# Bill Pentz cyclone design



## BGS (Sep 15, 2009)

One has to admire the dedication, intelligence, and generosity of Bill Pentz.

http://billpentz.com/Woodworking/Cyclone/CyclonePlan.cfm

But I am of little brain and have been unable to decipher the use of the spread sheet he includes to calculate Cyclone separators below his recommended sizes and parameters.

If one were using a 1hp Harbor Freight portable blower and 4" pipes and if one follows the narrative of the spreadsheet it is clear that a wider, squatter cyclone would be in the offing. I have attempted to enter these numbers and can't get the spread sheet to give me dimensions. The Clearvue Cyclone site has stopped selling their smaller model due to copyright litigation and I would want to build one myself in any event. It seems that a properly dimensioned cyclone of this design, while limited in volume is competent at reducing small particle dust in a limited space. I have just a corner of a garage and don't run more than one modest tool at a time. I am not especially dust sensitive and I might be able to get away with a smaller scale cyclone.

Can someone give a feller who has to drop his drawers to count to eleven a leg up on the dimensions, using the Pentz spreadsheet for a cyclone driven by a 1hp blower and using 4" pipes?

Thanks to all in advance.


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## dbhost (Jul 20, 2009)

Well, to be blunt, according to Pentz' own web site data, 1HP and 4" duct is not gonna cut it.

(At a minimum he recommends 2HP, and 6" duct).

From real world experience, I think Bill's data is typical of an engineer. Over engineered for the real world.

Take a look at Phil Thien's separator design.

There is a particular project that you will want to look at, where a fellow made a Thien Cyclone Separator and placed a 1HP HF Red DC with 4" duct on top.

Those small DCs have always intrigued me, but the coarse filtration from them turns me off. I think a mounting donut for a Wynn 35A, and a short jumper of hose, and / or S&D pipe can connect the two…


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## BGS (Sep 15, 2009)

It is true that he advocates a 16inch impeller and 6inch ducts. But his spreadsheet is scalable and he describes the efficacy of fine dust removal by small units run by shop-vacs. Clea- Vue http://www.clearvuecyclones.com/ does a nice implementation of Pentz's design and they sell a scaled down version for a shop vac and a very sweet cylcone that they have pulled for the time being because of a legal challenge around the design.

I want to build a scaled down Pentz cyclone, but for the life of me can't figure out how to use the spread sheet to get the dimensions for a unit that would use a 1hp Harbor Freight blower and 4" pvc pipe. 
Any help with this spread sheet would be much appreciated.

Bruce


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## jevarn71 (Sep 30, 2009)

I started building a cyclone based on his design and spread sheet. The problem you will face wanting to use a low HP motor is the size of the cyclone will actually increase to so as to lower the static pressure. IIRC a 5HP motor with a 16" impeller will call for a cyclone around 18 inches in diameter. I planned my for a 3HP motor with a 14" impeller and I had to build my cyclone with a 22" diameter. Of course as the diameter increases, so does the height. This is ok as long as you have the room. I think he was trying to keep the design viable for those who have low ceilings around 8 feet. The ceiling in my garage is 9.5 feet, so I was ok. I haven't had a chance to get it hung and in operation, but I do have it built. I have to finish a project for the wife before I can finish the cyclone.

Jason


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