Hard Ducting For The HF 2HP DC

[LarryG]

Has anyone ever tried using 5" stove pipe?

Partially answering my own question, I now see that Penn State Industries has a line of "Economy Metal Ductwork" that is nothing more or less than ordinary metal stove pipe by another name:

http://www.pennstateind.com/store/deco.html

(Prices are about DOUBLE what I saw at HD last night, though. Ah, marketing!)

The intro page says "Recommended for dust collection systems with less then 10" of maximum static pressure." What does that mean for those of us who have the usual hobbyist-type 1HP-2HP DCs from HF, Grizzly, JET, Delta, etc? Loring?

[ssmith1627]

Well that site certainly has all the parts in the various sizes. Has anyone used their stuff ?

My challenge is still getting rid of the long runs and re-grouping the tools so that one doesn't interfere with another but also so that the ducting for one tool isn't in the way while you're using another.

Who knew this would be the hardest part of the shop layout ??

Steve

[rsjimenez]

I have included some pictures of the runs in my shop with 4" PVC pipe and I have not had any problem. I probably have 40' runs.

[LCHIEN]

Partially answering my own question, I now see that Penn State Industries has a line of "Economy Metal Ductwork" that is nothing more or less than ordinary metal stove pipe by another name:

http://www.pennstateind.com/store/deco.html

(Prices are about DOUBLE what I saw at HD last night, though. Ah, marketing!)

The intro page says "Recommended for dust collection systems with less then 10" of maximum static pressure." What does that mean for those of us who have the usual hobbyist-type 1HP-2HP DCs from HF, Grizzly, JET, Delta, etc? Loring?

The point being that if you have more than 10" of static pressure capability from your DC, if you accidentally close off all the blast gates, then there is a danger this ducting may collapse, this based upon the relative strength of the walls of the ducting

i think its safe to say the HF DC and other eunits of similar size and power can't put up more than 10" of static pressure. Probably more in the 6-8" range.

[Tom Miller]

i think its safe to say the HF DC and other eunits of similar size and power can't put up more than 10" of static pressure. Probably more in the 6-8" range.

Then again, I think this might be getting close to borderline. My DC spec is 11" max static pressure. Considering that the marketing hyperbole of the DC and of the piping would tend to cancel, I'd probably steer clear of the stuff.

Regards,
Tom

[Kristofor]

Considering that the marketing hyperbole of the DC and of the piping would tend to cancel, I'd probably steer clear of the stuff.

Regards,
Tom

LOL, I like that... Is that the distributive property of marketing hyperbole? Sort of the opposite of the subtractive property of marketing hyperbole where compressors come up short on CFM ratings, and air tools really want more than what they claim?

Kristofor.

[SVO]

Two Cents

The HF "2 HP" "1600 CFM" is about 550 CFM in the real world. To keep the best balance of airspeed vs turbulance in the pipe, that volume would indicate 5" pipe. Remember a 5" pipe has a 55% larger cross section vs. 4", and 44% smaller than 6". That is a difference too large to dismiss or fudge (assumming you work in a space that shares HVAC with a home or has to be enclosed much of its operating time and you don't religiously wear a mask).

So, those of us looking to home brew an inexpensive solution are stuck with purpose-built metal fittings (5" PVC or S&D pipe is an urban legend) and fussier connections and splices. But that's the hard reality. The snap pipe from home centers will probably serve fine, but the wyes and Ts are not suitable. A good source is Kencraft (google it) for fittings. The blast gates sold by Lee Valley are a notch above and no more expensive than most sources.

I am in the middle of this myself, having built a custom designed cyclone powered by the HF motor and impeller (Pentz/Wood Magazine hybrid). I will be running 5" metal pipe to the machines and then branching to 4"/3" (same cross section as 5") and then the 3" will have to be reduced to 2.5" flex at most machines (BT3100, eg). But that should collect fine dust for the machine types I have.

Bear in mind that the 800 CFM at the machine Bill Pentz recommends is for cabinet saws and other types that have large gaps and openings in the frame and base. If you use well-designed baffles and shrouds (and this site is a good source for examples) and have machines with decent collection designed-in (BT3100 vs cabinet saw), then a much lower airflow can still be highly effective, IMHO. In other words, you have to use finesse and care if your collector system lacks top-end power and capacity.

I personally would also factor-in the hours of use anticipated. If you regularly undertake extensive projects that involve, say, twenty hours a week or more in the shop, then a 3 HP Oneida system is proably justified. And while DCs are neither sexy nor exciting, I personally believe the rest of the shop and budget should be designed around them. With Craigslist providing an excellent venue for cashing-out of tools that don't fit a careful DC shop scheme, there is no excuse to do it half-arse. I actually sold a fine cabinet saw and am replacing it with the combination of a BT3100 and a Festool rail/plunge saw/table system. The Festool system will be used to cut-down sheet goods outside, and the Ryobi can handle everything from there.

Oh, and commercial systems are designed with pipes of various cross section sizes (large trunks and smaller branches) because multiple machines are typically used simultaneously. This approach maintains the proper air speed throughout the system. As home/hobbyist systems essentially never have more than one machine operating at a time, all the duct should be the same diameter throughout because there is effetively a single pipe in use, machine to impeller, at any time.

FYI: I'm a competitive cyclist and have small children under the same roof as my shop, so I am very sensitive to the lung health issues and have done a lot of reading.

[BizCoach]

SVO,
You say that DCs are neither sexy nor exciting. Yet it's amusing that since I've been following woodworking forums (about 3 years) in several different web sites, one pattern I've seen consistently is that threads about dust collection are the longest by far. Somebody must think they're cool.