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Dust Collection

Started by scleigh, November 29, 2014, 10:47:33 PM

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scleigh

I'm at best a novice wood worker, so please excuse my lack of knowledge.
I have been trying to get a few pieces of equipment to go in my shop and decided to get a dust collector. The instructions say to run a ground wire inside the tube from the machine (i.e. jointer), to the dust collector. I understand why but here's my question: How can you use a ground wire inside the tube and use a blast gate at the same time?
Thanks for any advice.

beenthere

There are varying opinions as to the validity of the ground wire. The idea is to drain off any static electricity that might spark and start a combustion fire.

Not sure I would put it in, but prolly would worry about it happening at the most inconvenient moment.

Probably could shunt around the gates by going external to the tube with a strap at the gate. But depends on the gate construction and the materials.
south central Wisconsin
It may be that my sole purpose in life is simply to serve as a warning to others

hackberry jake

Static fires in dust collectors is an old wives tale. Dont worry about the wire.
https://www.facebook.com/TripleTreeWoodworks

EZ Boardwalk Jr. With 20hp Honda, 25' of track, and homemade setworks. 32x18 sawshed. 24x40 insulated shop. 30hp kubota with fel. 1978 Massey ferguson 230.

Andries


SCLEIGH:
Smart move putting the collector in - working in a dust clogged shop is just plain unhealthy and dangerous.
Taking the time and trouble to install the grounding depends on humidity.
In the summer, my 2 hp General dust collector works like it should with no back-talk.
Yesterday, 'cause the humidity is so low, it gave me a static shock that pucker'd me up for a three count!
Most of my system is metal pipe, but it's time to ground the plastic hose for general floor clean-up.

Dust collector fires in a small shop aren't an issue like Hackberry says, and down South where you are, well the moisture in the air will keep things shock-free.
. . . and what the hay, you can always pop in a copper wire later if you want to.
LT40G25
Ford 545D loader
Stihl chainsaws

Dan_Shade

I've been zapped pretty good with a PVC dust collection system.  I didn't have a wire in the PVC. 

Do any of you guys with a wire have static problems? 
Woodmizer LT40HDG25 / Stihl 066 alaskan
lots of dull bands and chains

There's a fine line between turning firewood into beautiful things and beautiful things into firewood.

red oaks lumber

using pvc and not having it grounded is asking for trouble. i have all metal and its still grounded, the shock off it will about knock you over.
you don't need to have a wire inside the pipe, you just need to have it grounded in a few spots. static fires are no wives tale ;) its a very serious saftey issue
the experts think i do things wrong
over 18 million b.f. processed and 7341 happy customers i disagree

scleigh

Thanks for all the suggestions.
Most likely, I'll only have the jointer and a planer on the dust collector, using the rubber flex hose. Would a ground wire from the machine to the collector, outside of the hose work?

yukon cornelius

if I were installing the ground to the inside I believe I would drill through and use a bolt to go through to the inside. I would attach the wire to the outside of the hose but the bolt head would be inside. then on the gate I would jump around it outside then back in on the other side. I don't have a dust collector built yet but this is how I plan to do it when I do.
It seems I am a coarse thread bolt in a world of fine threaded nuts!

Making a living with a manual mill can be done!

mesquite buckeye

Dust explosions are no joke. I remember a demonstration in high school chemistry class where the teacher set up a tin can with a blow tube, a lit candle, and about a tablespoon of flour. He blew the flour upward out of the can, it ignited, just about roasted his face, and scorched the 10 foot high ceiling. :o


Lots of grain elevators blow up with many deaths from dust explosions.

Just throw a handfull of fine sawdust over a campfire sometime and watch the action.
Manage 80 acre tree farm in central Missouri and Mesquite timber and about a gozillion saguaros in Arizona.

Andries

Agreed, dust explosions are a very real hazard. Any industrial setting for flour or seed mills, wood dust of any kind - the hazards are there. It all goes back to whether the operation produces a dust to air ratio which could make an explosion possible. The big operations have all manner of fire and explosion prevention systems in place.
However, the original post is for a small home set-up, and I've never heard of a dust explosion in a small shop. From ShopVacs with a plastic cyclone (sold by the thousands) to a modest 1 to 2 HP dust collector system - has anyone heard of that happening?

Grounding the system is a good idea, mostly to prevent static shock though.

