LED Guitar #2 - Drilling, Milling, etc.

I show here how I draw lines, drill holes, and mill the back side of the fretboard. Later on I will glue this fretboard onto the neck that I removed the old fretboard from. I chose to make a new fretboard rather than use the old existing fretboard. Drilling holes through the existing fret dots would not have worked very well. The plastic dots tend to chip and crack, and drilling a hole exactly in the middle of a 1/4" plastic dot is not very easy. Plus, purpleheart is just such a pretty wood, I just really enjoy using it.

Mark the centers with a pencil and use a center punch.

 Use a drill bit which cuts a 5mm hole (for a 5mm LED), this is about 0.191-0.193" in diameter.

Next, use a 1/4" forstner bit to cut a flat-bottomed hole on the back side. 

Only drill in about 1/16" deep. 

 Draw lines where you want to mill channels.

 Cut off the sides and bottom with a band saw.

 Semi-finished product. Ready to wire up and solder.

 Warm white 5mm LEDs from allelectronics.com

Unfortunately I did not know the forward voltage drop that these LEDs require, so I put them in series with 300-ohm resistor to measure the voltage drop with my multimeter. These particular LEDs measure a 3.0 V drop. Good to know when choosing resistors. It also measures about 3.0 V when I use a 600-ohm resistor, or even a 150-ohm resistor. The voltage drop should be more or less constant since it is a rectifying component rather than an ohmic one.

Resistance R= (9V-3V)/0.020A = 300 Ohms. Looks like I'll be using 300 ohm resistors for this one, and a 150 ohm resistor for the two LEDs in series on the 12th fret.

The resistor should be able to handle enough power. Power P=I*V = 0.020A * 6.0 V = 0.12 Watts.
So I should technically be safe using a 1/8 W resistor, but just to play it safe I will use a 1/4 W resistor instead. It would be a disaster if your resistor burned up inside of your guitar neck, so use a slightly higher power rating for your resistors.