Exhaust fan question

[Neil Pabia]

I felt like I was hijacking another thread so I started this one. I was told that a strong bathroom vent would be adequate for an exhaust system but many seem to disagree. I have a dust collection system but was worried about a fire due to the wood dust, should I just set up a dedicated dust collector for the laser or run a separate line that has a water trap on it for the laser? Or is that overkill, I just don't like the idea of drawing anything hot into a container of sawdust. What type of systems are being run? Thanks for any help.

[Kasey Maxwell]

I bought one of these---> http://www.grainger.com/Grainger/items/3AA30

It works great, however when I set it all up with a ducting to the outdoors and started engraving, there was a strong smell of wood burning, the unit is very powerful and does the job great but I took the mail side plate off and to my surprise there was no gasket :eek:, just metal on metal, major ash and smell from that being blown around the about 12" plate, so I put silicon all the way around it and screwed it in place wet so it would make a great seal, and it wont be hard to get off if I need to as it will peel off, that and nice tight clamps on the hoses, now it works great with just a small bit of smell that goes away after your done engraving........

not sure if this helps but there ya go :D

[Joe Pelonio]

I too went with Grainger, but with a 20' run to the nearest outside wall I needed more power:

http://www.grainger.com/Grainger/items/5C519?Pid=search

Although mine was blue and over $100 less than this new model, 6 years ago.

[Dan Hintz]

I just don't like the idea of drawing anything hot into a container of sawdust.
Very bad idea... a couple of years ago a member here lost a portion of their workshop because the dust collector connected to both the woodworking equipment and the laser caught fire.

[Richard Rumancik]

Very bad idea... a couple of years ago a member here lost a portion of their workshop because the dust collector connected to both the woodworking equipment and the laser caught fire.

Dan, I tried to find the post and I did see a post by Phyllis Meyer but in that incident the laser did not catch fire, the dust collector did. ( I did not find any other posts.)

I looked through her post and did not see that the laser was determined to be the cause. There are other possible reasons why the dust collector caught fire in that incident.

I am not suggesting that it is a good thing to do, I really don't have experience with dust collectors. But I have never seen burning embers generated when I laser anything.

[Richard Rumancik]

Neil, if you REALLY want to meet the laser manufacturer's spec then neither of the suggested blowers will quite do it. But a lot of people seem to get by with considerably less than what the manufacturer requests. I don't know how to explain the discrepancy.

If your spec calls for 400 cfm at 6" water column then you need to find a spec that specifies both simutaneously. Kasey's fan will achieve 550 cfm at .93" water (the max. flow will result in min. pressure). Joe's blower can achieve 400 cfm at 1" water column.

I have to assume Kasey and Joe are satisfied with their setups - but if you buy a blower that can only generate 1" pressure be aware that it is probably much lower than your manufacturer recommends. The bathroom fans (as I mentioned in another post) can generate very little pressure - .1" to .4" is in the ballpark.

[Dan Hintz]

But I have never seen burning embers generated when I laser anything.
With the amount of times people have said "So and so substrate caught fire, luckily I was there to open the top and blow out the fire", flying pieces of paper catching fire and being sucked out of the exhaust, etc. I wouldn't trust sending the laser's exhaust into any bin filled with potentially combustible material.