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Tips for Installing a Dust Collection System

47K views 121 replies 34 participants last post by  DesertRatTom 
#1 · (Edited by Moderator)

There's no way around it: wood dust is a health hazard. Multiple health agencies have classified wood dust as a carcinogen. As a woodworker, whether professionally or as a hobbyist, safety should be the top priority -- even ahead of creating a quality product. This is where dust collection systems come in - the name is pretty straightforward for their purpose: they collect the dust that can harm your lungs and cause health problems later down the road. Dust Collection
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#3 ·
This is perfect timing as I recently added a sander and relocated my dust collector . I need to find out which way would be best to plump the machinery . I'm assuming 4" ABS and waste gates but I'll post a pic and see what the experts have to say
 
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#4 ·
While the plastic duct system is more air tight (less leakage) it has the highest chances of sustaining static. Plastic dust must have a good grounding system attached to every foot of it. Inside the plastic ducting is the most efficient. I used metal ducting to eliminate the need for a ground wire along the entire length of the system. Beside the ground wire from the motor to the electric supply I have an external ground from the dust collector to the grounding rod that is used for the electric panel located outside the building. Being an ex USCG Damage Control (Fire Fighter) I cannot be safe enough from fire hazard, especially when we were out at sea.
 
#65 ·
Just got back to this thread.

That is why I stated to run the wire inside the pipe. I don't consider running it on the outside to be effective at all. I am not worried about chunks of debris getting caught on wire. Even on the metal systems I used, I made particle separators at each station that collected the chunks so they wouldn't make it to the collector.
Sounds like no one uses the metal ducting. I found it lighter to support, easy to make alterations and cheaper to use.
 
#6 ·
Static discharge from a dust collection system has always seemed to me to be a bunch of hooey!!! I've never noticed enough static in my system to even consider it being a potential problem. That is not to say it wasn't there, I just never noticed it.................until!!!! Recently hooked up a Dewalt 735 planer. (an outstanding piece of equipment by the way). While running the first few board thru the new planer, I would reach around to grab the board as it exited the machine. I'm telling you what.. from 6"s away, there was enough static to make the hair on my arms stand on end!!! I will now incorporate some sort of grounding medium into my system.
 
#7 ·
My DC system is 4" PVC no grounding and I have never noticed any static problems. As for the DW735 you shouldn't be having a problem there if the electrical supply to the planer is properly grounded because that grounds the metal body of the planer. I recently got a DW735 and again not noticed any problems.
 
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#8 ·
Guys I've heard of grounding but never bothered . No incidents yet but I was using the hose to pick up dust off the floor and for the first time I noticed the hair standing up on my arm . Made me wonder :|
 
#10 ·
Why take a chance? Very little effort and cost are required to avoid that potential problem. If static did cause a fire, the results would likely be catastrophic from your point of view.
 
#9 ·
I also question the idea of grounding the outside of a plastic pipe. The plastic piping systems I've seen advertised suggest running a wire down the inside and drilling a hole through near a connection so you can attach the inside to a bolt and another wire to the bolt on the outside. My preference was to use galvanized ducting instead. It's cheap and easier to ground. I still used the bolt idea but no wire needed on the inside. I also still used plastic ducting at the corners instead of galvanized bends. The plastic ones are much smoother. Use the aluminum foil duct tape at all joints and it works just as well.
 
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#16 ·
Dont rely on foil tape as an electrical connection. Each layer of tape has a non conductive layer of glue on the underside. If you make several turns of foil tape what you have built is a capacitor, which actually stores and multiplies electricity. A well wrapped foil joint is a much greater hazard than an unwrapped joint.

Each plastic elbow acts as an isolator unless there is a metal connection between each cuff so every section of pipe between each elbow needs to be wired together, and to then to ground preferably at each end.
The only 100% way of curing that problem would be to drill a hole through each cuff (and tube) and bolt each together with an earth bonding wire. Which would play havoc with your air stream :crying:
 
#12 ·
I to had never grounded my DC but after getting a pretty good static shock I run a bare copper wire inside my PVC and aluminum tape wrapped around the outside about 3" apart running the length of the pipe. The inside wire and outside tape are connected together with a screw and from the screw to electrical ground. I did a lot of reading of Dr. Rod Cole on grounding PVC. Not sure if it is right or wrong but I have never had my hair stand up on my arms or got a static shock again.
 
