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K-Bar
03-15-2008, 07:01 PM
I am a certified welder. I went to welding school several times, the first time when I was 20, to the Todd Shipyards welding school here in Houston. The second time I attended the county technology school in San Francisco and certified as a Coast Guard certified hull welder. As part of that combination welder school certificate, I certified in oxy-acetylene, TIG, MIG and SMAW (stick.) The emphasis was on heavy steel plate welding with E7018 (1" thick steel plate and greater, like hull plates) but the first process we had to master was oxy-acetylene, then stick, then TIG and finally, MIG. My instructor said "Learning MIG welding without knowing stick is like learning to drive in an automatic transmission car. You're not really driving, you're just steering."

Yes, MIG is easy to do. Yes, you can weld things together without really knowing very much. Yes, the chipping and clean-up is less work. But unless you actually know how to weld, you're just mud-daubing it on there. Thats a little hazardous, too, because after you have mig welded something together with blobs of chicken poop, you are then going to go out and ride around on it! The important part is not how pretty it looks on the outside (although a good looking outward appearance does tell you what the weld is like inside, to a degree) but whether the weld has integrity on the inside.

I have no doubt that everybody on this website has the ability to weld "good enough" to get by. And, after years of practice, people may just sort of figure out the best way to produce quality welds. But, IMHO, one should at least read a book or two about welding and practice a WHOLE LOT, if they are not going to take a community college course or something in combination welding. The kind of welding that you guys should really aspire to use is TIG welding with Direct Current Straight Polarity (DCSP). It is more expensive to set up for it, but the actual welding process has a lot in common with oxy-acetylene welding. And the welds, if done correctly, are of the highest quality.

If you are satified with MIG, though, then here are some welding tips:

1.) Run Direct Current Reverse Polarity (DCRP--the work is "negative" and the wire is "positive"). Straight polarity is impractical for MIG welding, will cause a lot of spatter and the welds will be wide and shallow.

2.) Clean the steel of the weld area very, very well. Use a wire brush that is not rusted or greasy (you don't want iron ozide or petroleum impurities included in your weld.)

3.) Adjust the welding amperage and the wire feed speed correctly for the size wire you are using. If you are experiencing "burn back" on your wire, the wire feed speed is probably too slow, or you may have some sort of friction problem in the gun cable, or slippage where the drive wheel grips the feed wire.
If you are experiencing wire striking the work before the weld is created ("plunging"), the wire feed speed may be too high, or the welding amperage too low, or a poor ground connection between the MIG welders' ground clamp and the work. Be sure you are grounded to a clean piece of steel. Paint, rust, grease, dirt, etc. can create a poor ground.

4.) Mig welding can fill a gap, but you are better off running a bead on the edge of each piece before making the pass that closes the gap. Mig welding "uphill" vertical position is possible, but messy. Most MIG welders run downhill on a vertical weld. I welded wood stoves for Woodcutter's MFG in Washington State for about a year, and they insisted we "turn the machine up and run downhill!" I did it, but I did not like the quality of the welds, particularly. Generally speaking, "spray arc" in the the flat position produces the best MIG welds, especially in thicker steel. "Short arc" using CO2 25/ argon 75 is the best for thin material, although a lot of CO2 short arc is being done too. MIG welding using a cover gas requires a good air exchange. Don't weld with cover gases in any enclosed space, like a basement or a closed garage (unless you are feeling suicidal.)

When I learned to weld well, in 1982, the constant potenial (voltage) power supply (that automatically self-corrects the voltage supplied to the welding wire and puddle) was kind of a new idea. Today, most MIG welders have even more advanced technology and it is even easier to produce a good weld with MIG.

5.) Keep the wire and the machine clean and free of dirt and spatter and anti-spatter spray. Keep your tip and the gas nozzle clean. I always kept a pair of MIG pliers (to clean the nozzle and clip wire stick-out to the desired length) in my hip pocket. A pair of needle-nose pliers with a loop of rubber tubing connecting the two handles works pretty good too. A box of tips doesn't cost much. If it gets burned up or ruined from spatter, replace it.

