I use a 6" in-line duct fan for my laser exhaust that is mounted in the attic. I had noticed that it had recently picked up a vibration, like the blade was unbalanced or a bearing was going. Today the fan would not turn on at all. So while it’s cold I decided to bite the bullet and pull the fan out of the attic as it’s a pain to get to and work on.
As expected, lots of exhaust residue build up from about 3.5 years of laser crafting.
Wired it up to a plug and it worked, abet with a noticeable vibration. Not sure why it did not turn on before as it had power and the switch was working.
Went ahead and pulled the fan blade and scraped and scrubbed the residue off in some hot soapy water. Scraped most of the reside off from inside the fan housing as well. Reassembled the fan and powered it up. It runs now with a lot less vibration, but I have a replacement coming from amazon any way. Reinstalled the fan for now.
I had always been curious how flammable laser generated residue would be (like creosote in a chimney). Took a pile and tried to burn it. I had to hit it with a small butane torch for at least 5 seconds to get it to light and even then it did not want to stay lit long. So it will burn, just not very readily. Of course my residue is mostly from plywood and hardwoods so if you do a lot of acrylic or pine wood your residue may be more flammable.
How far away from the laser is this fan? How efficient does a laser burn a particle compared to that of a fire in a fire place. I would guess that the laser would burn much more of the material. Interesting observation. Do you cut any acrylics or materials other than wood based products? Thanks for your time…
The fan is about 6 feet away from the laser. All things being equal, the power intensity of the laser beam should have a much higher burning efficiency then a common fireplace fire.
I etch and cut mainly birch plywood and hardwoods. They are low sap content materials, so less likely to generate flammable residue. If you do a lot of high sap content materials, like pine, then there is the possibility for a more flammable residue.
I do cut acrylic, but not that often. I’ve seen examples of fires in a laser caused by someone cutting a lot of acrylic and letting the vaporized acrylic accumulate on the bed. So build up in the exhaust system of this type of residue is also potentially hazardous.
Thanks… I’m pretty new to these devices so input like this is helpful. I was thinking the same about the intensity, that’s why the question about other materials. I have a real problem with the milling operation making some good kindling for a magnifying glass… Thanks. Take care.
One thing to keep in mind is how important air assist is. It supplies lots more oxygen to the material being cut, so it burns more thoroughly. Not having air assist is like an engine running rich; it doesn’t completely combust. Running lean is both hotter and more complete combustion, both in an engine and in a laser cutter.
