Posted by Scott Ellis (188.8.131.52) on November 21, 2002 at 00:55:20:
A little while ago Dave Roberts suggested that I include a section on the website about test platforms and construction designs. And he offered to help get the ball rolling by offering up his own suggestions. I think it's a great idea, but until I can find time to create a new area on the website, we can just use the discussion board to get started.
Dave sent me some pictures and text describing his setup, so I'll post those here and then follow-up with commentary about my own setup.
As promised, attached are pictures of the wheel and stand that I work with. It is very crude, but rigid and balanced. My work area isn't neat, but is functional. The wheel itself is 5 feet in diameter. I tried smaller ones but need room to work and not be so precise. If anyone wants to copy, they can upsize or downsize accordingly. I am sure there are others out there who have more functional and neater designs and hope that they submit them. To make a wheel such as mine, I offer the following suggestions:
- Center shaft: Using all thread or standard steel rod is not recommended as they do not support much weight before bowing. I used a 5/8" O.D. hardened precision shaft, 24" long from McMaster Carr. They have a website.
- The center shaft will need to ride on bearings (of course) and I used a flange mount with set screw lock from McMaster Carr #6244K52. This lets you shim under the bearing to get good alignment.
- To be able to connect the sides of the wheel to the shaft, I used a 1/2" pipe nipple and flanges available at any hardware store. Some nipples will slide right over the shaft, others have to be filed on the ends as they compressed too much in the threading operation. The flanges can be bolted to 1x4's or whatever. I also drilled and added a 1/4 bolt through the nipple and shaft so the shaft turns with the wheel.
As you can see from the pictures, Daveís wheel is huge! It makes a great testing platform because Bessler said the wheelís power was proportional to its size. This means that the "magic" principle might be revealed more easily at larger scales. But such a large test wheel may not be practical for everyone. I use a 1' diameter wheel for most testing, but will be moving up to a 2í diameter wheel soon.
My test platform consists of 3 main parts:
I buy bearings at my local specialty hardware store (you wonít find them at Home Depot). Use the Yellow Pages and ask for speed bearings. When you find a place that sells them, get the biggest one you can afford. They can be quite expensive! Be careful when pressing the bearing into the wheel (and getting it back out). It will be very tight, and itís easy to accidentally damage the bearing. Some sanding helps but be careful... the tight fit is crucial to an even, wobble-free rotation.
The setup described above works great for quickly and easily testing most 2-dimensional schemes. Lever arms and pendulums can be attached anywhere on the wheel, using the following method:
Lately, however, Iíve been more interested in 3-dimensional schemes than 2-dimensional ones. Iíve been especially curious about how a "wobble" effect might be applied. Testing these ideas will require a new platform apparatus which I have been working on. But more on that laterÖ
If youíre still reading this and have done any experimenting of your own, I hope you will consider offering up your own experiences and suggestions.
Post a Followup