Replies

1. 
   DougB | Dec 27, 2004 07:42pm | #1

   I used standard tin heat ducting for my dust system.  I will collapse under the vacuum if blast gates are installed at the point where the tool is, however I have a 2600cfm machine and really do not use my blast gates much at all.  This kind of ducting is really cheap and naturally deals with static. 

   Doug

1. 
   mvac | Dec 27, 2004 11:56pm | #2

   Thanks, Doug.

   I'm a little confused, though. My shop vac doesn't pull anywhere near that CFM, and while I imagine I'd have blast gates, I doubt I'd use more than one tool at a time.  But are you saying that standard tin HVAC ducting will collapse under the shop vac's suction at the point where the blast gate is located?

   Sorry, i'm pretty ignorant about this area, so please excuse what might seem like some dumb questions. I appreciate the help.

   Regards,

   Mitch

1. 
   DougB | Dec 28, 2004 04:15am | #3

   I don't have a shop vac which usually suck about 600-800 cfm.  I have a 220v, 3 hp twin bag dust collector that can run about three machines with no blast gates without compromising efficiency.  What that kind of suction common hvac ducting will collapse under the vacuum.  Having said that, 4" or 6" hvac ducting would likely work just fine with a standard shop vac.

   doug

2. 
   JohnCabot | Dec 28, 2004 07:29am | #4

   In addition to a 2 hp Dust=boy and a 1 and1/2 hp Penn State dust collector  I use individual shop vacs for individual machines.For ex. my router table has a dedicated shop vac (allegedly 6.5 hp, actually less than 2 real hp) and so is the 6" belt sander etc. The shop vac is adequate for a single machine and saves me running 4" ducts all over the shop  (30x30 )with loss of efficiency. The Dust boy takes care of the planer and a cut off saw wich are adjacent too each other . The Dust collector takes care of the table saw, big Mini-max band saw and joiner. Again they are close to each other and to the collector.  I buy my shop vac at  substantial discount at Big Lot, (74 dollars for the big 6.5  hp vacuum).

   John Cabot

1. 
   mvac | Dec 28, 2004 06:55pm | #5

   Thanks, John.

   I've never heard of Big Lot before. Is it local? I'll search for it online.

   Regards,

   Mitch

3. 
   RandMCapozzi | Jan 04, 2005 06:54pm | #6

   mvac,

   Shop vacs and DCs are different animals when it comes to collecting dust. Shop vacs pull low CFM (about 100 - 150 max) under high static pressure (90" plus SP). Dust collectors pull high CFM (anywhere from 400 and up depending on impeller size and HP) at relatively low SP (typically under 12"). A 10" TS ideally needs around 500 CFM. A 14" BS, 12" portable planer, and 6" jointer around 400. So you can see that shop vacs just don't move the air needed to ideally collect the dust that is thrown from many larger WW machines. DC is basically about moving a lot of air at the hood and maintaining around 3500 FPM velocities through the ductwork to keep the dust in the air stream so the dust makes it to the collectors bags and doesn't settle in the ductwork.

   Before getting my current DC, I used a small 8 gal Craftsman shop vac for my DC. It was next to useless on my Unisaw (poor hood design), but did a good job on my planer, hand sanders and routers, and router table (all with very good hoods that focused the air stream at the location of dust production). The shop vac was just plugged into the tools without any ductwork. 

   A shop vac is not a viable DC device if you plan on hooking it up to a large piping network (ready any really). If you did use piping you certainly could not use 4 or 6" size ducting. The shop vac pulls so little CFM that the velocity of air in a 4 to 6" pipe would be so slow that the dust and chips would not remain suspended in the air stream and would settle in your ductwork. You would need to use a very small diameter pipe system (say 1.5 to 2.5"). Such small piping is completely unusable for an actual DC because it would generate to high a SP. You need significant SP to pull a lot of air through a small pipe. A shop vac can do this while a DC can not.

   HVAC piping (26 gauge) is probably sufficient for most hobbyist DCs. When you start getting into the larger 3HP 14" plus impeller units (moving "real" 2000 CFM), you may want to use heavier 24 gauge piping. (A quick tip, most manufactures CFM ratings are like the shop vac HP ratings. They are not real world. Go by amps instead of HP ratings. Unless otherwise stated, assume any CFM marketed on a DC is "free air" and will likely equate to half that once you add piping and dust bags.)

