Replies

1. 
   TJB | Dec 26, 2005 05:15am | #1

   Check out http://billpentz.com/woodworking/cyclone/index.cfm

   They have a good article about what you are trying to do.

1. 
   Danceswithwoods | Dec 26, 2005 08:53am | #2

   Thank you TJB.  That is what I was looking for and more!  A lot of good info there and I intend to follow it.

2. 
   DougF | Dec 28, 2005 10:47pm | #3

   There is disagreement about the need to ground PVC and most of the articles I have reviewed basically say that fires/explosions in DC's using PVC were almost always the result of sparks caused by metal objects striking the impeller.  Several experts have gone so far as to label the need to ground PVC as an "urban myth".  But, grounding PVC certainly won't hurt anything.

   To get the best performance from you DC, I think you would be better off running a main line of 5" or 6" PVC or sewer pipe then branch to 5" to as close as you can to the machines and then run your 4" flex to each machine.  I seem to recall that Lowes carries 5" sewer line and fittings.  It is lighter, cheaper and works every bit as well as schedule 40 PVC.  You want to achieve the right balance of air flow (CFM) and particle suspension.  To large of a line that particles will fall out before they reach the the DC.  However, running all 4" line will increase the static pressure (resistance) - not good.  Bills web site goes into this in much greater depth. 

   Try and locate the blast gate as close to the 4" port on each machine as possible.   The blast gate is restrictive since the inside diameter is smaller than the line diameter and the basic construction causes turbulence so the closer to the dust and chip source the better.  On the really heavy chip producers, the joiner/planer and the planer, try to run it all on 5" lines, ports and gates and locate the planer as close to the DC as possible.  This will get you better performance. 

1. 
   Danceswithwoods | Dec 29, 2005 12:43am | #4

   Doug, 

            Are you saying that I should up the diameter from the four inch ports at the collector to five inch pipe to the machines?  It seems to me that may lessen the power of the vacuum.  I won't be setting this up until mid-Jan. at the earliest and haven't read all the info in the previous posting to make all the pertinent decisions yet but I do intend to and also take advice from users as yourself and others.  P.V.C. is out and sewer line is what the material will be.  Thank you, Tim

1. 
   VanderLaan | Dec 29, 2005 01:08am | #5

   I struggled with this last summer and I eventually used 6" sewer and drain pipe (green) from Lowe's and built my blast gates as detailed here on this site.  http://benchmark.20m.com/articles/BlastGate/blastgatebuilding.html 

   According to Bill Pentz, running 4" sections from your machine to 5" or 6" pipe essentially negates using the larger pipe at all.  I am not an air engineer, but it makes intuitive sense if you think about it.  That said, I ended up cutting 6" holes in all of my machines and used HVAC starter sections and tempered hardboard screwed to the openings.  I also used 6" flex tubing and connected it to the 6" wyes and 45s.   It works like a charm.

   When you lay out your runs, be sure to minimize the length as best you can and avoid using any 90s - better to use several 22.5s for a wider turn.  I also made an effort to locate the gates as close to the collector as I could.  

   Good luck and let us know how it goes.

   Best-

   BVL     

1. 
   Telemike | Dec 29, 2005 08:37am | #6

   The reference for blast gates tells how to make a closed end blast gate. I've made too many of these. Now my blast gates are open at both ends and the gate has a circular hole the size of the tubing that connects to the gate. A gate with three closed sides and one open has slots that trap dust and shavings. Quite quickly the gate hits the packed dust in the closed end and doesn't close completely until you clean it out. I've got a tool I made from 1/16" steel strip that I use to clean the trap on the gates but the newer gates (open on two sides) work much better. I'll take some photos and post them on friday or this weekend. We going to the mountains tommorrow since it seems to be the first and only hole in the storms for some time.Also, putting stickum felting on one side of the gate body (towards the DC) helps seal the slider.

1. 
   VanderLaan | Dec 29, 2005 06:08pm | #11

   Actually, the reference makes it clear that you should not close off the end of the gate for the exact reason that you mention.  Specifically, it states:

   The most common error I've seen in magazine articles that describe how to build a blast gate is that they close off one end of the thing.  It is VERY important to NOT to do this.  When this is done it guarantees that this pocket will eventually become filled with compacted dust and the gate will not completely close resulting in a pressure drop in the system.