On the other hand, stuff happens right? My Dad was cleaning up his shop with a 2 HP dust collector and happened to suck up some 'strike anywhere' matches.
Well, they did. Strike anywhere that is. At 2AM he woke up to smoke alarms and a sawdust collection bag that was smouldering. He was embarrassed and lesson learned.
LT40G25
Ford 545D loader
Stihl chainsaws

hackberry jake

Quote from: red oaks lumber on November 30, 2014, 11:36:34 AM
using pvc and not having it grounded is asking for trouble. i have all metal and its still grounded, the shock off it will about knock you over.
you don't need to have a wire inside the pipe, you just need to have it grounded in a few spots. static fires are no wives tale ;) its a very serious saftey issue
I retract my previous statement about the wives tale. red oak has definately been around and seen more than I have. The only reason I said that is because of a couple different studies (One of them being on the Mythbusters tv series) that tried to get wood dust to ignite by a spark in some of the worst case senarios. They used oven dry fine dust with zero percent humidity and a constant spark source. The volume of air going through the pipe dilutes the dust to air ratio too much to ignite. Pvc is also an excellent insulator, so any wire you run along the pipe has little to no effect on the static build up of electrons. There are things that happen in the real world every day that are hard to re-create in a lab though.
https://www.facebook.com/TripleTreeWoodworks

EZ Boardwalk Jr. With 20hp Honda, 25' of track, and homemade setworks. 32x18 sawshed. 24x40 insulated shop. 30hp kubota with fel. 1978 Massey ferguson 230.

Dan_Shade

I used to work for a fella who's brother sanded floors for a living. 

He was sanding floors in a house once, and a phone rang, causing an explosion.  It put his brother in the hospital.
Woodmizer LT40HDG25 / Stihl 066 alaskan
lots of dull bands and chains

There's a fine line between turning firewood into beautiful things and beautiful things into firewood.

Dave Shepard

My mother was sanding floors once and ran over a .22 caught between two floor boards. That caused an explosion. :D Fine dust is definitely an explosion hazard. You don't wan to use a steel shovel around finely ground grain. Our grinder/mixer has a pin hole in the bottom of it and there is always a little pyramid of the finest corn powder you've ever seen under it. Feels even finer than confectioners sugar. I bet that would blow up under the right conditions.
Wood-Mizer LT40HDD51-WR Wireless, Kubota L48, Honda Rincon 650, TJ208 G-S, and a 60"LogRite!

WDH

Quote from: Dave Shepard on December 09, 2014, 09:04:34 PM
You don't wan to use a steel shovel around finely ground grain.

I have never had grits blow up. 
Woodmizer LT40HDD35, John Deere 2155, Kubota M5-111, Kubota L2501, Nyle L53 Dehumidification Kiln, and a passion for all things with leafs, twigs, and bark.  hamsleyhardwood.com

Dan_Shade

that's cause they're blown up before you buy them

Woodmizer LT40HDG25 / Stihl 066 alaskan
lots of dull bands and chains

There's a fine line between turning firewood into beautiful things and beautiful things into firewood.

POSTON WIDEHEAD

Quote from: WDH on December 09, 2014, 09:09:12 PM
Quote from: Dave Shepard on December 09, 2014, 09:04:34 PM
You don't wan to use a steel shovel around finely ground grain.

I have never had grits blow up.

smiley_clapping
The older I get I wish my body could Re-Gen.

Just Me

 You will not get an explosion on a small dust collector like you are looking at. Commercial systems are a whole different ball game because of the volume of chips causing static. Thats why they have fire suppression inside their systems.

On the static thing....... It is dangerous, but not because of fire. I helped out a friend at his shop last winter and he had dust collection in plastic and it would jump 6" and really zap you. I was running a jointer and it Zapped me when my hand were close to the cutter, scared the crap out of me and I jerked. That could be real bad.....

I took a coil of bare copper and wrapped it around the pipe and grounded it, and that was all it took, no more getting zapped.

