Hard Ducting For The HF 2HP DC

[LarryG]

A question for the engineering types, and those more familiar with Bill Pentz's web site than I am.

I have a Harbor Freight 2HP dust collector, currently in stock form. An upgrade to a Wynn cannister filter is imminent.

In my current shop, the tools are all closely grouped and I am able to connect them to the DC with 4" hose in lengths not exceeding about 15 feet, including all fittings, blast gates, etc. Now I'm about to move my shop into a different, larger building, and would like to upgrade to hard 4" ducting for as much of the runs as I can.

The sketch below shows the worst-case branch. Leaving the impeller, the pipe will need to extend up 6' to the ceiling, then laterally 11', then drop down 4' and terminate 3' above the floor. At this point a piece of 4" hose, not to exceed about 6' in length, will make the final connection to the tool:

So that's 21' feet of hard 4" pipe, and 6' of 4" hose, for a total run of 27' feet.

My question is: will the 2HP HF unit perform adequately with a setup like this? I realize it won't move enough air to get all the fines that Pentz wants a DC to collect; for that, I'd need a bigger impeller, and a bigger motor. I'm just wondering if the performance should be at least as good, or even better, than the current all-hose setup I have now.

If anyone has a similar setup, or can run the numbers, I'd be grateful ...

[Russianwolf]

Hey Larry,
While I can't answer your question directly, I can say that I am currently running the HF DC (stock) with a trash can seperator and 20+ foot run of flex tubing for my longest run (planning on going to hard at some point myself to reduce jams) and it picks up all the chips at that length without a problem.

My total is 3 foot to trash can, 4 foot to ceiling, 20 foot ceiling run, and 8 foot drop to floor. It may compact a bit but I think I have at least your 27 foot covered.

[LCHIEN]

Larry, you may want to use two 45's instead of one 90° elbow at each corner to reduce loss due to the bending.

I've looked at those Pentz curves assuming 800 cfm for the HF DC which might even be optimistic after seeing reports of measurements vs. mfr. ratings in different DC reviews. And it would indicate 5" ducting for most reasonable lengths of hard runs. Trouble is, it's hard to find 5" ducting parts and 4" is too small and 6" is too big.

Anyone else read Pentz's charts and tables that way?

Maybe the thing to do is to get the first half run at the DC in 6" and then neck down to 4" for the last half run to the machines.
Or the same thing but using all 4" parts, run twin 4" lines to a plenum box halfway to the machiens then 4" lines from the plenum box (with gates perhaps) to the machines.
That'll get your velocity high at the machines but keep the overall pressure losses lower and the total CFM higher.

[IBBugsy]

Hey, Larry!

I have approx. the same setup in my garage. I have a trash can separator right before the DC. The last bit of hose is a 4" tube to the BT3100 dust port and a 2.5" tube to the shark guard. The saw is directly under the hard pipe so the hoses are only about 3 foot long each.

I'm a novice at WW but I'm also a neat freak. If I only make a handfull of cuts this way, I don't even have to vacuum up afterwards with the shop vac! The other use so far is just using the 2.5" hose as a area vacuum port (just keep the hose near what I'm cutting or drilling and the velocity picks up the loose chips).

I don't have any big-time sawdust makers (planer, jointers, lathe, etc.) so no experience there.

My next experiment will be trying to hook a router dustport to this. I might have to drop to the shop vac due to the approx. 1" opening on this dustport but I'm hopeful the DC will do it.

[Tom Miller]

Maybe the thing to do is to get the first half run at the DC in 6" and then neck down to 4" for the last half run to the machines.

As Loring knows, though, it's not so straight forward to do this, since you have to maintain a minimum velocity to keep chips/dust entrained. IIRC that minimum velocity is ~3500 fpm. To get that in a 6" line requires ~700 CFM, which would be pretty difficult to match in the 4" line. You'd have to open up another 4" port in the 6" line to get enough flow there, but that'll affect the other 4" line, etc. etc.

FWIW, my longest run is ~26 feet of 4" S&D, with ~5ft of flex hose on the end. The hard pipe makes three 90* turns, passing through several wyes along the way. At the end, I swap the hose between my jointer, planer, and DP. The DC is a Grizzly 2HP, with ~1um bag on top, and a plastic bag on bottom. I'll leave it to you to compare that to the HF with cannister, but since they're both very popular systems you might find some hard info out in cyberspace.

I feel like I get 100% collection from the jointer, and at least 95% from the planer (using the planer's 4" pickup from the dust hood).

So, if you have enough DC on the end, I think the 4" line you're proposing can do a reasonable job of keeping the shop clean. Maybe the figure of merit should be MTTS (mean time to sweeping).

Regards,
Tom

[LCHIEN]

As Loring knows, though, it's not so straight forward to do this, since you have to maintain a minimum velocity to keep chips/dust entrained. IIRC that minimum velocity is ~3500 fpm. To get that in a 6" line requires ~700 CFM, which would be pretty difficult to match in the 4" line. You'd have to open up another 4" port in the 6" line to get enough flow there, but that'll affect the other 4" line, etc. etc.

