Can't get 100% of smoke/smell to exhaust out

[Kev Williams]

I can't quite tell from from what I've read, so I'll ask--

Are the blowers outside, or inside?

Because if they're INside whatsoever, you will have positive pressure inside the room, which will push smoke and smell into the room. No matter how well you think the blower or your vent piping is sealed, positive pressure from the blower will find a way out, thru the vent or the blower housing itself...

The only sure fix is to have the blower OUTSIDE. This way, ALL of the moving air within the vent tubing will be in a negative pressure/vacuum condition until it reaches the blower outside. Any leaks in the plumbing will draw room air INTO the vent, not push smoke OUT...

[Todd Mueller]

I can't quite tell from from what I've read, so I'll ask--

Are the blowers outside, or inside?

Because if they're INside whatsoever, you will have positive pressure inside the room, which will push smoke and smell into the room. No matter how well you think the blower or your vent piping is sealed, positive pressure from the blower will find a way out, thru the vent or the blower housing itself...

The only sure fix is to have the blower OUTSIDE. This way, ALL of the moving air within the vent tubing will be in a negative pressure/vacuum condition until it reaches the blower outside. Any leaks in the plumbing will draw room air INTO the vent, not push smoke OUT...

They are inside mounted directly to the board that have fixed into the window. I had never read anything about this yet. Keeping the fan outside in the elements and weathe proof could be a challenge from moisture, rusting, rain etc. How do most people handle this. It does make sense what you said. I'm sure it could find some small space somewhere to leak out

[Todd Mueller]

Elaborate on the you have two fans comment. Do you have two lasers or what is the other hooked up to?

There are two 4 inch exhaust ports on my machine. One goes to a kind of enclosed area that sucks from the underside of my cutting area, the other is below that one and sucks from the main lower cabinet area. Both on the backside of machine and both are factory installed ports

[Bill George]

There are two 4 inch exhaust ports on my machine. One goes to a kind of enclosed area that sucks from the underside of my cutting area, the other is below that one and sucks from the main lower cabinet area. Both on the backside of machine and both are factory installed ports

They both need to be on the same fan. Your blower is mounted correctly. Its inside out of the weather most or nearly all of the pipe is on the negative side of the fan and the exhaust goes directly to the outside.

[Lee DeRaud]

The suggestions regarding using the HF dust-collector are probably the best.

One further consideration: is the smell only while you're actually cutting, or does it linger for some time afterward? I've noticed the room where my machine is located smells smoky for awhile after cutting MDF, but the smell is only noticeable after the fan is shut off. Eventually figured out it was from residue on the honeycomb cutting bed...not much the fans can do about that.

[Lee DeRaud]

Your blower is mounted correctly. Its inside out of the weather most or nearly all of the pipe is on the negative side of the fan and the exhaust goes directly to the outside.

What he said. They call them "blowers", but they're much more efficient as "suckers".

[Todd Mueller]

The suggestions regarding using the HF dust-collector are probably the best.

One further consideration: is the smell only while you're actually cutting, or does it linger for some time afterward? I've noticed the room where my machine is located smells smoky for awhile after cutting MDF, but the smell is only noticeable after the fan is shut off. Eventually figured out it was from residue on the honeycomb cutting bed...not much the fans can do about that.

It increases while cutting so it's getting out. And yes it lingers afterwards too. I am ordering the big harbor freight dust collector today. 1550 cu feet per minute. I can't imagine anything escaping that power?

[Bill George]

Way over kill, but the picture shows two 4 inch intakes.

[Keith Winter]

It increases while cutting so it's getting out. And yes it lingers afterwards too. I am ordering the big harbor freight dust collector today. 1550 cu feet per minute. I can't imagine anything escaping that power?

Two different blowers pulling different amounts at different speeds...not good. Upgrading to a single more powerful blower will make a difference, you will like the bigger one fine. As for the lingering what are you cutting again that is smelling?

[Keith Winter]

Way over kill, and I am assuming the big one is 220 volts?

A little overkill yes, he could make do with the smaller I would think, his two 4" ports though is a strange setup. I haven't seen two 4" ports before in such a small laser, he might need more power than the small HF just from the standpoint of him having to divide the output into two 4" ports. I think the output off the small HF is only one 4" port, and the output off the bigger HF is a 5" port.

[Kev Williams]

About the HF 'green' -- or 'gray' blowers these days-- I've had 2 of them in my basement stairwell, once since 2002, the other since 2004. The 2004 model was literally out in the weather, on it's side, intake up, motor down, been rained and snowed on 24-7-365. I just barely replaced it maybe 6 weeks ago, because one of the motor bearings started seizing up and was tripping my power strip. The 2002 model had a bearing start to get noisy about a week later. '. It still works just fine, but the noise carries at night.

That's the longevity story, 14 and 12 years old, outside the whole time, one for at least 10 years in direct weather exposure. Not bad for a Chinese blower...

Now for the smell story-

The 2004 model, before it went outside, was inside right behind my LS900. No matter what I did, I could NOT keep the basement smoke and odor free. No amount of new hose, duct tape or clamps helped. Once I moved it outside, voila, my basement has been completely devoid of smoke & smells ever since. I've lasered leather in the ULS and deer horns in the LS900 at the same time, two of the worst smelling things you can burn. While you can smell faint odor from the machines while engraving, and for a minute or so afterward, you can stand 2' from either running machine and you can't tell they're lasering ANYthing.

However- in the garage is another HF blower, connected to my Triumph and GCC, which I've sealed up as best as I possibly can. From the output I'm running a 4" to 6" adapter and 6" plumbing out a window, about 6' worth. It's duct taped from Hades to breakfast, but it doesn't matter. If I engrave wood or leather in either garage machine, the garage smells for hours afterwards.

It's simply because the blower housing is under pressure and isn't perfectly sealed. There's no visible smoke, but plenty of smell.

The only reason THAT blower isn't outside is because I need to build a box for it to keep it quiet as it's much closer to neighbors than the other blowers. Just haven't found time, so I put up with the smells...

[Gary Hair]

It's simply because the blower housing is under pressure and isn't perfectly sealed. There's no visible smoke, but plenty of smell.

And no matter how hard you try to seal it, and I've tried, you can't... I disassembled my first one and silicon sealed every possible leaking point, still leaks. Like Kev, moved it outside. I made a 2x6 framed pedestal and covered the blower with a large rectangular plastic tote. It's been in the weather for 6 or 7 years and still going strong.

[Rich Harman]

It increases while cutting so it's getting out. And yes it lingers afterwards too. I am ordering the big harbor freight dust collector today. 1550 cu feet per minute. I can't imagine anything escaping that power?

No, stop! Don't get the big one. I have two of them, tried one on my laser and it really does no better than the cheaper (and quieter) one. The 13 gal 1 HP one is what you want.

[Lee DeRaud]

No, stop! Don't get the big one. I have two of them, tried one on my laser and it really does no better than the cheaper (and quieter) one. The 13 gal 1 HP one is what you want.

Second that. I'm using the smaller one (or the clone of it that Lowes used to sell), works fine.

I suspect the big one would work better if it had 6" ports and ducting, but yeah, if it's as loud as the big Jet dust collector I use with the bandsaw and planer, it would drive you crazy.

[Bill George]

Funny my blower exhaust fan is smaller than the HF one, its about 1/2 Hp mounted inside with 4 ft of metal duct to the machine and vented to the outside with a flex metal duct 7 ft long rated for exhaust fan duty. No smell. It is in my shop/garage that is sealed pretty tight but far from air tight so it can draw makeup air without a problem.