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I have decided to plumb my shop for the 2 HP HFDC. I do not have floor space enough for the 4" piping. I have 8' ceiling in my garage(shop). I am planning on hanging a central 4" or 6" pipe down the middle of the shop and creating drops from it. Do you think I will have trouble with the CFM or dust collection by doing this instead of having the central pipe on the floor?
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I'm debating the same thing. Have you looked at this site
http://billpentz.com/woodworking/cyclone/index.cfm
Basically you need 3000 cfm in horizontal dusts and 3700 cfm in vertical ducts to keep dust suspended. I'm not sure the HF DC can do it with bags (my setup) or I'll have to upgrade to the Wynn filter to get more CFM.Gary -
I think that's 3000 fpm and 3700 fpm, fpm is a measure of linear velocity andquote:Originally posted by gary
I'm debating the same thing. Have you looked at this site
http://billpentz.com/woodworking/cyclone/index.cfm
Basically you need 3000 cfm in horizontal dusts and 3700 cfm in vertical ducts to keep dust suspended. I'm not sure the HF DC can do it with bags (my setup) or I'll have to upgrade to the Wynn filter to get more CFM.
cfm is a measure of volumetric flow rate.
for a circular duct, fpm = cfm/area
where area = 3.14 x D x D / 576
if D is the inside diameter in inches.
for a 4" ID duct, then the required CFMs are 263 and 325 respectively.
with a 6" ID duct, the required CFMs are about 600 and 730 respectively.
With totally umimpeded flow the HF 2 HP DC is rated for 1600 cfm
but the general suspicion is it's really more like 1200 cfm.
With a bunch of ducting it may drop to something in the range of 600-1000 cfm. IT's very hard to measure accurately.
The consequence of the equation is the air velocity speeds up
when the pipe is narrowed, but its counter-productive because narrowing the duct causes pressure drops that reduce the CFMs
still the HF DC can make the velocities Bill recommends
as long as you keep the ducting short and smooth and adequate diameter.
Loring in Katy, TX USA
If your only tool is a hammer, you tend to treat all problems as if they were nails.
BT3 FAQ - https://www.sawdustzone.org/forum/di...sked-questionsComment
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I put my HFDC in a corner of my garage/shop. I took the "Y" off and ran 6" (it might be 5") straight up to the ceiling. I put the "Y" on at ceiling level and then ran 4" duct along two walls. I also "Tee'd" into one run to go across the center of the garage (I made a drop down from the center of this run to suck from my Shark). I have had this set-up for almost two years now and it satisfies my needs.
MikeComment
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I've got a spine of 4" pipe running about 15' down the length of my shop, driven by the HF 2HP unit. It works fine.
Pentz's site is very informative, but a bit of a blizzard of DC info. I wanted to get on with the job of collecting dust, so I ignored everything Pentz says and just hooked the system up.
Perhaps I've become a victim of Nike advertising - Just Do It is my new shop mantra.
JRJRComment
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One pit-nick. Correcting for D^2 vs "pie are square" and sq-in to sq-ft, gives you 576. Not a huge difference, but there are some three-sick-figs folks around here.[quote:Originally posted by LCHIEN
cfm is a measure of volumetric flow rate.
for a circular duct, fpm = cfm/area
where area = 3.14 x D x D / 572
if D is the inside diameter in inches.
)]
Ray"A human being should be able to change a diaper, plan an invasion, butcher a hog, conn a ship, design a building, write a sonnet, balance accounts, build a wall, set a bone, comfort the dying, take orders, give orders, cooperate, act alone, solve equations, analyze a new problem, pitch manure, program a computer, cook a tasty meal, fight efficiently, die gallantly. Specialization is for insects."
--- Robert A. HeinleinComment
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I Have the HF 2hp DC equipped with a Wynn filter. I'm using 4" pipe, I have 3 main drop downs and each is split for 2 machines with blastgates on each port. It works! I even have a trashcan separator in line at the DC and all the small paricles get sucked out of it.(about 70% of the sawdust stays in the separator) Seems like a good 2 stage to me.Opinions are like gas;
I don't mind hearing it, but keep it to yourself if it stinks.
Comment
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you got me, Ray. My first type-up has 2 x 2 x 12 x 12 in the denominator and I figured that was too much math for some poeple herequote:Originally posted by ElRay
One pit-nick. Correcting for D^2 vs "pie are square" and sq-in to sq-ft, gives you 576. Not a huge difference, but there are some three-sick-figs folks around here.[quote:Originally posted by LCHIEN
cfm is a measure of volumetric flow rate.
for a circular duct, fpm = cfm/area
where area = 3.14 x D x D / 572
if D is the inside diameter in inches.)]
Ray
so I did a WAG with mental arithmetic as i was on my way out the door this morning and late to work. (Yes I check BT3C before i head to work, sick, isn't it?).
All: Pentz's theories and math are all OK, but he goes a little overboard, maybe he's trying to catch 99.9% of the bad particles.
