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| Patent Drawing for Eli Whitney's Cotton Gin Image Courtesy en.wikipedia.org |
Patented in 1794, the Cotton Gin in retrospect has a dark side to its history. Before its invention, cotton seeds had to be laboriously removed from the fiber by hand. In general, this time-consuming process held back any large scale production of cotton until Whitney's revolutionary machine arrived.
Once mechanical ginning was established, cotton production soared in the South. Some historians today name the Cotton Gin as the root cause of the Civil War. I think that's a bit of a stretch but it did play a part in the expansion of slavery even though it was intended to reduce labor.
In order to build a working model, I had to understand the basic function of the Gin. The three key elements in Whitney's design are the rotating claw-like hooks (that grab the cotton fiber), the slotted comb that they rotate through (the narrow width of the comb's spacing keeps the seeds from being pulled through by the hooks) and the rotating brushes that remove the seedless (ginned) fiber from the hooks.
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| Original Patent Model Note the Ginned Seeds in the Lower Front and the Cleaned Cotton in the Upper Rear Image Courtesy history.com |
I started by studying the 1794 patent drawing but was disappointed to learn that the accompanying description is unavailable. Two original models of the Gin have survived, one is the patent model and the other a later version used in the court battles against infringement. After studying the few pictures of the models online, I finally figured out the mysterious curved, springy comb that allows the ginned seeds to fall through.
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| Close-up View of Another Early Model Note the Hooks, Slotted Comb and Springy Wire Comb Image Courtesy of newsdesk.si.edu |
My first attempt at making a wooden drum with hooks was a dismal failure. I drove wire nails into a large dowel and cut them to length. After bending them all into directional hooks, it started to look pretty good. What I discovered was, the hooks tended to rotate, which doomed their chances of proper alignment with the all important comb. Whitney had used flat metal hooks but I didn't see myself cutting out a bazillion of those little things.
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| My Version of the Hook Drum Photos Courtesy Lindy Miller 2013 |
Instead, I created little circular saws in sheet steel used in a latter patent improvement by Hogden Holmes. In order to build up a cylinder, I sandwiched my little sawblades between discs of 3/8" plywood. Once stacked, I ran two rods through and riveted the ends over washers to assure stability. I squared the center shaft hole by driving a piece of 1/4" square stock through the existing 1/4" round hole. The finished drum turned out to be about 4 3/4" long by 3" in diameter.
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| View From the Top Showing Hook Drum in Place, Spring Comb and One Brush Section |
The rotating brush drum was created using a 2" dowel and four sawed out sections of a new scrub brush. Little by little, it was starting to come together. The previously mentioned curved, spring comb thingy had to angle into the rotating hook drum at such a degree to cradle the raw cotton. I made mine removable as that's what the orignal model appears to have.
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| The Finished Model Cotton Gin Showing the Completed Brush Drum and Pulleys |
Last but not least was the crank handle (mounted on the hook drum shaft) on one side and the two pulleys on the other. The ratio of my pulleys is approximately 2.5 to 1. For a belt, I used a rubber band and twisted it in the middle to reverse the direction of the brush drum pulley as per the orignal design.
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| View From the Other Side Showing the Crank and Slotted Comb |
Now came the test. Luckily, my wife had some unginned cotton bolls so we didn't have to wait months for her crop to mature. Cranking away, it made this great primitive machine noise and the best part was.....................the darn thing WORKED and................. my wife is happy. Mission accomplished !
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