Blowing dust directly outdoors ?

[gjbuilder]

I am building a shop that will have a mitre saw on a nice long mitre saw table, and I assumed I would build one of those hoods behind it that connects to a 6" hose and collects everything coming out of it.

However, it turns out there is a window directly behind the mitre saws eventual location, and we haven't installed any glass yet - it's just framed in right now. The framed in space for the window is 3 feet tall.

See where I'm going with this ?

Instead of building a fancy hood, around the back of the mitre saw, why not just put a 3' fan directly behind it, venting outwards ?

I'm trying to think of why this would be a bad idea and ... a 3' fan would move a lot of air....

 

[gungatim]

because it will **** air out of the shop, which presumably is conditioned (heated/cooled?) and draw in outside air that presumably isn't...not to mention possibly blow dust back in the open window. my sliding mitre is directly in front of a window in my basement and I tried this before I got my cyclone system. did not work well for me...

 

[gjbuilder]

because it will **** air out of the shop, which presumably is conditioned (heated/cooled?) and draw in outside air that presumably isn't...not to mention possibly blow dust back in the open window. my sliding mitre is directly in front of a window in my basement and I tried this before I got my cyclone system. did not work well for me...

Thank you - that is well taken.

May I add that I live in northern california - the heat will be off most of the year and there is no need for AC.

If those considerations are set aside, does this remove dust effectively ? It seems like it would ... I could have an inlet elsewhere in the shop that allows replacement clean air when I run it ...

 

[DCarr2]

in my old shop, my dad made a vacuum system that did exactly what you want to do... but its a closed system, and vents outside... It automatically kicks on when you turn on one of the pieces of equipment connected to it, or you can manually turn it on.... and the way he set it up, it doesnt really **** out the warm air in the shop in the process, just dumps the dust.

with that said, you may want to 'enclose' your dust dump or shield it in some way as to not bother the neighbors.

also, sawdust soaks up water like a sponge, so you may want to take that inst consideration as well.

 

[ItsNemo]

Not to mention where does it go? If the window is out onto a big open field of several acres than might be okay...but if the window is 10 feet from the fence line with your neighbour, might not be so good.

 

[Showkey]

Isn't there a law in California against releasing saw dust in the air.....?

 

[gjbuilder]

Not to mention where does it go? If the window is out onto a big open field of several acres than might be okay...but if the window is 10 feet from the fence line with your neighbour, might not be so good.

Yes, exactly - windows point outward to a 4 acre pasture ... which is surrounded by 8000 acres of open space.

No neighbors in any direction.

 

[D1005]

That's exactly what I'm planning on doing. Louvered fan where the fan blows the louvers open, and they close via gravity. I'm not 10' from a neighbor. Air conditioned building? Being able to turn the fan on on a hot day would be TERRIFIC! Actually change the air instead of just blow it around. In winter it's too cold to do anything, so no heat lost as there isn't any.

 

[rsanter]

You could buy I would not.
How about a gust of wind that blows it in your face. How about rain, security...etc
How about sawdust that collect against the outside wall and get wet and starts to cause issues?

If it was me I would go through the window and into a box or container of some kind of container. Then you can either spread it in the field or flower beds or use it for oil pickup

Bob

 

[iajonesy]

Isn't there a law in California against releasing saw dust in the air.....?

Isn't there a law in California about everything?

Mike

 

[turbowoodworker]

On occasion, you will be squaring the end of a board and a sliver as big as a couple of millimeters will get shaved off and thrown into your fan, and maybe back at you.
Not to mention all of the other good arguments above.

 

[gjbuilder]

On occasion, you will be squaring the end of a board and a sliver as big as a couple of millimeters will get shaved off and thrown into your fan, and maybe back at you.
Not to mention all of the other good arguments above.

Thank you - that's a very good point.

Weather and security and so on are not issues, so those weren't very compelling for my situation.

But you've raised a good point of function.

Thanks.

 

[rslaback]

My concern would be that it is going to leave whatever is outside the shop at that space coated in a layer of sawdust. When that gets wet it will turn into the nasty wood putty/mud and be there for good. Eventually it will break down but not with any kind of reasonable speed.

The sawdust your miter saw puts out isn't going to be fine enough to just blow away to the ends of the earth. It's going to settle on whatever is right outside that wall and be a mess.

 

[boiler7904]

If there are so many good reasons to just let it vent directly outside, why not save the shop space and put the saw itself outside?

