Extraction for Laser cutter

[Keith 66]

A question for the collective! I recently packed in work, dunno if you would call it retirement yet, I am seriously thinking to invest in a laser cutter / engraver as i had use of one at work & change of my work type means one is going to become more desireable, I now have the space for such a machine.
Im pretty sure i have found the right machine but the extraction is a possible issue due to potential noise of exhaust.
It would be going into my home workshop, basically a large double garage & i'm limited to exhausting through the end of the eaves centrally over our driveway.
Exhaust requirements acording to the manufacturer for such machine are 1800 m3 per hour which is a lot of air to shift.
Question is is it possible to obtain a blower that can do this relatively quietly without upsetting the neighbours who i get along with!
I can put the fan itself in a sound proofed enclosure any other ideas on what type of fan is quietest?

 

[brightspark]

they had a laser cutter at the school I do work at for wood and plastic the fan on it was crap so I fit a 4inch woodchip extractor ducted out and it worked fine dunno what your requirements are mind

 

[Wany]

The best place to source quiet extractors is probably the specialist indoor horticultural websites that tailor to the "alternative grower" if you catch my drift. You might find they actively display both volume shifted and noise. You might even find they stock products to dampen sound like acoustic ducting etc so the fan noise doesn't make it's way out of the extractor vent, I think Amazon does as well. BTW before anyone says anything the only thing in my loft is a Heat Recovery Ventilation system and the original bodywork for my TZR

 

[MattH]

I have a 300mm duct with a inline centrifugal fan that exhausts two 130w laser cutters.
It is not that loud at all.

 

[Keith 66]

There seems to be a huge difference in requirements between manufacturers, the "indoor gardening" route is interesting & worth a look at!

 

[Wany]

Our HRV uses something like this: https://greenshydro.co.uk/acoustic-ducting

 

[Agroshield]

Have a look at extraction systems used in commercial kitchens (local fried chicken shop). You can buy silencers that go either side of the fan itself. Also, the fans are variable speed so slower is quieter. Flakt-Woods are the Hoover of the fan world.

Is the machine in an enclosure or just out in the workshop? If it is enclosed, or could be made enclosed using an aluminium extrusion cabinet, the air requirements will be a lot less. If you can get the extraction close to the source of the fumes, again the requirements will be lower.

Have a look at this sheet randomly pulled from the ether: https://www.tlc-direct.co.uk/Technical/DataSheets/SolerPalou/Cased_Axial.pdf

315mm fan (on 300mm pipework) is more than adequate. 54dB at full chat.

 

[Keith 66]

Machine has a 100mm exhaust port at rear & needs good airflow to pull smoke away from the optics It will be sitting on a bench in the workshop.
Thinking variable speed as many fans come with this option.

 

[Agroshield]

Machine has a 100mm exhaust port at rear...

You can probably do some rudimentary calculations, but this seems very small for the 1800m3 per hour you quoted elsewhere. Look at the area of the port and the velocity needed to get that volumetric flowrate.

 

[Ali]

Exhaust requirements acording to the manufacturer for such machine are 1800 m3 per hour which is a lot of air to shift.

General rule: laser cutter manufacturers know naff all about extraction, they’re often badly designed from that point of view and the fan figure might even be excessive to make up for poor airflow in the enclosure. Have a look at the specs of BOFA/Purex machines. If you’re cutting plastics it’s going to be well worth thinking about something filtered if it’s near the neighbours or wind over the eaves could take it up to a window, the smells could be more of an issue than the noise and the fumes are pretty nasty.

It’s not too difficult to make your own carbon filters, but you do need a pre filter as there’s a lot of particulate matter too, worse with some materials than others. Otherwise your carbon filter will clog straight up.

You can visibly tell if it’s working, but what you can’t see are the VOCs which hang around for ages after the process. I did some tests with £4K worth of gas sniffing monitor recently and after cutting a few small bits of acrylic VOCs were emitting for a good 10-15 mins afterwards. Most of the specialist units have a built in over-run now but they never run long enough out of the box.

