Too cheap to buy real dc pipe!
user-247493
| Posted in Power Tools and Machinery on
Here I go with yet another question about dust collection. See, my idea is if I spend all my time talking about making dust, I’ll have no time to actually make any and I won’t need dust collection. Really, I was in my local HD the other day, looking at metal pipe and fittings (HVAC) and noticed some flexible aluminum duct. I think it’s for venting dryers, but it seems fairly sturdy and it’s very cheap. Has anyone tried this stuff?
Replies
Remember, a dryer vent hose is under positive pressure which acts to push the walls out. Dust collector hose is under negative pressure, so i could see a good DC unit actually sucking that vent hose flat.
There's a good article in one of the current mags about DC systems, part of which discusses why not to substitute pipes and fittings that aren't made for them. I'm at work right now, but can post the title tonight. Doesn't sound like it's a good idea to scrimp.
PS: Turns out the main thing they were advising against was PVC (being substituted for metal). They do make a point about using 5" diameter pipe, 26 gauge.
forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
Edited 4/11/2003 10:51:24 PM ET by forestgirl
I used 4" PVC pipe and fittings because it was fast and easy and not too expensive. I was able to build the whole system in one afternoon. Biggest concern is static charge with PVC. I ran a bare 12 gauge wire through the entire system and grounded to an electricial outlet ground. Another member here, I forget the name ("shop hints" thread), used pop rivets through the PVC pipe every 6" and ran the ground on the outside. Good idea to stop jamups. I've been able to clear all but one jamup by reversing the flow.
Correction: I'm sorry (I checked today), I use 3" inside diameter PVC, with standard plumbing connections and cutting off those stupid numbs, the outside diameter is around 4" perfect for flex pipe and auto clamps.
Enjoy, Roy
Edited 4/12/2003 10:54:38 PM ET by ROY_INMD
Regardless of the type of material you use, you want to balance the components.
I use 3" Schedule 40 PVC for my lines and the usual 4" flex tubing for connections to machines. No ground on the PVC. There is no static hazard in a wood shop dust collector.
This works well with my 1-1/2 HP duct collector and 55 gallon centrifical collector. (100% of my sanding dust falls in the bottom of the 55 gallon drum until it is 1/2 full.)
Go to this site & read & learn about dust collection.
http://cnets.net/~eclectic/woodworking/cyclone/Index.html
Your 3" duct is choking your system.
Ignoring the fact that my engineering degree is fluid (including air) flow:
I have no complaints about my dust collection system.
1) If you are going to make comments about my dust collection system, you should know more about it than you do.
2) You should not believe a lot of the material posted on the internet.
Excellent point.
Alot of peeps just are silly.
Sorry George.
There is a bunch of well thought out stuff about DC that You might want to read before lamblasting others.
However, don't ask me, I'm one of the fools who bought one of those $119 HF units, used 5" pvc ducting w/no ground, hooked it up inline with a $30 chip seperator, hard wired the blastgates with a 12v relay all for about $240. The pipe (60+ ft) I got for free from a nice farmer. The fittings I made myself.
3" is shopvac size.The proof is in the puddin'
Static grounding necessity arguements aside, nobody ever mentions ABS as a possible alternative for ducting a DC system. I haven't made any price comparisons but based on smaller DWV (Drainage Waste & Vent) piping, size for size the ABS, as I recall, is cheaper than PVC,... no? It's just as easy to work with as PVC in my opinion.
For my part, I recently tore out the old forced air furnace in the house we're remodeling and managed to salvage quite a bit of the sheetmetal - round duct - for possible use in my new shop DC system.
...........
Dennis in Bellevue WA
[email protected]
Dennis,
Don't you just Love freebee's
Enjoy, Roy
> ....Don't you just Love freebee's
I'm the biggest scrounge you'll probably ever meet (or correspond with), Roy. My wife's convinced the only reason I wanted to move to the country with more areage than a typical suburban lot as to have more room to pack home "stuff".
