Bike Light Build: Part Two

I got around to playing with the light and the bench power supply last night and it appears that the light shows little or no dimming until the voltage drops below 12V. This means that in mild/warm temperatures I could possibly use NiMh batteries two, without going to the added trouble of buying two 8.4V packs instead of the standard 7.2V packs. At least that is what I have gleaned from wikipedia's information on NiMH batteries. The only other concern is the amperage draw, but I think that the sub-C size cells found in RC battery packs can handle the 500mA draw of the light, and then some.

Today I started building the body of the light with 1" square aluminum tubing that I bought at the hardware store down the road. I started with a 2" long section, which I then notched out so that a 7/8" long section of square tube could be held inside the notch.

I did this by first using a hacksaw to slit down the sides of the tube adjacent to the inner wall, up to a line that I had scribed one inch down the tube.


Next I drilled holes in the tube along the side of the scribed line where I wanted to remove material.


I then used a pair of vice-grips to break off the material at the line of drilled holes.


The next step is to file the bottom and sides flat. Then a piece of square tube is cut to 7/8" and filed to fit into the notch.

I was going to use a piece of aluminum extrusion intended to be a shelf braket as heat sinks, but then I remembered that I had some PC heat sinks that I never used on the PC in our office. I proceeded to cut those to two inches long and added a chamfer on one top corner. The picture below shows the pieces placed together as I intend them to fit.


I also placed an order with Newegg.com for some Arctic Alumina adhesive(AAA). AAA is thermally conductive, commonly used to attach heat sinks to CPU's and such. It has a good reputation for being a tough adhesive too, so I will at the very least use it to adhere the LED and heat sinks to the body. I will probably use JB Weld for more structural joints.

Next up we will finish constructing the body...