That said, if you wade thru the tables and figures, with the 2 HP HF DC, normal runs with 4" pipe are too restrictive to keep the airflow at the rate he says would suspend all particles for transport (given the linear velocities at 4" dia.
6" piping would maximize the airflow but it turns out the linear velocity would be too low in vertical runs (due to the larger diameter) to suspend the bigger particles.
It turns out that 5" is the correct size for the HF and other 2 HP machines to both maximize airflow and keep the linear velocity high enough. Unfortunately 5" pipe and fittings are very hard to come by.
I might imagine but haven't worked out the math that 6" pipe necked down to 4" or 5" in vertical runs would suffice to keep sufficient velocity to suspend all particles in the air stream.
Anyway, that's what I gleaned from reading Pentz's writings.
Me? I'm just using a 10' run of flex 4" hose from the tool to the DC for now. I've also got a Grizzly canister conversion ($165) on the DC.
I can see that the 4" to 2.25" reducer at the BT3000 really kills the flow rate. I'm thinking one day I'll put a 4" suction on the bottom of the saw and use two 4" hoses and also split off a 2" hose for the shark guard.
Loring in Katy, TX USA
If your only tool is a hammer, you tend to treat all problems as if they were nails.
BT3 FAQ - https://www.sawdustzone.org/forum/di...sked-questionsComment
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Oh yeah. If you read his history, he was hospitalized over IIRC, and allergic reaction to long term deep lung exposure. So he's gone ultra-healthy on this stuff.{quote]I can see that the 4" to 2.25" reducer at the BT3000 really kills the flow rate. I'm thinking one day I'll put a 4" suction on the bottom of the saw and use two 4" hoses and also split off a 2" hose for the shark guard.[/quote]I'll definitely go this route when I finally upgrade from the ShopVac to a DC.quote:Originally posted by LCHIEN
All: Pentz's theories and math are all OK, but he goes a little overboard, maybe he's trying to catch 99.9% of the bad particles.
Ray"A human being should be able to change a diaper, plan an invasion, butcher a hog, conn a ship, design a building, write a sonnet, balance accounts, build a wall, set a bone, comfort the dying, take orders, give orders, cooperate, act alone, solve equations, analyze a new problem, pitch manure, program a computer, cook a tasty meal, fight efficiently, die gallantly. Specialization is for insects."
--- Robert A. HeinleinComment
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Right now I've got a 4" hose running to the bottom of the saw where I have a DC port. On that 4" hose I have a Wye that has a reducer to a 2.5" hose to the back of the saw. I also have another 2.5" hose that runs on the main trunk that runs across my shop that I hook up to the shark guard.
With this setup I close down the blast gate that controls that back of the saw and under the saw hoses so that I get more air flow to the shark guard. After I'm done sawing I close the shark guard blast gate and open the other one to get anything that might be lingering.
It works pretty well for me.Comment
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Something to consider:
If you use a 6" main line for your DC, the 2.25" outlet of your BT3 alone may not allow enough airflow to keep the dust moving in the main line. In this case, you may have to open up another port somewhere (perhaps a drop to, e.g. a shark guard) to increase the flow in the main.
Regards,
Tom
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Okay..I think I understand it now.
Naught X big hole = good suck.
Naught X little hole = bad suck.[}
]
I have to take off my shoes to count to twelve.....(just kidding sort of).
Seriously, you guys have helped my dilemma. I now plan on running 6" piping with 4" drops as far as possible and only reduce it for the machine ports. Thanks for the info. Now if I could only get HF to put all the bolts in the packaging...HMMMMMMM?Comment
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What I'm thinking is I should run a pair of 4" hoses or pipe from the DC to a box (an example of a Plenum).
I'd put a bunch of outlets on the box for 4" and maybe some 2+ inch hoses and blast gates. Use three (one 4" for a belly pan, and 2 x 2" for hoses to the dust port and the shark Guard) when I use the table saw.
Use 4" for the jointer and the planer which have 4"ports, and use 2+"
for the sanders, bandsaw, etc which have 2" ones and obviously don't need so much suction/air flow because they produce fines only.
The plenum box goes in the center of the shop with the DC to the side of the shop (2 runs of 4" is approx equal to a single 6" hose). An the rest of the tools near the plenum.Loring in Katy, TX USA
If your only tool is a hammer, you tend to treat all problems as if they were nails.
BT3 FAQ - https://www.sawdustzone.org/forum/di...sked-questionsComment
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Loring, that sounds like the setup that Carlos had. He seemed to like it.quote:Originally posted by LCHIEN
What I'm thinking is I should run a pair of 4" hoses or pipe from the DC to a box (an example of a Plenum).
I thought about it for my long/skinny shop, ultimately rejecting it in favor of the backbone with branches concept. I guess it was my concession to Pentz's ideas about flow accross solid pipe vs flex. I still have flex going from the backbone to the tools, though.
JRJRComment
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