LumberJocks Woodworking Forum banner

Dust collector mod on the cheap- Will it work?

10276 Views 105 Replies 33 Participants Last post by  Jack_T
Cylinder Gas Composite material Nickel Metal

I have been using the 2hp/5 micron/1550cfpm Harbor Freight dust collector for over a year now and love it. But it's really intended to be rolled around the shop and hooked with short lengths of hose. A while back I mounted it in a corner, added a trash can lid cyclone and ran 4" pvc ducts all through the shop with blast gates. I love being able to just flip a switch and have every machine already hooked up and ready to go. The problem is with all the ducts, elbows and turns, you lose a lot of power. It still does a good job, but I want all of the dust collected, not just 80%.

Of course, I'm demanding more from a midpowered collector than I should be. But upgrading to a big stationary unit is EXPENSIVE and I'm all about saving cash. So here's my idea, let me know what you think…

Instead of selling this collector and getting a big cyclone system for about a thousand bucks, why not buy a second 2HP Harbor Freight collector, mount both of them side by side and connect the intakes with a big "Y" into a home made cyclone. If one sucks good, wouldn't two give me double the suction? That would rival a lot of the big units! (combined 3100CFM) And I can get a second unit now on sale for $189, plus I can always find at least a 20%-40% off coupon in one of the woodworking journals.

And as for the cyclone part, has anyone ever thought of making the cone out of 1/8" hardboard instead of more expensive metal?

And what about ducts? Bill Pentz (whom I believe is as close to an expert on dust collection as you'll meet) says you should use at least 6" ducts. But steel ducts cost a fortune for a complex system like I want. Even 6" PVC would be very pricey. But who says ducts have to be round? Couldn't you use hardboard to make rectangular ducts for a lot less?

Any ideas?


See less See more
1 - 20 of 106 Posts
Yeah I have done stuff like this before and after all of the modifications and the 2nd unit I wished that I just spent the money on a better unit.
There are a ton of mods for this DC on the net and this forum. Two would work.

One of the engineering types will have to comment but a square duct would be less efficient. You'll lose suction at the corners and eventually build up wood dust = fire.
Jim -

What about a manifold system so that you are only drawing air from one tool at a time? (There is only one of you after all). Just close off all but the section for the active tool, switch the manifold so that it is only open for another, and off you go…

Steve- That's what I'm doing. I use blast gates (manifolds) to open and close sections of the ductwork so that only one tool is open at a time. Like I said, it works well. But I want as good as I can get. I want NO dust in the shop and especially not in my lungs. If the collector is rated at 1550 CFM, you can bet it really pulls less than a thousand (every company WAY over rates their specs) and that is diminished with every foor of duct and every fitting along the way. To get ALL of the dust, especially fine dust, you need more.
Sergio- Do you REALLY know that to be true? I have heard very little about it. How would dust collect in the corners as long as the elbows are curved? I am really wondering about this and any help you can give would be much appreciated.
agallant- A 5HP 1800CFM Cyclone system from Penn State runs about $1,400. If I can use two HF collectors, one of which I already own to double my 1550CFM- even if that is in reality only half that (800cfm each) that would give me as much or more suction as the Penn State unit for less than $150 (plus $50-100 in cyclone materials). I think I can't help but save a fortune IF my assumptions about airflow and ductwork are accurate. (That's why I am asking all of you for input…)
So how much suction/air flow are you losing with the shop built cyclone? The first thing I would do would be to pull that out and see if it improves the suction at all. Just because that's the cheapest and easiest solution. If you have room for a 2nd DC I like the idea of covering half your machines with each rather than trying some dual suction type solution. I would also do some looking at getting a more powerful/efficient motor.

On my personal experience I got significant increase in efficiency when I upgraded to a canister filter for my Jet DC-1200. I then got another slight increase using plastic bags instead of the cloth bag it came with.

I do agree that in the end if you really need the additional CFM you should watch the old CL & auctions for a larger used dust collector. I see 3-5 HP DC's listed a few times a month. A friend of mine just picked up a 3HP double bag Woodtek for $400 from a local auction house.