Yes, free is the best price/performance ratio I have yet to come up with.! (grin)
...........
Dennis in Bellevue WA
[email protected]
I have a Degree in diesel technology but that still doesn't mean I know everything there is to know about the subject. I certainly don't go spouting off about my degree. For one good reason, there is always someone out there that knows a little more about the subject than I do & they don't always have a degree.
Since you have that degree you probably know that one of the most efficient home shop dust systems would have a 14" impeller & 3 hp motor turning at 3450 RPM moving dust through a 6" duct. This system will get the fine dust that will do damage to your lungs. Anything smaller when running through a ducted system won't. It takes 800 CFM to remove & keep moving the fine dust & chips & a small DC with a 3" duct won't do this period.
Where do you think all these degrees came from anyhow. From the people that spent their lives experimenting to find out what did & didn't work & they may have pre-existed any degree program.
But the true engineer or interested individual doesn't stop investigating & experimenting to find new ways or paths to improvement. Even the highly educated degreed person should keep on trying to find ways to improve a system.
You can keep sucking your dust & chips through a straw & keep your impeller from realizing it's full potential. Your DC is designed to move volumes of air to keep the chips floating in the tube. It is not a vacuum cleaner.
Have an open mind, go read these sites & prove that the saying that engineers are a dime a dozen isn't true.
Remember your never to smart or to old to learn a new trick or two.
Non of us knows everything about a given subject even if we have a degree.
Bill Pentz through experimentation using the proper instruments has proven that a lot of the information that the dust collection community (retailers) have been telling us is just plain bunk. There are others that have been doing the same thing.
http://cnets.net/~eclectic/woodworking/cyclone/Index.html
Bill Pentz & Terry Hatfield have co-operated on the cyclone that is on Terry's web site.
http://www.dusteliminator.com/
Oh by the way I told my wife about your DC system & she gave me a look like is he nuts & she isn't an engineer. I was going to purchase an 1100 CFM DC but the LOML said I think you would be better off with the 1200 CFM unit & get the remote switch too while you at it.
I have a 1200CFM DC hooked up to 4" PVC & know it's not living up to its potental. Why because the ducting is to small. I however have 2 big pleated filters mounted end to end in an enclosed housing so that the air flows from the outside through to the inside & out the top. This alone increased my air flow by bunch. In fact with the back of my contractors table-saw back closed up I can feel the air movement through the 0 clearance throat plate finger hole & blade slot. I couldn't feel the air flow with the 30 micron bags that came with the DC unit.
In the future I am going to purchase a cyclone from Terry Hatfield & build my own system with my current DC fan & as money will allow I'll upgrade the system to a 14" impeller & a 3 hp motor.
I have E-mailed back an forth with both of these men & have found them to be concerned honest men.
Edited 4/12/2003 9:24:02 PM ET by Bart
Edited 4/12/2003 9:27:43 PM ET by Bart
Edited 4/12/2003 9:39:56 PM ET by Bart
Dust collection and air filtration are two different things. I don't confuse them. You seem to.
Dust collectoion is concerned with picking up large particles, those that are not airborne - including most of the dust from my thickness sander. Air filtration is concerned with picking up small particles, those that are airborn.
My dust collector changes the air in my shop 10 times per hour. It will not clean the air. I just circulates the small particles. My air filtration system changes the air in my shop up to 20 times per hour. It removes enough to make me happy.
You wrote:
"Bill Pentz through experimentation using the proper instruments has proven that a lot of the information that the dust collection community (retailers) have been telling us is just plain bunk."
I don't have the need to investigate his claims. If you wish to pay me to do so, I can generate interest.
Since he has never seen my shop, he cannot address the issue of the suitablity of my dust collection. You do illustrate that Mr. Pentz and retailers have different opinions. I am sure each will be correct where their product serves the purpose best.
As I said my dust collector system works for me. The fact that you deny this fact means that you fail to understand or use the scientific method.
