Q. Most of the work I’ve done with aluminum has been either on my own projects, or just experimenting with processes. All of this was with brand-new metal, 3003 alloy. I have two customer cars coming in: a ’36 and ’40, both made in Italy. I assume these are made from 1100 alloy. Does 1100 start out fully soft and then work-harden from there?
My question is how to initially proceed. If I have a damaged panel that I want to straighten, how much can I work the material without annealing? Or would you usually anneal the material when straightening an area? I’m sure I will have more questions for you on this. I have a pretty good grasp of shaping it and welding it using new material, but am not real sure how differently I should treat it from steel when straightening.
Can you recommend a video that specifically addresses straightening aluminum? I found a video online regarding fixing aluminum damage, but thought I would see what you recommend before I purchase anything.
Via the Internet
A. Bryan, thanks for contacting me again. It sounds like you are constantly building your skill level, and getting into more interesting (and more demanding) jobs.
Number 1100 is the softest aluminum alloy. Technically, it is not really an alloy at all, it is commercially pure aluminum, with nothing else added. The 3003 is a manganese alloy, but there is only 3 tenths of one percent of manganese added to it, so it’s not a great deal different from 1100, but it is a little harder, and a little stronger.
Both 1100 and 3003 are available in the full gamut of “tempers” (hardness levels)—dead soft (H-0) 1/4 hard (H-12), 1/2 hard (H-14), 3/4 hard (H-16), and full hard. Both of them will work-harden, but the 3003 hardens at a slightly faster rate than 1100. With any given panel, you’re never certain what the hardness is until you start working it, since the initial temper and the amount of working it has received are generally unknown.
I almost always try to straighten an aluminum panel without using heat, if I think there is any chance of success. Heating the material to anneal it will most likely cause some warping, which could, in some situations, be harder to fix than the initial damage! If I had a very low-crown panel (like a doorskin) with a deep gouge, and I knew from the start that I probably couldn’t straighten it without some help, then I’d most likely work the stretched gouge off-dolly at an elevated temperature, rather than anneal the whole panel. Aluminum gets much softer when it’s heated to 300 or 400 degrees, and lets you “do stuff” to it that wouldn’t be possible at room temperature. It doesn’t actually become annealed until you get it up around 800 degrees, so if you’ve only heated it to 400 degrees, it will return to its initial temper when it cools back to room temperature. Once you heat it to 800 degrees, it will become fully annealed, and remain “dead soft” after it cools. You’ll have to determine which of these approaches to start with. Of course, if you heat it to 400 degrees first, you can always go back and anneal it if you want, but once it’s annealed, the only way to make it harder is to work-harden it in some way, typically by hammering on-dolly.
In most cases, the same techniques used for straightening steel panels transfer pretty well to aluminum. Aluminum is a softer metal, and the upside is that it’s easier to make it move. If there is a downside, it is that you may over-work it, and too much over-working may bring the hardness up to a point where it requires annealing.
I haven’t regretted watching any video on metalworking—there are always at least a few “nuggets” to pick up, although there is a wide range of “production values” in the videos and DVDs currently available.
You can email your questions to Professor Hammer at Use for Email Links: email@example.com, or mail to: Professor Hammer c/o STREET RODDER, 1733 Alton Pkwy, #100, Irvine, CA 92606; you’ll receive a personal reply. Ron Covell has made many DVDs on metalworking, and he offers an ongoing series of workshops across the nation. Check them out online at www.covell.biz, or call for a current schedule of workshops and a free catalog of DVDs. Phone (800) 747-4631, or (831) 768-0705. You can send a request by mail to: Covell Creative Metalworking, 106 Airport Boulevard Suite105, Freedom, CA 95019.