Tired of looking at your speedometer to know how fast you're going? make a wind-speed-meter calibrated to your car's speedo.
Step 1: Parts Layout
The dimensions of the wood used in this project are scale-able. I eyeballed based on availiable wood lying around.
- 1/2" X 12" X 12" plywood
- ~ 2' 1/2" X 1" plywood
- some nails & a hammer
- string & a pen
- drill & bits, jigsaw
Step 2: Measure and Cut Wood
The wood plate must be cut into a semicircle. see this project https://www.instructables.com/ex/i/3F01629E4BA41029AC23001143E7E506/ for more on drawing arcs and circles with string. Use a jigsaw or other formidable wood-cutter.
After cutting the arc, measure a piece of the wood rod to be a bit longer than the radius of the wood arc.
Also, cut a few pieces of wood for a handle. This is going to be helpful when going 60pmh down the interstate!
Step 3: Attach Handle
Attach the handle with a few nails. Make the handle comfortable for you. Ours is at a 45deg angle to the perpendiculars because that seemed like the most comfortable for holding out a window.
It may be easier to attach the handle with woodscrews instead of nails, but nails keeps things simple.
After attaching the handle, you've made plenty of other functional things including: a serving platter, a handy-sheild, a portable shade device.
Step 4: Attach Wind-meter
Pull out the nail used to draw an arc in the wood plate.
Drill a hole just wider than the nails you are using into an end of the rod.
Nail (through the rod) into the hole used to draw an arc. If the hole sued to draw the arc is busted,try to nail fairly close to it. The head of the nail should be almost flush with the rod but the rd should still rotate freely about the axis. Try not to use a nail that goes through both pieces of wood.
Step 5: Calibrate in a Car
This is arguably the unsafe step. Don't do anything to ridiculous!
Have a driver go (the speed limit) down streets at constant velocities (10 mph, 20 mph, 30 mph, etc.) and put tick marks in the wood plate. Go over the tick marks in marker when you're confidant in your calibration.