there's a sheet metal section anywhere on the unit itself or anywhere else that's for some reason vibrating badly - your hand should feel it. Holding it (if it's a large and fairly flexible panel) might quieten things down.

Big fans can be fairly noisy anyway (but there shouldn't be any rattling going on), especially if run at higher speed with a VFD. Hopefully it's not just that....

ian

[Dick Mahany]

I have an Oneida V3000 plumbed with 6" PVC, so I can't directly relate, but offer a few suggestions if you will.

1) Mine is was very noisy also on 4" blast gates and I could see the shutter/sliders vibrating wildy as these systems pull a LOT of air. The standard friction screw seemed to tame them considerably when tightened.
2) Even with that, I now hear a MUCH louder howl on my JJP12 jointer/planer combo and JCSX6 jointer with 4 and 6" ports respectively, when I slide the gate open. Don't like the noise, but love the increased chip collection!
3) Sounds like there may be resonance/harmonics at play. Any way to put in a small section of flex between the DC and ducting as a temporary way to see if accoustic coupling couls be reduced.


No matter what we do, something seems determined to get us............be it fine dust..............or noise ! I guess the only solution for us is to take up another hobby.......maybe gardening, or birdwatching (can't believe I just said that) :eek:

[David Kumm]

There will be a lot more air noise but the rattling can be stopped by tightening the thumb screws a little. You do need thumb screws with that much air running through a 7" duct. Impeller noise sounds like a jet and I'm assuming you don't think the vibration is coming from an out of balance impeller. They do need to be balanced but if that is a problem you should feel it in the cyclone. Impeller noise is generally heard through the filters. Dave

[James Baker SD]

Thanks for the ideas. To answer some of the questions;

I don't blame the Oneida or its impeller or its mounting stand--the noise level was tolerable when I simply ran 7" flex down to the floor and then connected a 7" to something fitting (7" to 4" reducer, 7" to 6" and 4" branch etc) to take smaller flex along the floor to whatever machine I was using. Painful to switch, so I often did not switch if making a single pass on the joiner or planer, hence defeating the whole point. That was the motivator for going with the permanent ducting.

Ducting is Nordfab quickfit and all the clamps are new so should have good sealing gaskets in them.

I had Nordfab make me a custom rectangular to 7" quickfit transition that mounts directly on the Oneida in place of the original rectangular to 8" raw transition. I kind of hate to remove this in order to isolate the Oneida from the ductwork, but as per my other observations, I don't think vibration is being transmitted from the Oneida.

Oneida supplied a "silencer" that is installed at the top of the filter.

Blast gates are Nordfab cast aluminum with quickfit ends. I installed several of them backwards (that is, with the thumbscrew pushing the plate away from the suction). Fortunately the two halves are identical castings so it is easy to move the thumb screw to push with the airflow. That helps on the ones I have flipped. I can also flip the whole gate if that would help. They do not seal 100%, I can feel a small air flow near them even when closed, less if I tighten the thumb screw hard, but never nothing.

With only one gate open though, the others rattle and that could be the sole source of my noise. It is worse if I have only a 4" gate open as compared to only a 7" gate open.

I did run the Oneida a few times for a couple of minutes as the ductwork grew like a tree sprouting branches away from the cyclone ( I could not figure out the whole plan to order everything at once due to elevation changes in combo with direction changes (weird house I live in), that is a 30 degree branch often divides its 30 degrees between two planes, I built out from the cyclone, then measured what I actually had, then ordered a few more parts, then repeated the experiment). I found tons of dust on top of things (like the top surface of the bandsaw, drill press and the suspended Jet air cleaner) that was probably a result of the many times I was too lazy to switch the original flex to another machine for a single cut or from my days with a Powermatic 1.5HP single bagger DC. Stirring this old dust up by trying to vacuum it sent my Dylos into orbit, so I would run the Oneida for 3 or 4 minutes with essentially open collection and reduce the particle count to something reasonable (did not want to overload the motor letting it move too much air, so I kept these runs brief). During these "air sweepings" there was no noticeable vibration on the ductwork that was in place. Noise level was tolerable.

I definitely do not want to change to another hobby. I bought this cyclone on order of my lung doctor who said it was that (and a 3M PAPR) or a new hobby. He said it was my choice.

James

[Ole Anderson]

There will be a lot more air noise but the rattling can be stopped by tightening the thumb screws a little. You do need thumb screws with that much air running through a 7" duct.

And make sure that your gates are installed so that the thumbscrews are pushing the gate toward the blower.

[Dick Mahany]

And make sure that your gates are installed so that the thumbscrews are pushing the gate toward the blower.

+1 on that.

[ian maybury]

Good news James that it seemed to run at an acceptable noise level before connection to the ducting.

I guess it's a case of working through the system step by step while checking for noise generating possibilities - but don't underestimate the ability of even apparently moderate levels of vibration to create a lot of noise if allowed to be transmitted into the ducting or the surrounding structure (it's not necessarily obvious that this is the source of the noise), or if there's stuff about that's loose it can rattle too. It can also make it into structures via the ducting mounts.

The latter in particular can be a low frequency rumble that sounds very like/is impossible to separate from normal fan noise, but it's not. You can get a bit unlucky so that something resonates/starts to flap about with it or whatever too.