...Tom

yeah, there's no easy answer short of getting a larger DC or custom pipe - easy answers but neither of which is easy to actually do... given our budgets.

[ssmith1627]

I have a run very similar to this but while up at the ceiling I have a Y, one split going to the shark guard on the BT and the other going to a connection I switch between bandsaw and planer.

My shorter runs are to the back of the BT, to my jointer and to my router table. I'm fairly happy with the results from those three connections. I don't feel like the long run to the bandsaw / planer is really adequate. Part of this to keep in mind is the fine dust in the air. You don't just need enough air flow to capture the chips from the planer -- you need enough to capture the fine dust before it escapes into the shop.

I keep going back and forth on this. Large 14" or 15" impeller and a 3-5HP motor and vent all this outside, replace my 4" PVC piping with 5" or 6", or a combination of both.

One other option is to simply buy a 2nd HF DC while it's on sale and use that in the other location. I'm sure it'd be plenty of power for those two machines and it would eliminate the long run that I have now. Certainly a cheaper solution than buying one of the big cyclone units. But of course you have to replace the bags on the HF unit as well.

I'm trying to figure out a way to keep the shop healthy without spending $900-1200.

Steve

[Jeffrey Schronce]

I can not help with the technical, only the practical application. My HF DC was in the attic above my shop. 4" PVC run 14' to a 90 degree to a 8' drop where I had a gate. Gate had section of flex, probably 8' with a quick connect on the end. It had no problem with TS, 8" jointer face joints. I had to remove the protective grill to keep up with my 15" planer. I did have an occasional clog, always at the inlet of the HF DC when making 12"+ passes on the 15" planer with a heavy cut. Light planings were no problem. I am of course speaking of the dust I could see. I can not attest to the fine dust, etc however I have to believe the fine dust was getting moved since the heavier chips were moving.

[JR]

I'm running my HF DC about 15' plus up and down. My planer and jointer are at the end of the longest run.

It pulls everything just fine, although, for a variety of reasons, I get some dust in the garage and need to shopvac the shop after working. I don't get any clogs.

IOW - you're just fine planning for the HF DC to pull that distance. I use long radius 90's and wyes when I can. I run as much hard pipe as I can. I put the blast gates as near the tools as I can.

I plan to install an air filter at some point and believe everyone should have that in his plan. You can not get everything with the DC. You just can't.

JR

[ssmith1627]

"It pulls everything just fine, although, for a variety of reasons, I get some dust in the garage and need to shopvac the shop after working."

JR -- I guess that's the scary part to me. Maybe Bill's site just really has me worried. But if you're getting that fine dust settling all over the shop it means it's in the air and that you don't have the airflow at the tools to capture it there. At least that's my understanding. And if that's the case, it's loose floating in the room and you're breathing that same air.

I just wonder how much large ducting will really help with our tools like the BT. It seems crazy to run 6" PVC up to the back of the BT and then narrow it down to 2.5".

It sure makes you look at tools in a new way when you think about buying. It's not just how the tool does the job it's how it allows for dust collection at the same time. It's certainly a lot more important than I knew in the beginning.

Not trying to be an alarmist.....just want to be safe in this because I'm 38 now and I hope this can be a long term hobby for me.

Steve

[LarryG]

Thanks to everyone for the replies thus far. It sounds like I won't at all be overtaxing my DC with the "plumbing" I will need. In fact, I've realized that the lengths of runs reported here will actually free me up to arrange my tools a little differently than I've been planning to do, just by adding a couple more runs of inexpensive pipe.

Loring: yes, I'm planning to use long-sweep fittings wherever I can, whether factory-made or cobbled together out of two 45s and a short length of connector pipe.

JR: I agree about the need for an air filter. It's one of the things I intend to get when I move into the larger building, as soon as I can work it into the budget.

Tom (and others): I know that you used the green S&D pipe, but ... tell me again, please, what kind of gyrations you had to go through to mate these up with standard 4" DC hose and fittings? Am I right in remembering that this pipe uses the standard white Schedule 40 fittings?

Lastly, the Lowe's here has the green S&D pipe, Schedule 35, for around $15 for a 10' piece. They also have a white pipe that has a bell on one end; it too says S&D but it's not Sch 35. It appears to be exactly the same stuff as the perforated pipe used for foundation drains and leach lines, sans the holes. Cost is seven bucks per 10' stick. Has anyone used this? If so, does it use the standard Schedule 40 fittings?

[IBBugsy]

"But if you're getting that fine dust settling all over the shop it means it's in the air and that you don't have the airflow at the tools to capture it there. At least that's my understanding. And if that's the case, it's loose floating in the room and you're breathing that same air."

