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Dust collection help - Michael Dow - 07-09-2019

I was able to do a major upgrade from a Harbor Freight DC (running through a Dust Deputy) to a Grizzly G0440. Craigslist was VERY good to me.


Prior to the upgrade of machine, I basically ran a hose to whatever machine I wanted to use. However, now that I have a "big rig" DC, I want to run ducting in my shop/garage. It isn't a complicated setup, really, but I want to get it "right".

The main input line for the DC is 7". You can buy the 'snap' ducting from Home Depot (et al) which is 30 gauge steele. These run about $12 for a 7"x5' length. The piece parts are also similarly priced.

While the G0440 isn't a monster, per se, I wonder if using cheap ducting like mentioned above isn't a mistake? It is *very* leaky stuff (which, I suppose, I can cover up with LOTS of aluminum tape) and is also quite weak.

I've looked around at various options for the "spiral" pipe (a step up in strength and air permeability) for at least the main runs. 22 gauge industrial grade spiral piping is $44 per 7"x5' length, but there is a 26 gauge hobbyist grade option (see airhand.com) that puts it at 31.75 per 7"x5' length. Yes, its spendy, but in reality will only cost about another $120-$150 over the "cheap stuff" to do my shop.

Does anyone out there have knowledge of such things to steer me into the right direction?


RE: Dust collection help - Turner52 - 07-09-2019

I reduced from 8"to 6" right out of the collector. I used sewer and water pvc. Works great. No air leaks. Used 45 degree bends instead of 90 degree. Longest run about 40'. Did NOT ground the pipe. In a little over 10 years, since installing it this way I have NEVER gotten a shock of any kind.

RE: Dust collection help - meackerman - 07-09-2019

I have both PVC pipe and HVAC pipe in my 3hp DC system.   I also reduced it straight off the DC to 6" main runs, then 4" runs to each machine, then possibly smaller depending on the particular machine.

Never had any problem with either pipe type being crushed.

RE: Dust collection help - EdL - 07-09-2019

My Oneida has an 8" inlet, I did 5' of 8" reduced to 7' for another 5' in spiral pipe, then 6" s&d pvc for the rest of the piping.
Reduced at the blast gates to 4" flex to connect to the machines.

Works great, no complaints.


RE: Dust collection help - Lumber Yard® - 07-09-2019

I reduced my G0440 from 7" to 6" right out of the inlet with a rubber reducing coupler. I then ran 6" S&D PVC mains and reduced to 4" at the machines. The 10' sections of pipe are cheap the fittings not so, much. The rubber coupler and most of the PVC fittings are available at a big box. The actual S&D PVC pipe I had to order from a plumbing supply store. Just another option.

RE: Dust collection help - fredhargis - 07-10-2019

To pile on, I'd also suggest 6" for the runs. With the Oneida I used to have they (Oneida) suggested about 5' of 7" into the inlet before reducing, which I did, something about the air flow was better (according to them). But I'd stay with 6", and if you go snaplock stay with a heavier gauge. Not only yo prevent the sometimes reported collapse, but it's just a little sturdier in the shop environment (dents, bangs and such). All the eams will need to be sealed with foil tape; or just go with PVC. (Thinwall 6" PVC can be a little hard to find.)

RE: Dust collection help - TDKPE - 07-10-2019

(07-10-2019, 06:23 AM)fredhargis Wrote: Not only yo prevent the sometimes reported collapse . . .

I use the really thin 6" HVAC duct, but my HFDC can't pull more than about 10" WC worst-case, and that's not enough to collapse a 6 ft section.  The long sections are more prone to collapse than the 2 ft lengths because each connection acts as a reinforcement.  But if/when I go to a larger blower, the main trunk will have to be upgraded.

RE: Dust collection help - Michael Dow - 07-10-2019

On another woodworking-related forum, someone suggested that I read the Bill Pentz site (something I knew years ago, but in my dotage have forgotten about!) regarding ducting. See: https://www.billpentz.com/Woodworking/Cyclone/ducting.cfm

Just putting it here for all to see, in case they didn't know it was out there. It is a veritable wealth of information, and it has helped me make the decisions I need in moving forward.

Thanx, All!

RE: Dust collection help - Michael Dow - 07-10-2019

From another forum:

I've gotten others (on another forum) who have stated they didn't go the route you mentioned, rather they reduced to 6" PVC immediately out of the DC and reduced to 4" lines fairly quickly. Then there are yet others who have recommended a mixture of the two (metal vs PVC, reduction "out of the DC"). My thinking is that I wouldn't want to reduce to 6" lines until after the first branch, and reduce for 4" lines for the down-drops.

Maybe I'm being too picky about "leaky" systems and the aesthetic of the spiral pipe vs. snap-steel vs pvc (thin wall or schedule 40).

My set up will basically be:

1) 15-18' run across the "back wall" of the shop which will service:
A) a small line to my bench (against a wall)
B) router table (Triton TRB001 2" dust collection hose)
C) radial arm saw,
D) 18" band saw.
-[The "small line" will be a sweep-type opening for brushing stuff into
and a 2" line for small cleanup]
-B and C will likely be a "Y" where both are either open or closed for air movement purposes.

2) a 10-15' run to the center of the shop which will service the Robland X31.

3) Somewhere in there I need to put in a floor vent for cleanup.

So I would think the following would be the starting point:

.....................Robland, 4" drop
. ....................6"
|DC |---7"----Y-----6"------T---------T---------X

(The periods are to be ignored -- they are there for spacing purposes only.)

Where the "T"s are each 4" 45 degree angles into flex hose. The flex hose runs will be about 6-8' each, coming from roughly rafter-height where the 6" line is. The "A" is a 4" Y 'splitter' that will either be both-open or both-closed (via a gate) to feed the Radial Arm saw and router table. I have these both open due to the restricted air flow from the router table and its expected decrease in efficiency. The "X" at the end of the run will be a "gradual 90" to 4" line to feed the bench sweep, and I'll put a 2" "Y" near the "bottom" of the run for the vacuum hose line.

Theoretically I could switch to PVC at the 6" runs. Savings would be measurable, but I'm blessed with a good budget. Is there an advantage (other than price) by switching to PVC?


I just read the Bill Pentz site article on Ducting (Thanx, Stick!) https://www.billpentz.com/Woodworkin...ne/ducting.cfm and it covers ALL of this stuff.

Stick, your initial advice is SPOT ON with that article in mind. I think my design idea (made before reading that article), with the thought of using the 26g spiral ducting, is correct.


I'm sure I'll come up with more stuff to dither about...


RE: Dust collection help - WxMan - 07-10-2019

Having recently set up my first DC system, and dealing with leaks, I don't think it's possible to be too picky about leaks.  Only takes a few small leaks to really kill the efficiency, particularly in the cyclone separator and how well it operates.