362 Rib Form Block

The complicated part of this was not making the parts. First I needed to take what we learned from the first tools and us it to shape the tool so the parts came out to the correct shape in one rolling operation.
To do that I traced the tool and the formed part so I could re-draw them in the CAD system. I needed to look at the bend angle created in the part vs the angle in that segment of the form block. To do that I divided each curve into 3/8" segments and measured the change in angle from segment to segment on the block and the part. Then I plotted this data to get the relationship. I tried 1/4" segments first but the data just had to much noise to use it. Now all I had to do was take the WACO part drawing and divide the curve into 3/8" segments and measure the angle between each. By applying the relationship in the plotted data I could now draw the curve for the tool to form .025" 5052-H32 aluminum. OK, I could have just done this with calculus by developing the equation for each curve and calculating the first derivative, etc., etc. I'll leave that for someone who has used their calculus skills more recently than I have. I'll save that for a retirement project.
With our new drawing printed out to full scale it's just a matter of gluing it to the aluminum and rough cutting it out on the band saw. The shape was finished to the line on the belt sander and then hand filed smooth. The 1" grid lines are there to check that it really printed correctly to scale. Holes were then drilled to allow screwing this piece to some angle for clamping it in the vice. John milled a nice curved hole in his, I used the band saw so I needed a way to hold the curved strip of aluminum while forming the parts.

The holes were tapped to allow screws to be threaded into the holes.

Another scrap of 1" x 1/8" aluminum from our old Ultralight project and we have a nice base for clamping in the vice.

When I made the roller I left as much metal on the inner roller as I could. As a result it was easier to use the actual parts to determine the spacing between the rollers to get the desired angle. This was done by laying the parts over the drawing and measuring the distance. Clearly I could have done this in CAD but it took less time this way than booting the software.

All the parts to assemble the roller handle.

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The roller handle and form block assembled in the vice.
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Next we needed a clamp to hold the end of the aluminum strip. I had band sawed a slot into the form to hook the end of the strip, but the roller will pull the strip out of it without a clamp.
The first clamp I made was to long to turn side ways with the roller down, and too tall for the roller to pass over it to the start position. The shorter clamp works perfect. It has a heel on it to allow for the thickness of the aluminum strip.

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The last change was to shorten the tip of the form block so the roller can move down far enough to make it easy to load the strip and clamp it. Also the area around the screw socket had to be filed and polished to stop it putting marks on the aluminum roller.

We're almost ready to form parts.