Exhaust System - 8'x4' Laser Cutter

[Ash Bentley]

Everyone, thank you so much for the terrific information.

Looking at the fans, I'm trying to finds ones that I'm able to purchase locally in Australia or have shipped. I also need 240V.

Would any of these do the job?

http://www.hydroexperts.com.au/Can-F...eed-Mixed-Flow
http://www.hydroexperts.com.au/Can-F...M-Plastic-Body
http://www.hydroexperts.com.au/Centr...-Carbon-Filter
http://www.hydroexperts.com.au/EP-FM...0W-78dBA-1.13A

And then something like this for the duct on the gantry??
http://www.hydroexperts.com.au/Blaub...M-Wall-Bracket

Thanks again guys, really appreciate it!

[Dave Sheldrake]

To be honest...not really...you need a squirrel cage fan with at least 1 - 1.5hp, those fans are great (I use them on some machines) but they drop static pressure very quickly if you start having any length of travel or reductions in bore

https://www.machinemart.co.uk/p/cde35b-dust-collector/

2 of these work quite well

[Bill George]

Everyone, thank you so much for the terrific information.

Looking at the fans, I'm trying to finds ones that I'm able to purchase locally in Australia or have shipped. I also need 240V.

Would any of these do the job?

http://www.hydroexperts.com.au/Can-F...eed-Mixed-Flow
http://www.hydroexperts.com.au/Can-F...M-Plastic-Body
http://www.hydroexperts.com.au/Centr...-Carbon-Filter
http://www.hydroexperts.com.au/EP-FM...0W-78dBA-1.13A

And then something like this for the duct on the gantry??
http://www.hydroexperts.com.au/Blaub...M-Wall-Bracket

Thanks again guys, really appreciate it!

None of the above. Please go to Harbor Freight or Penn State Industries and look for dust collector fans. I can not believe something like those are not available in Australia. You do not want a axial or propeller fan as they can not deal with the high static pressure your going to have.

[Tony Lenkic]

Try one of these woodworking dust collector suppliers down under..........

https://www.carbatec.com.au/dust-con...ust-extractors
http://www.machineryhouse.com.au/W332
https://www.timbecon.com.au/extracti...actors-filters
https://www.machines4u.com.au/browse/Dust-Extractors/

[Kev Williams]

the exhaust blower Triumph sent along with my big laser was different than most blowers, in that the squirrel cage was quite large in diameter, but was also quite narrow. And it moved an insane amount of air! When standing in front of both, it blew noticeably more air at me than my one green/gray HF blower (which I love btw)... but one day I plugged it in, it started to spool up, stopped and that was that. Rather than mess with it I got an HF to replace it.

Based on this pic of my machine being crated up, the blower housing would be 16 to 17" tall- I just measured my old disassembled HF, the housing is only 13" tall, and the blower rotor itself is only 9.3" in diameter...
trblower.jpg
It seems logical that a bigger diameter cage would move more air simply because the business end is moving much faster at the same RPM. Being narrower seems logical or it would need much more motor...

Just wondering if it's an efficient design? Most I see are short & squatty... It did work like gangbusters, and it wasn't noisy. Too bad I got a bad motor on this one.

[Michael Arruda]

I agree chinese blowers are a joke. I use a grizzly dust collector motor ducted in place on my laser. Works great. You need a good bit of CFM is the issue. If you go with the blower motor off a cheapie twin bag DC plumbed to a common plenum on the gantry with an intake at both ends and the center, it would take care of your smoke problem.

-Michael

[Ash Bentley]

Hey Guys,

Thanks so much for all of the terrific advice.

I've got one of these 2hp dust extractors I use on my CNC router https://www.carbatec.com.au/dust-con...ton-92-58-59cm

I hooked it up to the gantry of the laser cutter just to test how well it would work. Even with 3m of 4" (100mm) duct between the gantry and the dust extractor, it worked extremely well (1200CFM rated).

I'm wondering if there are any quieter options out there? This unit makes a hell of a lot of noise. Will the 1HP unit be sufficient? http://www.machineryhouse.com.au/W332

Or, as an alternative, are there any good guides to enclosures you can make for them to quiet them down?



