Starting over on dust collection

[tvrgeek]

It has become clear we need two totally different dust collection systems in our shop.
A high lift but low flow and a high flow, low lift. Neither can do all.

So, the high flow upgrade is just some moving of ductwork as my CV1700 is a beast. I need to do a couple more mods on the table saw to focus the airflow. Through a quick connect, it will service the planer, jointer and drum sander. I may include a hood over the miter saw. TBD. Sticking with the 6 inch ductwork. 4 inch and 2 1/2 drops go away.

Here is the big change. Going to hard plumb the high lift system. A couple small mods and both my spindle sander and disk sander are just about dust-free when run on the vac. Not by a far cry on the big cyclone. A central port for hand-held tools and for the long cleanup vacuum wand. One more to service the router and fence, one for the Kaypex.

Now the questions:
I want to use commonly available components. Home central vac systems have similar flow and lift. They run 2 inch OD piping. Larger shop vacs run 2 1/2 OD. I was testing to the sanders with 1 1/2 inch hose and it worked just fine. I did not see a difference with the 2 1/2 hose. Schedule 40 comes in 2, 2 1/2 and 3 inch. 2 1/2 would seem to be the logical and closest to shop vac hoses but is uncommon. Running a trunk in 3 may be fine but I need to do the calculations to see if it can maintain the velocity to prevent dropout. That leaves 2 inch ID as the other option. Any experience? Being smooth and we can get nice long sweeps, Ys, etc, it should have similar drop to a large hose and for sure less than the much smaller hoses in 20 and 30mm. I can get ball valves quite reasonably. They look like they should not clog and are airtight for sure. The other choice is spend a lot more and use "dust collection" hardware that is 2 1/2, but thin and much more expensive. Not sure the blast gates, Powertec or similar, are as leak proof. Maybe I am wrong, but in high lift systems, resistance is not as important as in high volume systems so running a larger main is probably not worth it.

I added some brush type door sweeps to 3 sides of the TS over-arm hood. Drilled a few holes in the throat plate where the jet of dust follows when ripping half a blade edge. Subjectively less than half the dust, probably more like 1/3. Next is to glue in some half round around the port. Same inside the saw cabinet.

 

[tvrgeek]

Found a leak in the ClearVue system and got my static max lift from 4 to 5 inches. I think I hear another one. The steel sheet blast gates do leak. In theory, it should be about 8 or 9 inches.

2 1/2 PVC is twice the price of 2 inch. 3 inch is only 50% more than 2 inch. Long sweep Ys and valves are the big hitters.

I think I am going to put the vac in the attic. Slightly less duct and quieter for sure. More height so I can make an easier to drop and haul dust bin. Full stairs so that is not an issue.

 

[Rwe2156]

I was looking at that collector but couldn’t justify as my system (that isn’t supposed to work) is adequate for my shop.

I know they specify 6” but that surpriseds me on that size blower you would think 8”. I’m running a 6“ on 1 1/2HP blower with a cyclone. Exhausted outside.

I can’t help but wonder what 8” ducts would do?

 

[tvrgeek]

On a low lift system you can use the spreadsheet calculators on ClearVue site. On the CV1700, it is sized for 6" output and drops ( single use) Yes you can move more CFM, but the LFM goes down too low. Too slow and dust drops out, accumulates and is otherwise very bad.

On my high lift system, I am down to Powertec or similar 2 1/2 OD system with their claim to be non-clogging, non-leaking gates or to go 2 inch ID schedule 40 with ball valves that will not leak. I am skeptical as all my metal and plastic gates leak some. With the high lift, 100 inches or so, the line restriction is not as detrimental. I proved that testing my Ridgid belt/spindle sander comparing a 30 foot Centec hose to a 8 foot 2 1/2 hose. No noticeable difference. Velocity was above my meter. Just ran some calculations. I should go 2 inch to keep the velocity. At least I can buy the pieces as needed from Home Despot and 12 foot pipes are better than 3 with joints.

Thought about venting outside with the high lift system. It does not move that much air to lose HVAC and would be quieter. The EPA would probably not like blasting the fines out, but whatever. Cheaper as no need for fine filtering. Heck, I would think so little gets past the cyclone, you could run nothing more than a screen over the vacuum motor and get away with the Ridgid or Bauer shop vac.

Running the big ClearVue outside would kill my HVAC as we would be talking one full air changes per minute. I think the neighbors would not like it either.

