How filterable is the exhaust odor?

[wstnporter]

The laser cutting I'm renting across town right now stinks to high heaven, it has a strong exhaust running outside but I don't know that it has any sort of filter on it. The Lasersaur I'm building will be in my home in my modified 3 car garage, I live in a deed restricted neighborhood but I'm allowed to run my own business as long as it's invisible in sight, sound and smell. Can I cut acrylic, wood and leather and filter the exhaust enough that little to no odor will be present outside the house? 

[Steve Baker]

CONFESSION: I once operated an unfiltered laser cutter for long hours
every day out of a 2nd floor bedroom in the middle of a dense apartment
complex for six entire months. Nobody even noticed it, nobody knew it was
there - no complaints!

However, we were cutting wood - and the smell is just like wood smoke from
an open fireplace...and that's probably where most people thought the
smell was coming from from. You could easily smell the smoke from 50 feet
away if the wind was blowing the right way...but nobody ever mentioned it!

The smell acrylic is dramatically different. Acrylic produces strong
"chemical" smells...and that's something people will worry and complain
about.

So I guess filtering would be necessary. I believe some people have built
charcoal filters with some success. Some laser cutter manufacturers sell
filters that claim to be good enough that you don't even need to vent to
the outside world!

If you have $2,000+ to spend:

http://www.allerairsolutions.com/laser_engraving.html

In most places there are legal issues too...size of vent, how high above
the ground it is, what you're venting and in what quantities are all
entangled in the laws.

The sound of a laser cutter comes from the water chiller and the exhaust
fan. Both are pretty loud - but once you're outdoors and about 10 feet
away, it's only as noisy as an airconditioner fan...and that's what most
people would think they are hearing.

-- Steve

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-- Steve

[Stefan Hechenberger]

All the filter systems I know basically run the exhaust though some
active carbon filter. To make them fill up less quickly they also use
pre-filterers of various density.

This being said, I have yet to find a filter system that does not leave
smell. Even with top-of-the-line USD 6000 commercial systems and
commercial laser cutters the fumes were unacceptable for me.

tl;tr; evacuating to the outside is a must and there will still be
noticable smell around the exhaust when cutting lots of plastic.

--
Stefan Hechenberger
studio: Nortd Labs - labs.nortd.com
work: Institut f�r Experimentelle Architektur, UIBK
resident: F.A.T. Lab - fffff.at
project: Lasersaur - labs.nortd.com/lasersaur

[Weston Porter]

I appreciate the advice, this dilemma is driving me crazy. What I said in my original e-mail, about working out of my garage in a deed restricted neighborhood was actually hypothetical, I live in an apartment right now and I'm in the process of buying my first house, in order to build my Lasersaur and launch my business. After weeks to bidding on different properties I finally got a successful option on house with a 3 car garage workshop, I was thrilled but I had to back out of the deal this morning because the neighboring houses are really close and I just don't think I can hide the acrylic/leather burning odor.

I've been talking with the sales department for the filter business Steve suggested but they haven't dealt with anything like the Lasersaur before, based on the size they are recommending a 4k filtration system and I'm worried it will be too powerful since I'll be cutting paper as well leather. Anyway, can anyone recommend any other filtration systems? I can build my own fan system and I will be evacuating the air outside but I have to filter the odor as much as possible.

I'm stuck in a bad limbo, I've got less than two months left on my lease and I can't buy a house until I figure out an exhaust solution and understand just how much odor will be unfilterable and at what range it will be noticeable.

On Sat, May 25, 2013 at 4:29 PM, Stefan Hechenberger <ste...@nortd.com> wrote:

All the filter systems I know basically run the exhaust though some active carbon filter. To make them fill up less quickly they also use pre-filterers of various density.

This being said, I have yet to find a filter system that does not leave smell. Even with top-of-the-line USD 6000 commercial systems and commercial laser cutters the fumes were unacceptable for me.

tl;tr; evacuating to the outside is a must and there will still be noticable smell around the exhaust when cutting lots of plastic.

--
Stefan Hechenberger
studio: Nortd Labs - labs.nortd.com

work: Institut für Experimentelle Architektur, UIBK

resident: F.A.T. Lab - fffff.at
project: Lasersaur - labs.nortd.com/lasersaur

On 05/23/2013 08:07 PM, wstnporter wrote:

The laser cutting I'm renting across town right now stinks to high
heaven, it has a strong exhaust running outside but I don't know that it
has any sort of filter on it. The Lasersaur I'm building will be in my
home in my modified 3 car garage, I live in a deed restricted
neighborhood but I'm allowed to run my own business as long as it's
invisible in sight, sound and smell. Can I cut acrylic, wood and leather
and filter the exhaust enough that little to no odor will be present
outside the house?

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[douglas repetto]

Can you vent up instead of directly out? That's the idea of a chimney
after all, to get some of the nasty things up in the air where they can
disperse a bit before drifting back down. You probably don't want to be
pumping laser exhaust through a house's ventilation system, but maybe
running a hose up the side of the house is an option?

