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Thread: The Generic 2HP DC
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28th February 2016, 08:21 PM #121SENIOR MEMBER
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Thanks Doug. I was counting on a lot of smaller openings with the Table saw, so will review, taking your comments into account.
Regards
Bauldy.
P.S. Some years ago when I first bought my bandsaw and very ignorant of this topic, the first thing I did was to seal every gap I could assuming that would help the DE work better!
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28th February 2016, 10:36 PM #122.
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29th February 2016, 12:38 AM #123
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14th March 2016, 06:11 PM #124SENIOR MEMBER
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Starting to look at doing the modification. Cleaned the machine up and took some measurements. It is a Ledacraft DC1500T. It has a rectangular connection from the Impellor outlet to the Bags. The pipework is 153mm x 117mm internal measurements as best I can measure. This appears very close to a 150mm dia pipe, which was presumably the idea.
IMG_5940.jpg
IMG_5941.jpg
So, it is not as restricted as many of these type DC's are. So two questions:
1) Given I already have the equivalent of 150mm of exit area, is the length of curved rectangular pipe causing enough restriction to bother modifying?
2) If it is, while I suspect it is preferable to turn the unit 90deg so the air enters axially, it would be a lot easier to just bolt the rectangular flanges together in the current direction they are
oriented. Does the difference warrant some sheetmetal work rather than a simple bolt job (and new support for the motor)?
Please note I will be opening the inlet to 150mm, but did not want to start pulling things apart until I had all of my planning done.
Regards
Bauldy
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14th March 2016, 07:22 PM #125.
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In terms of Xsectional areas the duct has 117 x 153 = 17901 mm^2
In comparison a 150 mm diam pipe is 17671 mm^2,
However the 150 mm pipe has a wall perimeter of 471 mm whereas the rectangular duct has a perimeter of 540 mm,so more surface ares to provide drag, and being asymmetric it will have slightly more drag between the narrower (117 mm) sides.
In practice the flow performances will be so close together that it shouldn't matter that much so I would leave it alone at this stage.
The only difference between my mod and this machine is then that the air coming out of the impeller is doing a 90º turn but it is a nice wide radius turn so it will have a minimal impact.
So concentrate on expanding the entrance to suit 6" ducting and see if you can incorporate that reverse bell mount.
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14th March 2016, 09:04 PM #126SENIOR MEMBER
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Thanks Bob. My impellor is listed as 300mm in the specs (haven't opened it up yet). presumably apart from the 150mm inlet that will be the limiting factor. Is 300mm standard on most of these?
Regards
Bauldy
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4th May 2016, 12:34 AM #127Novice
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Hi Bauldy - does it look like you can reverse the side the motor is on the blower?
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6th June 2016, 04:42 PM #128SENIOR MEMBER
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Hi BobL
I am about to modify my 2HP dusty. Does the 125mm gap between the blades (same on mine) mean that the impellor would be most efficient with a 125mm (5 inch) inlet rather than a 6 inch one? If so how much more efficient do you reckon. I will only have about 4 metres of ducting from my dusty to the my machines. Would any increase in efficiency gained by optimising the inlet be lost by using 5 inch ducting rather than 6 inch.
Cheers
Mike
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6th June 2016, 11:07 PM #129.
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150 mm is significantly superior to 125 mm ducting.
Provided the fan can physically move that much air, at the same pressure generated by a fan, a 150 mm duct can move about 3 times that of a 100 mm duct, and 1.72x a 125 mm duct.
In theory if the impeller can generate 8" of WC it matters naught what the size of the entrance to the fan is. You need to remember that most of the fan pressure is generate by the outermost tips of the impeller so provided that is covered and does not let too much air get past it that is what will generate the pressure
Now what really matters is the "fan curve", Flow rate V pressure. Where this matters is as ducting/bag/machine resistance is applied can the fan counteract this and maintain a flow.
The size and design of the generic 2HP impeller will produce a relatively weak fan curve compare to a bigger more carefully designed setup.
You also need to remember that in my mod that uses a reverse bell mouth hid the opening is even wider that 150 mm.
So to summarise, I'd say the slight loss in efficiency from opening up the impeller intake is well and truly over come by the ability of 150mm ducting to move more air.
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7th June 2016, 11:23 AM #130SENIOR MEMBER
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Thanks BobL
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7th June 2016, 06:20 PM #131SENIOR MEMBER
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7th October 2016, 06:27 PM #132
Yikes Ive read this, slept on it read it all again, fasinating and very informative,
But, now here will prove weather I'am, blind/stupid/combined/ or ???
but there is no mention of cyclones....I thought they were the ants pants or bees knees or warblers whiskers.
comments please or provide artillery to shoot myselfI would love to grow my own food, but I can not find bacon seeds
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7th October 2016, 06:45 PM #133.
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The reason I started this thread and undertook the conversion was because the generic 2HP DC
- is probably one of the most common DCs in DIY sheds
- when modified and using 6" ducting has at least a hope of approaching 1000CFM
- will run from a 10A socket (not everyone even has 15A let alone 3P power)
Most Cyclones added to existing DCs end up restricting the flow of air through the system and this thread was about increasing the flow through what is already a marginal system.
To be efficient cyclone and impellers have to be properly matched which is not a task for the average DIY.
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7th October 2016, 07:12 PM #134
BobL, you are a legend, simple clear answer, thank you. What more could a man ask for? well maybe one lives in hope but I think I know where you would draw the line Bob.
I would love to grow my own food, but I can not find bacon seeds
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8th October 2016, 08:59 AM #135Senior Member
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Hi Tonto,
The thread is TWO horse powered dust extractors and how to improve them.
Cheers Barry
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