J. Phil Thien's Projects

General Category => Thien Cyclone Separator Lid Discussion => Topic started by: phil (admin) on January 01, 2008, 10:04:38 PM

Title: Another 4" model (30-gallon can)
Post by: phil (admin) on January 01, 2008, 10:04:38 PM
Some time ago I purchased one of those little Harbor Freight mini portable dust collectors.  I got a helluva deal on it ($70 after stacking some discounts).  It is this one:

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=94029

It sat unused for a while because I was pretty happy with my Ridgid vac-based cyclone.

HF claims 914-CFM and 9.4" of SP.  We know that the CFM is nonsense, though.  It has a single 4" inlet.  According to BP a 4" pipe can carry about 400-CFM.  My somewhat scientific testing (using two different anemometers) seems to indicate that this unit pulls about 370-CFM.

This unit is only twenty pounds but achieves some pretty impressive specs by using a universal motor spinning a small airfoil type impeller at 6400-RPM (typical DC's use radial impellers spinning at half that speed).

So I decided I'd build a larger cyclone separator and start using it.  I started w/ a 30-gallon can and an MDF top.  Added 4" fittings and my baffle and did some additional testing.  I was happy to discover that adding the cyclone lid only causes an 18% hit to my CFM.  That is pretty spectacular by cyclone standards.

I also had a chance to try connecting the entire assembly to my router table's downdraft box.  I had to do this with a 2.25" reducer to a 2.25" hose, so NOT optimum.  I was stunned to discover that airflow through the tiny (1.5"?) aperture in my router lift was sucking plenty of air.  I had always imagined that real dust collectors would have difficulty moving air through such small holes, but this clearly isn't so, plenty of SP here.

I did limited testing with actual dust because I only have the stock (30-micron) bag filter for the DC at this time.  It was able to separate 98.7% (by weight) of the dust I fed it (mostly fines from machining MDF and hardboard).  It was perhaps a little better but I did have difficulty gathering all the dust from the garbage can when I was done with the test.

I had previously posted that the DC is noisy.  It still is.  Part of that is the noise form the air movement, but certainly part of it is the universal motor, too.  Still impressed with what a $70 machine can do, though.  While this still doesn't provide the 600-800 CFM that some say is needed for fines collection, it is providing over twice the CFM of my current solution and is still compact enough to use, so it will become my new DC until I can make my giant separator lid with 6" outlet and twin 4" inlets, and run 6" PVC to my tools (yeah, right).
Title: Re: Another 4" model (30-gallon can)
Post by: windmill on January 02, 2008, 10:55:56 AM
I'm impressed a DC that small actually pulls enough air to work, especially with a trash can separator. I wonder - would it be possible to hook two of them up in parallel? I.e. have two outlets on the trash can? That way, you could run a larger pipe for the intake without losing too much velocity.

It may not be that difficult to change the design. A 6" outlet that splits into two 4" branches ought to do it.

Bas.
Title: Re: Another 4" model (30-gallon can)
Post by: phil (admin) on January 02, 2008, 11:29:55 AM
Quote from: windmill on January 02, 2008, 10:55:56 AM
I'm impressed a DC that small actually pulls enough air to work, especially with a trash can separator. I wonder - would it be possible to hook two of them up in parallel? I.e. have two outlets on the trash can? That way, you could run a larger pipe for the intake without losing too much velocity.

It may not be that difficult to change the design. A 6" outlet that splits into two 4" branches ought to do it.

Bas.

I guess it is the design of the impeller for one.  It is an airfoil, which is more efficient than a radial vaned impeller.  Also, it is spinning twice as fast.