The hardboard pipe would be quite something to see, but you would have to figure out what the cost of your time would be. That is the one thing that people often overlook when attempting to "Save" money. The true cost is the materials plus the money(or quality of life increase) you could be making doing something else, then subtract the cost of buying the 6" pipe.
See less See more
Jim, I understand your theory but it may have holes in it. If you only get 80 % collection now will you be happy with 95% ? You will never get 100 %. But I will offer what used to work well for me. I once used two 2hp units similar to yours. I had one on seperate walls of the shop handling their own set of machines. Spiral pipe with blast gates. worked very well. Combining the two as one unit, well I question how much more effective that would be. On each of your units you could keep the trunk line 6 inch and reduce to five inch feeding your machines. I think youll be happy. Enjoy JB
I don't know how much air the HF collector REALLY moves. It is rated by the manufacturer at 1550CFM, but that's a LOT for a 2HP motor. Bill Pentz's site seems to indicate that a 2HP motor and an impeller like the HF system has would move much less. Perhaps half that. 800CFM is not enough to collect all of the fine dust and keep my lungs healthy.

If I use one of the collectors for half of the shop, and one for the other half, it would reduce suction lost from long runs of pipe. But I am still not getting the serious CFM I need for the finest dust.

My question is, if i use TWO of the collectors, would it DOUBLE the airflow? It seems to me that it would.

And would retangular ducts work?

And could you use hardboard rather than metal for cyclone and ducts?
Crush- That's what I'm trying to figure out. if TWO would double my effeciancy, why spend $400 on a used one when i can spend $150 and do it this way? I just don't know if connecting two together with a "Y" would actually double the airflow or not.

And as for time, I'd rather work in the shop than watch TV, and since nobody gets paid for the 3-4 hours the average person watches in TV every evening, that time would be free. If I had to take the time away from money making work, it'd be a different story…
Take a look at my setup. For starters you don't mention if you upgraded your filter bag or not. If you haven't you have a dust pump, not a dust collector. Upgrade to a Wynn filter, or at the very least a 1 micron or better bag.

Unless I recall incorrectly, I believe that Pentz recommends at least 5" duct, most people say 6" because it is the most commonly available in plastic which is cheaper…

I sort of split the difference, and upgraded my hoods at the same time by using the 5" port on my HF DC, going through a Thien separator with a 5" side inlet, and THEN using the Harbor Freight OEM 5×4x4 wye to run a 4" duct to the top, and a 4" duct to the bottom of the major tools.

Another Pentz recommendation I went with is the Wynn canister filter. This thing does REALLY improve air flow in this DC… Not sure how the 1 micron bags are, but the canister is a HUGE shot in the arm…

And of course keep your runs short, straight, and with as little ribbed flex hose as possible…
bentlyj- Your reasoning sounds plausable. That's what I am struggling with. Perhaps if I better describe my setup idea- Each machine is hooked to a 5 or 6" duct. Air is pulled from the machine through the duct system to the cyclone where it does it's thing, then out of the cyclone through a 6" exit duct, and into a "Y" where it is divided between two dust collectors and into the filter bags of each.

The question is, if I have one collectod drawing 800 or so CFM and another drawing the same through the same cyclone, would it be 1600cfm or would they cancel each other out like you suggested.
Dbhost- not sure if I understood- do you have a HF collector?

I am still using the 5micron bag. I know that is not the best, but does that really affect airflow? I would think a filter would reduce it, or not effect airflow. But increase airflow… is that the case?

So, you use the HF system and a Wynn filter. This does the job? How long are your longest duct runs? Are they all straight? Does it collect ALL of the dust or do you still have to sweep up once in a while? (If you are sweeping chips, you are definately breathing the even finer stuff)

I have a modest sized shop (17X24) but I want the collector to be in one corner and suck from a machine in the other. If it is just getting the big chips, it isn't enough. Clean floors is only half the reason for a dust collector.