   PVC (in a non-industrial setting) does not need to be grounded to be "safe", if by "safe" you mean a potential explosion of the dust in a pipe due to a static electrical discharge. Grounding can help reduce those annoying static shocks you can get with PVC piping, but is not necessary in a hobbyist situation. Don't just take my word for it though. See the attached article for additional discussion on this subject.

   A separator is very useful for single stage dust collector systems (like a typical shop vac). A separator would be most useful for large chip producers like a planer or jointer. Chips take up a lot of space and can quickly clog up the small shop vac containers. Separators are also useful in reducing the maintenance of a shop vac filter which can quickly clog with saw dust. Most of the dust collected with my shop vac was end up in the filter with little or no dust in the actually container.

   Please take a few moments to read up on dust collection from Bill's site http://billpentz.com//woodworking/cyclone/index.cfm. I think you will find it very helpful in learning about dust collection.

   If you want to use a shop vac for DC purposes, I recommend foregoing any ducting plans. Just hook the vac up to the tool as needed. A shop vac, actually, is better at collecting from small tools (hand held sanders, routers with small DC hookups) than a DC any way so you can never go wrong with a good quality shop vac. Shop vacs and DCs are complementary tools not mutually exclusive. You can probably get into a very nice DC for under $200 but that won't get you any piping. The piping can quickly add up to a lot of $$ when you start including, wyes, hoods, and gates.

   Good luck,

   --Rob

    

   
1. 
   mvac | Jan 05, 2005 06:56am | #7

   Rob,

   Wow. Too bad you don't know anything about DC. Thank you for the wealth of information, both on the cyclone site and the grounding article.

   One question - Would you recommend the "mini-separator" that attaches to a 5-gallon can, or the regular one that attaches to a 30-gallon container, for a shop vac directly connected to a tool?

   Once again, thanks so much for your primer. When the time is right, I'll go for the ducting, but for now will keep using the shop vac, perhaps with a separator.

   Best regards,

   Mitch

1. 
   RandMCapozzi | Jan 05, 2005 06:01pm | #8

   Your welcome. That's the great things about these forums. That's how I have learned about this stuff.

   As long as you have an tight seal around the lid of the separator, I would go with the 30 gal. The vac should be able to handle the increased pressure of the separator. The whole idea of a separator is to introduce the shavings/dust to an area with very slow air speed. This allows the dust to fall out of the air stream. The larger separators probably have 4" ports on the lids so you would want to reduce those to 2.5" using a reducer to keep the pipe small enough to keep the air velocity up within the pipe (you want the dust to settle in the separator not the pipe. When you use a planer with that separator you'll discover how nice it is to have. Those chips will fill up and shop vac in a hurry. If fact, a planer can very quickly fill up a 30 gal container.

   Bill's site is truly awesome on DC info! It totally changed how I approached my setup.

   --Rob

2. 
   DougF | Jan 13, 2005 08:42pm | #11

   Mitch,

   A 30-gallon separator inline with shop vac will probably render it useless.  A mini separator may work but you will lose air flow and, with a shop vac, the static pressure will be substantially reduced.  This is also true with a separator inline to lower hp bag-type DC systems.  Before I went with a cyclone, the separator on my bag-system caused a tremendous reduction in air flow and static pressure but it's convenience out-weighted the reduction in dust collection.  There is a difference between "dust collection" and "chip collection".  Most low cfm system will collect chips but not do well in removing the finer particles that actually cause respiratory problems.   

   I run a 2hp cyclone system for most of my tools and I have a 2.25" plastic pipe system with blast gates along one wall to handle smaller machines like the drill press that create chips but little dust and for general cleanup and floor vacuuming.  This system is hooked to a shop vac.  Both can be independently operated off of a single remote transmitter. 

    

   Doug

1. 
   mvac | Jan 14, 2005 06:39am | #12

   Doug,

   Thanks for the input. I think the clear bottom line on this is that until I'm ready to get a dedicated dust collector, ducting is out of the question, and even though the separator would add some capacity, I wouldn't want to sacrifice suction.

   So, I'll continue to use my 8 gal., 3hp shop vac connected directly to the tool I'm using, make sure the shop-made, 1200 cfm air filtration system is running whenever I'm in my basement shop (that's right, no ventilation), and wear my dual-cartridge respirator whenever I'm using a power tool on wood.

   Ya think maybe people turn pro just so they can justify a nice, clean, well-lighted and well-equipped shop? It can't be for the money...

   Thanks to you and everyone who contributed - it's been a great education, and will serve me well in the coming years.

   Best regards,

   Mitch

1. 
   x372sailor | Jan 18, 2005 12:31am | #13

   I tried to use my Craftsman 4HP shop vac when I first purchased my jointer and found it totally useless.

