Yet Another Cyclone Question

[Gump in Renfrew]

Someone had posted that they were going to weld their cyclone together. I have a Miller 150 mig welder that hasn't been earning it's keep lately. This idea knind of interests me. I have never welded galvanized ductwork before and am curious what advice you guys might have on the issue. I also have access to a TIG at work if I would be better to go that route but am very inexperienced with it.

Thanks,

Gump

[Allan Johanson - South Su]

Hi Gump,

You probably read my post on the subject. I have a Miller 175 MIG and I'll be welding my cyclone together. My MIG can go as thin as 24ga, but I opted for 22ga to make things a little easier (less blow through).

Sheet metal will typically have some kind of oily substance on it from manufacturing, and you must clean it first before welding or soldering. I opted for lacquer thinner. Careful with that stuff!

The most important thing to note is that welding galvanized metal releases toxic fumes. You *must* use a proper cartridge respirator with the appropriate cartridges for fumes. If possible, weld outside too (or in the garage with the door open).

I'm certainly no expert in this area, but I've never turned my back on a challenge. :-) Just find a comfortable welding position and take your time. If you find the sheet metal is starting to warp on you, then you'll probably have to do what the body shop guys do - "stitch welding". Weld little 1/8" long joints at a time, several inches apart. This helps to keep the heat level down and minimizes warping. Having one of those cool "auto-darkening" helmets really helps here. I have one and they are nice.

When done welding, break out the grinder and smooth things out. Patch up a little here and there where you may have missed spots, prime with a galvanized metal-happy primer, and paint.

Easy as pie. At least that's how the theory goes. I'll find out in the fall. :-)

Allan

[Ed Snyder]

I would think very carefully about welding galvanized metal . The fumes can be lethal . They can cause brain damage.

Ed

[Allan Johanson - South Su]

Hi Ed,

I firmly believe that a person has no business welding without the proper respirator. People need to make sure their health and safety is the #1 priority.

There are options if you still want to weld:

#1 - mandatory (not an option) - use a respirator
#2 - for galvanized metal - sand off the zinc coating for a few inches each side of the weld prior to welding
#3 - use "regular" mild steel instead. When done welding, apply a couple of coats of "weld through primer" which is essentially pure zinc. Then you've given your metal a "cold galvanizing" treatment for extra protection.

Cheers,

Allan