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Cost: $??.??
Obtained from: Myself! Custom engineered and built.
Condition: New
Current Status: I need to fabricate a frame for the components and work up the electronics.
My objective with this project is to build a cheap spinner myself so I can have 4 on a control panel. I wanted to build the project using materials I could easily obtain and fabricate. If I end up with a product that other people can easily make by looking at mine then I'll be even happier.
To complete this project I've broken it into stages. They are as follows:
 | Build the physical/mechanical prototype |
| Construct the spinner electronics |
| Construct the decoding electronics |
The physical/mechanical prototype involves making a frame of some sort to hold the shaft and allow it to spin freely. This also includes a stroboscopic wheel that will either contain holes or a pattern of white and black segments.
The spinner electronics are quite simple. The physical prototype will have a small PCB with two infrared emitter/detector pairs. The pairs will be spaced at 1/2 the width of a stroboscopic segment. This will generate a unique and uniform pattern of detectable pulses.
The decoding electronics will supply +5 and ground signals to the spinner electronics. It will also connect to the 2 infrared emitter/detector pairs and will convert signals from them. The decoding electronics will output PC mouse signals and/or toggle a switch on and off depending on the direction of shaft rotation.
To begin, I needed to find some hardware to build a physical prototype. My first thoughts were of small ball bearings and a solid steel shaft to fit between them. After researching the cost of bearings and finding limited sources, I decided to go with brass bushings. The bushings are very cheap and will move faster than sealed bearings. The best source for small bearings seemed to be replacement router tip bearings. They cost around $7-$10 each!
I picked up 4 bushings at my local Ace Hardware. I've since seen the same bushings in a mouser electronics catalog so I know that I have at least 1 other source.
For the shaft, I bought a piece of 1/4 inch brass rod from Home Depot. The rod was about 3-4 feet in length. I cut 2 pieces of rod into 3-4 inch lengths. I'm not sure how much I need just yet. The best thing about the rod is that it fits perfectly in the bushings with a very tiny gap around it. It spins very quickly.
To make the spinner faster and more responsive, I'm leaning towards having 2 shafts. The shaft with the spinner knob will have a larger diameter wheel/gear and the shaft with the stroboscopic pattern will have a smaller wheel/gear. This will also allow me to put a flywheel of some sort on the secondary shaft. This should give the spinner a nice feel and allow it to continue spinning slightly after the player lets go.
I had a very hard time finding gears or pulleys made of metal. I really wanted metal gears or pulleys with a nice strong belt between them. Because I couldn't find a source, I've settled for nylon pulleys. I found the pulleys at Home Depot and they're sold as rollers/wheels for sliding closet or screen doors. They fit tightly on the shaft but I'm sure I'll need to somehow fasten them more permanently. There are 2 sizes of wheels available and they'll connect together nicely with a small rubber band.
To hold the shafts together I need some sort of frame. After looking at some other spinners I decided to try a sheet metal frame. I tried cutting and bending sheet metal several times to get the frame I wanted. I just couldn't get the metal to bend properly without a sheet metal brake. I gave up the idea of using metal and thought about plastic.
A plastic block could be drilled, cut and formed using hand tools. I thought about using 2 pieces of plastic cutting board stacked on top of each other. I even found a place in Mexico that can fabricate injection molded plastic forms. For the meantime, I've also put the idea of using plastic on the back burner. Maybe injection molding will work but I need to have a prototype first.
I think for the meantime I've settled on wood. I plan on cutting a piece of 2x4 and milling it down. Wood is easy to drill and the bushings can be wedged into it. It would also be a nice prototype if I can get the company in Mexico to make me a small quantity of them (say 20-50 or so).
The only other hardware I haven't discussed are e-clips, a flywheel and a stroboscopic pattern. I picked up e-clips at Home Depot and they'll be used on the shaft to hold it next to the bushings. To insert the e-clips, I'll cut around the shafts with a hacksaw. This makes a groove to insert the e-clips into. The flywheel and stroboscopic wheels will probably be fender washers screwed to each end of the secondary shaft.