The flexible joint to isolate the ducting from fan vibration should be close to the cyclone inlet, but doesn't have to be right beside it (as long as the cyclone inlet stub is not so long that it can't be left unsupported/needs to be rigidly mounted to anything) - maybe you can retain your adaptor and mount a joint between it and the ducting? (there's a picture of mine below - it's got two joints in as it was also used to line up the duct and the cyclone inlet) Flex hose is easy to use with jubilee clips for a joint like this - just slip a male joining sleeve (there's a 160mm example fitted in the blast gate in the photo) for whatever size your ducting is in the end of the piece of duct is to make a handy stub - then rivet and foil tape it.

Should the worst come to the worst and the cast aluminium gates prove troublesome the Clear Vue moulded plastic gates seal tightly (apart from a purpose made bleed hole that keeps the slide free - photo below), but the mounting sleeve is sized to suit PVC sewer pipe (the opening is about 160mm dia) so it might need a bit work to find fittings to suit.

You mention reducing down to 4in branches in place(s). Perhaps there's not much choice due to the type of machine/layout of machine ports or whatever, but reducing to a single 4in dia opening anywhere is going to heavily restrict the airflow you achieve from what is a generously sized fan and main ducting system. When you get that far it'd probably not be a bad idea to investigate the possibility of getting more open area (ideally 6in) right through to the inlet at whatever machine it is...

Chances are the noise is something pretty straightforward. Good luck with the lungs.....

ian

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[Lee Schierer]

Your problem is that your DC trying to move air (1973 cfm) through your 7" duct at 123+ feet per second and that is faster than the speed of sound (116 feet per second). You need to have more than one blast gate open at a time and/or a large diameter main trunk line.

[Jim Becker]

The only time that the noise level "goes up" when I'm using my Oneida 2hp unit is when I'm working on the J/P combo...the high level of air flow seems to amplify the noise of the machine. Otherwise, even before I built my DC/Compressor closet with baffled air return, the system was not significantly noisy. Check your mounts to be sure that the system isn't vibrating. And do call Oneida to discuss.

[James Baker SD]

I flipped the blast gates that had the thumb screw pushing away from the cyclone and that helped (Murphy's law, more than 2/3 of them were backwards). I also put a sheet of UHMW self adhesive plastic on one gate both to reduce the leakage and absorb some of the rattle. Works pretty well in quieting that gate, plus easier to open and close the gate with the cyclone running. Only one really noisy branch (single 120mm port for J/P) but I think the idea of another branch at least partially open may solve my problem, at least to a tolerable level. May put the UHMW on the other gates (only had enough for one) as I get around to it. I suspect that flex hose connected to a machine will deaden the sound levels a bit as well, as just placing my hand near the 120mm port to feel for the air flow quieted that branch significantly.

James

[ian maybury]

Are you sure of that Lee, or am i missing something? 60mph is 88ft/sec, so is 123 ft/sec not about 80mph?

I've run into that noise issue on my planer thicknesser too Jim. It might not apply to yours, but it proved possible to quieten mine down by quite a bit by installing a DIY spring bolt to fix the position of the dust chute when jointing. (see photo - the tables are folded up here but would be down when jointing) As supplied the hose end of the dust chute was dropping down under its own weight and that of the hose so that the lip at the other end was being pushed tight up against the bottom of the infeed table.

Which by blocking the possibility of air bleeding in from underneath increased the speed of the air passing over the cutter head. Which led to the 'siren' effect.

Some jointers as you probably know achieve the same effect by 'toothing' or slotting the lips of the tables - the slots seem to be intended to allow air to be pulled down into the chute without it passing over the cutter block at too high a speed....

ian

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[John Lanciani]

Your problem is that your DC trying to move air (1973 cfm) through your 7" duct at 123+ feet per second and that is faster than the speed of sound (116 feet per second). You need to have more than one blast gate open at a time and/or a large diameter main trunk line.

Better check your math Lee, 123 fps = 83.86 MPH. ;)

[Jim Andrew]

I put my cyclone and system in about 8 years ago, time flies, but was thinking I got a 6" rubber plumbing boot to fasten to the cyclone and then mount the first piece of pipe into, to keep the pipe from making a racket. Also hung my cyclone on the outside of the shop, with rubber pads bolted to boards, and then bolted the boards to the wall with rubber pads to insulate the cyclone from the wall. It is a LOT noisier out by the cyclone than in the shop.

[Lee Schierer]

Are you sure of that Lee, or am i missing something? 60mph is 88ft/sec, so is 123 ft/sec not about 80mph?



Yeah, you're right. I mis-read my calculations, darn slide rule....speed of sound is 1116 ft/sec.

[ian maybury]

Easily done Lee....

ian

[James Baker SD]

Yeah, you're right. I mis-read my calculations, darn slide rule....speed of sound is 1116 ft/sec.

Darn, I thought I had a Chuck Yeager dust collector. :-)

[Ole Anderson]

My dad (also a Civil Eng) used to always drill me on making sure that your answer is reasonable by telling the "story" of the guy that multiplied 2x2 on his slide rule and gave the answer 3.99. Ok it dates both my dad and me, but you get the idea. TI and HP both came out with their calculators just as I was getting out of school (late 60's), so I saw plenty of slide rule practice.

[Jim Becker]

Ian, my FS-350 does have the "toothed" table insert surrounding the cutter head. I've never considered that the noise increase on mine might seem to be related in any way to the dust chute position--it's a similar increase in noise when thicknessing, too, but it's certainly worth investigating at some point...thanks for that hint! Regardless, the amount of air that transits the 120mm port from my 6" drop is pretty nifty and it clears things out very well. So much so that I have to empty the 55 gallon bin very frequently when I'm face jointing and thicknessing stock en-masse...