Homemade Fume Extractor

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Guys,I'm starting a new home shop for weekend warrior-type work. I wanted to see what you guys thought about venting gases outside. I'll be doing MIG welding only at this point. Do you think if I put a 200cfm in-line fan in a 6" duct and vented it outside it would be enough cfm to remove the welding smoke? I'm sharing this space with my dad who will be doing carpentry on and off, so I want to keep the air in the place clean during winter.I wanted to run duct work from the ceiling, then out the window with a custom fit sheet metal cover to keep the cold out. On the welding table side, I figured I'd use a magnetic clamp to hold the semi-rigid tubing. I'm not sure how much the suction effects the inert gases, but I've read that 100cfm is minimum.Does anyone know of someone who has done this before, perhaps in a better way?
Reply:It is better than nothing but I would think you are probably looking at 600cfm as a starting point.
Reply:I use a dust collector blower I bought from Harbor Freight, and 4" tubing meant for a clothing dryer. Very effective. Miller Bobcat 250Syncrowave  200Millermatic 252Spoolmatic 30ASpectrum 625 X-TremeMaxstar 150SVictor O/A torchesDewalt angle grindersWelded on/off for over 40 years.
Reply:I would step up the cfm significantly. Looking at a couple Miller ones they range from 700 to 1200 cfm.
Reply:That size tube is more suited for a bench grinder.Use 8" duct for my junk.Charl
Reply:Charl, where did you get the black duct work and what is it?
Reply:Charl: yes, tell us more, what kind of fan are you using?Harbor freight sells an 8 inch exhaust fan that has 1600cfm high and 1400cfm lowhttp://m.harborfreight.com/8-inch-po...not%20providedI was thinking of going with that or the dust collector blower.  Even 1400 seems like a lot thoughSent from my iPhone using Tapatalk
Reply:You will get only a fraction of the rated CFM of a fan once you add the pipe work...Like above grab a small proper woodworking dust extractor much better for the intended purpose, just bin the filter and feed the exhaust outside.Oh and keep your ducting/pipe work short as possible with the least amount of bends and dont use to much of that flexi tubing as the inside shape of it is a flow killer(unless you spring for the smooth wall stuff).
Reply:8" flex tube is from McMaster. Got a fiberglass 8" tube also. Haveinspected inside that "blue flex tube". A few small pencil size burns is all I could see. Crack garage door 3 or 4 feet, keeps glare out, as opening faces west. Ventilations not a 100% solution, butworks better than just a fan.2 foot fan, sits on chair, blows air on my back.Charl
Reply:Originally Posted by xmancharl8" flex tube is from McMaster. Got a fiberglass 8" tube also. Haveinspected inside that "blue flex tube". A few small pencil size burns is all I could see. Crack garage door 3 or 4 feet, keeps glare out, as opening faces west. Ventilations not a 100% solution, butworks better than just a fan.2 foot fan, sits on chair, blows air on my back.Charl
Reply:I made a fume extractor, a few decades ago, using a blower out of a discarded clothes dryer.  I connected the sucking end of the blower to a 4" flexible dryer exhaust hose, connected to a "hood" made from the top to a galvanized garbage can.  The blower exhausted, via more 4" hose, through a dryer vent, installed in the gable end of the garage.  The hood was supported by a small rope that ran through two pulleys, one directly over my work table, the other to a corner in my garage.  The hood was counter-balanced by an empty gallon paint can, containing rocks.  The rope support allowed raising and lowering of the hood.  Since fumes tend to rise from the heat produced, during welding, I found the hood much more efficient than side extraction, which requires many more cfms do the job.Last edited by Weldordie; 10-07-2015 at 10:15 PM.
Reply:Eww, ouch. I'd be careful with that. If you're welding with Argon, it's more dense than atmosphere, so it will slowly purge the air out of the basement, potentially leaving you (and your rescuer) unconscious. Make sure whatever air you take out is put back in and be careful welding indoors.
Reply:Originally Posted by josh.petroEww, ouch. I'd be careful with that. If you're welding with Argon, it's more dense than atmosphere, so it will slowly purge the air out of the basement, potentially leaving you (and your rescuer) unconscious. Make sure whatever air you take out is put back in and be careful welding indoors.
Reply:Ha! Good man.!
Reply:IgnoreDuplicated posted to the flash-back . . .Moderators - if convenient - please expunge.Opus.Last edited by OPUS FERRO; 10-27-2015 at 11:05 PM.Reason: Mind-Vapor