A Miller Electric Syncrowave...
A Miller Electric Syncrowave 250 was the TIG welder used in our demonstration.
The rods come in different sizes, from 1/16- to 1/4-inch. A good rule of thumb is to have one size smaller rod than your base metal. So if you are welding on 1/4-inch base plate you will need 1/8-inch rod of filler metal. A rod too large will require more heat to melt and run the risk of burning a hole into the base metal. There are larger size aluminum rods available, but for welding on a racecar these sizes will work perfectly.
Welding aluminum requires practice, practice, and more practice.
"I took a class back in '92 that taught me the basics of TIG welding, but the only way I have learned as much as I have is by experience," Chuck says.
It's crucial to practice and learn the pedal control, in particular, and to develop the skills needed to weld the thin pieces of aluminum. Your hands are going to be doing two things at once and, in addition, your foot will be controlling the heat that is going into the aluminum. It is a skill that cannot be mastered in one evening. It takes a lot of scrap aluminum that you can afford to throw away.
Also you need to learn from the right people. Visit Miller Electric's website, www.MillerWelds.com, for information on how to TIG weld the correct way.
I know how tempting it is to purchase a used seat. Although I don't advise it for obvious safety concerns, sometimes you can find one that's very inexpensive. A used racing seat, however, will more than likely have several drilled holes from someone else having mounted it in their car. With a TIG welder you can fill those holes very simply. Chuck Gafrarar had an old seat lying around his shop and filled a hole to demonstrate the process.
The key when filling a hole or repairing a crack in aluminum is to use a backing on the opposite side when you start to weld. Steel is good to use because the aluminum will not stick to the steel. To illustrate this, Chuck took a small piece of steel and C-clamped it to the back of the seat making sure that it was flush against the back.
"The steel will allow the aluminum to fill the hole in the seat," he says. "The aluminum TIG welder will not weld the steel to the aluminum and the same can be said for when you are welding steel, if you need a backing to fill a hole in steel, get a block of aluminum and it will provide the backing you need."
Begin by starting a puddle in the hole and slowly filling it with the rod of aluminum held in your other hand. It will start to melt and fill the hole that you are working on. Be sure to dab the aluminum rod in the hole.
"One thing to remember is once you have the hole pretty much filled, you do not want to jump right off the pedal (or dial) as this will cause a small indention in the weld you just made," says Chuck. "The thing to do is slowly lift off the pedal and it will close the weld instead of leaving a small hole in the weld."
Don't worry about the aluminum coming up out of the hole when you are welding it. After it cools you will be using a grinder to smooth it out anyway.
Once it has cooled a bit, undo the C-clamp and flip the seat over to fill the backside of the hole. Even though we had the steel attached to the backside there is still going to be a small gap that needs to be filled. The same principles will apply from welding the front side of the seat but you will not need the piece of steel as a backing because your weld is already creating a backing for you.
This piece of steel was used...
This piece of steel was used as a backing because the steel will not weld to the aluminum and it provides a place for the aluminum puddle to form.
This is what the finished...
This is what the finished aluminum weld should look like. After we finish welding the other side, a grinder will clean it up.
Now all we have left to do...
Now all we have left to do is weld this side and the hole is filled.