 

[tvrgeek]

This is getting way too complicated. Second thoughts and not enough facts on almost everything.

Powertec suggests schedule 40 ball valves wear too fast in a dust collector. True, or protecting their market? What is that abrasive? Grit off the floor, sand paper grit, or sawdust? Or falls in the "it depends" bin? They say they have no complaints about their new orange gates leaking, but are others as anal as I am looking at this? I want measurements.

Reference to a video from StockroomSupply, they suggest a common lift value for measuring high volume collectors is 4 inches. This is in contradiction to Bill Penz wo suggests they should be higher in the 9 or 10 range. Any truth, or is it that the Rikon they were advertising can only do 4? Going to disconnect my duct and see what the CV1700 actually does. Also need to test to see how much my filters are loaded by removing the cleanout and measuring the velocity. How sensitive it the volume to the filter status? If a couple of 90 elbows can kill the flow, I bet we are getting far less flow than we think.

I am beginning to wonder if ALL of the common solutions are actually wrong. Record Power may be on the right track, but I am not sure about their implementation. Is it possible to have one system that serves a one-person, single tool shop for all uses?

About all I am sure of is :
You need to start with a cyclone or your filters will clog in minutes. The taller the more efficient.
Cyclones have optimal flow ranges, so sizing or number will matter.
High volume, low lift is super sensitive to the slightest duct/machine restriction. High lift not so much.
High lift is needed for low volume things like ROS and other hand held tools. Optimal for shop cleanup.
If you can collect within an inch of the source, then high lift outperformed high flow. If further away, then massive flow is better.
High lift is needed to overpower bad designs like most miter saws at the shroud.
I do not know about high lift at a TS shroud as my saw does not have one.
Planers and jointers need flow. Not much leakage to overpower.
Common design for machines intended for high volume are poorly designed. Leakage, restrictions, placement and so on.

I THINK I am concluding:
The TS overarm could use more lift and a little less flow. Especially those with smaller ports than my 4 inch SawStop.
A TS could use less flow, more lift, if it was designed optimally for it
A band saw is maybe the most complicated as it is difficult to get collection near the source. Without some sort of duct/plenum/nozzle then high flow seems to be how to get fines collected but a better design may go back to high lift.
Router tables are also in the middle. Using the shroud, it needs lift on the router, flow on the fence. Again, a balance using a sealed box may be better.
Odd man out is things like a hood for a lathe. Very low lift needed but massive airflow. Maybe the only solution for a miter saw hood. This could be the deciding factor that makes a single system not possible. Pulling 2000 CFM and 100 inches of water may need huge power unless something like a DVR drive can manage the current load dependent.
Much higher lift with moderate flow may be superior for a single use multi-purpose shop. Is 80 inches enough for say the Kaypex? Or is it hopeless and a hood forgetting the shroud and relying on the blade fan effect to send what does by luck hit the boot to head out to the hood port?
4 inch ducting may be optimal for such an in-between system. Enough lift to overpower the restrictions but maintain enough flow for low volume tools not to have drop-out.
Ability to change volume may be necessary for hand held tools. Too much vacuum can cause issues. Bleeder valves seem counterproductive but may be necessary. The Fein going to my ROS seems OK with mesh disks but too much on my Bosch with punched holes disks.
The multi-blower concept may be better here rather than a variable speed blower. May be too difficult or expensive to test.
Modifying the CV blower with tighter entry to wall for higher lift, but does it burden the motor too much? What does 10 or 15 inches do compared to 4 or 5 at the point of duct creation?
In a multi-blower system, with only one blower powered, without internal gates it will back flow the "off" blowers? Is a one-way flapper enough to prevent this? ( See Hooked on Wood HEPA box with flaps) Record Power does not have this built in. Seems like an oversight.

I don't have a vacuum gauge that reads high enough and my aerometer is also too small. I need to make access ports right at the vacuum and collector ports for consistent comparisons and a "standard" duct inlet I can move between solutions.

On my " what is wrong list" I get back to when buying $1000 machines, lack of things like pressure sensors, bin levels, and the like is inexcusable. I blew the bag off a Jet cyclone when the filter loaded up because I forgot to rotate the flapper for a week. High lift systems without overpressure valves, dust bins that can overflow. This should not be aftermarket!

I have 2 shop vacs, the Fein extractor and the big ClearVue. Time for some testing.