#13 ·


This link might help with understanding and methodology of the grounding of plastic pipe.

Everyone has to understand a couple of basics; any time you have air flow across a surface, you will build static, moisture (humidity) contributes to the control or generation of static.

With all that being said, I have never seen or heard of any definitive evidence of a fire starting in a hobbyist type wood shop environment, which was caused by a static discharge in a dust collection system. If anyone has such evidence I would like the details for my own edification.

In my opinion (as a safety professional for over 35 years) I do not see it as the huge danger that some folks claim it to be. However, the grounding of ducting, even PVC is not that difficult to do. So why not do it?

Is there a danger? Static can always be an issue in a fine dust environment (look at grain silo explosions). Is it prevalent in a hobbyist wood shop? Probably not.

I think the real issue in not the grounding of ducting to prevent an explosion, but more of preventing a static discharge shock that might result in an unintended reaction by an individual. The use of volatiles near a static source is always a paramount hazard.

I'd be interested in hearing from some EE types, if there are any out there, or anyone familiar with the installation of commercial duct systems, as to what their opinion is on the matter.

Bill
 
#19 ·
https://www.youtube.com/watch?v=sCPiu0zQwyI

This link might help with understanding and methodology of the grounding of plastic pipe.

Everyone has to understand a couple of basics; any time you have air flow across a surface, you will build static, moisture (humidity) contributes to the control or generation of static.

With all that being said, I have never seen or heard of any definitive evidence of a fire starting in a hobbyist type wood shop environment, which was caused by a static discharge in a dust collection system. If anyone has such evidence I would like the details for my own edification.

In my opinion (as a safety professional for over 35 years) I do not see it as the huge danger that some folks claim it to be. However, the grounding of ducting, even PVC is not that difficult to do. So why not do it?

Is there a danger? Static can always be an issue in a fine dust environment (look at grain silo explosions). Is it prevalent in a hobbyist wood shop? Probably not.

I think the real issue in not the grounding of ducting to prevent an explosion, but more of preventing a static discharge shock that might result in an unintended reaction by an individual. The use of volatiles near a static source is always a paramount hazard.

I'd be interested in hearing from some EE types, if there are any out there, or anyone familiar with the installation of commercial duct systems, as to what their opinion is on the matter.

Bill
I have a couple of quite major issues with that video.
I have been a mechanical engineer in commercial catering installations for 20 years, and part of that job involved earth continuity installing and testing. Admittedly this was in the UK, and I know the USA has some variations of regulations, but even so, nobody can say the UK is backward in safety regs.:nerd:

The first issue is he is advocating a certain type of wire crimp tool that does not meet safety regulations any where in Europe.

The ratchet crimp as in this pic
https://www.google.com.cy/search?q=...Wire_end_Ferrules_Crimping_Tools.html;450;314
is far safer, giving a consistant pressure on each use. the thin model used by the guy will give wildly varying pressures according to who uses it. Arnie would cut the crimp in two, a person with arthritis for instance will make a joint that is not secure, and unsecure joints are a big cause of sparking.
The ratchet crimp will only release when the correct pressure has been applied, even if that means a frail person has to use two hands, or even lean it against the bench, but at least you know every joint is consistantly good.

My main concern is the BARE metal wire he is using. I repeat, BARE metal! he is attempting to stop static sparks by looping BARE metal all across the place? He's not insulating the equipment, he's radiating the static.

If the wire was loaded with static and anything metallic was passed anywhere near that bare wire, he would soon learn about static sparks.

Standard household insulated ground wire should be used everywhere on a small earth continuity circuit. If anyone wants to test its efficiency, use a multitester set to Ohms, and check between any of the connections to a known ground. The power socket ground will be enough. While youre there, test your equipment metal case to the same ground screw. Hell, test everything! >:)We tested to achieve LESS than 0.2 ohms.

