Note to readers: I received a flurry of e-mails following the June '06 "Professor Hammer" column-apparently welding issues are some of the most important to our readers. Here are two letters that follow up on that column. I think many readers will benefit from this information!
Q.Ron, I read the e-mail from Gary Schmidt regarding the trouble he is having with his 220-volt MIG welder. I was also having trouble with mine from the start. It turned out that it came with the polarity connected for flux-coated wire, and I was using solid wire with gas. I switched the polarity and it works great now!Bob SilvaVia Internet
A.That's a great tip, Bob, and I didn't think to mention it! For the record, the welder is set to electrode negative for welding with flux-cored wire, and electrode positive for gas-shielded welding with solid wire. On many welders you need to move some cables inside the machine to change the polarity.
Q.I too wear bifocals, actually transition lens, which do the same thing. That means I have to tip my head back to see things up close. That's OK for reading SRM in my lap, but not so great for shaving or welding-especially out-of-position welding. So I have a pair of single-focus glasses I wear when shaving or welding. What you do is decide how far your eyes are from your welds and have your optician make you a set of glasses that is in focus at exactly that distance. Don't worry about the shaving part. Believe me, Ron, it will be just like your auto-darkening hood-you'll never go back! And they will cost a lot less.
Another minor point, you didn't mention the importance of lighting. Think of your welding as performing on a stage. I have a clip-on flood that I attach to the work piece or to a stepladder-big help! I just purchased a magnetic base flexible neck lamp. If I can see it and I can get comfortable, I can weld it.
Picture this: I recently had to re-weld some brake line brackets under my front crossmember. I did this flat on my back, with one knee drawn up so I could work the foot pedal control for my welder. Could I have done that without my single-focus lenses, my auto-darkening hood, and my floodlight laying next to my head? Maybe.Russ YoungVia Internet
A.Great tips, Russ, but you have to remember, I haven't shaved for 25 years!
Q.The decklid on my 1947 Ford is badly caved in from collision damage; is there any hope for saving it? I have purchased a stud welder dent puller and I have a small Porto-power and a fair collection of body tools. Any advice will be appreciated.Alvin GabelTorrington, WY
A.Thanks for sending the photo of your decklid (not shown). Although it has serious damage, it certainly can be fixed. The biggest question is whether your current skill level is up to the task! If you are just starting to develop your skills at metalworking, I might suggest that you do a lot of work on junk car parts, or areas of your car with less damage before you tackle your decklid. I don't want to discourage you, but unless you are fairly proficient with a hammer and dolly, and understand how to use the stud gun correctly, you could actually make the panel worse rather than better!
Decklids are often more difficult than other panels because they usually have an inner panel that limits access from the backside. The most direct way to straighten metal is to work with a hammer and dolly, hammering off-dolly to lower high spots, and hammering on-dolly to raise low spots. Sometimes on decklids you can use a "spoon" as a dolly, and often there are holes in the inner decklid panel that may allow you to get the spoon into the proper position.
If the spoon technique isn't feasible, you can cut "windows" into the inner panel, or remove it completely. Of course if you do cut out a section, or the entire inner skin, these can be easily replaced by welding, as long as the initial cutting is done with care. This is the best way to attempt a repair that will require little or no filler.
On the other hand, with a stud gun, you can weld studs onto low areas, and use a slide-hammer to gently raise low spots without needing access to the backside. These tools are used extensively in the collision-repair industry, and they work very well, within limits. You might reasonably expect to get out 80 or 90 percent of the damage this way, and then you can use plastic filler to smooth the panel to the final contour. When working in this way, it's important to get the edges of the panel into the proper contour first with a hammer and dolly. Once the edges of the panel are properly straightened, you can start using the stud gun. It's best to start at the edges of the large dents and work steadily toward the center. If you start in the center of the dented areas, you'll create a lot more work for yourself!
Again, this type of work is fairly delicate, and I suggest you develop your skill to a certain level by working on practice panels before you tackle a difficult panel like your rumpled decklid.
Now you can e-mail your questions to Professor Hammer at covell@cruzio.com or send mail to Professor Hammer c/o STREET RODDER, 774 S. Placentia Ave., Placentia, CA 92870. We'll print your name and city unless you request otherwise. Ron Covell has made several metalworking videos, and offers an ongoing series of workshops across the nation covering all aspects of metalworking. Check them out online at www.covell.biz, or call (800) 747-4631, or (831) 768-0705 for a current schedule of workshops, or for a free catalog of videos, books, and fine-quality metalworking tools. You can also send a request by mail to Covell Creative Metalworking, 106 Airport Blvd., #105, Freedom, CA 95019.