If you smoke don't keep your Bic lighter in your shirt pocket, been there...... ::)

mikeb1079

we were having some static shock issues with the sandblast cabinet at work.  ended up doing the bare wire through the hose and grounding it method and no more shocks.   :)
that's why you must play di drum...to blow the big guys mind!
homebuilt 16hp mill
99 wm superhydraulic w/42hp kubota

5quarter

I was expecting to see some impressive collections of dust...I don't want to brag, but my personal collection contains over one million individual specimens.  ;D
What is this leisure time of which you speak?
Blue Harbor Refinishing

mesquite buckeye

Manage 80 acre tree farm in central Missouri and Mesquite timber and about a gozillion saguaros in Arizona.

Sawyer697

Blow mine outside, with plastic 4 " pipe, with grounding wire wrapper around the outside, it ends up in a metal sided building about 20' away from the shop. A planer sure makes am lot of shavings!
1997 LTHD40G24 WM Mill. 640 Bobcat. 555 ford Backhoe, Husky 365XP
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Build my own solar kiln
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sandhills

Not trying to hijack this at all but one day I was filling a tractor with diesel and kept hearing a popping noise, gravity fed 500 gal. barrel, finally found the source, it was jumping a spark about a 1/4" from the hose to the frame holding the tank.  After 20 some odd years with that barrel I'd never seen or heard it do that before, it's now grounded, just glad it wasn't gas.

5quarter

Sandhills...Now that's what I'm talkin bout!   ;D ;)
What is this leisure time of which you speak?
Blue Harbor Refinishing

Busy Beaver Lumber

I have read much on this topic and the prevailing opinion is that there are no documented cases of EDS causing fires in home sized dust collection systems using pvc pipe.

A more common cause of fires in home dust collection systems is from a metalic object ( such as a nail) getting sucked into the dust collection system, striking a metal blade on the blower, them sparking and smoldering , thus causing a fire. This threat can be eliminated by installing a cyclonic separator in series with the dust collection system prior to the vac unit

Having said that, I would still ground the PVC pipe and fittings on your dust collection system by wrapping bare copper wire around the pipes and fittings and attaching it every few feet to the outside of the pipe with a small sheet metal screw and aluminum tape. Without that wire grounding, the outside of the PVC can build up enough of a charge that it will be quite painful when you act as the discharge path.

Wire is cheap. 50 foot of bare 14ga wire with crimps ran me about $7 on amazon. the aluminum tape from 3m was about $15 for a 50 yard role on amazon as well. $22 is a cheap insurance policy to keep from being painfully zapped every time you touch your dust collection pipes.

One last side not, spend a few more dollars and get the aluminum blast gates. The plastic ones are terrible and in a short time the collect debris in the path of the gate and leak like anything. Also minimize the use of flex hose, as the ridges can greatly decrease the movement of dust and debris though the system. Finally, although some wood working tools have 4 inch diameter dust ports, many machines have ports smaller in diameter than that. In that case, run the dust collection pipe work to the machine with large diameter pipe ( like 4" ) then reduce the diameter as close as possible to the machine to match the machine. Makes a big difference.
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Grizzly 15in Spiral Cut Surface Planer
Grizzly 6in Spiral Cut Joiner
Twister Firewood Bundler
Jet 10-20 Drum Sander
Jet Bandsaw



Save a tree...eat a beaver!

Swatson

Quote from: Busy Beaver Lumber on January 25, 2015, 11:56:33 AM
Also minimize the use of flex hose, as the ridges can greatly decrease the movement of dust and debris though the system.

Busy beaver nailed the flex hose issue.  Smooth walled pipe will give you more velocity and volume of air moved.  The difference is not small either.  I used to work in HVAC and small things make huge differences in airflow.  Smooth walls and large radius corners can give 30% or more improvement in air flow.  There are tons of variables in the calculations (the equations used are pretty crazy) but smooth walls will allow air to flow faster and smoother with less turbulence and carry more air...  and take the debris with it in a vacuum system.

On another note I have a 2 x 72 inch belt sander.  When I use it during the winter it likes to deliver very painful static shocks.  It is grounded well but it runs the belt on rubber tires.  I havent found any good way to discharge the static that builds up other than through me or something I am holding. 
I cant figure out which one I like better: working with wood or making the tools to work with wood.

Just Me

I had a Kalamazoo that was biting me like that. I rigged up a ground strap like you used to see on old cars to take the static off of the belt. Machine is long gone now so I can't take any pics, but it was simple and it worked.