A Quick point here for people not used this kind of test on a multimeter, first put the two leads together and measure the resistance of the machine and leads themselves. Its possible to get a reading of 0.6 or so from the machine depending on quality, and this number can vary every single time you use the tester.
So, when making the real test, you should check the machine EVERY TIME. Then when you test you should see the original number plus no more than another 0.2. So in this example, if you got 0.6 from the tester, and then checked the installation, If you got more than 0.8, that would be bad.

(1 decimal point either way would be regarded as fluctuation on a cheap tester, if you got more than 3 decimal points you should be worried)
If you want to be really anal about it, test between every connection on the run, and the run to ground at both ends.
Again, if your leads arent long enough, you can use extra wire to wrap around the test leads to reach, but you must make the self check again before testing the installation.

If you do not achieve these numbers then my advice is to go over the entire installation checking until you do. Or get a QUALIFIED electrician in, not a mate who has done "a bit of that".

Hope this helps.
 
#14 ·
Bill I was debating to connect a ground wire from a ground rod to the duct . I'm not sure if what that guy did was neccesary ?

Or a guy could go from an electrical outlets box to the duct as all your electrical boxes are grounded by code
 
#15 ·
I basically agree that extensive grounding may not be necessary. However, why not ground the system.

As far as grounding goes, you are right! If you ground to your electrical system it would go to the buss bar and to the ground rod. Some may say that it may not be a good idea, but I'm not sure that it is against NEC codes. Your electrical codes may be different in Canada.

I have all of my reference books packed away in storage so I can't research the codes requirements.

Bill
 
#17 ·
Opinions vary on the need for dissipating static electricity in home dust collection equipment. I have yet to see a shop vacuum with a static grounding feature. Neither of my dust collectors came with a static grounding system. As far as dust separators go Oneida includes a static grounding kit while Clear Vue Cyclones and Rockler do not. Festool is now offering anti static hose as an option to use with their vacuums.

Grounding the static is easy; look at the Dust Deputy Deluxe in the photo to see how this is done. Metallic tape, some wire and a washer is all that is required. As long as your separator is sitting on the ground I do not think this is really needed.

More to follow on this soon.
 

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#18 · (Edited)
I just put a bare copper #12 wire from my machine to the DC pipe. The machine is grounded so it grounds the pipe. I don't run copper along the pipe,and especially inside as it keeps the chips from moving smoothly thru the PVC and can cause build up that cuts your air flow. I only do it to keep from getting shocked at the planer and drum sander.
Herb
 
#21 ·
out of curiosity, I have just gone to the workshop and conducted a quick experiment with foil tape.

This is obviously a spur of the moment test, but the results surprised even me.

Using my test meter on a metal paintbrush section I got the following results.
meter leads test to 0.3 ohm.
metal paintbrush body tests to 0.3 ohm (perfect, as I would expect as the leads are only two inches apart)
single layer of foil under one test lead tests to 0.3 ohm (perfect, no loss)
double layer foil tests to 0.4 ohm (not so good, a significant loss of continuity)
triple layer foil tests to wildly varying numbers right up to infinity that would be an instant fail on any installation I have ever tested.

Conclusions; do NOT use foil tape in any area regarded as electrically sensitive unless you make sure there is no more than 1 complete turn of tape to stop the draught.
More than three turns would be a capacitor because the glue is storing the electric
 
#23 ·
Bob your measurements of the continuity of layer after layer of tape I'm sure are correct, especially if the layers were separated from each other as opposed to a continuous loop 3 layers thick, but the end of one pipe is crimped so that it will slide into the end of the next pipe. There is approximately 2" of overlap between the two. The tape only prevents suction loss. It has no effect on the continuity of current from one pipe to the next. It would be a factor if you were grounding from the outside layer of the tape.
 
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#24 ·
granted under those circumstances. What concerned me was the use of plastic elbows which are non conducting.
If you have a grounded metal tube sealed into a plastic elbow with foil tape, the plastic elbow disconnects each section from each other. Under those circumstances, a metal conductor should be used to bridge the plastic elbow and re connect with the next metallic section and not rely on a piece of foil tape to do the job.

But it is worth bearing in mind the capacitor effect, and not winding the foil tape around more than is absolutely neccessary to seal the tube (1 turn)

I originally had 4" metal for my dust collection system, small as it is, but the cost of fitting 5 blast gates (1 for for each appliance) turned me to a smaller, 63mm clear plastic tube and elbows with blast gates for each. Still not cheap, but a much nicer appearance and more space behind the machines.