And I suppose you could run two of them in tandem.  If I did this I'd be inclined to not only increase the outlet size, but add another input, too.  There would be some (minimal) loss from the splits, and it might be kinda loud.
Title: Re: Another 4" model (30-gallon can)
Post by: LittleRob on November 17, 2009, 05:51:13 PM
I couple questions. I'm new but have looked thru each thread/topic. This forum is great!!!! I was considering that mini DC from HF. Was wondering how it performed by itself, than see you guys spiced it up a bit making it better i'm guessing. Now here is my question before i start building. The 30g can has ridges on it. so does the baffle inside actually seal with the can(with arrow in pic) or does it not matter. Also while its running for example like on pic 3 do you still attach the filter bag on it? And does this setup work better with a shop vac or the mini dc? If the S Vac what size would you recommend?
Title: Re: Another 4" model (30-gallon can)
Post by: phil (admin) on November 17, 2009, 05:59:28 PM
Quote from: LittleRob on November 17, 2009, 05:51:13 PM
I couple questions. I'm new but have looked thru each thread/topic. This forum is great!!!! I was considering that mini DC from HF. Was wondering how it performed by itself, than see you guys spiced it up a bit making it better i'm guessing. Now here is my question before i start building. The 30g can has ridges on it. so does the baffle inside actually seal with the can(with arrow in pic) or does it not matter. Also while its running for example like on pic 3 do you still attach the filter bag on it? And does this setup work better with a shop vac or the mini dc? If the S Vac what size would you recommend?


(1) Don't worry about the ridges, they aren't large enough to cause problems.  (2) Some final filter (like a bag) is required, or you need to exhaust outside.  (3) This unit moves a lot of air.  It is a great compromise between a shop vac and a DC.  The caveat is:  It is LOUD.
Title: Re: Another 4" model (30-gallon can)
Post by: LittleRob on November 17, 2009, 06:42:22 PM
Sweet, ear plugs is a must in a woodshop or garage anyways so loud is okay while the saw or what ever is being used, these dowels in the picture they are about 5inches? and is there a rule of thumb as far as dowel length & the PVC size? If i did use the shop vac i could use it for more stuff thou vs the HF one purpose, what size vac for the 30g can do you recmd to get the most outta both? Thanks for the quik reply by the way :)
Title: Re: Another 4" model (30-gallon can)
Post by: servant74 on November 17, 2009, 08:14:34 PM
http://www.wynnenv.com/cartridge_filters.htm

You might consider these folks filters for fines.  It is the ones
Clear Vue uses (the clear plastic design of Bill Pentz collectors).
Title: Re: Another 4" model (30-gallon can)
Post by: LittleRob on November 17, 2009, 08:50:29 PM
Actually came across those before i found this forum. Great filters. Pricey but worth it.  The reason i ask which would be more worth it is, i would like a shop vac to be able to vacuum the cars. And with the Mini costing $99, that almost the price of a good vac i would think. Either way im building this lid, just wanna get the most bang for my buck. but if i need a real expensive vac to make this work correctly effeciently i get the hf mini with a coupon or find one used ... :) :)
Title: Re: Another 4" model (30-gallon can)
Post by: TomH in WI on November 22, 2009, 06:24:31 PM
Hi Phil,
Hate to get sidetracked here, but could you show some pictures of your table saw. I was wondering how you mounted the extension and router onto the BT saw rail.
Thanks,
Tom
Title: Re: Another 4" model (30-gallon can)
Post by: rhossack on November 28, 2009, 05:33:16 AM
Quote from: phil (admin) on November 17, 2009, 05:59:28 PM
It is a great compromise between a shop vac and a DC.  The caveat is:  It is LOUD.
Phil ... when you say loud like it would wake the neighbors?  My rigid shop vac is pretty loud and I put a muffler on it.
Title: Re: Another 4" model (30-gallon can)
Post by: phil (admin) on November 28, 2009, 06:47:32 AM
Quote from: rhossack on November 28, 2009, 05:33:16 AM
Quote from: phil (admin) on November 17, 2009, 05:59:28 PM
It is a great compromise between a shop vac and a DC.  The caveat is:  It is LOUD.
Phil ... when you say loud like it would wake the neighbors?  My rigid shop vac is pretty loud and I put a muffler on it.

I'd say it is about as loud as the loudest shop vac I've heard.
Title: Re: Another 4" model (30-gallon can)
Post by: Adam on December 01, 2009, 12:48:44 PM
Quote from: phil (admin) on January 01, 2008, 10:04:38 PM
HF claims 914-CFM and 9.4" of SP.  We know that the CFM is nonsense, though.  It has a single 4" inlet.  According to BP a 4" pipe can carry about 400-CFM.  My somewhat scientific testing (using two different anemometers) seems to indicate that this unit pulls about 370-CFM.

