I am planning on building the cyclone from Dec 2001 issue of best-ever Workshops from Wood Magazine. It seems to me that I read somewhere that one of the recommended enhancements was to extend the inlet pipe several inches inside the cyclone cylinder to force the rotation of the airr current. Unfortunately, all magazine and internet searches for this enhancement have turned up 0 results.
Does anyone have a list of recommended changes to this cyclone?
Thanks, Kevin Meier
Never mind, I just found what I was looking for on rickswoodshopcreations.com
Kevin
I'd recommend a much stronger material, besides, you may want to re-read the magazine some time.
;-)
-JR aka Wiseass
Hi Kevin I purchased the plans last winter and have been using the cyclone for a few months, it works very well the way the plans are, the only thing I did was to move up to a higher gauge of tin than was stated, worked well you cant dent it now.
The absolute master of home made cyclones is Wayne Davey. His messages and the pics and instructions for the cyclones he makes are free and they are easy to build and work.
Wayne posts on Australia's woodwork Forums
Wow, he has quite the web site discussing cyclones. Thanks for the reference to it Glenn.
I built a cyclone based on the Wood version a few years back. Since I lost my job I've been researching cyclones again with a view to making a living from selling them - no product yet though.
There are quite a few improvements that people have made to improve the Wood cyclone. It was a pretty rough design. The good news is that even rough designs work reasonably well. However, if you'd like to build a better cyclone, here is my list of recommendations.
Use heavier gage galvanized iron. I used 26 gage and that seems fine to me. My local steel companies sometimes stock 26 gage but often the lightest they have is 24 gage.
Note: cyclones are described in terms of the diameter of the barrel. This dimension is called D. A 1D3D cyclone has a barrel that is as tall as it is wide and a cone that is 3 times the height of the barrel. a 2D2D cyclone has a barrel and a cone that are both twice the height of the diameter.
The most efficient dust separating cyclones are 4D tall. Either a 1D3D or 2D2D design. The papers I've read consistently get slightly better but not statistically significant dust separation with a
1D3D. Many people consider 1D3D the best design.So, if you have space, use a 1D3D cyclone. Bill Pentz claims that a 1D1.67D cyclone is a sweet spot for shorter cyclones.
Use a rectangular inlet. The standard dimension for a 1D3D cyclone (h x w)is D x D/8. However, there are studies that show better performance with a D/4 x D/2 inlet. The D/4 x D/2 inlet is also less likely to clog than a narrower design. The dimensions also work out nicely if you use the vortex finder modification.
Use a bigger vortex finder. Bill Pentz (see link below) recommends D/2.
Use a shorter vortex finder. It needs to stick into the barrel down to at least the bottom of the inlet to prevent excessive short-circuiting (dust blowing directly from the inlet to the outlet without spinning around). If it's too long (say down to the bottom of the barrel or longer) the air can have trouble making a smooth change of direction up the vortex finder. There is a CFD (Computational Fluid Dynamic) model that shows a torodial eddy around the vortex finder just below the cylinder head. The eddy can carry dust straight down the side of the barrel and then straight up the vortex finder. I'd make the vorex finder extend an inch or two below the level of the inlet bottom.
Use a neutral vane. IOW, extend the inlet into the barrel and end it on a radial plane that runs vertically through the barrel. This reduces the amount of energy required to run the cyclone. If you're really particular, you can test your cyclone and slide the inlet in until you get minimal pressure drop. Once you find the optimal location, lock it down.
Use an air ramp. This is just a spiral ramp that starts at the top of the inlet and spirals down to meet the bottom on the inlet. This reduces the pressure drop of the cyclone.
If you have space for a 1D3D with height left over, use a downcomer tube. This is just a straight pipe between the bottom of the cone and the dust bin. It's the same diameter as the dust outlet. The optimal length seems to be about D.
An alternative to a downcomer tube is to put a cone in the dust bin. The paper I read used a 90 degree apex angle cone about 10% bigger than the dust outlet. Both the cone and the downcomer tube reduce the re-entrainment of dust from the dust bin. The additional pressure drop is about the same for both approaches.
Another approach is to use a vane, about one inch tall near the bottom of the dust outlet. This vane is just fastened to the cone wall. IIRC, the paper I found that in used a length of 1D on a 3D cone. They reported that it improved collection efficiency. Unfortunately, I haven't been able to find that reference again. I suspect it works much as the downcomer tube does.
The bad news is that the modifications to improve separation efficiency increase the pressure drop. The downcomer tube costs about 20% more pressure drop. Using the D/2 x D/4 inlet in conjunction with a D/3 dust outlet (about what Wood magazine specified) costs about 20%.
That means that it is important to use the modifications that reduce pressure drop. In particular, use a neutral vane. Bill Pentz reports that a neutral vane reduces pressure drop by about 30%.
On one of his spreadsheets, Bill Pentz estimates that using an air ramp saves about another 15% in pressure drop.
You can also make the cyclone a little bigger; running a 1D3D with an inlet velocity of 2,600 fpm costs less pressure drop than the standard 3,4200 fpm but does little to collection efficiency, it may even help.
To keep the air flow up, you'll also have to make sure that you have nice smooth transitions and long-radius curves in your ductwork. You'll probably want to run 6 inch pipe.
And don't forget to get a big enough blower.
Whew! Sorry for the long post.