   I bought on sale a Delta 50-660, 3/4 HP dust collector, which comes complete with roller wheels, drum collector, filter bag and about 8 foot 4" flex. hose.  I find this does a great job in my garage shop.  I use it for my jointer, 13" planer, router table and ROS sander.  For the latter 2 devices, I attach a 2-1/2" shop vac hose to the end of the 4" hose.

   I am delighted with my purchase.  Unfortunately for you, it appears to have been discontinued.

   Brian

2. 
   mvac | Jan 18, 2005 05:39pm | #15

   Funny thing about the jointer. You guys will think this is really strange - but it works like a charm.

   We have three cats - my wife's idea, since I'd love to get a golden one of these days - but it means we buy cat litter in 25 lb. plastic containers w/ handles.

   I take an empty container, slip it under the jointer's chip ejection chute (no dust port attached), and tape it real good with duct tape. That usually lasts about 3-4 weeks. Then, I cover the whole thing with an unopened contractor's trash bag, and tape that to three sides of the jointer so it completely covers the container. I haven't had to replace the bag cover yet.

   When I'm using the jointer heavily, I have to take my shop vac and empty the container out every three or four long boards, but it's practically free, if a bit inconvenient, and kicks up no dust at all.

   They say that necessity is the mother of invention...

3. 
   MarkRD | Jan 20, 2005 03:05am | #18

   Actually, Jared Diamond, the author of Guns, Germs, and Steel said that Invention is the mother of necessity.I suspect somone "Invented" a vaccuum system for a shop, then every sawdust maker (aka woodworker) had to have one. :-)Mark

4. 
   firemann | Jan 06, 2005 01:55am | #9

    mvac,shopvacs have good suction but have very little cfms. for a good dust collection you need cfms. hvac ductwork is way too big for this job unless you have a machine that can produce 20,00 cfms. pvc,4 " is what i use wrapped w/ bare copper wire for grounding. it works very well

1. 
   RandMCapozzi | Jan 06, 2005 11:50pm | #10

   4", 5", and 6" round snap-lock HVAC pipe is perfectly acceptable for ducting for hobby DCs. Most of this stuff can be had at the big box stores in 26 gauge which should be ok unless you get into some of the monster 3+ HP DCs (the big DCs could collapse the line if you close off all the blast gates with the system running).

   You do have to be careful about how the transitions are attached, however. Make sure the female end of the fitting is the one closest to the DC for the least amount of air flow turbulence.

   --Rob

5. 
   woodensplinter | Jan 18, 2005 03:58am | #14

   I was in the same boat as you.  Never could justify (to myself) a dedicated DC.  Now that I have one, I don't know how I ever worked without one.  I'm a convert.  I figure a dust collector should be one of your first purchases.  Forty years from now, if you can't breath, a dust collector will have looked like such a logical purchase!

   I don't have an extensive collection system.  I have one branch running to my table saw and one to my chop saw.  For my other tools I simply disconnect the chop saw and add a hose.  Not ideal but there's not very much dust in my shop, so I guess it works fine.

   BTW:  I'm using HVAC ducting on my 2 HP collector.  So far so lucky.  If it collapses, its easy to replace.

1. 
   mvac | Jan 18, 2005 05:49pm | #16

   Believe me, 'Splint, if I thought I could do it now, I would. I've borrowed someone else's planer (which, when I duct tape my shop vac's hose the the ejection port generates almost no dust), and don't have a bandsaw or mortiser either. While I get by without them, it costs me a lot of time to do that.

   As I said before, I never use any of my power tools without wearing my paint/fumes-graded dual-cartridge respirator and swithing on my 1200 CFM air filtration system. So, while imperfect, I think my lungs are keeping pretty clean with those precautions until I can step up to a real DC system. Also, from what several guys on this thread have said, it sounds like, as with most tools, you don't want to skimp on a DC system. So, because my wife and children insist on being fed and clothed (the nerve!), I don't have a choice but to wait. Still, your comments are greatly appreciated. I can't wait for the day when I can run my finger over most of my shop stuff and not come up  a ton of fine dust...

   Mitch

1. 
   woodensplinter | Jan 18, 2005 10:31pm | #17

   As long as you're not forgetting your lungs!

   Actually, I know exactly where you're coming from.  I didn't get my DC until the kids were all growed up and bought me one.  (I think the coughing kept them awake as kids.)

   Careful what you wish for.  If you're not making any sawdust your shop will be dust free.