Dust Collection Questions

[brian lanning]

As if the $799 uni and the $223 incra fence wern't enough, I decided to get the dust collector. The one on sale is 4800cfm and 5hp compared to my current 1100cfm and 2hp. So four times the suck, if you can quantify such a thing. :cool:

The new one has a 10" inlet port with a manifold (is that what it's called? reducer?) that brings it down to four 5" ports. So I have several options:

1 - I could run 10" ducts to all the machines, get 10" blast gates and covert all the DC hookups to 10" (haha)

2 - I could use the 5" reducer thingy and keep three of them plugged. Then run the fourth with 5" blast gates to each machine. I would then need to either reduce the 5" hoses further with an adapter or make/buy adapters on the machines that work with 5" hoses.

3 - Immediately reduce the 5" ports to 4" and run 4" hoses with 4" blast gates everywhere. This is the cheapest since I have a lot of 4" flex hose and 4" s&d pipe.

4 - Run 5" or 4" with a reducer to each machine and quit worrying about blast gates.

5 - Find a 10" to 6" reducer and run 6" pipe/hose to all the machines with 6" blast gates. This seems like the option that makes the most sense to me.

More points: I'm unlikely to ever run more than one machine at a time. But in the future, say over the next five years, my older kids could easily start woodworking, so the extra capacity could be nice. Also, the DC runs are likely to be short since I'm going for the centralized DC shop layout with machines orbiting rather than running DC pipe along the walls to a DC in the corner.

And lastly, what do I do with my old DC machine? I'll probably sell it and use the money to buy 6" (or whatever) hose, clamps, and blast gates. Any reason to have two?

Here's my old one:

http://www.amazon.com/Delta-50-850-Horsepower-Vertical-Collector/dp/B0000223BE



brian

[Richard Keller]

Option 2 won't work at all. The most you can pull thru a 4" pipe is about 800 cfm, so you will waste your new purchase.

Option 3 would be a good "stop gap" solution. If you have more than one port on the DC open, it will work fine and let you use all the materials you already have.

The *BEST* thing to do long term would be to run a 10" header across your shop and simply drop out to your machines with 4" or maybe 5" for the planner, and 6" (or two 4") if you have a big thickness sander.

Richard.

[brian lanning]

Option 2 won't work at all. The most you can pull thru a 4" pipe is about 800 cfm, so you will waste your new purchase.

I read somewhere about someone running 6" hose to their machines. I'll have to dig to see if I can find it. iirc, they had to make new adapters for their machines, but it worked well.



Option 3 would be a good "stop gap" solution. If you have more than one port on the DC open, it will work fine and let you use all the materials you already have.


Where I am now is sort of temporary. We're planning to buy a place with enough land for a separate shop. So maybe I should be doing the quick and temporary thing until I can put a real pipe network in a real shop.



The *BEST* thing to do long term would be to run a 10" header across your shop and simply drop out to your machines with 4" or maybe 5" for the planner, and 6" (or two 4") if you have a big thickness sander.

A drum sander is next on the list in a few months. I had been worried about dust collection since my current DC feels gutless. I have the grizzly DJ-20 clone and the DC isn't enough to get everything. I also hear stories about people getting plugged hoses from their planer when they run through wide boards. The widest I've sent through is about 8" and it hasn't plugged. The large diameter hose would help there I think also.

I also noticed that some of the larger drum sanders have multiple DC hookups. This DC should make that not a problem at all.

Thanks for the input.

brian

[Rod Sheridan]

Hi, if you use a 10 inch header for the shop and then use 4 inch or 5 inch drops to the tools, you will have a problem unless you run a large number of tools at once.

If you have the correct velocity to keep the dust entrained in the airstream in a 4 inch pipe (3,000 to 4,000 FPM or 261 to 349 CFM), and then run that into a 10 inch pipe, the velocity will drop to 480 to 640 FPM, and all the dust will settle out in the duct.

To achieve 3,000 to 4,000 FPM in a 10 inch duct will require an airflow of between 1,636 and 2,181 CFM. This would require slightly more than 6 four inch pipes open at one time to clear the dust in the pipe closest to the collector, farther away the pipe would have to be reduced in size to keep the velocity in the correct range.

5 inch pipe works out to 409/546 CFM, or 4 pipes open at once.

You are certainly better off running the correct size pipe to each tool, assuming that your collector will really deliver that airflow at a reasonable static pressure. I would check the fan curves bedore doing any calculations.

Most 5 HP collectors will only develop about 2,000 CFM with any static pressure, so as I indicated above, check your fan curves with filter attached, to begin the duct design process.

Regards, Rod.