Until now, I had not considered static a problem on my system. I still think the risk is extremely low for me, where the system doesnt run all day, and I am quite paranoid about using the floor vac at the end of each day, sometimes twice if theres been a lot of activity (sawdust in the house is a BIG BIG issue!!!), but I shall study the problem, and may well end up earthing the tubing
 
#25 ·
well, I've studied my system, and i dont think there is any point in adding ground wiring to it.
Its only a 12 ft long run, with 5 outlets. Theres a cyclone (all plastic) at the end of the run between the tube and the vacuum unit, which also has an air filter between the void and the electric motor.
the plastic cyclone feeds dust down into a sealed plastic bucket. Plastic flexible hose connects everything to everything. Although there are metal clips holding the pipe to the wall, they are held with screws into plastic plugs. there are even wooden spacer blocks behind each clip.

So, theres no way any mains electricity can reach any part of the system or travel along it. Any static could only come from inside the pipe itself, and the travelling time of the dust moving 12 ft is just not measurable. I dont believe it would be possible for enough friction to form to produce any static.
I think I'm good to go. (G)
 
#26 ·
simplify the thought process...

every place there is combustible dust static electricity is an issue....
the possibility exists...
choose to blow it off, ignore it, gamble, play chicken (w/ yours and other's) w/ life, limb and propertybelieve ''not me,'' or it's all just rhetoric and if the day ''should'' arrive enjoy the I tol'ja so's...

https://www.osha.gov/dsg/combustibledust/index.html
https://www.osha.gov/dts/shib/shib073105.html
NFPA 652: Standard on Combustible Dusts

A wide variety of materials that can be explosible in dust form exist in many industries. Examples of these materials include: food (e.g., candy, sugar, spice, starch, flour, feed), grain, tobacco, plastics, wood, paper, pulp, rubber, pesticides, pharmaceuticals, dyes, coal, metals (e.g., aluminum, chromium, iron, magnesium, and zinc). These materials are used in a wide range of industries and processes, such as agriculture, chemical manufacturing, pharmaceutical production, furniture, textiles, fossil fuel power generation, recycling operations, and and metal working and processing which includes additive manufacturing and 3D printing.
 
#27 ·
Stick,

It's not that I'm disagreeing with anything you have said, and I agree with "belts and suspenders" in this case. However, The real danger of explosions is evident in commercial operations where the use of the dust systems is a continuous operation. The possibilities of static discharge are probable and possible.

However, in a hobby or small shop operation where continuous operations are unlikely the probabilities of a static event are very low.

I have never, in all of my research, ever come across a documented event in a small workshop that caused a fire or explosion due to static discharge in the ducting. I am not saying that there aren't any but I have never found a credible documented case.

That is why in my first post I asked if anyone who has knowledge of such an event to provide me with the details.

I spent 30 years of a much longer career as Safety Engineer for a large aerospace company. My first assignment was to oversee the construction, testing and operations of a building that had a self contained "Mix Room" and three spray cells.

We sprayed primer on a 27 foot by 100+ foot Aluminum tank and then coated it with a cork based mixture in a heptane slurry.

The mix room is where the slurry was made.

We dealt with Heptane, Toluene, Alcohol, and Methyl Ethyl Ketone in the processes. Needless to say, grounding and static was a big issue, right down to the non-conductive flooring and the use of wrist stats for static.

We never had an incident and thank God we eventually did away with the some of the processes.

My point to the ramble is that I have extensive experience in grounding and the techniques involved. Sonnybob is astute in his observations, but for a hobby shop I just don't see a high level of concern over static in the dust system.

I would, personally ground my own systems, but not for the fear of a static discharge fire and certainly not an explosion, but to keep from getting my fingers zapped.

Bottom line, ground the system, it's not "rocket science", if anything it will keep you from getting zapped when you get near the ducts or machinery.