Regarding Dust Collection and Air filtration. I think that you (George and Bart) are both right, but about different things. As I read the evidence (and I have looked at a lot), four inch pipe will work perfectly well for collecting chips. It will not effectively collect fine dust at the source. Fine dust IS a significant health hazzard and woodworkers should be concerned IMHO. I have a reasonable chip collecting system in my shop, but I have to wear a powered mask when I use it. I plan to upgrade to a DUST collection system as soon as I can. My hope is that I will be able to dispense with the mask at that point.
My personal preference is to use the term Chip Collector for something that collects stuff you could broom up. I reserve Dust Collector for something stronger. For that I think you do need five inch ducts and 800 CFM for the larger machines.
BTW, I do agree that manufacturer's information is misleading and cannot be easily compared. An exception would be the Woodsucker information which explains clearly what it is and what it means.
I'm not an engineer but I do have access to the tools. I brought home a couple different types of anemometers to measure CFM flow in my PVC-piped DC system. I have a garage-sized system employing a commercial type 3HP 1300CFM 2-stage collector. Its 6 inch inlet has been reduced to 4 inch to connect to the 4 inch main lines at ceiling level. All drops are 3 inch. I'll skip all the gory details but will state that at the end of my longest run (where it's a 3" drop down the wall and into the slab & over about 6 feet to the saw) I'm only left with under 200CFM. Calculations said I would have problems, BUT IT WORKS GREAT. I often use this same port to hook to my portable planer and never get any jams.
The real world sometimes defies the rules.
800 CFM is the new standard that the dust collection industry & OSHA are migrating to. Its better to get the dust at the source then let it get into the air. I have a air cleaner hanging from my ceiling too, but that isn't good enough.
It's not how many times your DC or air cleaner change the air per hour thats important. Its how many times you inhale per hour. This is how many times per hour your lungs filter what your Dust Collector doesn't get at the machine that still has to get to your air filter system.
It has been proven that is is better to get the fine dust at the machine & not wait for it to get into the air.
We cannot get it all the fine dust but must try to get as much as we can at the machine.
It is wood workers like us that can push the industry to safer health standards but if we set around & do nothing it won't happen.
The words are Dust Collectors not Chip Collectors.... do you suppose that name was selected for a reason or is is just generic.
No I am not arguing just sounding the alarm loud & clear. Facts are facts folks, you only have one set of lungs.
Dust collector is the industry name. It may or may not relate to the function.
CFM has little to do with chip or dust collection.
If I hook a 800CFM unit to my window and suck the chips and dust out of the shop, I will get very few chips or dust out. (There are industrial machiines that dwarf my shop and 800CFM will do little for those machines.)
If I hook a 50CFM shop vac to my scroll saw I will pick up every chip and bit of dust created.
An important measurement is the linear feet per minute that the air flows at. Higher speeds generate more turbulace and draw more chips and dust into the air flow. (CFM has importance here as it relates to the cross section of the duct or tool that the air flows through.)
The more times per hour you change the air in your shop (either by filtering it or exhaousting it) the lower the density of the dust in your shop and the less work your nose needs to do to filter the air. (CFM has important here in that it relates to the volume that is cleaned.)
Always: Think about what you need to do then try to do it.
Wow! I love it when a can of worms gets opened up because we can all learn from it.
I corrected my post above, I use 3" inside diameter PVC pipe (I checked today) and standard plumbing connections for that perfect fit to 4" flex pipe with auto clamps. I am happy with my dust collection system, unmoded for the last 12 years. My planned mod is the upper cloth bag will replace the lower plastic bag (because I'm out of them) and the upper 20x36 bag will be replaced with a 20x48 from LV. Bigger lung is gooder right! Add the 2 stage cover and can and I have the mod I should have done years ago. I'm a lazy and slow learner.
