Earlier this year my father purchased a Miter saw and light kit to make a blade shadow line. Unfortunately the light kit did not fit his saw and was returned. So, he asked if I might be able to come up with something that would work. The light kit that was purchased was about $35, this kit is about $3.00 if you pay full price for the flashlight.
Supposedly the shadow line is more accurate than the laser guilds and it shows the saw kerf as well. After installing the light, the shadow fell exactly where blade cut and I was able to see my mark the whole time.
I will note that setup does not work well in bright light or sun light, but if your using this indoors it should work just fine.
First thing you'll want to do is remove the guard so you can gain access to where you'll want to mount the light. This saw's guard was held on by 4 torx screws. Pull those out, and the grey plastic piece just pulls right off. Fortunately this saw had a small plastic that could be removed by unscrewing the 2 torx screws, and made an ideal spot for mounting the light.
Not all saws will have this, so you might need to fabricate a mount using some abs plastic.
The flashlight that was used can be found at Harbor Freight for a couple of dollars. If you look at their flyer they usually have it for free. The diameter of the light is about the same size of a quarter and has 9 LEDs in it, in case you need to find something similar.
Unscrew the end cap, and remove the battery holder. Set the battery holder to the side you'll want that later.
This is the destructive part and the step where you are most likely to cut your hands, so use caution. Use the tin snips to cut the flashlight from the battery end up to the LED end. You may need to grind the housing off to get the LED/reflector out.
Once you have the LED circuit and reflector out, you will want to grind the plastic down to the edge of the circuit board that holds the LEDs. Even if you go into the track a little that is fine, you'll just want to make it fit into your mount.
Once you have the light down to size you'll want to solder on a couple of wires to the light and the battery pack.
Solder on a wire onto each track using one of the solder connector for the LED. Usually the outside track is the negative side and the center the positive. Touch a single battery to the wires to see if it lights up. If it doesn't light up flip the battery around end to end and test again. If it fails to light up don't leave the battery on for too long it will burn out the LEDs. Just touch the battery to the wire ends briefly. Once you know it lights up and which wire is positive, mark the wire.
Next you'll want to solder on leads onto the battery pack. The end that goes toward the light end is usually positive, but you can use a multi-meter to double check it. Once you know which end is positive solder on wire that matches the light's positive wire.
This will take a little bit playing around, but you don't want the light to shine along the diameter of the blade. You'll want to the light to point about 30 to 45 degrees down from perpendicular. After you find the angle that you think will work best for your saw, you will want to glue the light to your mount. I used hot glue to hold the light in place, I would have rather used epoxy, but the stuff I had was old and wouldn't setup. So if you're going to use epoxy make sure it's fresh.
As you are mounting the light keep in mind that you will need the wires for the light to come out where you can route them over the top of the blade shield.
I had foil tape available, so that is what use to secure the wires to the top of the shroud and over toward the power wire for the saw.
Use a couple of zip ties to secure the switch to the back of the carrying handle. You will want to run the positive wire from the light to the one wire of the switch. The other wire from the switch to the positive end on the battery pack. Run the negative wire of the light to the negative on the battery pack.
( Note: if you happen to have a 5 volt transformer, like those used for charging a cell phone, you could use that in place of the battery pack.)
A velcro strap will hold the battery pack securely in place and makes is easy to access when you need to replace the battery.
Put the safety guard back on, and enjoy cutting with precision for cheap.