There is a wealth of information at Bill Pentz's web site:
Bob S
What would be the estimate cost for a 2 HP cyclone?
job I've been researching cyclones again with a view to making a living from selling them - no product yet though.
cyclone. It was a pretty rough design. The good news is that even rough designs work reasonably well. However, if you'd
My local steel companies sometimes stock 26 gage but often the lightest they have is 24 gage.
dimension is called D. A 1D3D cyclone has a barrel that is as tall as it is wide and a cone that is 3 times the height of
height of the diameter.
design. The papers I've read consistently get slightly better but not statistically significant dust separation with a
cyclone is a sweet spot for shorter cyclones.
x D/8. However, there are studies that show better performance with a D/4 x D/2 inlet. The D/4 x D/2 inlet is also
nicely if you use the vortex finder modification.
least the bottom of the inlet to prevent excessive short-circuiting (dust blowing directly from the inlet to the outlet
barrel or longer) the air can have trouble making a smooth change of direction up the vortex finder. There is a CFD
vortex finder just below the cylinder head. The eddy can carry dust straight down the side of the barrel and then straight up
level of the inlet bottom.
radial plane that runs vertically through the barrel. This reduces the amount of energy required to run the cyclone. If
until you get minimal pressure drop. Once you find the optimal location, lock it down.
inlet and spirals down to meet the bottom on the inlet. This reduces the pressure drop of the cyclone.
is just a straight pipe between the bottom of the cone and the dust bin. It's the same diameter as the dust outlet.
I read used a 90 degree apex angle cone about 10% bigger than the dust outlet. Both the cone and the downcomer tube
drop is about the same for both approaches.
dust outlet. This vane is just fastened to the cone wall. IIRC, the paper I found that in used a length of 1D on a 3D
haven't been able to find that reference again. I suspect it works much as the downcomer tube does.
increase the pressure drop. The downcomer tube costs about 20% more pressure drop. Using the D/2 x D/4 inlet in conjunction
drop. In particular, use a neutral vane. Bill Pentz reports that a neutral vane reduces pressure drop by about 30%.
about another 15% in pressure drop.
velocity of 2,600 fpm costs less pressure drop than the standard 3,4200 fpm but does little to collection efficiency, it may
smooth transitions and long-radius curves in your ductwork. You'll probably want to run 6 inch pipe.
Kevin
Have a look at Bill Pentz website
Regards George SA
At this point I just have cost targets. For my first product, I want to be able to sell a cyclone without the blower for something in the $300 to $400. That's still more of a kit than a complete solution but it would allow someone to put together a 2 HP dust collector for less than the comparable PSI model.
I'll have a better idea of the cost after I get some quotes for manufacturing them. I'll need to finish my drawings to do that.
One thing that I have learned so far is that I can't fabricate cyclones fast enough to make a living!
Bob S
job I've been researching cyclones again with a view to making a living from selling them - no product yet though.
cyclone. It was a pretty rough design. The good news is that even rough designs work reasonably well. However, if you'd
My local steel companies sometimes stock 26 gage but often the lightest they have is 24 gage.
dimension is called D. A 1D3D cyclone has a barrel that is as tall as it is wide and a cone that is 3 times the height of
height of the diameter.
2D2D design. The papers I've read consistently get slightly better but not statistically significant dust separation with acyclone is a sweet spot for shorter cyclones.
D x D/8. However, there are studies that show better performance with a D/4 x D/2 inlet. The D/4 x D/2 inlet is also
nicely if you use the vortex finder modification.
least the bottom of the inlet to prevent excessive short-circuiting (dust blowing directly from the inlet to the outlet
barrel or longer) the air can have trouble making a smooth change of direction up the vortex finder. There is a CFD
vortex finder just below the cylinder head. The eddy can carry dust straight down the side of the barrel and then straight up
level of the inlet bottom.
radial plane that runs vertically through the barrel. This reduces the amount of energy required to run the cyclone. If
until you get minimal pressure drop. Once you find the optimal location, lock it down.
inlet and spirals down to meet the bottom on the inlet. This reduces the pressure drop of the cyclone.
This is just a straight pipe between the bottom of the cone and the dust bin. It's the same diameter as the dust outlet.
paper I read used a 90 degree apex angle cone about 10% bigger than the dust outlet. Both the cone and the downcomer tube
drop is about the same for both approaches.
dust outlet. This vane is just fastened to the cone wall. IIRC, the paper I found that in used a length of 1D on a 3D
haven't been able to find that reference again. I suspect it works much as the downcomer tube does.
increase the pressure drop. The downcomer tube costs about 20% more pressure drop. Using the D/2 x D/4 inlet in conjunction
drop. In particular, use a neutral vane. Bill Pentz reports that a neutral vane reduces pressure drop by about 30%.
about another 15% in pressure drop.
velocity of 2,600 fpm costs less pressure drop than the standard 3,4200 fpm but does little to collection efficiency, it may
smooth transitions and long-radius curves in your ductwork. You'll probably want to run 6 inch pipe.
On Bill Pentz's website (the link was given above), he gives the email address for a guy named Clarke Echols. He's selling snap together kits using Bill's design. Cost is $150 + $35 shipping to the Continental US. He's also selling steel blowers for the same price. You would still have to buy a motor ($79 from the guy on Ebay Bill used in his airfoil design), an impeller (I'm going with an airfoil for $135 I think), and the filter. Just another option.
Cheers, cc
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