6.) Wear protective clothing and a dust mask. If you are going to be doing a lot of welding, you should be wearing a DOUBLE-FILTER MSA RESPIRATOR. Arc welding (all types) is at least as dangerous to your lungs and trachea as spray-painting or sand blasting. I know several old welders who have emphysema and one who didn't smoke cigarettes, but died of lung cancer. Obviously, 15 minutes of MIG in a well-ventilated work space is not going to give you cancer. But ten years of custom bike frames might.
Getting flashed by the arc and burning your eyes is the greatest hazard, probably. Buy a good welding hood, check it often for damage, especially a cracked or chipped lens. Change the plastic cover plates pretty often. (I used to change them almost daily when I was working full-time as a welder.)
MIG creates a lot of spatter. Spatter is a hazard to your eyes as well as your skin. Grinding creates thousands of minute particles of steel like little needles. Chipping creates little pieces of slag like hot glass chips. WEAR PROTECTIVE GOGGLES, especially when grinding or chipping. Eyes are very difficult to replace. You only get two. Take care to avoid injuring them.

I always wore leather welding gloves and a leather welding jacket in winter, and "sleeves" with a snap-on leather welder's apron in summer. (Yes, it was HOT.) You can weld in a long sleeved shirt, but you are going to get a sunburn, right through the cloth, and you are going to get burned by spatter. Don't do this. Again, 15 minutes won't kill you. Ten years of exposure to welding light could damage your skin, maybe even give you skin cancer (melanoma---Google it) if you are very fair-skinned.

Last of all---you need a fire extinguisher close at hand, and should have a friend standing "fire watch" making sure you aren't setting the house on fire. (Make sure he doesn't try to watch you weld without a welding helmet.)

Welding is a very valuable industrial process and technical skill. It fed my family for years, but you have to have enough respect for it, and for yourself, to do it the correct way.

AtomicZombie
03-17-2008, 01:07 PM
Good advice, thanks.

Brad

wheelenwilly
03-17-2008, 07:36 PM
Thanks for the advice and tips.

Richie Rich
03-17-2008, 10:49 PM
Thanks for sharing.
This just proves once again that 'Atomic Zombie' KREW members are some of the most talented builders on the Internet.

....Richie >>

easyped
03-17-2008, 11:23 PM
Some interesting points you made; I went in for a MRI last year for some upcoming knee surgery. As soon as the nurse found out I had worked in a machine shop she threw the brakes on and dragged me out for head x-rays to make sure there were no nasty little metals hiding in my eyes! She said it was common for factory workers and they don't even realize it. You still out in the Northwest Territories?

K-Bar
03-23-2008, 10:55 AM
Easyped---
I live in Houston now, but my wife still has family living in Washington State. It is beautiful up there, but steady employment is very difficult to find. The town in which we lived had several transcontinental bicycle riders pass through town nearly every summer. They almost always got their picture in the local paper. Since there is a college in town, there are a lot of bicycles around. My father-in-law has been a huge bicycle advocate pretty much all his life, because of the "non-polluting transportation" aspect. He operated a hobby recycling route around town for many years, and when younger, he often pedalled a bike and trailer around town to collect the recyclables.
People in small cities are extremely resourceful. I had a difficult time making a living there because, like in most small towns, "Everybody can do everything." Just about every high-school boy in the county knew how to weld, as well as do automotive mechanics, pour concrete, do house construction, plumbing, tractor repairs, irrigation technology, drive tractor-trailer wheat harvest truck combinations and everything else.
Summer employment in small Washington towns means that the local kids learn a LOT of skills.

easyped
03-24-2008, 09:23 AM
Yes K-bar you are right about small town folks being Jack-of-all-trades.

I grew up about an hour from the central Oregon coast and would see a steady stream of cyclist from early spring to early winter cycling hwy 101. A lot of Europeans would fly into Canada and cycle the coast down into Mexico.

If you are going to cycle ya gotta see the Northwest at somepoint.
I never gave up my web feet and hope to paddle on back there before long! :D