Control becomes an issue. Can I control a multi-blower system with pressure sensors or maybe just switches on the blast gates? Open a gate at the point of use and blower comes on. Or, open the gate and the preset for how many come on so a remote can switch it on and off? Or tool current as the trigger. Could just a pressure sensor see too low a vacuum meaning insufficient flow and stage on more blowers? If a bank of say four blowers, wire to a 220 branch and split the phases?

 

[tvrgeek]

Testing issues.
Tryiing to measure into a small diameter pipe is bogus. As an example, if I hook up my gauge to a vacuum nose, then the restriction is roughly that of the meter so it goes off scale at over 40 meters/sec. But what is the restriction? Equivalent to an inch? If so, then that calculates not far from the FEIN spec of 151 CFM.

So, how to get consistent measurements. I think I need about 5 feet of 6 inch pipe and then use nicely tapered connections to it. Then the size of the aerometer will not have a significant impact. It does need to be in a consistent location from the end and enough off the wall. 1 m/s is about shop vac spec. 10 m/s is about expected from the CV.

Ordered a 30 inch/Hg vacuum gauge from Amazon. That will allow lift comparisons on the vacuum systems. The above pipe should work on both high and low lift systems.

I have an amp clamp so I can see what loading does on the motors. I wish I had a power factor meter as I suspect changes would show up there larger and easier. I do have an IR thermometer so I can at least see changes in motor case temps.

Picked up some 2 inch PVC and a Y so I can see how ganging vacs works. Also ordered one of Powertec "orange" gates so I can measure it's leakage and compare to an older non-self cleaning one from them.

Of to the shop to build some test jigs. Data. I like data. Data does not lie, just mislead us.

 

[Rwe2156]

Scott, at some point I think you have to stop analyzing the just set up a system. If it works it works. I see guys with measuring velocity, calculating CFM's etc, etc, the bottom line it's either collecting well enough or not. Agonizing over optimizing a system doesn't seem to have much a return to me.

You have a huge collector I don't understand what's the issue?

I collect my SawStop with a shop vac and it works great. The retractable hood I built that is hooked to my DC is coming down.

IMO somethings just aren't worth collecting, like drill presses and lathes. And table saw cabinets - just clean it out once in a while, focus on what coming at your face.

Also, based on your comment in the router table build thread, I went with point of production collection with my radial arm saw. I have a dedicated 1HP blower exhausted out side. I can close that gate and use a length of flex to my router table for the fence and box. Very happy with the set up.

I doubt I'll ever buy a 5HP collector, simply b/c what I've got is working well.

 

[JimD]

For my high lift system I just use a Rigid shop vac with a dust deputy pre-filter and a quasi HEPA filter in the vacuum and a Bosch 5 meter hose. I have PVC going up along the ceiling to where my assembly table is and the hose connects up there. I just move the hose from tool to tool. Some people have swing arms for the hose and I would like to but it would have to swing under the DC 5 inch pipe and can't really go to the wall when stored because of all the stuff on the wall. But that is another way to do it. I get pretty good suction at the end of that long hose. Works well for my sanders, track saw, and domino.

 

[tvrgeek]

If you choke down the 6 inch duct on the clear view to a 30mm port, it still only has 4 inches of vacuum to pull through it. In other words, nothing. A shop vac is more like 150 inches so it will force a flow through a restriction. That is the difference between high volume, low lift and high lift low volume. If you need to pull from a large ambient space ( saw or lathe hood) then volume is what you need.

My table saw is an older design and does not have a blade shroud so I am currently stuck with needing high volume. I have some ideas for mods, but lifting the table to get in there is not on the top of my list yet. I think proper focused airflow with higher lift would do a better job than the high volume big leaky box. I may stand a better chance on the band saw as it is more accessible.

Bob, yes! Key is the fines that get airborne. I can clean out the box and sweep the floor. Fines kill you. On the lathe and miter saw, it is the fines from sanding or cutting something like MDF.

Anyway, back to the shop. First testing suggests using a 6 inch tube is marginal but would be consistent. New vacuum gauge should come today.

I am starting to think the Record Power system is closer to best all-around for one person, one machine shop. Lift is only about 80 inches so a little more care with the ductwork may be needed. Not the best for the Kapex, but as suggested, almost a hopeless cause. Three or four motors ( totals about 5 HP BTW) may be enough to use a hood. Going to test with ganged shop vacs.

While optimizing tools, I found a manufacturing tolerance on my HF 12 inch disk sander that let me reduce the bleed air by about 1/3. Now with a vac on it, almost dustless like the Ridgid spindle sander. It also had the port to suck from the far side almost blocked by dust catching on rough casting. Fixed that. A bit of foil tape on the rear plate and sealing the bottom of the front port.

