Good afternoon all,
I’ve had an Oneida Dust Deputy for about 8-9 years and I’ve always been happy with the job it does. But one thing has bothered me from day 1. The shop vac I’ve always used is a 5 hp Craftsman model, and it’s got great suction. In normal use, the cyclone bin fills up, as it should, but I’ve always ended up with quite a bit of the dust/chips in the shop vac bin itself. And I’ve also noted that often the dust in the cyclone just spins around the cyclone. Even when there’s low or no dust in the cyclone bin and I’m not actually picking up any dust/chips, I still see dust swirling around the collector as if it’s pulling dust up from the bin.
So, I’m wondering, is it possible to have a shop vac that’s too powerful and it’s not allowing the heavier chips to drop out into the separator bin? I am going to address this question to Oneida, but wanted to get your experience as well.
Thanks as always for your thoughts,
Erick
Replies
I had the same issue and question several years ago. I asked their customer service if there was an optimal hp range for the vac, via email. I didnt get an answer to my question, but did get on their mailing list forever.
I went to a smaller vac, and it's been OK. But it still seems to be a fair question.
Only when the collection bin exceeded 75% full did I get chips in my 4hp vac. Is the bin connected to the dust deputy airtight? If not, the vac may be drawing air from the bin or through one of the seals and affecting the cyclone efficiency.
Hi JF1,
Good question. I have noticed the issue even with a freshly emptied cyclone bin. As far as I can tell, the lid is as airtight to the bin as it was on Day 1. But, as a test, I'll try putting on some duct tape around the seal to see if anything changes. I'm also going to try a lower power shop vac, as a another test.
Thanks for the suggestion.
E-
You can lower the power of your current vac by venting the hose between it and the cyclone.
Good point mj.
I'm going to give the whole system some love (new Hepa filter, cleaning up the connection from cyclone to shop vac, etc.) and I'll try venting the connection as well to reduce suction.
Cheers,
Erick
The main purpose of a dust collector is to remove chips and dust at the source, venting or reducing the power is a compromise in favor of emptying the chips vs your health. If I am not mistaken, the purpose of the cyclone is to precipitate the heavier particles, the fine dust is meant to be filtered subsequently so it’s normal that fine dust swirls in the cyclone and make its way to your shop vac.
Hi Gulfstar -
I'm using a shop vac connected to an Oneida Dust Deputy to pre-clean the chips/debris that I pick up for general shop cleanliness and connected to my ROS. As you say, the purpose of the cyclone is to separate (precipitate) out 99+ of the chips/dust into the bin at the bottom of the cyclone, with just some of the finest dust passing through. However, in my case, it appears that much of of the chips/dust do not precipitate out into the cyclone bin, and pass right through the cyclone and into the dust collector along with the fine dust, which a) is more difficult to clean out, and b) is clogging up my shop vac hepa filter and reducing suction. That's what led me to the hypothesis that my shop vac suction was too strong, and overcoming the gravity effect of separating out the chips/dust.
So, you're right, reducing the suction will have an affect on overall dust collection, but at the moment, I'm already suffering reduced airflow and dust collection because the filter clogs much more quickly than it should. I think it will be a balancing. Reduce suction to a point where the cyclone effect works properly, and keeps my filter clean. :-)
Cheers,
Erick
This is an interesting thread. I have a related question: I use an Oneida Mini-Gorilla DC. Does a good job, though the bin is a bit small. The cyclone successfully dumps all but the smallest stuff into the bin, as advertised. The job of the big HEPA is to catch the really small (and most dangerous) stuff.
Here's the question: How to know when it's time to clean the HEPA? I've
sometimes clearly waited too long and then the job is a real pain. I've thought about installing a pressure gauge just ahead of the HEPA to see
how the pressure drop across it rises as it begins to clog up.
Any advice/thoughts would be appreciated.
Hi jpe52,
Well, for what's worth, I usually clean my HEPA filter about 2-3 times a year, taking it outside with a brush, or using my compressor when I have a bit of extra time. I like the idea of a pressure gauge, but don't know how I'd mount it with the cyclone separator. Another alternative is to get a "cheap" anemometer ($15-30 on Amazon) and measure the air speed every once in a while.
Just a thought,
Erick
I noticed a significant decrease in suction after a long session with the drum sander. Using the exhaust port on the shop vac, I blew out the pleats from the outside. That was enough to get it back to normal. Other than sanding, a few knocks on the sides every few weeks.
