optimized for power hand tools

[Bruce Seidner]

I would like to build a Thien separator optimized for power hand tools like a router, planer, belt sander, etc. There is no good option for making the discharge ports larger on these tools and besides it would make the hand tool a lot harder to use with some ginormous duct attached to it. I have a couple options for my routers. One is the factory inset that uses a 1.5" discharge outlet and the other is a homebuilt base extender that goes right into a 4" duct that resemble a large soup can screwed to the base of the router with a cut out for the edge I am routing. But most of these tools have to discharge up rather than down, through a 1.5" or so outlet.

I have used shop vac's connected to these tools but thought I could build a small tag along unit that was purposed for these tools and powered with a Harbor Freight 1hp blower that is collecting dust (on a shelf unused).

My question is this. Because I want maximum static pressure and the HF blower is rated at 914CFM (no mention of static pressure) I am unsure of the optimal dimensions for the top hat. I would imagine that I would just mount the blower up top and center with its 4" inlet dropping into the hat.

There are two major design questions. Well, three, but the third has been answered persuasively by Retired and a rectangular inlet is both appealing and the way I will go. The remaining questions have to do with the dimension of the hat in terms of diameter and height. The other question has to do with the question of inlet port size. The easiest would be to use 1.5" duct from the hat to the tool. Then again maybe it would be better to use 4" duct to a "half way" point and then use a PVC reducer that goes from 4" to 1.5" closer to the tool. But, because there are any number of trade offs and 7ways till Sunday to choose, I am looking for factual help in optimizing static pressure and collection for these hand tools. I will exhaust through a filter, to be decided later, that will maximize capture of fines and minimize back pressure, all compromises to be sure. But first I would like to tackle the front end. I will save my hind end for later where I end up showing it on a regular basis.

[retired2]

Bruce,

I tried collecting the dirt from my bandsaw through it's original 2" port, and using my Delta 50-760 DC.  The delta is a highly rated DC, but the max S.P. is around 8.5".  Bottom line, it worked very poorly.  My shop vac, S.P. unknown, worked much better, at least until I cut a 4" hole in the door and reconnected the DC.

Now I realize 4" connections for the tools you are talking about are not the answer, but that probably means a DC isn't the answer either, at least not totally.  DC's have very low S.P.'s, in the 8" to 13" range, and that is the max.  Hooked to small pipes, the losses will knock it down more.   A HF with 914 CFM is most likely rated at something less than 8".  A good shop vac may have eight or ten times the S.P. of that HF, and for those tools I think that might be your best option.  There are plenty of shop vac separator builds on this forum that can give you lots of design ideas.

Now having said the shop vac might be the best bet, there is still the issue of the dust that escapes and gets airborne.  Solving that problem will probably still require the high CFM's of a dust collector, and some kind of hood arrangement that doesn't get in the way of your work.

Isn't dust collection fun?  You can hardly find time to do any real work!

[Bruce Seidner]

It really is fun. As critters go, a big part of our success (and potential for demise) is our tool building proclivity.

So, I think you are right and I should find the gnarliest shop vac I can find and use a separator between it and the tool. So I will get off the idea of using the HF blower that I only use when working outdoors and want to generally direct the chips from a table saw to the garden and not all over the driveway.

What size hats work best with 50 to 60 inches of static pressure and less than 200 CFM? Or do I just buy one of those converted plastic milk jugs made by Oneida?

[retired2]

It really is fun. As critters go, a big part of our success (and potential for demise) is our tool building proclivity.

So, I think you are right and I should find the gnarliest shop vac I can find and use a separator between it and the tool. So I will get off the idea of using the HF blower that I only use when working outdoors and want to generally direct the chips from a table saw to the garden and not all over the driveway.

What size hats work best with 50 to 60 inches of static pressure and less than 200 CFM? Or do I just buy one of those converted plastic milk jugs made by Oneida?

Sorry Bruce, I'm afraid I'm not much help with the shop vac separators.  I have a crummy shop vac and no separator, so I have no experience to share.  Maybe some of the guys who've built one or more will,jump in here and offer some words of wisdom.

[Sub-Dooood]

It seems to me that DC blowers are better utilized with 4" hose (or greater), while shop vacs excel using 2 1/2" hose and smaller.  That said, I made a bucket-sized Thien separator for use with my Fein Turbo I that I use with my ROS, OSC, routers and benchtop bandsaw.  The setup does a great job at both collecting nearly all dust and chips at the source and separating the debris in the bucket so the filter in my vac never gets plugged.  I will say that the collection at the bandsaw is the least effective of all the machines I use this with, but it works much better than a 4" to 2" reducer hooked to my 50-760 DC.

My build was made with a 7 gallon pool chemical bucket.  I goofed up when I cut the hole in the side for the inlet, placing it much lower than I needed to.  However, the oversized top compartment may contribute to the excellent separation I realize, as in over 2 years of usage I have not had to clean the filter in the vac despite the fact that the majority of use is with my ROS.