I run unfiltered laser exhaust out a window via a 4" hose. There are
apartments across an alley about 30' away. I mostly only cut wood and
paper, so as someone else mentioned it just smells like burning wood. If
the wind is blowing back at the window then it can get a little smokey
in my studio, but never intolerable. On the few occasions when I've cut
plexi in my machine I've been very unhappy with the resulting unfiltered
fumes, so I almost never cut it.

Good luck,

douglas

> studio: Nortd Labs - labs.nortd.com <http://labs.nortd.com>
> work: Institut f�r Experimentelle Architektur, UIBK
> resident: F.A.T. Lab - fffff.at <http://fffff.at>
> project: Lasersaur - labs.nortd.com/lasersaur
> <http://labs.nortd.com/lasersaur>

>
>
> On 05/23/2013 08:07 PM, wstnporter wrote:
>
> The laser cutting I'm renting across town right now stinks to high
> heaven, it has a strong exhaust running outside but I don't know
> that it
> has any sort of filter on it. The Lasersaur I'm building will be
> in my
> home in my modified 3 car garage, I live in a deed restricted
> neighborhood but I'm allowed to run my own business as long as it's
> invisible in sight, sound and smell. Can I cut acrylic, wood and
> leather
> and filter the exhaust enough that little to no odor will be present
> outside the house?
>
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[Erik Moon]

Hi Weston-

​I live in a planned community with very nosy neighbors...

I vent outside with an 8" centrifugal fan like this one:

http://www.ebay.com/itm/8-Duct-Blower-Centrifugal-Inline-Exhaust-Fan-For-Odor-Control-Carbon-Air-Filter-/230686073092?pt=LH_DefaultDomain_0&hash=item35b5f62104

​

I attached the fan to 6" duct work that was originally intended for a "smoke eater" in a finished basement rec room (was originally going to be my "poker room"). It vents directly outside with no filtration. It vents about 2' above ground level.

My nearest neighbor is about 40' -- they are not outside very often and I have never received any complaints while cutting wood or acrylic. I do most of my cutting in the late evening, so they would really need to be on a mission to figure out which house it was coming from... Cutting plywood is not all that different from fireplace smells, so probably would draw no attention. The acrylic definitely smells different - but no one has come knocking yet...

​I agree with Douglas - vent at roof level would probably ensure an undetectable dilution of the venting, but make sure your ductwork inside the house has no leaks. Otherwise you could fill your house with burned acrylic stink.

-Erik

​ 

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[Weston Porter]

Yes, I can vent up, at least to the roof line and I could maybe snake a rubber duct hose through the roof and up the back of a chimney. It's good to know that helps, I wasn't sure about the physics of particulates and odor in laser cutting. I do feel much better now and I'm sure I could ghetto rig some sort of carbon filter onto that to further reduce the smell and increase legitimacy.

Thanks again for the prompt advice, this community is awesome!

[Steve Baker]

The thing with smoke is that it needs to be diffused into the air ("The
solution to pollution is dilution"!). As the smoke moves away from the
source, it should ideally be able expand outwards in all directions and
the smell should follow an approximately inverse-square law: Double the
distance from the source and the smell should be four times less -
quadruple the distance, 16 times less small. However, if the air is
funneled down a narrow gap (like between two buildings) then it can't
expand outwards and the smell will travel over long distances at full
concentration.

The ideal then is to get the source to be as far from neighbors as
possible - and not blowing through tight spaces.

Getting your outlet up high is a good idea because it increases the
distance to anyone standing on the ground - but also because there are
less problems with the air being funneled between buildings or whatever.
That's why factories that emit smoke often have those tall smoke-stacks.

So, I agree (in principle) with trying to get the outlet vent as high
above the ground as you reasonably can.

However, long hose runs reduce the effectiveness of your vent fan. The
more friction and turbulence you cause through long pipes and pipes that
take twists and turns, the more powerful the fan will have to be to
achieve enough air flow.

Because the goal is dilution - a higher CFM (cubic-feet-per-minute) fan is
a good idea because you're diluting the smoke at the outset by that number
of cubic feet. If you have a long/twisty exit tube, you'll reduce the
number of cubic feet that the fan can shift per minute - and that will
result in more concentrated exhaust gasses.

So you wind up with the contradictory need to have a short, straight run
for reasons of fan efficiency versus (probably) a longer, twistier run to
get the smoke outlet as high as possible.

Incidentally: With regard to your plan to put the lasersaur into a garage
- I don't know what part of the world you live in - but here in Texas, it
gets pretty hot - and because most garages are not air conditioned - they
get VERY hot in summer (ours reaches 45 degC on the worst days!).

The cheaper water chillers that we use don't actively refrigerate the air
- they rely on having relatively cool ambient air temperatures. For that
reason, they wouldn't work well in a texas-hot garage. Running the laser
too hot would likely shorten the life of your laser tube dramatically.
Hopefully you don't live someplace where it gets that hot though.

-- Steve

>> On Tue, May 28, 2013 at 9:00 PM, Weston Porter <**wes...@wespor.com**

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