I started experimenting with annealing and bending months ago since I was planning a tight 4 in radius on my doors. By accident I found that cutting one leg of my ¾ in angle to 5/16ths (confirmed a couple of days later in a Madjack post) resulted in a smooth bend with little distortion, twist, or rippling. I built a bending jig to ease the process so I could make precise bends. Imagine my surprise when I couldn’t find any candles that would soot the aluminum (at least around my house). Since I don’t have an oxy/acetylene rig, and I didn’t want to just guess, I searched the web and found this article and the reference to the Tempilstick. http://www.tinmantech.com/html/aluminum_alloys_continued.php
I liked the idea of using a product that melted at a precise temperature as opposed to guessing on how much soot to apply and burn off.
I don’t know the specific alloy designation of the aluminum found in the big box stores that I have been using, but I decided to try a Tempilstik rated at 650 degrees and ordered it from Drago Supply. For me, it worked with only one snag in the learning process. Since the stick didn’t come with directions I tried applying first, heating up, and expecting to see some color change. Nope. Crusted aluminum. My next try worked by heating the angle and frequently drawing on the aluminum until it left a black mark, indicating the stick was melting at 650 degrees. Working on 2 to 3 inches at a time, I found it took about15 to 20 seconds the heat to the proper temp where the stick left its mark. After annealing the piece, I used the air gun on the compressor to cool the piece-in 30 to 45 seconds.
My angle is 1/16 and I am using a small torch with Mapp gas. I anneal on the inside of the piece aiming my flame into the inside corner where I figured the metal is thickest. The black can be cleaned off, but I am lazy and it will never be seen. The Tempilstick cost about $9.50.
Here is the picture of the Tempilsick in use (recreated—can’t torch and draw and take pictures all at the same time!)
Here is a picture of my bending jig . .
. . . and making the final blows with the mallet to flatten the piece.
Finished product . . .
The jig works for making both my door trim (4 in radius) and the body side door trim (4-1/4 in radius). By the way, the 5/16 leg around the door opening became 7/16 inch beacuse of a stupid fabrication mistake.
I just bent the piece on the centerline mark, not the corner radius mark. Determined not to loose this piece (at $22 a joint), I go back and anneal it and bend it flat--sort of. The seventeenth law of physics is that any material, once bent in the wrong place, can not be returned to its original pristine flat and square shape without lots of skill, pressure, or return trip to Home Depot. In my defense, it was 101 degrees and I lose all but autonomic nerve and muscle functions past 96 degrees.
