AC TIG welding with the Multimatic® 220 AC/DC
I’ve been fascinated by sculpture for decades. Many years ago I went to art school with the idea of pursuing a career in sculpture. But after getting a master’s degree, the economic realities of the art world forced me to change direction. After much deliberation, I switched to the world of specialty automotive fabrication (which is actually a lot like doing metal sculpture). Still, I love the joy that comes when making “pure” art.
I’ve always had a strong interest in geometry, and I’m particularly intrigued with the Platonic solids. These are constructed of identical, regular faces — triangles, squares or pentagons — which fit together in elegant arrangements. The basis for this sculpture is the icosahedron, made from 20 equilateral triangles.
![metal art sculpture pattern](/-/media/miller-electric/images/images-for-articles/making-metal-article-series/2018-2019/article-5-ron-covell/sculpture-001.jpg?h=232&w=350)
I’m using a stellated (star-like) version of this figure, with each of the 20 faces extended with three more equilateral triangles.
I used .063-inch 3003 H-14 aluminum sheet, and I designed the sculpture with a hole in each face, knowing this would open it up and introduce a light and airy character. I recently got a set of the triangle punch and flare dies, which were ideal for perforating each face. I chose the 2-1/2-inch die, with a 5/8-inch border around each opening. This resulted in a sculpture about 16 inches in diameter.
I used the brand-new Miller® Multimatic220 AC/DC to weld this sculpture, making full use of its newly added AC TIG capabilities.
The sculpture required A LOT of welding, so I looked for any way to streamline the construction. I realized I could combine two triangles as one element, joined at the valley by a fold, which cut the number of pieces from 60 to 30. This eliminated a considerable amount of welding and made the assembly easier too.
Next, I looked for a way to make each element with precision. When fitting components together to make a closed shape, even tiny irregularities can stack up, leading to problems.
If I punched and flared the holes after the triangles were cut to size, the drawing action of the dies would distort the narrow edges. That’s a big problem for welding thin sheet metal, so I punched the holes before the edges were trimmed to size. The punch and flare dies require flat metal where they strike, so I had to make the center bend after all the openings were punched.
A press brake would have been ideal for making the bend in the part, but I don’t have one, so I devised another approach. I cut a groove on the back side of the aluminum blank, which located the bend precisely, and this enabled me to bend the part with light pressure. I made a backstop for my band saw that limited the depth of cut to about .035 inches, and with the part held vertically, I cut a groove on the back side of each blank.
![cutting aluminum sheet metal](/-/media/miller-electric/images/images-for-articles/making-metal-article-series/2018-2019/article-5-ron-covell/sculpture-002.jpg?h=356&w=350)
Next, I made holes in each blank for the guide pins of the punch and flare dies. Each opening requires two 1/2-inch-diameter holes, so I made four holes in each blank, spaced equally from the bend line. Next, I used the dies in a hydraulic press to make two openings in each blank.
![holes in aluminum sheet metal](/-/media/miller-electric/images/images-for-articles/making-metal-article-series/2018-2019/article-5-ron-covell/sculpture-003.jpg?h=239&w=350)
After the holes were punched, I trimmed the edges of each blank. I made a fixture for my shear, which located the blank by the triangular openings, and trimmed all four edges.
![](/-/media/miller-electric/images/images-for-articles/making-metal-article-series/2018-2019/article-5-ron-covell/sculpture-004.jpg?h=251&w=350)
With the relief cut in the back of each blank, it was easy to bend them to 85 degrees — forming two faces from one blank. With all the elements prepared, it was time to join them together. The Pro-Set™ technology on the Multimatic 220 AC/DC is great: As you change the parameters on the digital face panel, the numbers turn blue when you’re in the recommended expert settings. I used 90 amps and 120 hertz, with a balance of 75 percent electrode negative. My electrode is 3/32-inch 2 percent ceriated tungsten, sharpened to a fine point.
![Front view of Multimatic 220 AC/DC](/-/media/miller-electric/images/images-for-articles/making-metal-article-series/2018-2019/article-5-ron-covell/sculpture-005.jpg?h=284&w=350)
I started with groups of three elements, tack welding them at the tips.
![AC TIG welding an aluminum sculpture](/-/media/miller-electric/images/images-for-articles/making-metal-article-series/2018-2019/article-5-ron-covell/sculpture-006.jpg?h=302&w=350)
After joining the tips, I made several tack welds along the edges of each assembly. I found I could fusion weld these tacks, since the fit-up of the sheared edges was very tight.
Next, I started joining these sub-assemblies into more complex arrangements. Since each element was made precisely, they fit together with no problem, and the angles between each segment aligned themselves with only light clamping pressure.
![aluminum pieces of a metal art sculpture clamped together](/-/media/miller-electric/images/images-for-articles/making-metal-article-series/2018-2019/article-5-ron-covell/sculpture-007.jpg?h=299&w=350)
I’ve had experiences with similar projects where the last piece didn’t fit due to the stacking up of minute irregularities. Keeping this in mind, I divided the sculpture into two main segments with a joint near the equator, which gave me the most leeway for the final alignment. I was able to join the two sections with only a small amount of tweaking of the angles between segments.
![attaching the top of an aluminum sculpture to the bottom](/-/media/miller-electric/images/images-for-articles/making-metal-article-series/2018-2019/article-5-ron-covell/sculpture-008.jpg?h=300&w=350)
My strategy worked to perfection, and I didn’t need to trim any edges or fill any gaps. Any misalignment was easily corrected with light clamping pressure.
With all the segments joined, I finish welded every joint. My fit-up was very tight, and because I cleaned each joint with degreaser and light wire brushing, I was able to fusion weld all the edges. While welding, I kept a piece of 1/16-inch 1100 welding rod in my left hand, ready to fill any keyholes that might appear.
I started welding at the center of each cluster of triangles and worked out to the points. I had to reduce the amperage with the foot pedal as I approached the end of the weld since the heat built up quickly as I neared the tips of the triangles. This sculpture required 300 inches of welding to complete!
![AC TIG welding an aluminum sculpture with the Miller Multimatic 220 AC/DC](/-/media/miller-electric/images/images-for-articles/making-metal-article-series/2018-2019/article-5-ron-covell/sculpture-009.jpg?h=256&w=350)
This sculpture was lots of fun to build, and I look forward to doing more work of this nature. I enjoyed exploring the new features of my Multimatic 220 AC/DC, and it handled the intricate joints with ease!
![completed aluminum metal sculpture](/-/media/miller-electric/images/images-for-articles/making-metal-article-series/2018-2019/article-5-ron-covell/sculpture-010.jpg?h=400&w=350)
About Ron Covell
Ron Covell is a talented welder and metalworker in the automotive industry. Covell is a contributor for Hot Rod Network, where he has a popular column titled, "Professor Hammer's Metalworking Tips." He also owns Covell Creative Metalworking, offers instructional metalworking DVDs and hosts workshops around the country.