Originally Posted by i812
Care to share what you plan on using for the LED's?
I looked into the 2.5 mm OD CF Round Tubing from RCFoam, and their website states 1.7 mm ID, which makes the wall thickness about 0.4 mm. I'm guessing 0.4 mm wall thickness might be too weak to be used as a Main Shaft, especially if we have to grind the end into a double-D for the Main Gear.
I'm thinking the wall thickness can be thickened by inserting a 1.8 mm OD CF Tube into the 1.7 mm ID, by first lightly sanding it to correct diameter so it fits inside.
Also, copper tape (a youtube video said it is available where doll houses are sold), might be an overkill both in what is required electrically and weight wise. The thinnest, lightest conductive material that might work is conductive paint/marker/pen, but it looks like that will run $10-$30 for the smallest size. That's a little too "rich" for me to experiment with for a one time fly-by-night job. I'll probably just go with the thinnest possible wire/thread I can find and carefully glue it.
There are a few different ways to power the LED's. The quickest and easiest would be to use existing LiPO (or Button Cell on top of Rotor Head as farmer suggested) and surface mount resistors. For long term usage, a DC/DC Voltage converter, or a Constant Current Driver would probably be more efficient but would cost more in parts and weight.
I wish I knew which LED's were being used in this Day Glow one:
I actually emailed rcfoam to ask about the i.d. of the 2.5mm. I must have missed it. Yeah 1.7 sounds too big, 1mm would be prefect. I plan to use the dc/dc converter to avoid using resistors which waste precious mah as heat and the button cell would work and you wouldn't need to find/ fab a hollow main shaft but I'd rather do it the more complicated way, lol. As for leds, I'm using 1206 smd's.