Larry

Just Me

On the subject of dust explosions, it will "probably" not happen in a home shop. A lot of the guys on here are small commercial and it is a lot more likely in that setting. I know of two in shops the size of mine. One was an article in a trade magazine years ago that made me study up. Blew all the walls right out of a small cabinet shop like mine. The other was a local shop that burned. It blew out one wall, and there was nothing in the shop that would have caused an explosion of that magnitude, other than dust. The local fire chief had never heard of secondary dust explosions, blamed a water heater. But everything was blown into the wall that the water heater was behind. The guys shop was a dust nightmare.

The only ones we hear about are the huge ones where people die, as that is good news material, Small country fire chiefs often do no even know about the phenomenon. From my research I learned that my shop was a prime candidate. Two overhead gas box heaters, exposed beam ceilings, poor dust collection, 55x20 storage loft with tons of fine dust. All it would have taken in a furnace malfunctioning.

It is interesting, there are actually as many as four explosions in indecernably rapid succession when dust blows out a building. In my case it could have been the heater, every once in a while they would light with a "whump" The original blast unsettles existing dust, that explosion unsettles more dust, and so on till the walls blow if there is enough fuel.

The likely hood of the conditions all being just right are slim, but by eliminating just one of the five conditions needed there is no risk at all. I fixed my heaters, cleaned up the 2" of dust on my beams and cleaned up the attic. Death by fire is not how I want to go.

The size of the building makes no difference, its the conditions. Like I said, we only hear about the big ones because of the media, and they are the only ones that get investigated. The two mills that blew up in BC recently got a lot of press because people died and the pictures were impressive on the 5 oclock news.

I'm not saying the sky is falling, just that a small amount of cleanup can get rid of the risk. There are some new regs coming down the line that are a bit too extreme for accumilated dust. Hope they back off a bit, but if you have a business that hires employees you might want to figure out ways to cut down on accumilated dust before they go into effect.

Busy Beaver Lumber

Just Me

I am 100% in favor of what you are advocating....good maintenance.  Even with dust collection systems at both of my facilities, I never ceased to be amazed at just how much dust escapes them.

At the home shop, at least 4 of 5 times a year, I open both garage door and set up two large fans blowing outside. I then use a compressor with a 3 foot extension wand, start at the back of the shop, and blow everything off in the shop. It is amazing the cloud of dust that leaves, even though I do it several times a year.

At our building where we bundle firewood and run the sawmill, jointer, and planer, the same it pretty much true, although with the taller ceilings and a lot less places for dust to collect, I don't get nearly the dust cloud as I do at home. Those 3 foot wands come in handy for blowing stuff off and at the building i made a longer wand using a piece of pcv to get the rafters and hard to reach higher places. Insurance agent likes the idea that I do this as well to eliminate dust buildups.
Woodmizer LT-10 10hp
Epilog Mini 18 Laser Engraver with rotary axis
Digital Wood Carver CNC Machine
6 x 10 dump trailer
Grizzly 15in Spiral Cut Surface Planer
Grizzly 6in Spiral Cut Joiner
Twister Firewood Bundler
Jet 10-20 Drum Sander
Jet Bandsaw



Save a tree...eat a beaver!

scleigh

For now, I only have the jointer connected to the dust collector, but hope to add a 20" planer in the future. My building is not insulated, has a cement floor and has a 14' vaulted ceiling. If I use a wood stove to heat the building, am I asking for trouble?

beenthere

Might be in trouble if you are venting the dust collector outside... likely will pull smoke back down the chimney.  But provide make-up air for the draft in the wood stove and it might work ok. Then will just be blowing heat out through the dust collector. There may be designs that will work around this, with air exchangers built in the system.

What do you have in mind for the dust collector and the wood stove?
south central Wisconsin
It may be that my sole purpose in life is simply to serve as a warning to others

thechknhwk

I like this thread.  Something I hope to be dealing with in the near future.  Could you guys post some pics of your grounding setups?

mesquite buckeye

Hook your dust collector up to your forge and you can have a real blast. ;D

BOOM BLAST, that is. ;D 8) 8) 8) :snowball:
Manage 80 acre tree farm in central Missouri and Mesquite timber and about a gozillion saguaros in Arizona.

scleigh

I've got a 2hp Grizzly dust collector and an older Fisher wood stove. The wood stove will not be burning at the same time the dust collector is running very often. The stove will be used maybe a few times a week, dust collector less often. I think keeping the area clean will go a long way.

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