I had this idea for a while now and finally got around to making it happen. It’s all relatively easy lathe work.
First, I severed the head where the bottom of the star sits, leaving it a little long so it can be sanded to it’s final length later. Fortunately, everthing ran true with the battery tube clamped in a collet and the head screwed on. Not having to deal with a jawed chuck for this particular operation was nice! Next, I cut the remaining threaded portion of the head down to a wall thickness of less than a millimeter (1 inch total diameter).
For the heatsink, I used 1.75” diameter x 6” aluminum bought on ebay (2 for $10) and bored into it with a .75” drill bit. Then, I widened it to about .0003” (just a guess) less than 1” to give the previously saved threaded section enough interference to be pressed in permanently. (Cutting new thread’s isn’t a option for me at this time, nor is it necessary. Plus, I’m trying to keep it simple.)
The fins are cut with a .090” tool leaving them .085” thick. Varying the depth over it’s length should insure better thermal transfer to the lower fins than just a thin sleeve.
The pill gets modified to screw in from the battery side and the LED gets mounted directly to the finned heatsink topside. Installing the driver and soldering is done after what’s left of the pill gets screwed in. It shouldn’t be much more difficult.
Still not finished but this is how it’ll look.
I need to make a yoke to secure the top half of the head in place. I could just use screws alone but it wouldn’t be very durable.
Having screws in the head also means I can quickly convert it to direct drive by simply removing a makeshift insulator and connecting the (-) to ground.
The yoke is made and now things need to be drilled and tapped. I’m using six 3mm screws which I want evenly spaced so hopefully it can be assembled in any position.
Inside the thin wall looks a little rough because I hit a nasty resonance on the last pass. Using a long boring bar and not taking time to support the piece very well are to blame but it wasn’t the critical side so I didn’t care. On the positive side, it gives it that original Chinese quality look.
I used a Sharpie and etched 6 arcs at a radius of 15mm carefully using my caliper.
Then, I measured and scribed across each arc at 15mm to get my centers.
Using a pin vise rather than a punch to start the hole helps center the bit more precisely.
After the holes were drilled to 2.5mm, the yoke was super-glued to the heatsink and used as a guide to start holes into the heatsink. The holes in the yoke are drilled to >3mm and heaksink drilled/tapped after the the parts are separated and cleaned with acetone.
In hindsight, I should’ve measured the screw head diameter before I bored the inside diameter. I thought 5mm would be enough. Doesn’t hurt anything but looks funny.
It’s all done except for the electronics. For test fitting, the LED is just held in by pressure from the reflector.