Bill
 
#28 ·
I worked in the R&D department of an explosives/munitions facility for a number of years...
not to mention the years of grain mill work... (millwright)
static being an issue is a very real thing...

as long as static is an issue.. would it be be prudent to cover your butt...
single digit humidity here enlarges the issues...
even if there are no fire/explosions, static discharges to a person get to be very annoying...
forbid if you should be wearing a pacemaker...

preventative medicine here goes a long ways...
doesn't take much to accomplish either...
ask Ray what it was like when got a shock and his hearing aide went nuts...
his screams were something else...
 
#29 ·
preventative medicine here goes a long ways...doesn't take much to accomplish either...
ask Ray what it was like when got a shock and his hearing aide went nuts...his screams were something else...
Exactly the reason(s) that I advocate doing it (LOL). However, in a small wood shop I still don't believe that not grounding the ducting is a fire or explosion waiting to happen.

Working as a millwright and especially in the explosives field speaks volumes on your expertise on grounding and static. I dealt with low order ordinance in my job and we were extremely careful about grounding and static discharges. I can only imagine what it was like in the munitions operations.

Bill
 
#33 ·
A buddy of mine had a contract to build specialized shipping containers for them and when he fell behind I helped him...
after a marathon building session we both took them out to the plant... 2 trucks two trailers...
so as we waited for the crates to be inspected/accepted two guys walked and wanted to know what I was doing...
holding this stool down watching those two guys spin their wheels building what ever it is they're building...

spoke what I saw...
spoke what I thought...
ended leaving there w/ 10 tables and 5 times the material needed for the build...came back a week later w/ 10 slightly differently constructed prototypes....
they got tested...
I got paid...
and it was hit the ground running there after...

w/ jigs, different fastener regime, lighter materials and standardization I reduced build time from 32 man hours to 10 not to mention cut material costs by 40%...
not to mention a way better table...
f you hurried a base table happened in 7 man hours....

back then rated polycarbonate in 3x5 sheets depending on thicknesses was 3 - 8,000 $$$ a sheet...
 
#34 ·
My response to all of this is a BIG TO DO over a non issue, I read a study awhile back when building my first system that an engineer did , He stated that the dust to oxygen levels in a home shop DC systems were no where near high enough or long enough duration to cause an explosion. And that it was a waste of time to run a bare copper wire inside or outside the ducts as the static electricity is formed on the inside walls of the duct work and the wire would be useless and would cause restriction especially at the elbow where material could catch on the connectors, Further since shocking is a nuisance a wire can be run from the machine which is grounded and attached to the duct thus eliminating any shock to the operator.

Herb
 
#35 ·
Its always worth bringing potential safety issues to the attention of people, but each person has to make their own risk assessment, based on their particular circumstances. I would not sneer at any one who made a proper job of grounding the pipe (NOT BARE WIRE!), but i will not be doing mine.
But I would like to make one more mention of a post here. One person said he got a static shock from his machine when leaning across it. Thats a VERY BAD thing. I suspect that machine does not have a ground connection.
Using my explanation of testing resistance with a multitester, Every body should test each of their machines from the metal body to the building ground. Obviously any 2 wire double insulated tools are exempt from this.
I have seen many poor grounds on equipment, all of them potentially life threatening.
For any one man or very small shop, ground (or earth continuity) testing is far more important than static grounding.
 
#36 ·
I have a perfectly grounded electrical system in my shop,and when I plug in my machine which has the proper ground plug from the factory, I feel that I am safe. I have no expertise to test all things electrical to see if they are grounded. I am a woodworker not an electrician and have a multimeter and don't know what any of those symbols on it mean anyway. All I know is that the needle wiggles and the sparks fly and then it doesn't work anymore so i have to throw it in the garbage.

As far as reaching over a machine and getting a shock of static E , has nothing to do with the grounding of the mach. It has happened to me numerous times on my drum sander and planer until I ran a wire from the duct to the machine to ground the plastic ductwork and give the static E a way to the ground.

Herb
 
#37 · (Edited)
No offense intended in any of my posts, but I do advise you to check with the tester. As I said, in my working life I came across several (many) wiring situations that the operator was completely unaware of but were lethal. I even had to shut down an entire school kitchen once, leaving a couple hundred kids without dinner, but that was better than a chef getting killed.
On your tester there will be a greek omega symbol, like an upside down horseshoe. Thats Ohms. Its used to test any wiring circuits continuity. It might be the type that just beeps, thats no good for this testing, you need digital numbers.
Set it to ohms and put the leads together, if you get a number around zero point 6, then thats your base number. put one test point against any bare metal on your machine, and the other test point on a ground connection anywhere in the shop (not the same machine!). if the number goes higher than zero point (your base number plus another zero point three) then you need to check it out. If the number goes above 1.00 then stop using the machine untill its checked.