What it's only pulling 370 CFM.  I thought it felt rather weak and was suspect of the 900 number.  So why so you think there is such a large differance.  That not even in the ball park of 900CFM.  Are there any units that actuall pull what they say or are close? 

Title: Re: Another 4" model (30-gallon can)
Post by: phil (admin) on December 01, 2009, 06:35:32 PM
Quote from: Adam on December 01, 2009, 12:48:44 PM
Quote from: phil (admin) on January 01, 2008, 10:04:38 PM
Are there any units that actuall pull what they say or are close? 


I don't think so.
Title: Re: Another 4" model (30-gallon can)
Post by: dbhost on December 02, 2009, 09:33:25 AM
Quote from: Adam on December 01, 2009, 12:48:44 PM
Quote from: phil (admin) on January 01, 2008, 10:04:38 PM
HF claims 914-CFM and 9.4" of SP.  We know that the CFM is nonsense, though.  It has a single 4" inlet.  According to BP a 4" pipe can carry about 400-CFM.  My somewhat scientific testing (using two different anemometers) seems to indicate that this unit pulls about 370-CFM.

What it's only pulling 370 CFM.  I thought it felt rather weak and was suspect of the 900 number.  So why so you think there is such a large differance.  That not even in the ball park of 900CFM.  Are there any units that actuall pull what they say or are close? 



The ratings are done, pretty dishonestly, with no hoses, no filter bags, just wide open...

It's sort of like taking a Suburban, yanking the body off of it, and big V-8 out of it, putting a little 2 liter 4 banger and an aluminum / plexiglass bubble in place for a body and getting the EPA estimated MPG for the truck that way...

On average, I believe CFM ratings are easily twice or more what the end user will actually see. And that is not specific to Harbor Freight, it is across the industry.

Wood Magazine did an honest air flow test a couple of years ago, when they did the comparison of lower dollar dust collectors. But they only reviewed the upright two bag type, not the smaller horizontal single bag jobs... The Harbor Freight units, aside from their filtering capacity, compare favorably to the competition...
Title: Re: Another 4" model (30-gallon can)
Post by: bridger on January 14, 2010, 08:05:46 PM
another down side to cheap, loud universal motors is short life span. factor that in when deciding if it is the right deal for your situation...
Title: Re: Another 4" model (30-gallon can)
Post by: mbecerra on October 15, 2013, 10:37:11 AM
Hello, I am replying to this particular topic because what you show here is exactly what I want to do. Phil, if I do an arrangement like this one only with a smaller separator and a smaller bucket (maybe 5 gallons) would it work ok? I want to place both the mini dust collector and the separator with the bucket inside a small cabinet. Thans in advance for your reply. Miguel
Title: Re: Another 4" model (30-gallon can)
Post by: phil (admin) on October 15, 2013, 09:32:48 PM
I don't think the DC blower would leave enough room on top of your bucket for a top inlet.  You might be able to get away with a side inlet, but there wouldn't be much room left in a 5-gallon bucket for debris.
Title: Re: Another 4" model (30-gallon can)
Post by: tvman44 on October 17, 2013, 06:53:32 PM
I have HF's other small 1HP DC, the green one with a induction motor and have it connected to my scroll saw thru a Thien separator built on a 20 gal container with 4" intake & outlet on the separator and it connects to the scroll saw with "Y" to a 2 1/2" line under the saw and a 1" line on top of the saw and I will say it picks up every bit of saw dust and is a lot quieter than a shop vac I am very pleased with it.  No filter bag I just vent it outside but nothing comes out that I can see.  I did one mod to the DC and that was to remove the grille behind the 2 flanges on the DC and that increased the flow considerably (estimated 30% increase).  I figured I did not need them as the separator catches all the pieces that fall into the under table line, so I do not need to worry about messing up the impeller on the DC.