Sunday, February 7, 2010

Terminator Chopper Build - Part 3

Figure 16 – Spot welding the edges to create the tubing shapes

To create a 3-dimensional tube out of sheet metal pieces, the three or four pieces that make up a tube must be welded together at their corners. This is done by tack welding one of the ends and then bending the strip along the arc as you continue to add a tack weld every inch or so. By tack welding as you bend the strip, it will seem easy to work around the arcs and corners, even if the piece you are bending seems fairly stiff. After you have made the first few tack welds, check the two parts with a square or a bit of square tubing to ensure the tubing pieces are at 90 degrees to each other. Of course, you may want to make a triangular shaped tube, so only three pieces are needed.

Figure 17 – Tack welding all parts together

Figure 17 shows the first strip tack welded to the fork tip (top photo) and the second strip on the other side (bottom photo). Although this tack welding process is certainly ugly, it makes a surprisingly strong shape that would probably hold up without any other welding done along the corner. I wanted my entire frame tubing to look perfect all the way around, but maybe this rough tack welded look could be used in some kind of rough-look theme? So many ideas, so few hours in the day.

Figure 18 – Using a clamp to help force the pieces together

When you begin welding the top of bottom of a custom tubing shape, you may need to use a clamp to force the pieces into alignment as the tack welding does make a very strong shape. Figure 18 shows how a clamp can help push the edges together after welding the other side. Some distortion is bound to happen as you add all of the tack welds along the thin sheet metal joints.

Figure 19 – The bottoms of the front forks completed

Figure 19 shows the result of cutting and tack welding eight pieces of sheet metal together – half of a front fork. The front wheel will sit between the two curved forks, and the upper area will curve outwards to create the handlebars.

I am still working with no plan whatsoever, but do know that the front forks need to be the same distance apart as they are in a typical bicycle, so that will help determine the basic shape of the pieces that will join the two fork legs together over the next few steps.

I know - this hasn’t really been too much work so far, but just wait until the welding of the edges begins! You will feel like you put in a good day’s work when we get a little deeper into the journey, I promise.

Part 4 coming soon...