I've been wanting to try this for a while as crazy as it sounds; make a mini electric generator with a small engine and a treadmill motor, add this to some car headlights and you get one very loud flashlight/spotlight.
An electric motor is basically a generator and an electric generator is basically an electric motor. The chainsaw provides the power to spin the motor and booyah....electricity. I'm sure all kinds of electrically proficient peeps will shake their heads at the methods here, but it's all just fun, nothing serious.
(I want to add that I squeezed this project out to meet the flashlight contest deadline; it still needs a voltage regulator, a protective shield for the chain and sprockets, plus some adjustments and fancy paint work.)
Final adjustments to this machine, a voltage regulator is not needed if the saw throttle can be incrementally adjusted with a hose clamp. Hook up a multimeter and set the throttle before plugging in the light. Also the gearing in this instructable is way too high, the DC motor sprocket needs to be much larger to slow it down. I can hand turn this DC motor and get 2 to 3 volts, so the chainsaw should barely be running above idle to get the right voltage. This project is a little dramatic; maybe next time I'll use a lawnmower engine ;).
Here we go:
1 old chainsaw
1 treadmill motor (DC permanent magnet motor)
1 one-piece 12 volt car headlight bulb
odds and ends tubing, wires, switches (see detailed steps)
motorcycle voltage regulator
scrap wood and screws
welder or someone who can weld a sprocket to a chainsaw clutch and treadmill motor flywheel.
(Extra: With a few alterations, this project can be made into a mini generator or a go kart.)
Warning, this can be dangerous. I'm not liable for any injuries or whatnot incurred using the shown techniques. At your own risk and stuff.
Step 1: Remove Sprockets From Bicycle and Line Up Best Fit
I needed a bike sprocket on the chainsaw and on the electric motor. An old bike somebody threw away worked well for the parts. I used the smallest outer sprocket on the hub to attach to the saw and the larger set behind it for the DC motor. Don't ask me how I got this apart, I'm not a bike mechanic; and all that is left of the wheel is a pile of spokes, ball bearings, and cut up pieces of the axle hub thing. ;)
Step 2: Weld the Sprockets
Most people would probably say "ahh, nevermind" at this step, but it's the only welding part. This is important to get straight an centered. I tried not to over-weld and warp things from too much heat. Then I cleaned up the weld splatter with a die grinder.
Also once everything was aligned, I put a spot weld on the treadmill motor shaft to keep the flywheel from unscrewing, it's not the usual lefty loosey, it is righty loosey here.
Step 3: Design and Configure the Machine
l lined things up for a best fit, brackets, handles, and lights will all be different with different models of chainsaws and stuff. A little creativity is needed here. I used metal plumbing straps, screws, scrap plywood, and some odds and ends here.
I tried several configurations until it seemed to look like it would work.
Step 4: Add Some Wood Framing
Wood screws and some scrap wood work well for attaching accessories to the saw platform. Like I said earlier, different engine models and motors will need different techniques to patch together. Not many people probably have a 1960's era chainsaw like the one used in this project. Look at how plumbing strap and wood screws are used in the pictures.
Step 5: Add Chain and Make Final Adjustments
I picked up one of those bicycle chain breaker tools and shortened the chain to what I needed.
I made sure the bicycle chain was lined up straight and snug, not too tight or loose.
Step 6: Mount the Light and Regulator
In the video I didn't use a voltage regulator and burned out the bulb . I'm going to get a better bulb/spotlight next round and an old motorcycle voltage regulator. If the chainsaw engine is not revved up too much, one could get by without it, but not for long. The negative (black) and positive (red) wires from the electric motor are connected directly to the bulb here; ideally a voltage regulator would be in between. I had one laying around the garage somewhere; when I find it, I'll repost the pictures and video.
Step 7: Video and Extra Notes
Also, I would use a pulley and belt next time instead of the bicycle chain; it's so hard to get it lined up and it likes to pop off and roll across the yard.
Runner Up in the