 

[McRabbet]

For Table saw dust collection use Shark Guard with 4" port. Available for several brands, plus many accessories.

 

[tvrgeek]

For Table saw dust collection use Shark Guard with 4" port. Available for several brands, plus many accessories.

I have the SawStop 4 inch. Modified with brush door sweeps on 3 sides that reduces top side spray by quite a bit even on half blade trims.
It needs further mods as the port has square edges so it could flow even better.

First readings with 6 inch flow tube with 1 foot flex hose coupling:
Fein into a cyclone, bag and HEPA filter flows 103 CFM which is 31% less than free air spec
Ridgid into the cyclone, standard filter flows 117 CFM which is 11% less than free air spec
Ridgid with no filter, no cyclone flows 139 CFM which is just a shade over spec.

30% delta between "free air optimum" and configured for use with a cyclone is close to numbers I have seen tossed about.
My tube is not as long as I wanted as it is what I had and the mouth is only a 30 degree flair as my arm got tired tinkering it into a flair. So numbers may be a couple percent off, but are consistent and make sense. Next is to make a port close to the entrance of the big ClearVue. Then make an intake adapter for the different hoses and port sizes to measure the effect. Truth is when I use that to measure the actual flow from each machine. Once I get the new vacuum gauge, I can test gate leakage.

If anyone is wondering when I talk about port geometry, the optimum is a 270 degree radius of 1/4 port diameter into a 17 degree taper of 3 times the diameter. This gives virtually no loss. A bit impractical. Happily, a nice radius to a flat plate is within a hair of it. No radius can lose several percent flow due to the air running into itself and causing turbulence which artificially restricts the intake. Fortunately on the exhaust end it just about does not matter as the airflow is "bound up" and not interfering with itself. This is why a step down is not a problem, but a step up is.

 

[Wilsoncb]

Have you ever used smoke to see what the air is doing, or to find leaks? Maybe this is not the right application for it, I guess that’s why I’m asking. I tried some pellets used by bee keepers to see what my air filter was doing and it was a disaster. The whole shop smelled like it was on fire and it didn’t generate enough smoke to see any air movement. I’m sure a proper smoke generator would cost a pretty penny.

 

[tvrgeek]

One way but a microphone also works. Or the brute force way, foil tape.

Oh, I have a stethoscope as used in automotive repair. It can really narrow down a small noise.

 

[tvrgeek]

Another detail I don't see mentioned. Big cyclones with canister filters are still only MERV 15. Far from HEPA. HEPA filters have much higher drop so they would kill a cyclone unless a very expensive bank of them. Vacs with their higher lift can afford the 1.5 to 2 inch drop.

I have seen comments, but no dats that suggest multiple small cyclones have higher velocity and so are more efficient that large ones. Can Dyson be right? If I had three shop vacs I would do better with three Dust Deputies over one super deputy it suggests.

 

[Rwe2156]

I just don’t see the point. You’re never gonna eliminate dust so dialing up a collection system to do that is more or less a waste if time.

Not when there are air filtration fans, and HEPA dust extractors for sanders.

 

[tvrgeek]

A difference between eliminating and optimizing. I lost two friends to lung disease and the estate I bought my drill press from was a long time dusty woodworker.

I have an ambient MERV 18 system. A patch for after the fact.

 

[seaver61]

We only have one set of lungs. Many of us abused them before finding woodworking. Care for them now.

 

[wbarnes]

While I don’t have the patience (or money) to look into this as closely as you are, I am very interested in what you find and will approach your conclusions with an open mind. Thanks for taking the time and effort to do this, even if it may be considered overboard.

Who knows? Maybe 15 years from now this could be the initial research that brings about a paradigm change for hobby shop dust collection.

 

[Rwe2156]

100% agree on protecting the lungs, I just think tweaking a DC to squeeze every bit out is not the way to do it.

Seems to me the dust collection features of the machine are more important than the blower set up. There are some machines that just have lousy DC design that I don’t believe can be overcome with an optimized dust collector.

You have to address air quality you have to do even if your DC is 100% optimal.

I’m sure I’m not as aware of protecting myself as I should, even now. And for 35 years I never had DC on my table saw. I never wore a mask. but I have done some things of late I didn’t used to do:

— using the blade guard collection
— getting rid of my miter saw and going to a radial arm, which is much easier to collect
— using a high quality dust extractor for hand tools
— prioritizing dc when buying tools


There are some things a DC can’t help you with such as a router.