To add more thought to this thread......

Why not just leave the DC running for a while after you're done cutting? The DC should "turn around" all the air in the garage fairly fast and filter out the fine dust that's hanging around (assuming you have a low micron bag or cannister on the DC)? That fine dust doesn't settle fast and at 1600 cfm a DC should "turn around" the air in a two car garage in under 5 minutes.

I don't do a lot of cutting so I can't vouch for this but it just seems logical to me??

[ssmith1627]

"Why not just leave the DC running for a while after you're done cutting? The DC should "turn around" all the air in the garage fairly fast and filter out the fine dust that's hanging around (assuming you have a low micron bag or cannister on the DC)? That fine dust doesn't settle fast and at 1600 cfm a DC should "turn around" the air in a two car garage in under 5 minutes. "

Interesting idea. Maybe with ALL the blast gates open ? Would be acting as an air filter at that point. I don't know how effective it would be.

Steve

[LarryG]

Dave and Steve, this excerpt from Bill Pentz's web site covers that very topic:

"My respiratory doctor recommends installing a good quality ceiling mount air cleaner to help keep the shop air cleaner. He said the ceiling units are worthless for protection while you work, but they do help to clean up the air so every time you go back, you don't start with the same problems. I asked which one and he said that the magazines rated Jet, Delta, JDS, and Penn State all pretty close, but he bought a Jet for himself because he likes Jet tools. In looking at many woodworker posts and some magazine reviews, it appears that he did pick one of the best.

"In following up I decided that if I caught the dust at its source and just let my cyclone run, an air cleaner would not be needed. An air engineer friend said that AAF had done extensive testing and found that was not accurate. An air cleaner is setup to stir the whole volume of air in a room. Without that stirring, much of the fine dust will be missed. Unless you setup your cyclone system so the air coming out of the filters blows in a directed stream at close to ceiling height, what happens is the air creates a narrow racetrack between whatever gate is open and the cyclone filters without doing a good job of cleaning the rest of the air. Moreover, a good air cleaner uses a small motor, meaning my dust collector would use more power and cost far more to run, plus is noisy."

Don't forget too that the CFM ratings of virtually all DCs are shamefully exaggerated. IIRC Wynn's testings found the 2HP HF unit that many of us own, and which is rated at 1600 CFM, actually moves more like ~550 CFM.

Also, I read somewhere -- although I've not been able to find it again -- that even the air cleaners with their larger intake areas will not scour all the air in a shop ... a given filter may move (say) 1000 CFM but it will do this by repeatedly recycling easily-moved air within the immediate vicinity while the air in the far corners of the shop, or blocked by tools or fixtures, will remain undisturbed and will never get filtered. This seems somewhat at odds with what Pentz says above (which is why I wish I could find wherever I read this again).

[Tom Miller]

Tom (and others): I know that you used the green S&D pipe, but ... tell me again, please, what kind of gyrations you had to go through to mate these up with standard 4" DC hose and fittings? Am I right in remembering that this pipe uses the standard white Schedule 40 fittings?

Lastly, the Lowe's here has the green S&D pipe, Schedule 35, for around $15 for a 10' piece. They also have a white pipe that has a bell on one end; it too says S&D but it's not Sch 35. It appears to be exactly the same stuff as the perforated pipe used for foundation drains and leach lines, sans the holes. Cost is seven bucks per 10' stick. Has anyone used this? If so, does it use the standard Schedule 40 fittings?

Schedule 40 fittings do NOT fit the green (schedule 35) S&D pipe. At my HD, the S&D fittings, which may be made of styrene, are in a smaller section next - to the Schedule 40 fittings. Also, the schedule 35 pipe I get at HD has one flared end, to allow connecting pipe end to end, FWIW.

I'm not sure how well the thinner wall white stuff fits these fittings, or how it will work with the stock dust chutes on machines. So you'll have to do your own research if you go that route.

One more note about nomenclature: the schedule 35 stuff is also referred to as ASTM 3035, and the thinner white stuff is ASTM 2729. You may see these markings on this pipe.

I find the schedule 35 pipe fits OVER the following:
- aluminum blast gates (use a screw or two if you need rigidity)
- most 4" plastic machine dust ports (Jet jointer, Ridgid planer, Performax drum sander)
- most plastic (Jet brand, e.g.) DC fittings, INCLUDING 4" to 2.5" REDUCERS. While it also fits over the elbows, wyes, etc., I recommend against these in favor of the styrene fittings for better air flow.

The schedule 35 pipe will fit INSIDE:
- the styrene fittings made for it. D'uh!
- the clear DC flex hose that you get at Rockler or Woodcraft, but you first need to remove a couple turns of the reinforcing wire. I usually use a hose clamp, too. With a 4"-6" piece of pipe inside the end of such hose, it is now a quick-connect fitting for a 4" DC port on a tool.

Here's a pic that shows some of this:



Regards,
Tom