Dust Collection System Design

Bigdog72 · 03-31-2008, 10:02 AM

I know that DC system design is a matter of personal preference but I still need some advice. I have seen dc trunk lines run overhead, under the floor (can't do it) and somewhere in between. My shop is 16x24 and I plan on running the main line at approx 36" off the floor with drops to all the main tools. I have a Griz 2hp dc with a separator. My question is, does the location of the line add to or detract from the efficiency of the system? If I run the line overhead will I gain anything? My reasoning for running the line at 36" is most of the line will be hidden in a recess behind the Norm's miter bench I am planning to build.

RandyJ · 03-31-2008, 10:18 AM

Geoff, I'm glad you asked this question. Sorry I can't help you because I have been wondering the same thing. It seems an overhead line would require more force to "lift" the sawdust up to the ceiling just to drop it back down to floor level

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I"ll be interested to see the responses here. Thanks for asking.

Glennbear · 03-31-2008, 10:27 AM

Good morning fellow NJ refugees, I will be running mine at ceiling level to conserve usuable wall space. As far as "lift" problems , I use a Delta 50-760 and the inlet is a few feet off the floor anyway so no matter where I put the line I will be either going up or dropping down at some point.

Alan in Little Washington · 03-31-2008, 10:54 AM

First question- have you read Bill Pentz site?

There is a lot of good info out there, and I am a long way from being an expert but have done a lot of research and put DC's in two shops. Here is info minus the technical jargon-

You need to decide if you are using a DC to collect chips and dust, or using it to collect chips and dust AND have healthier air in the shop. The last point is the tough one.

If you live in an area where you can discharge outside that is best for both issues. If you are using a DC with a bag (bad with regard to point 2) put the DC and bag outside. That helps with the noise too. What kind of separator do you have? A "true" cyclone is much more efficient at separating and better on flow than a trashcan separator. If you can, get a cyclone with cartridge filter(s).

As far as running pipe.

Use PVC (S&D, ASTM 2729- NOT BORG schedule 40!!!). The price, especially fittings, is cheaper than metal. DON'T glue it, you WILL reconfigure someday!!! TRUST ME ON THIS ONE!

Run 6" as far as you can, reduce only at the machine. Enlarge the machine outlets if you can and don't mind modifying your machine.

Use as little flex hose as possible.

Make all runs as straight as possible.

Limit turns since they impact efficiency. NO T's. Use wyes and 45's. Use 2 45's or long sweep 90's if you must.

Don't worry about multiple branches, what counts is the how straight the path is from each machine to the blower. With a 2 hp DC you'll only be using one machine at a time.

If your tools are along the wall, running the pipe at 36" off the floor should be fine and actually better than overhead- no vertical runs. Remember, wyes, not T's.

Build, don't buy blast gates- you can easily build them better and cheaper than commercial ones.

Bas · 03-31-2008, 11:24 AM

Geoff, it's all about minimizing the length of the run. Unless you have a 5HP cyclone, every extra foot counts. If running the main trunk along the ceiling is the shortest route, that's preferable.

But, you gotta go with what works. I ran the DC pipes in my basement shop along the wall, because I had to contend with the A/C trunk and drain pipe. Some I ran at ~3ft, others along the top of the ceiling. I did that to maneuver around the well tank. I would have preferred to run everything at 3' height, but sometimes, your shop makes the choice for you.

I suggest you make a drawing and figure out the best placement for the DC, and design the duct work accordingly. Running along the walls looks nice, but cosmetics should be the last consideration. I put my DC in the middle of two branches, again to minimize the runs.

I wouldn't worry about "lift". The shavings and dust are extremely light. Remember that going up requires more effort, but going down less effort. The two almost cancel each other out. Of course, a vertical movement usually implies elbows and turns, and that's what really impacts efficiency. It's hard to tell whether a 20ft run with 6ft of vertical travel (3 up, 3 down) and two turns is better or worse than a 30ft run with one turn. The math gets complicated. So don't worry about it

Far more important is to minimize the amount of flex hose, long corners (no 90 elbows) etc.

I have more info on my web site. Since you have a 2HP dust collector, you should seriously consider using 6" pipe for the main line. Lots of folks on this site that can advise on that.

