An interesting design, and an interesting discussion on IP. (Intellectual Property… patents, copyright, etc.) The CD community does a pretty good job of giving solid information on the challenges and benefits of patents, and dispels some common myths such as the protection offered to engineering designs through copyright.
It looks like these could be mass produced fairly easily on a table saw with some fairly simple jigs. There are also some alternatives to UHMW that are worth considering. A local firm (North Vancouver, BC) produces a graphite/epoxy composite for lubricating the side of train wheels. This is an extremely hard-wearing, low-friction compound that can easily be shaped with wood-working tools, but has the added benefit of lubricating the chain (or wheels) as it slowly wears away. They gave us some and we used this to tension our chains three years ago, with a grooved sliding tensioner that was adjusted cam-style on just one side of the chain. It worked great. But I’ve lost their contact information, sorry.
As far as the profitability of marketing this design, the tensioners would end up being a fairly low cost item (the raw materials are commonly available and the machining steps relatively simple) so it would require a significant volume of sales to generate a large amount of revenue, and, as mentioned several times, a large amount of revenue is required to justify the cost of a patent.
However it is possible to file for a provisional patent at a much reduced cost ($500 is the ballpark figure that runs through my head), and while that only protects your design for a year, that may be enough time to test market it and/or license the design to someone who is willing to pay the costs of obtaining a full patent.
Whether or not this is a patentable or profitable design, it is a good one and one to be proud of. It may well be worth the effort of doing a patent search (google patents and freepatentsonline.com help the individual inventor get a start) as well as a search of the web for similar designs. (Remember that what matters is that you were first to invent, not first to patent. Even if you were to get a patent, if someone were to demonstrate that the device had been invented 50 years ago they could have your patent overturned… regardless of whether the original inventor had filed for a patent or not. There is a whole section of patent law on the issue of “first to file” vs. “first to invent”, but your main concern here is to look for “prior art”… ie. has anyone done this before?) It may also be worth going through the exercise of setting up a small-scale production run, developing a brand name for your product, and marketing your product just as an educational exercise. If it turns a profit… great!
P.S. Also remember that a patent doesn’t prevent someone from using your idea… it merely gives you the right to sue them for damages if they do… and a US patent only protects ideas in the USA. If a US patent is expensive, then protecting your idea world-wide is phenomonally expensive (any idea what it costs to get a patent translated in to Japanese?) That doesn’t mean don’t “go for it” if you want the experience… in many ways the educational value of developing your design is likely to be far, far greater than the commercial value… just as the educational value of building a FIRST robot is far, far greater than any commercial applications the robots might have.
P.P.S. Should you decide to patent in Canada, I can introduce you to some excellent Canadian patent agents who know a thing or two about FIRST.