   That said, I am always interested in learning new ways to do things, so I will keep an eye out for your pics.

   Keep safe-

   BVL

    

    

2. 
   BarryO | Dec 31, 2005 11:50pm | #12

   According to Bill Pentz, running 4" sections from your machine to 5" or 6" pipe essentially negates using the larger pipe at all.  I am not an air engineer, but it makes intuitive sense if you think about it.  That said, I ended up cutting 6" holes in all of my machines and used HVAC starter sections and tempered hardboard screwed to the openings

   I wonder why you did that.  If you look at Bill's site, the main reason he recommends 6" pipe is that some tools need 800 CFM to capture fine dust.  But if you look at the table he has for CFM requirement for various tools, almost all those that need that much CFM use 2 pickup points - for example, a table saw, which has one on the cabinet and one on the guard.  About the only tool with only one pickup point that needs more than 400 CFM is a big planer.  For the tools with two pickups, the 6" pipe would branch into 2 4" pipes (4" can support 400 CFM).  So I don't see the need for enlarging the holes on most tools, although it can't hurt.

    

2. 
   DougF | Dec 29, 2005 05:51pm | #10

   Tim, there is a fairly common misconception that by reducing the size of the pipe/line you increase suction and more suction means moving more material. right?  No so - you need to have sufficient air movement to lift and sustain the chips and particles over the entire run of the line.  Maintaining adequate CFM is a balance of the size and design of the impeller, horsepower, the diameter of the line, the line material (flex hose has more friction, PVC less friction) the length of the run, the number of turns/curves, the radius of the curves (sweeping gentle curves produce less friction) and the port size at the machine.  The overall design needs to provide sufficient CFM to each machine to remove that machine's maximum chip/dust output and keep it moving until it reaches the waste container or bag.   

   For example, a 13" bench-top planer needs the most CFM or any tool in most shops.  Odds are pretty good a 4" port on a 4" line will plug real fast when planing a 10" board unless you are taking microscopic cuts.  Running a 6" port and line will handle the output with little or no problem.  A 5" line and port is problematic for larger boards.  That is also why I recommended placing your highest output machines the closest to the DC to minimize the friction caused by turns and length of the run.   

   Doug

1. 
   Danceswithwoods | Jan 01, 2006 11:47am | #13

   I don't know if I had made this clear in the initial post, but the ports on the "Y" coming from the "squirrel cage" are 4" diameter (I believe, if memory serves me correctly (( Been so busy that I haven't even opened the box yet)).).  So I'm definately not going to decrease the size and I don't want to increase it as I believe, as has been stated, that the suction efficiency will decrease.  I've seen this with my shop vac when I put a larger wand/tool on the end of the hose.

   I've also read about setting up a "cyclone" to dump the larger chips before they contact the fan.  I believe I have a good idea on how to apply this from the designs I've seen.  Any thoughts/experience with this from anyone?

     Boy, am I sure glad I didn't go about setting this up immediately.  It seems the longer I wait, the better this set-up will be (I hope).  Thanks all, and a happy, safe, and creative new year to you!..Tim 

   P.S.  I've been wondering if there is such an animal as a 4" ball valve and if this would be a more efficient gate if one does indeed exist?

   Edited 1/1/2006 3:50 am ET by Danceswithwoods

3. 
   USAFRet | Dec 29, 2005 09:21am | #7

   Hey Tim;

       Personally, I don't think there's enough dust in one of those bags to cause a real explosion.  A grain silo, yes.  A little teeny 40 gallon bag, no.  But I've tempted the Gods before and lost every time so I grounded my system.  I guess it's a matter of faith :)

   BTW...you know me from another forum...JohnS

   regards,

    

   John

4. 
   jigsawjohn | Dec 29, 2005 05:04pm | #8

   Why not use galvanized like our woodcraft store did? then you are grounded from the start. can anyone respond I am also going to set up a system this month.

   JigSawJohn
1. 
   DougF | Dec 29, 2005 05:13pm | #9

   Cost - galvanized is more expensive.