George, Interresting comment about the static issue, esp. from a Flow Engineer. I read, from several sources that was a concern and grounded my system. I sucked a string with small wooden block through the pipes and pulled the bare copper wire through. Now that its installed I'm leaving it.
Am I restricting my air flow with 3" pipe, sure. My DC has a 6" opening and a 4" "Y", I have never used the 6" and never used both 4" at the same time. I can run my table saw, the last tool in line (about 30 feet, all horizontal) and hear the system doing its job. My old Mustage GT and Volvo could do 120+mph and love it, but I never did that either.
Lets all keep our heads, take a deep breath and have some fun talking. So far so good. Really, this stuff is great.
Enjoy, Roy
George,
What is a cintrifical collector? That's a new one to me. Sounds like it's very efficient.
Jeff
I think the centrifugal collector you're talking about is a garbage can, 45 gal. drum, whatever with a special cyclonic lid. This is placed in the line upstream of the dc (obviously) and captures a lot of the bigger particles, saving you from emptying the dc bags so often. Lee Valley sold me mine, but you can get them just about anywhere. Check out the lee valley link below. They explain it quite well.
http://www.leevalley.com/wood/page.asp?page=30282&category=1,42401&ccurrency=1&SID=
Hello JIMSPRAGUE
A frind of mine just showed me his new dust collection system, for pipeing he used was old carpet roles with pvc 90 deg. elbos. (screwed to the pipeing he used some kind of tape to make sure he had a good seal on the elbos.) he painted the cardboard pipeing,It looks great! and realy works well.
He told me the pipeing was free and the 90's are sec.40 the hole cost was less then $60 to make. (not including the flex hoses,which he already had.)
I already have my own pipeing system instaled on my DC so this idea realy dosnt help me,
BUT I sincerly hope someone else can use this idea .
C.A.G.
Leftover cardboard carpet rolls,
now that is clever.
I wonder what the inside dia. is?The proof is in the puddin'
Curtis,
I'm afraid that your friend will have a very leaky system in short order. The friction of the dust and chips passing through the pipes will soon wear holes through the cardboard. If, however, his system will see very little use, it may last him a year or two.
Jeff
Hello Jeff
I relade your comments to Sam (my frind that made the carboard collector) He said Free is Free! and he has used this idea before,
He stated ,the idea only works in you have seperators at the drops, to pick up the dust, the pipeing just moves air. He also said he belives he can get 5-6 yrs out of this system.
Sam is 86yrs old ,He said he should have to replace his system proberly three of four more times before he is ready to leave this world. Until then he has lots of things to do,and will not hear of it,Im to young (under 50) so I cant see the BIG picture. :)
"O"Well I guess FREE IS FREE and Time is just to be spent.
Sam feel its worth the trade off.
C.A.G.
I use the aluminum flex duct pipe to connect my planer to the overhead metal dust collection pipe. It has worked great over the last 5 years. I leave it compressed as much as possible ( verses stretching it out). I use the 6" heavy black stove pipe for my dust collection system's main lines. The spiral stuff is pretty - isn't it.
Hi Jim,
If you're talking about that very, very thin-walled 4" aluminum venting pipe, I did my first shop with that...the whole thing; bought it at Home Depot.
I have the 1100 CFM Jet DC...and it basically collapsed some of the pipe and the other was so flimsy that it eventually pulled apart from connector fittings, grounding screws, etc.
I'm building a new shop and, this time around, will use 5" "real" dust collector pipe...even if I have to piecemeal. You get what you pay for.
Good luck!
lp
A decent dc system will collapse that stuff relatively quickly.
After reading these post 'bout dc systems,I haven't any using the pipe that I have on my system.I used 4" pvc sewer pipe sch 20.
You can buy long sweep 90's & 45's that work great and they are almost the size as the blast gates that the big stores sell. A 10'joint of pipe cost less than $5.I use mine to collect carbide dust. The pvc fittings are about 1/4 the cost of the almost identical Dc fittings
Texas Sharpologist
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