My version w/6" duct

[Greg McCallister]

dbhost,
The inlet is used from Bill Pentz site excel spread sheet ....

While I have skimmed most of his site .... Are you saying that you calculated both the size and how far into your baffle the inlet extends from Pentz's spreadsheet?

Pretty much yes. I did not use the total height from Bill's site but mostly just the inlet. The inlet angles downward about 1 in. All it is - is a 6" piece of metal duct from HD that I soldered the seam and using 2x4s and other scrap wood was able to hammer out the round to rectanglar shape. Hope that made sense...
To put it in a nutshell, its is a combination of both Bill and Phil's ideas. Inlet and basic cylinder is Bill's and the baffle is Phil's.
I thought about this for a while after reading Bill's site. Phils idea, I have been also looking at from the beginning. He started out with 2 1/4 Vac and it has gone up from there.

Looking at the Clearvue site you can see how the dust travels after entering the cyclone. I thought  if you could get the debris below the suction port (as in Phils baffle design) it would work pretty close, if not better then a cyclone because of much less CFM loss due to turbulance and required air flow (big motor - big impeller).
I don't know how well the unit draws as far a CFM but to be honest it really draws some air and seems to trap 95 +% of the dust.
This is actually a different concept using both, or in another hand, the best of both worlds...

[Greg McCallister]

I drew this up - hope it helps...

[CheapScotsman]

Thanks for the picture. It should be very helpful as I hope to build a 6" all metal baffle (I have a welder) in the new year.

A few questions, if I may

• Why did you use PVC for the outlet?
• Assuming that your collecting drum is 24" wide, why did you make the baffle 18" wide as opposed to wider?
• What is the distance from the baffle to the top of the unit?
• The leading side of your inlet is 6" round (28.27 sq inches of surface area) while the trailing side of your inlet is 7x3.5" rectangle (24.5" sq in of surface area). Why the reduction?

Thanks again.

[Greg McCallister]

CheapScotsman,

I used PVC due to that I had cut off the overlap end or expanded end to join two pieces of PVC of  a 10' length I purchased and and used it to increase the blower unit. You can use metal it was basically what I had on hand.
The 30 gal metal trash can has a 20" top diameter (at least the one I have).
The distance between the baffle and the top of the unit is adjustable - right now it is about 10 inches.
The reduction for the inlet is derived from reading Bill Pentz cyclone site. He recommends to go from round to a rectangular for better air flow and less turbulence. Highly suggest your read his web site for a better understanding on cyclones if you have not done so already. (Be warned it will scare you a bit).

I uploaded another version with some added dimensions you noted above.

[CheapScotsman]

Thanks for the updated picture. Much appreciated.

I have skim read most of Pentz's site and it doesn't really scare me. There are a lot of health hazards in everything we do so .... its just something that need to be accommodated.

I did see on his site where recommends to make the inlet rectangular and extend it into the cyclone (aka neutral vane) but I haven't found the part that calls for a reduction in cross sectional area of this intake.

[Greg McCallister]

CheapScotsman,

He does not require a reduction which just looking at his site is 4" x 10" and requires a modified transition to 6" round. Yea I lost a few square inches but in the process created a better cyclone effect using the majority of the sidewall of the cylinder instead of running a round tube at it. I am also not using a 3 hp motor and 14" impeller. In another aspect the outlet from the impeller housing on the HF blower is only 5" so there is a loss there too. 
Would it make a difference - maybe, probably, then again I am really not sure. I have no way in which to measure the CFM and this was made pretty much off the cuff. What I do know is the separation is pretty good (much better than I expected to be honest) - actually it is great after looking at the filter and emptying the can 4 times now. The air flow blows away a trash can separator in which I had used before.
This is no cyclone in the true sense but it is pretty close, then again I do not have a cyclone to compare it to.
Also thinking about this, the amount of airflow to create a prefect cyclone action requires more airflow due to loss because of turbulence. This version I believe has much less loss of airflow do to the limited amount of travel in the cylinder. Then again, I am no engineer but hey it works...

[CheapScotsman]

Greg,

I was asking about the reduction in sizing on the intake only so ascertain if I should "design" it the same way for mine.

hey, no problems at all and I appreciate you posting your build and your results here. Between your and the others who have done a baffle build, it gives me much encouragement that things will work out well.

I don't have any dust collection at the moment and would love to have a cyclone but with the CDN $ at US$.83 a Grizzly 2HP would cost over CDN $1000 (not including a days round trip + gas to go get it) ... vs what will cost me less than CDN$400 (used 2HP dust collector $200; $20 in sheet metal, currently have a welder, a free collection drum and around CDN$200 for a canister filter)

I have no doubt it won't perform quite a well as a cyclone ... but it should do quite a veru good job especially given I have nothing now and the cost can't be beat.

[Greg McCallister]

CheapScotsman,

If my last reply seemed condensing, please accept my apology.
It was not meant to be that way, but after reading it again I can see it did have a rather bad tone. I have been under the weather for a couple of weeks now but that is no excuse.
If you can improve on the design, I am all for it. Asking questions helps improve anything as well as enhance creation, if not why would we bother posting  ;D.
Thinking about this some more, a true cyclone will circle around the cylinder at least one or more times to cause a vortex allowing the material to separate from the air stream.
Phil's baffle allows the separation without really creating a vortex as the majority of the material is dumped in the can almost right after entering.
Just because a cyclone works does not make it the only way to create separation. I would really like to do some static pressure and CFM testing on this as well as the exact amount of separation. Was thinking about creating one out of Plexiglas like the clearvue to see how it separates and if modifications would improve the design. What do you think - anyone?

[Greg McCallister]

I updated the drawing to allow a larger inlet rectangle which was brought to my attention that the previous version resulted in a square inch reduction which could restrict airflow by CheapScotsman (thanks). Also with the ability to mount to blower directly to the top.
If installed in a frame of some type (have not come up with that yet) the blower assembly and the cyclone/baffle assembly would be stationary and mounted to the cart. If the assembly is off the cart high enough to drop the can down 1" or so underneath the assembly would allow for easy removal. The can can be shimmed from the bottom to held it in place (simple).
Working on the outlet filter assembly design.
I am open for idea's - anyone???

[BernardNaish]

Hi, This thread has been inactive for a long time. Does anyone have any more information regarding this interesting design? I am particularly interested in the way the inlet duct extends into the chamber rather than terminate at the chamber wall.

[alan m]

i would guess that greg intented to cut the end of the inlet transition to folow the shape of the seperater. if you didnt you would create a lot of turbulance as the air would hit it evertime it went around

[BernardNaish]

Hi Alan, That is exactly what he did not do. The end of the inlet trunking was not shaped to the chamber wall but extends into the airflow as far as I can see from this picture:

http://www.jpthien.com/smf/index.php?action=dlattach;topic=90.0;attach=221;image

Interesting to me.      Regards,     Bernard

[BernardNaish]

Hi Alan again, I have looked more closely at the other pictures that look up towards the top of the chamber and I think I can see some dust that shows just what you are saying.....the inlet protruding into the airflow caused the airflow to be deflected away from the wall. Wish I could see a picture of the top of the baffle! I also note that the baffle is 3/4" or more thick. The inlet pipe is also angled down as Pentz suggests.

Seems to me that this design appears to work better than most. Hence would it work even better with a smooth ended inlet pipe and a thinner baffle or do these two deviations from what we believe is the way to do it actualy make it work better? OR--- is the downward angled input duct contributing significantly?    Cannot stop thinking about these designs. B