Or, you could just stop wearing the nylon underpants :surprise:>:):laugh2:
 
#38 ·
Thanks Bob, I still am not totally clear, "on a ground connection" is that like the ground point on the electrical receptacle that the motor is plugged into? And also do you do this test while the machine is running or plugged in and shut off?

Thank you for taking the time to explain this.

Herb
 
#39 ·
I have to be a bit vague on details. I'm English, and all my experience is with UK systems.

All earth testing can be carried out while a machine is operating, but its much safer to shut it off.

So I'll do my best, I'll start right at the beginning as I have no idea what you do or dont know about electric.
All of your electrical equipment indoors and at work, has either two wires (double insulated, and not relevant to anything here).
three wires (medium powered stuff that plugs into a socket)
or more than three (could be 4 or five wires, this is known as 3 phase, and its heavy machinery or big ovens usually hard wired or with huge plugs) Only relevant here if it has a known earth wire.
anything in Europe that has more than two wires uses one of them as a ground (we call it earth) wire. The usa sometimes uses a system that does not have an earth wire known as delta wiring. This is not covered in my tutorial (g).
So what I'm talking about here is everything that plugs into a wall socket and can be disconnected just by pulling the plug out and has three wires.

In the UK and Europe, that earth wire is green /yellow. I really dont know what USA uses, find out, its important.
The machines will run fine without an earth, its there purely to save your life.
If anything goes wrong inside the machine and the frame becomes live, the earth shorts that power to ground, and the fuse / trip blows.

Sometimes a motor inside the machine can cause static build up. If the machine is not fully earthed, that static can eventually build up and spark just like a car spark plug. The more static, the bigger the jump.

So, this is why I go on a bit about testing the earth. Visual check is NOT GOOD ENOUGH. I've seen wires that look perfect, and are broken inside the insulation.

The digital meter measures the resistance through the circuit. Its possible to have a circuit, but with corroded or loose connections that will not operate correctly.

If there is too much resistance, the excess electricity does not travel fast enough, and then theres trouble brewing.

So, getting back to the point. you need to make sure not only that the earth (ground) wire is connected, but that it is connected well enough to save your life.

This is where the numbers come in. What you have to do is put one end of the test leads FIRMLY onto a bare metal section of the machine (paint, grease, corrosion, rust, even dust will make the connection erratic).
Find the wall outlet and find the earth pin.(this is where I'm vague, i believe its a little metal piece on the outer edge of the circular socket)
Press the other test lead FIRMLY onto the earth pin . Make sure the socket is turned off for safety.

What youve done is now made your own circuit, through the meter and the earth wire to the machine. If the earth wire to the machine is faulty, you will get a big number, anything right up to infinity.
You should get a very low reading. the circuit itself should be in the zero point 2 (0.2 OHM) area. But this is where I told you to put the leads together first. All test meters have their own resistance inside, the better the meter the lower the resistance, and you need to know that number before you measure your wire.

using the example I gave, put the leads together and you might get 0.6 on the scale. so, measure the machine to the wall outlet, you should get around 0.8. Its worth noting that the numbers may vary a little bit as you look at them, but the same rule applies.

If you get anything bigger than 0.5 ohm plus your test meter number (that would be 1.1 in my example) you should get the wiring checked. The bigger the number, the more scared you should be.

You can do this test all over your house as well. If its an old house, you might get scared there as well (lol) I have found sockets in kitchens that have NO earth connection,. where sockets either side have been fine. Just use your test meter and wander around, checking earth pin to earth pin. You should get the same low numbers everywhere.
This test is especially important on electric showers where you are wet, inside a wet box, and the power is only a few mm away. Nobody survives a shower shock.
Not much to do with woodworking I know, but I feel its very important because you very rarely get over an electric shock, even a minor one.
 
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