 

[Firebird 1]

I have an exclusive wood shop, and do so professionally. I have a dust collector on my table saw and portable outlets to switch between tools that need it at the time. My mitre saw has a window directly behind it. I have installed a louvered exhaust fan in that window. I do not have dust collection on the chop saw and most of the time I have the exhaust fan running to help clear the air. I have never had problems with anything blowing back in. It vents outside to 5 wooded acres, I don't thing the trees mind, and if they do, I just tell them be thankful they're not the dust!

 

[NUTTSGT]

My shop vac for the blast cabinet vents outside through the roof. I have no issues with that. However, it doesn't get tons of use like the miter saw or radial arm saw. If I had though plumbed outside, I'd lose a ton of heat during the winter.

 

[nh_yota]

If there are so many good reasons to just let it vent directly outside, why not save the shop space and put the saw itself outside?

This.

 

[D1005]

Some points against, I'll admit, but isn't there always? I'm still going forward with something that costs less than 1/4 as much for the same amount of air movement, which really matters on a tight budget. Something that runs on less than 1/5 the electricity, which means not having to run more electric circuits, and something that takes up no floor space when floor space is at a premium.

As for it piling up, it does the same when set up outside, which is what I do now when I can. Since I'm not a professional running it all day every day, build up is a non issue, though the dust build up inside makes one heck of a mess over time.

The fan will help with air exchange within the building, so it'll also be of use for welding fumes, something a collection system does nothing for.

Everyone's needs are different, but on my budget, with my needs, an exhaust fan vs. an expensive dust collection system is a no-brainer. It's the fan I can afford, that will work for multiple tasks, as it'll work far better than nothing, which is essentially what a collection system I can't afford amounts to.

 

[R6 Racer]

May I add that I live in northern california - the heat will be off most of the year and there is no need for AC.

That's exactly what I'm planning on doing. Louvered fan where the fan blows the louvers open, and they close via gravity.

gjbuilder There will be many more times your location will come up in a thread. This is a perfect example. You should probably put your location in your profile.

D1005 The fan you describe here sounds to me like an industrial exhaust fan. Something with at least a full 1HP & commonly up to 3HP. Also often with a 220/230V motor. (Not a cheap fan buy any standards. Typically as much or more than the 2HP HF dust collector )

A typical box fan wouldn't cut it! Not nearly powerful enough the wind will blow in on one of those easily. They don't have the power to grab the dust that isn't thrown directly into it.

I see that type of industrial fan commonly used as greenhouse exhaust fans. If that is the fan your talking about, there is no wind that will blow back on it. (short of a hurricane)
I do see flying debree(sp?) as maybe being a problem but adding a basic screen in front of the fan might solve that issue. I think that with that type of fan you would get way better clearance of all unwanted particulates than you would with a cheap dust collector. The downside would be the mess it would make of the side of your shop & the surrounding land. It wouldn't be a small mess! If not cleaned up quite regularly it will become a rotting stinking mess & it will eventually do permanent damage your shop/structure.
Look at a saw mill. Some have sawdust expelled but they all have long ducting (usually with a down turned 90 that fires the dust straight down & some even use a long sock to get closer to the ground with the waste) that insures the waste is far from the structure.

Maybe ducting after the fan to direct it into a waste container of some kind. I do think there would be a lot of guess work involved making ducting after a fan tho. I really don't know I'm just throwing out a thought.

To both of you.
Good luck & welcome to GJ .

 

[LS6 Tommy]

It will need to be explosion proof and if it's a public or commercial place it will needs to have finger guards if it's less than 8" from the ground...

Tommy

 

[D1005]

R6, yes, I have an industrial fan, two actually, totally enclosed motor w/shutters. Watched them for several months, from several vendors, before catching what I wanted on sale at a very reasonable price. They're about 1,000 cfm, each, which can be done with a fractional horsepower motor directly driving a blade. A 1,000 cfm dust collection system runs into many more dollars than the combined cost of the 2 fans, and requires a much bigger motor to run.

I still don't see any accumulation to worry about. Currently, I set up outside, which really ***** in the rain, and the "pile" soon disappears. If I was doing tons of cutting on a regular basis, that could be different.

If a pile was to accumulate, a simple pad outside the garage to sweep up, would be a simple solution. Beats the heck out of having to dust everything in the garage!

For me, an exhaust fan is pretty much needed anyway for various other operations, so why not put it to one more use? After 40 years of "just breathing it", some air exchange will be very welcome.

Maybe it'll work, maybe it won't, time will tell. Plenty of time though as it'll be close on to fall by the time I'm up and running. Things happen real slow on tight budgets.