Steve

[Peter]

Bruce:

I built a top hat style separator for my shop vac, (a real deal official ShopVac brand, big, noisy, red, awkward), and I put it atop a 30-gallon metal garbage can.  Other than the awkward bulk of the affair, it works GREAT. All the big gunk goes in the garbage can, only fine flour winds up in the shop vac and on the vac's pleated filter.

I wouldn't hesitate to make one again, to top a smaller container (it'd be LOTS easier to empty) and to put the whole thing on ONE cart (mine is on two: one for the can, and the shop vac itself). [ETA: see the post immediately above--a very cool solution!] If you're only interested in a 5-gallon sized affair, don't discount Phil's original design (available elsewhere here in these forums).

Shop Vacs work just fine coupled with a Thien separator, and it's fun to hear that long-lost brass wingnut go clank! in the bucket. :)

[Bruce Seidner]

This is exactly what I want to build and I was wondering if there is some thought on the internal volume of the separator relative to static pressure/cfm. Then there is the issue of how to dimension the volume. The design seems to be incredible forgiving and people seem to design based on the size of the bucket and fittings they will be using. But x cubic inches of volume can be wide and short or skinny and tall. I have not seen the issue of volume relative to the static pressure/CFM digging through the archives or on the web. The slot size and percentage of the baffle to circumference has been discussed so I keep thinking I must be missing something.

[Peter]

This is exactly what I want to build and I was wondering if there is some thought on the internal volume of the separator relative to static pressure/cfm. Then there is the issue of how to dimension the volume. The design seems to be incredible forgiving and people seem to design based on the size of the bucket and fittings they will be using. But x cubic inches of volume can be wide and short or skinny and tall. I have not seen the issue of volume relative to the static pressure/CFM digging through the archives or on the web. The slot size and percentage of the baffle to circumference has been discussed so I keep thinking I must be missing something.

Bruce:

Although there is no doubt some SP loss in the separator, I doubt it's enough to be a detriment when using a shop vac. When I made my first Thien separator, I had an interesting experience.  I was happily sucking up junk, including 1/2" hex nuts, when the hose picked up a small piece of plywood. I heard a "thunk." I removed the plywood and turned to see that my can had a big dent in the side. While pondering how that could even be possible, the hose picked up one of those plastic bags they put your stuff in at the store, and there was a big "KAFWUMP!" and my 30-gallon galvanized steel garbage can collapsed. Yep, it imploded.

Not wanting to buy a new can, I banged out the dents and installed some external ribs to prevent this from reoccurring. In so doing, I introduced some leaks into the system, but not enough to hamper the effectiveness of the overall assembly. I failed to take photos of the initial damage, but you can see my fix in reply #2 here.

I guess the internal diameter of my separator is about 19 inches, and it's about 5" high inside. If I remember correctly, the drop slot is 1" wide. I made the baffle out of 1/2" plywood, and after reading discussions here, beveled the inner circumference of it to about 1/8" thick. I don't see any improvement (or detriment) from doing that, but then, the thing works so damned well to begin with, I really don't care.

The issue of static pressure drop would be an issue, however, when installed in a large volume dust collection system. As has been discussed ad nauseum here and elsewhere.

[Bruce Seidner]

Peter,

What is the design of your separator inside the square box on top? Are you using some sheet metal or hardboard to round it internally or is square?

[Peter]

I used a coil of 6" aluminum flashing I had left over from a remodel project.  A picture of my unit with the lid off is here. If you're interested, I can give you the SketchUp file I use. It's for my next build, but the concept is similar.

[Bruce Seidner]

I would appreciate the picture, or a thousand words, your choice.

This has gotten interesting because as I was looking into replacing my 25 year old Craftsman shop vac I have run across a whole industry of commercial vacuum motor replacements for carpet cleaner extractors, Car wash interior vacuum cleaners and yes, the redoubtable and venerable wet/dry shop vac design. But there are a limited number of companies that sell the same motors to these very expensive commercial units with similar specs and costs that are very reasonable. You don't get the hoses, vacuum body, filters, etc. But for a hundred bucks +/- twenty bucks what would you say to a Triple Stage vacuum unit (meaning 3 internal to the motor cooling fans), Rated at 104 CFM, with 137" water lift drawing 12.5A?

Now THIS is a vacuum cleaner! And would suck the chrome off a trailer hitch. Since the intent is to use 2" hose to a hand tool over a relatively short distance I am thinking of a modification of the Thien separator that would make the separator tall enough to replace the body of the shop vac, do just enough filtration so the vacuum impeller did not clog and then exhaust into my central dust system where only 105 CFM would not be all that disruptive. Is this mad scientist or is there something to pursue here?

[tenfingers]

I read somewhere, may have been on the Pentz site, that it's not good to run blowers in series. I don't see why it wouldnt work though.

[Dasmith]

Do you have a web site for these blowers?