Basic Pivot for Whirligig or Weathervane
In this post I wanted to go into more detail about the whirligig or weathervane pivot and how it is put together. The diagram below is intended as a basic guide and can be adjusted in size or scale according to the size whirligig or weathervane that you're creating.
For basic demonstration purposes this is a basic 12 inch pivot for whirligig or weathervane. Were using a heavy screw with threads that only go halfway up and a non-tapered shaft. The type of screw head does not matter as it will be cut off once the screw is installed in the vertical mounting board. Screw the screw into the vertical mounting board just enough to cover the threats. Making sure to keep shaft of screw vertical. It may be necessary to drill a pilot hole to help keep the screw straight, as this is what your project is going to pivot on. This should leave the upper half of the screw without threats exposed. Then using a Dremel tool (with appropriate safety goggles and other protective equipment) use a cutoff blade to cut off the screw head and a grinding bit to either round the top of the screw shaft or grind a concave dimple. Once you've completed your vertical board with pivot it is time to create the horizontal part of your pivot.
One of the important things to take in consideration before drilling a hole is the metal or plastic sleeve that will fit inside the hole. The metal or plastic sleeve should fit tightly in the hole but the screw should fit closely but not so tight as to inhibit the upper part of the pivot from rotating. Any wobbling in the rotation of the upper pivot will simply create excessive wear and erratic movements.
At the bottom of the hole place a 1/4" hunting shot (slingshot ammo found in the sporting good section) or a small ball bearing, or BB depending on the size hole being used for the vertical shaft. The basic reason for placing the metal ball at the bottom of the hole is to prevent metal rubbing against wood and to reduce friction as the upper pivot rotates. Using a metal ball that is slightly larger than the metal or plastic sleeve and then placing the metal sleeve on top of the metal ball in the hole will help keep the metal ball in place.
Using wood stock that is approximately 1/2" X 1/2" X 12" long measure 3 inches from one end and drill a hole. Where you position the whole will depend on how you want the pivot to react to the wind. The closer you position the hole to the center, the more erratic the pivot will act. The closer to the end you position the whole the greater the force that will be applied not only to the pivot reacting to the wind, but also to the pivot itself. I have found that a quarter of the total distance gives a good balance to the pivot and does not put excessive strain on the pivot.
Once you have the metal ball and sleeve in place the two parts to the pivot should be ready to go together. You can put a small amount of graphite lubricant at the bottom of the hole before you put the two together.
There you have it a basic pivot to mount your whirligig or weathervane on. For this and other ideas please be sure and check out our website www.nevadacrafter.com and our blog's at http://craft44.blogspot.com/ and http://nevadacrafter.blogspot.com/ and http://3dpenideas.blogspot.com/
If you have any questions please be sure and post those questions to the blog and I will try to answer them as promptly as I can.