DC ducting advice needed...

[Jim Green]

Hi all,

I'm new to this forum and I’m looking for some advice (actually, answers to the questions below). I’m a hobbyist and I have been fortunate enough to be able to buy a Jet 1.5HP DC from a friend for next to nothing and I’m planning to hook it up shortly. I have done some homework by reading some articles online as well as some threads on this forum. My workshop is in my basement so I think the DC should be an improvement over the existing shopvac that I wheel from one machine to the next.
I have the following machines:
§ Table saw (contractors type)
§ Router table
§ Miter saw
§ 13” planer
§ Band saw
§ 16” drill
All but the drill is along one wall. I plan to run the main duct (6” PVC, grounded) along that wall.
Here are my questions, bear in mind that most of this I have picked up from my nosing around various web sites:

• Is there any real advantage to running the main duct at machine height rather than overhead and using drops?
• I’ve read that blast gates should be close to the machine but is that really an advantage? Strikes me that closer to the main duct would make more sense?
• Should the connections from the main duct (using flex hose) be 6” or 4” as most of the connectors at the machine ends are 4”?
• If the blast gates should be close to the machines and I do run 6” flex hose to the machines, would it make sense to get 4” gates if I’m reducing to 4” at that point anyway? I may in the longer term get around to converting some of the hoods to 6”…
• As I got the DC itself so cheap, I might buy a canister kit (it’s the bag sort). Worth the $200 to do it?

I think that’s about it – thanks in advance.

Jim.

[Eric Wong]

Welcome to the Creek!

I'm sure you'll get lots of answers, but here are mine:

>Is there any real advantage to running the main duct at machine height rather than overhead and using drops?
Not that I can think of, except that you might be able to keep your runs shorter if they are at tool height.

>I’ve read that blast gates should be close to the machine but is that really an advantage? Strikes me that closer to the main duct would make more sense?
I don't think it matters too much. Just put them where you can easily reach them.

>Should the connections from the main duct (using flex hose) be 6” or 4” as most of the connectors at the machine ends are 4”?
Best airflow would be using 6" all the way to the machine, and fitting 6" hoods on your machines.

>If the blast gates should be close to the machines and I do run 6” flex hose to the machines, would it make sense to get 4” gates if I’m reducing to 4” at that point anyway? I may in the longer term get around to converting some of the hoods to 6”…
Blast gates are pretty simple to make, and so are most hoods. All you need is some plywood and some thinwall 6" PVC.

>As I got the DC itself so cheap, I might buy a canister kit (it’s the bag sort). Worth the $200 to do it?
Generally, a cannister is better than a felt bag, which is better than a 30 micron (stock) bag. I'm in the camp that says its always worth it in the long run to spend money on protecting your lungs. But not everyone agrees with me.

[Joe Chritz]

Do a search for Bill Pentz and read his stuff on Dust collection.

Very good stuff and well worth the time.

The above answers are correct as far as I know as well.

Joe

[Jim O'Dell]

Joe, let me correct this for you:

Do a search for Bill Pentz and read his stuff on Dust collection.

Very good stuff and well worth the lifetime it will take to read.

The above answers are correct as far as I know as well.

Joe

Just kidding!!! Joe's right. Excellent information there. It is VERY comprehensive. Jim.

[John Miliunas]

Jim, great coverage for your questions, thus far. Additionally, the canister filter will not only help your lungs but, because it has far more surface area for filtering, it will also help in the "suckability".

Also, unless you're really touchy about getting a little static tingle every now and again, (like wool socks across a rug & touching a door knob) save the time/money from grounding the PVC. If you're doing it to "prevent" a static-induced fire, the fact is, there's not enough static produced in a typical home DC to produce a spark large enough to do that. Plus, most folks "ground" the PVC around the outside of the pipe. If you're intent on preventing static for fire prevention, the grounding HAS to be on the inside of the PVC duct.

Largest diameter ducting the DC will handle to as close to the dust collection point as is practical. Keep any flex tubing to a minimum distance. I have found little difference in exactly where the blast gates are in a run, though I imagine there's a reason for various methods. If the duct is not in the way, keep it as close to the level of the machine as is practical; Eliminating or minimizing the amount of "lift" the DC has to do, will make the system a tad bit more efficient. Limit all bends to 45° or real wide 90° (for instance, run a 90° using two 45's) whenever possible. Install an extra "Y" somewhere toward the end of the run for possible expansion later on, as well as having a point for clean-out, "just in case".

[Bob Dodge]

[quote=Jim Green]Hi all,

• Is there any real advantage to running the main duct at machine height rather than overhead and using drops?

Yes, there is an advantage, especially with a smaller dc. You'll save up to three 90 degree bends, as well as pipe length. You won't need a riser to get to the ceiling from the dc, and you won't need a drop-pipe at the machine. Furthermore, a horizontal 6" pipe, only needs 3500 FPM velocity, which translates to 685 CFM. If you use a 6" ceiling-drop, you'd have to flow a minimum 785 CFM to adequately feed that drop-pipe. There's not a chance that a 1.5 HP Jet will get you there unless you have a short run, and your machine has a 6" port, or a pair of 4" ports.

• I’ve read that blast gates should be close to the machine but is that really an advantage? Strikes me that closer to the main duct would make more sense?

Put them at the most convenient location. When a duct is cut-off, it doesn't matter where that blast-gate is.

• Should the connections from the main duct (using flex hose) be 6” or 4” as most of the connectors at the machine ends are 4”?

If you insist on using a 6" main to your machines with single 4" ports, use a 6" take-off at the main, then reduce to a 5" drop-pipe. Reduce to 4" directly at the hood. Do not use several feet of 4" flex at the hood, then a blast-gate. Your 4" flex will provide too much resistance, and you won't adequately feed the main. Don't forget, that 6" main always needs a minimum of 685 CFM flowing through it.

Frankly, you might be better off running a 6" main only as far as your largest machine, then a 5" main to your machines with single 4" hoods. When I say largest machine, I'm thinking your tablesaw, with twin 4" ports.(saw-base, and an overarm blade-cover). If you're not going to use an overarm blade-cover, then a 5" drop is fine. I'd HIGHLY recommend a good OA-BC. and a 6x4x4 drop.

• If the blast gates should be close to the machines and I do run 6” flex hose to the machines, would it make sense to get 4” gates if I’m reducing to 4” at that point anyway? I may in the longer term get around to converting some of the hoods to 6”…

Your blast-gate, should be the same diameter as your drop-pipe. 5" drop = 5" gate.

• As I got the DC itself so cheap, I might buy a canister kit (it’s the bag sort). Worth the $200 to do it?

If you want a VERY good filter that's low on maintenance, and easy to keep clean, get yourself a pair (upper and lower) of high-quality 16 oz. needle-felt filters. The absolute best deal on the real McCoy, is via Process Systems. They'll sell you a pair of standard-size or custom oversized filters, at an incredible price. As I recall, standard-size will run you roughly $69. / pair. This is a sensational price for this quality of filter. Process Systems is a manufacturer who sells direct. I believe they charge something like $20. more for custom-oversized filters.

http://www.processsys.com/dust.htm

Bob

[Eric Wong]

Ditto on Bill Pentz's website:

http://billpentz.com/woodworking/cyclone/Index.cfm

He's one of my heroes