Agreed, especially when having long sanding sessions with the ROS.
I never "know" when it's time to clean the filter. If you "know," it's already late. For me, it's just part of routine maintenance. Do that, and you don't have to worry about making it look new again. Shake it out, brush it off, maybe a quick blast with a blower, and back to work.
Didn’t realize they made 5 hp shop vac, must be on a 240V, 20 amp outlet.
Ha Ha Gulfstar :) Yeah good point. Shop Vac ratings are historically inflated.
My little sister has that same vac... MINE is 3-phase!
Ooooh, I have "Peak HP envy"
I would think that the approach would be to create an air flow that permits more of the chips to precipitate in the cyclone bin than they actually do. There is no rule that says that 99% should stay in the cyclone bin, if you create chips that may be but if you are hooked to a edge sander, all the dust may bypass the cyclone bin. So in your case, if you want more to precipitate I see two ways, reduce the air flow velocity , not the suction. It’s air flow that moves the particles. This can be achieved by increasing the inlet diameter. You could also try to extend the exhaust pipe lower in the cyclone or put a diverted in front depending on the design. I find cleaning the filter a few times a year is very little, clean filters are essential to good efficiency.
Hi Gulfstar,
I agree, achieving 99% collection in the cyclone bin is not necessarily the goal. But having the larger "chunks" end up in the cyclone bin, with fine dust only passing to dust collector bin is what I am expecting. Based on videos I've seen about how the Dust Deputy should perform, I'm just seeing more of the debris in the dust collector bin than I expect. And, as I noted earlier in this thread, it's also interesting that with some dust in the cyclone bin (less than 10% full), and not actually collecting anything, I'm seeing that dust collector appears to be pulling dust up out of the cyclone bin and spinning it around the cyclone itself. That's partly why I thought the collector was too powerful.
To your point above, I can look at increasing the inlet diameter (putting a 2.5 to 4" adapter and using 4" hose). I think that's worth an experiment. Thanks for the suggestion. I'll report back with results :-)
Cheers,
Erick
PS: Cleaning the filter is not a big deal as you suggest. But because I've bolted my DC to a mobile platform, emptying out the DC bin is a bit more of a PITA. :-)
Gravity or weight of the chips is not the only factor here separating dust from chips. It’s the ratio of the shape/surface area of the particle relative to its density that will decide if it precipitates or gets carried away, it’s called Blaine Index.
Interesting thread. As others have pointed out, at 120 volts, a 5 HP motor would draw nearly 32 amps! Those HP claims are based on the "inrush current" that the motor draws for a very small fraction of a second when the motor is starting from a standstill. It's pure marketing and 100% meaningless. Better metrics for comparing performance include lift and airflow.
With that said, I never had any trouble with chips making it through my Dust Deputy DIY using either my old Ridgid (probably marketed as 5-ish HP, I don't remember) or Fein Turbo I, which doesn't have a crazy HP claim but is more powerful in practice. If anything, suction and airflow through the same hoses and separator means more velocity and a faster spinning cyclone, which you would think would be more effective at flinging debris to the outside.
What I *did* have trouble with was hand plane shavings making it through. Supposedly that's addressed by the new-ish Dust Deputy 2.5, which has bigger in- and outlets for 2.5" shop vac hoses and doesn't reduce your airflow as much. I upgraded a few weeks ago and stopped picking up shavings before vacuuming up the dust but I haven't checked the vacuum yet.
I would recommend checking that things are reasonable airtight and maybe consider upgrading to the 2.5 model.
I have a small Dust Deputy, and two larger homemade dust collectors. one is 40 gallon, and the other is 20 gallons. They all work very well. As mentioned above, check for an air leak. What is the size of your collection bin? When the collection bin on mine fill up the chips and dust are pulled into the vacuum or expelled into final collection bag.
My suggestions:
- get a larger collection container. Make sure it is strong enough so it will not collapse from the vacuum suction.
- Empty your present container before it gets full,
- Always use a bag inside of your shop vacuum. The bag will collect most of the fine dust before it gets to the filter and the Hepa.
I run a couple of Ridgid "6.5 HP" units with original Dust Deputy separators. Very little gets by the DD. I cleaned the filters just the other day for the first time in about 3 years. I do use a bleeder when I run a reduced whip for smaller hand tools. This is a shop made affair. An overall shot of the current version (ver 3) is also attached.
Nice setup !