But I get what you’re trying to do and I’m sure the info will be valuable to people. To me the real issue is when we’re younger and invincible we didn’t think about it and the horse has probably left the barn.

 

[tvrgeek]

Did a proof of concept for measuring velocity. I only had 3 feet of 6 inch duct so for proof, used that. I can see why more like 5 feet is suggested as it flutters just a tad. Now with an adapter plate, I can hook up various hoses and tools to see their impact on flow. I also cut a port into my big cyclone input.

I believe it is a fault of my anemometer in that the readings I get are about three times what is expected as real. I get 2.2 m/s for the vacs, which is about 450 ft/min. More than double advertised and I am pulling through a cyclone, bag, and HEPA filter. On the big system, with one 6 inch gate open into my table saw, it reads 3800 feet/min or roughly 3000 CFM. Well, it is a CV1700, as in 1700 CFM. Considering filters are not new, several elbows, and poor port aperture, 1000 or 1/3 would be believable. It is not just reading the scale wrong, as I can go to m/s, or f/min and get correct values in scale. Guess a $15 Chinese wonder is not very accurate. BUT it is consistent in expectations if I divide by 3. Hmmm. I could have sworn I measured about 1200 CFM when I installed it. Battery?

I agree totally and have made clear, the design for dust collection of most tools is inexcusably incompetent. This is why tweaking some machines makes a significant improvement. We don't have specifications or measures for this, so it is a difficult parameter to buy for. It was surprising how terrible my Kapex is but at least it's saw performance is good. Hard to remember my old RAS. It was so dangerous I was glad to be rid of it. Of course, I did not have a table saw to do rips on and the million dollar stick had not come out. I do remember it was too flexable to do precision miters for picture frames which is why I still have a Lyon miter trimmer. Oh yea, I hate respirators. I wear a good organic one when doing any volatiles, one fits inside my welding helmet. and a dust one when using the leaf blower for the weekly shop blow-out.

If tweaking a tool or the DC system significantly improves the results, why not? Far more significant is understanding what kind of DC works of which kind of tool. It is clear, you need high lift for a router, router fence, disk sander, spindle sander, hand held like a ROS, belt, planer and so on. I think, and have a lot of work to do, if your TS had a full lower shroud, a high lift right to it will be much better than a high volume trying to suck the entire cabinet. I watched a demo of the Record twin motor high lift on a lathe scoop and it did as well as a similar scoop driven my my CV1700. I think I can simulate that with two shop vacs. I am going to have to find a way to add a shroud and intake port to my TS to use a high lift. I can compare top-side spray high lift to high flow. Saving a big cardboard box to rough a hood for the miter saw and compare the CV with multi-vac. IN other words, I spent big bucks on the wrong system technology for my use. Not a fault of the equipment, a fault of not understanding the true requirements. I believed the vendor design guides which of course are written to sell your their solution.

I am really thinking that for a "real" shop, one needs two different systems. One high flow that can service big chip tools like jointers and planers, maybe more than one at a time and an independent high lift, or maybe point of use small vac based systems. But for us one-person hobby shops, it is looking like multiple motor to gain flow, high lift blowers are the way to go. A big question is if a 2 inch duct can pull chips through 20 or 30 feet. I doubt it. So a 2 inch for dust and 4 inch for chips ducts. If you have more smaller tools like my DeWalt planer, 6 inch jointer and so on, you can do with the 4 inch provided enough lift. If I had an 18 inch planer, I bet you would need at least 6 inches if not 8 and a machine powerful enough.

Of course the cheapest solution is to work outside with a nice large fan. I have an outside bench where I do most spray glue or rattle can painting. We have such great weather here, I really could expand it and do more outside.

One totally clear fact: "It depends"

Factoid to expose marketing not quite lying but close.
MERV 15 is only 85% efficient at 1 to .3 micron.
MERV 16 is at .5 to .3 micron 95%
HEPA is 99.7% at .3 micron.
Ducting outside is 100% effective.
As I understand it, it is the .5 to .3 size that is most hazardous to your health. Larger gets trapped by your flem, but the .5 gets imbedded.
Cyclones do their best at larger, 10 micron and larger. So replaceable or cleanable fine filters is still needed. I find the volume to be so small, cleaning my canisters or replacing the bag and filter in my vac to be infrequent.