I checked out your workshop page, but can't see your system. (by the way- my grandfather runs a Water Softener business selling that exact same unit in your shop. Small world…)
I think you may be "going where no man(person) has gone before"! With the HF return policy being what it is you can pick one up and give it a shot and if it don't work take it back. Maybe start with seeing if it makes a difference running into your existing system. I know that the prevailing opinion is a 5" or 6" pipe is going to be premium but I can't imagine that you are getting enough suction to max out a 4" system. If you hook them both up tio the 4" pipe and you get additional suction at the machine then you know you are on the right track.

As far as wood ducts go I can't imagine it being a very clean solution, dust would eventually build up in the ducting. As far as efficiency goes aren't many building HVAC systems setup with rectangular metal ducting? If that was an inherently bad shape for air flow I don't think they would be used. Especially since they leave buildings open for Movie & TV spies to climb through them! ;)

Out of curiosity what problems are you running into that are brining you to this point? When you say you are only getting 85% of the dust sucked up, where is the dust escaping into the air? What machines is this a problem with? I am building my workshop piecemeal and have thought about doing a setup like yours. I am curious about the details of what is going on so I can see if I am going to have the same kind of issues and therefore avoid building a system that won't work.
See less See more
Crush- I don't know if it is actually 80%. Here's what I get- The system collects almost all of the chips from my planer and jointer, but not all. The table saw still sprays chips from the top. The router is almost 100%. But I figure (based on Bill Pentz's site) that I am not getting the fine stuff. Proof is found in the fact that it takes only a short time for a good film to develop on the television screen in the shop, not to mention the tools.

It's the fine stuff I worry about. Chip collection is cosmetic. Dust collection is a matter of health.
Ok now I understand! You have the same issue I had a few months ago. I took another tact at fixing it and it worked very very well. I know longer have a layer of dust form in my shop. If you read my blogs you will see that I have a huge issue with fine wood dust. I have horrible allergies and sinus issues so I can tell what is going on before it is visible in the shop.

As I mentioned earlier the biggest difference maker for me was the upgrades to my existing Dust Collector. The filter bags on the Jet were rated at 30 microns which essentially makes that a dust circulating pump. Without proper filtration at the DC you are taking the worst and most dangerous particles and blasting them into the air. The other upgrade I made was a central dust filtration. I got a Jet 1000 centralized shop filter with all the bells and whistles. It immediately made a noticeable difference. I run it whenever I am in the shop and for 2 hours after I leave. There isn't any dust anywhere in my shop anymore. The real difference is when there are odors from chemicals are wood burning and they disappear within minutes. If that central filter can remove odor from the air I feel pretty good about small dust particles.

The proof is in the pudding. Before the upgrades I got physically ill with a head cold or worse(purple heart gave me flue like symptoms for 3-4 days) every time I worked in my shop. Since the upgrades nothing. After all it's not the wood chips you can see it's the dust particles that are the health issue. I still wear a dust mask when sanding but I haven't blown black wood dust out of my nose in a couple months.

If you wanna go on the cheap you can make a very very good central shop air filter for next to nothing. Do a search for "shop built air filter" or the like and you will find some pretty cool systems. It is worth doing even if you decide you need to upgrade your system, central air filtration is important if you are concerned about the long term health effects of wood dust.
See less See more
Jim: just my 2 cents but if it's the really fine stuff, you may need to take a look at an air filtering system of some
sort. I find myself in the same boat.
You can connect collectors either parallel or sequentially. Each setup will have different benefits. Parallel will increase flow volume (not necessarily double), sequential will double pressure head (benefits of vacuum cleaner). Doubling pressure head will also result in increased flow. Which one is preferred will depend on your particular system. That includes types of shrouds on your tools, etc. I.e. on portable sander or Festool type track saw shop vac works great, but your regular DC will not do any good. Alternatively, on a downdraft table shop vac won't help. If you have a lot of friction losses, you may want to connect sequentially.
You could try both connections and find out experimentally what works better (and it WILL work better with two of them). And no, 2 DCs will not "fight for air".
1 - 20 of 106 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.