Thursday, July 30, 2009

One step forward, Two steps back

Well, I thought I was making progress on the lower battery tray. The concept is a single sheet of cleverly cut and bent aluminum to form a "belly pan" that actually is a tray for holding batteries. I've got an initial 3-d model designed and printed ready to mock up.

The issue comes down to bending radius. The recommended minimum radius for bending 5052 Aluminum is .5 to 1.5 times the material thickness. With my 3/16" sheet, I figure that a .25" radius is about as small as I want to go. In discussing bending capabilities with the premier bending shop in the area they only had small radius tooling on their Brake, admitting that some cracking will occur at the bend.

I'm not to0 wild about cracks in my battery tray, so I will be building a homemade Brake on my workbench. Another project within a project. Obsessive? Anal Retentive? Ridiculous? Sometimes it's a gift, most days a curse.

I bent a 2" strip of 3/16" aluminum (6061-T6) in a vise using vise grips and small aluminum plates with a rough .25" radius, just to get a feel for the force required, and judge the bracket layout better. It took a lot more force than I imagined but turned out pretty good. Even with the .25" radius tooling, there were lots of micro-cracks in the radius, but that shouldn't be a problem with 5052 since it's more pliable.

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