 

[Keith 66]

Some good info & points, the 1800m3 quoted would seem to indicate a speed of 63.66m/s or 142mph through the 100mm port, that is going to howl however you do it!
Alis point about fan spec being excessive to make up for poor airflow is i think on the money.
Lasercutter manufacturers are quoting anywhere from 800 m3 hr, 1200m3 hr to 1800m3 hr, If you are pulling air through a machine with a vacuum there comes a point where it makes no difference how big & powerful you make the fan if it stalls cos its reached a near vacuum .
The inlets into the machine enclosure are just as important, if you only have a few tiny louvres not enough air will be able to throughput beyond a certain point. Likewise you need air intakes from outside into the workshop itself otherwise there wont be enough air.
So paradoxically a fan half the size could work better if the intakes & ports are sized correctly.
Alis point about fumes being nasty are well said, i used a laser cutter for the last 5 years, It used an Oracle Bofa filtration unit & i just googled that its flow rate was just 380 m3 hr. The unit had no over run & the recomendation was that you let it run on for 1 minute after the laser had finished.
You could smell the fumes if it had been working for long & the filters needed changing twice a year really, the service provider did it just once a year because they were about £500 a pair! So its likely that the unit was underspecified like the rest of the crap extraction.
Glad im not working there now!
If im going to invest in one of these its gotta be right.

 

[julianf]

A question for the collective! I recently packed in work, dunno if you would call it retirement yet, I am seriously thinking to invest in a laser cutter / engraver as i had use of one at work & change of my work type means one is going to become more desireable, I now have the space for such a machine.
Im pretty sure i have found the right machine but

Keith, can I ask you what you're buying and what the specs are on it?

I know very little about them and don't know if I'd have to spend 6k or 30k to get what I want, and most companies won't give pricing without calling them up, which I can't be bothered to do at present.

So I'm curious as to what you've selected and what it will do?

Thank you.

 

[Keith 66]

For most peoples purposes inc mine, cutting & engraving organic materials, wood & some plastics, there are two basic types of Co2 laser, Glass tube DC water cooled & metal ceramic core RF systems. All the cheap ones are DC watercooled. RF systems typically are more reliable & have a tube life of around 10 years. A DC tube has a lifespan a fraction of that with some cheap tubes going pop in 6 months or less, even a good one you are looking at tube replacement every couple of years though some may last a lot longer.
The one i used at school was a 30 watt RF tube machine probably most of it built in china but assembled & set up in Uk by lotus laser systems. It was a good machine but bulky & took up a lot of space, bed size was 600 x 400mm.
Im looking at getting a 600 x 360mm bed size machine preferably RF if i can justify it! Power wise 30w RF would be a minimum & will cut up to 4mm plywood, 45w will do a bit thicker, if you want to cut 10mm you got to get something with 100w or more & they get spendy.
There are hundreds of cheap lasers on ebay & amazon for anything from £300 - £500 upwards, 99% will be chinese & will often need work before they are usable. Then you have the likes of Epilog (American) or Trotec (Austrian) very high quality & lightning fast machines but with prices over £12,000
I have found two UK manufacturers CTR in northampton & Kent lasers in Maidstone, the latter company seems to have a good reputation & is very good value for money.
Software with the chinese ones is usually RD works & i found it horrible to use with an unintelligible manual written in the worst Chinglish i have ever seen, There are others such as Lightburn which is reputed to be far better.
Secondhand is a lottery there is a good chance some klutz has been inside it & tubes are likely to need replacing.
There is a Trotec for sale near me but at just under 6K for an 11 year old machine he can keep it!

 

[julianf]

Thank you.

To cut metals, I'm guessing the price multiplies quickly, right?

Eg 3mm 5005 alluminium alloy?

 

[MattH]

Thank you.

To cut metals, I'm guessing the price multiplies quickly, right?

Eg 3mm 5005 aluminium alloy?

The wavelength of C02 lasers is wrong for cutting metals (very inefficient), a 300w C02 laser with Gas assist and a metal cutting focusing head will cut upto 2mm Stainless but much less in aluminium.

You need to be looking at Fibre laser based machines, sit down....

They start at about £40K up.