Thanks again guys!

[Kev Williams]

That unit is identical to the big Harbor Freight blower, I've had one for years. I've never found it particularly noisy?

I'm curious about your setup, such as, are you going to have the blower inlet 'track' the laser head? If so, I have a little advice that probably no one will agree with -- which is, do NOT use 6" inlet at the source of the smoke. 4" may even be too big, but it's cheap to experiment. Me, I would run typical 4" flexible ducting suspended from above that can travel around with the gantry easily. Then I would funnel it down to 3" at the 'nozzle'. The reason is air velocity, which is what you need to draw the smoke. You'll lose some air FLOW, but not enough to hurt anything with that blower. The air will move much faster thru a 4" duct than a 6" duct, and at the nozzle the velocity will pick up even more. What this will do is draw the smoke from much farther away, as the air will be moving towards the nozzle very quickly in a narrow path, creating a very low pressure area that smoke will be drawn to. Works just like a tornado. Put a wide nozzle on, and the velocity slows down to the point the nozzle will have to be much closer to the smoke source.

I've been experimenting with this on my fiber laser. I have a 3-1/2, 4, and 5 inch nozzle tips, and the smaller I go, the farther away the nozzle can be from the work and still draw smoke. The 5" nozzle won't draw powdercoating smoke horizontally from 8" away, half the smoke just drifts up and away. But the 3-1/2" nozzle will draw the smoke easily from 12" away, and this with a 'green' HF blower AND sharing airflow with my LS900.

Could be 2-1/2" would be even better? Or maybe at that point it will start reducing the flow to the point the results diminish. I don't know, haven't got that far yet!

And a side benefit from choking air flow to increase the velocity-- the blower will have less work to do, and will use less electricity...

[Ash Bentley]

That unit is identical to the big Harbor Freight blower, I've had one for years. I've never found it particularly noisy?

I'm curious about your setup, such as, are you going to have the blower inlet 'track' the laser head? If so, I have a little advice that probably no one will agree with -- which is, do NOT use 6" inlet at the source of the smoke. 4" may even be too big, but it's cheap to experiment. Me, I would run typical 4" flexible ducting suspended from above that can travel around with the gantry easily. Then I would funnel it down to 3" at the 'nozzle'. The reason is air velocity, which is what you need to draw the smoke. You'll lose some air FLOW, but not enough to hurt anything with that blower. The air will move much faster thru a 4" duct than a 6" duct, and at the nozzle the velocity will pick up even more. What this will do is draw the smoke from much farther away, as the air will be moving towards the nozzle very quickly in a narrow path, creating a very low pressure area that smoke will be drawn to. Works just like a tornado. Put a wide nozzle on, and the velocity slows down to the point the nozzle will have to be much closer to the smoke source.

I've been experimenting with this on my fiber laser. I have a 3-1/2, 4, and 5 inch nozzle tips, and the smaller I go, the farther away the nozzle can be from the work and still draw smoke. The 5" nozzle won't draw powdercoating smoke horizontally from 8" away, half the smoke just drifts up and away. But the 3-1/2" nozzle will draw the smoke easily from 12" away, and this with a 'green' HF blower AND sharing airflow with my LS900.

Could be 2-1/2" would be even better? Or maybe at that point it will start reducing the flow to the point the results diminish. I don't know, haven't got that far yet!

And a side benefit from choking air flow to increase the velocity-- the blower will have less work to do, and will use less electricity...

That's terrific info. Thanks so much Kev.

I checked the DB of the blower with an app on my phone. Is 77db from 1m away and about 67db at 5m. So it's actually not all that loud - I'm probably being ultra sensitive. haha.

Like you mentioned, I was thinking of using 4" flexible duct suspended from above so it can travel with the gantry. I might even try 3" if the results aren't great.

What would you recommend i do for the two outlets on the bottom of the laser cutters bed? There are 2 x 6" outlets. Would you recommend joining them into a single 6" duct with another separate blower?

So essentially there would be 2 blowers. One for the gantry. One of under the laser bed. Hopefully that makes sense.