JimmyC · 03-31-2008, 11:49 AM

Geoff,
What everybody is saying is good. I have the same Grizz DC as you and the 2hp is good for 1550cfm, but the only way your really going to get the most out of those 1550 cfm is by using 6'' pipe everywhere you can, making a good dust seperator to work with that 6" piping, and by using the filter on your system instead of the bags. The 6" works well with the Grizz 2hp and if you ever upgrade to a cyclone system its already in place.

I will be going with 6" hvac pipe ( I got it free, and no, it won't collapse, ask Travis), but for now my system is mobile. As everyone said, running the piping underground or overhead is only for convenience. The shortest runs and least amount of bends are what makes the system the most effective. The Bill Pentz site is very informative, but realize that he has lung problems and gets very particular about things that wouldn't effecta normal person as much.

Remember that the better the infrastructure (ie. piping) is set up now the easier an upgrade will be at alater date.

Jimmy

Travis Porter · 03-31-2008, 11:58 AM

My advice is to use the minimum amount of pipe and the minimum number of joints possible. Every joint and every foot of pipe counts. I would also recommend putting blast gates before you go to flex and minimize the amount of flex.

Bigdog72 · 03-31-2008, 02:07 PM

Thanks to all for some very good advice! Please keep it coming!

I have the system figured out for now. All I need to do is buy some pipe and fittings and go to work. I will add the cartridge when it arrives from Grizzly (sometime at the end of May!). I am to the point where I might even carry the camera out and take some pictures.

To those who suggested a cyclone in my future: All I can say is I doubt it!!

Travis Porter · 03-31-2008, 04:20 PM

If you are running metal pipe my prayers are with you. I did, and I cut my hands to pieces. Do not buy the joints (wyes, elbows, etc) at the BORG. Straight pipe is OK, but the joints are not designed for dust collection and will make your suction horrible.

If you go plastic, there are a lot of good threads on the site.

Bigdog72 · 03-31-2008, 04:40 PM

Originally Posted by Travis Porter

If you are running metal pipe my prayers are with you. I did, and I cut my hands to pieces. Do not buy the joints (wyes, elbows, etc) at the BORG. Straight pipe is OK, but the joints are not designed for dust collection and will make your suction horrible.

If you go plastic, there are a lot of good threads on the site.

Travis, Thanks for the heads up but I go with what I know (plastic)!

McRabbet · 03-31-2008, 10:30 PM

Jimmy/Geoff,

The Bill Pentz site is very informative, but realize that he has lung problems and gets very particular about things that wouldn't effecta normal person as much.

Once upon a time, Bill Pentz had no respiratory problems at all and it was fine dust that he was not capturing in his shop that caused his lung ailments. Many of the woods we work with have some toxicity -- some of us are more sensitive than others -- but removal at the source remains the best alternative.

I had a woman that worked for me many years ago invite me to meet her husband who was a true old school furniture maker. He made beautiful furniture -- carved four poster beds, chests, tall case clocks, etc., but he had no DC system and never wore a mask. He worked with Mahogany and Walnut and died 16 months after I met him from acute respiratory failure. I'm certain that fine dust caused it.

I'm a strong believer that the dust must be captured and the stronger a DC system, the better. 6" duct is a must and unless it destroys a machine, enlarge the dust port to accomodate a short transition with 6" flex to the blast gate. I also am a believer in making my own blast gates (although my ClearVue comes with 6 and I picked up 3 more from Trog777).

Jim Murphy · 03-31-2008, 10:38 PM

Originally Posted by McRabbet

... 6" duct is a must and unless it destroys a machine, enlarge the dust port to accomodate a short transition with 6" flex to the blast gate.

Rob, are you gonna bore out the port on that green saw?

Or use 4" below and 2" to the overblade?

McRabbet · 04-01-2008, 12:51 AM

Originally Posted by Jim Murphy

Rob, are you gonna bore out the port on that green saw?

Or use 4" below and 2" to the overblade?

I'm building a new port from 1/2" Baltic Birch that will replace the plastic 4" port held on with a few sheet metal screws. I'll make it with a 90 degree turn and a built-in blast gate and flex connector toward the rear of the saw to keep it out of the way. It will need to fit under the motor bumpout on the left side of the saw, shown here:

I'm trying to conjure up some control rods to be able to pull/push the blast gate open/closed with a simple handle near the shut off switch (there is about 2-1/2" of clearance between the motor box and the left extension wing).

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