Need a bottle opener? Need a DIY gift? Make a bottle opener out an old cassette and a chain or just an old cassette.
1) Acquire a cassette and a chain. Grab an old cassette, bum one off a friend, or ask your local bike shop for an old one. Chains and cassettes are the most common parts replaced in a bike shop and have no good use once they are worn out. Make sure that the spider of the cassette is a suitable shape for opening bottles. Most high end cassettes (XT, SRAM 990, etc.) use a ‘carrier’ and will not work. If you want to use the chain, make sure the cassette has ‘speed holes’. Refer to the photos to get an idea of the shape you’re looking for. Any chain should work.
2) Disassemble the cassette. Most cassettes have one to three pins holding it together. If the pins have allen heads on them (usually 2, 2.5, or 3mm), simply undo the bolts and it should fall apart. If it has rivets, you will need to take them to the grinder. Simply grind the heads of the three pins and pry the cogs apart with a flat blade screwdriver.
3) Now is a great time to grab a beverage and test which cog will actually open the bottle. On most cassettes it will be the largest or second largest that will fit the cap.
4) Clamp the appropriate cog in a vice and cut away the spider to get the shape like the one in the pic. I used an angle grinder with a cut-off wheel on it, but other methods will work. Use your imagination.
5) Take the cut off piece to a bench grinder or replace that cut-off wheel with a grind disk and smooth out those edges.
6) If you haven’t already, now is a good time to make sure it is nice and clean. Clean it with a (preferably biodegradable) degreaser. If your cassette doesn’t have speed holes, you are done. Go open a bevvie of your choice to ‘test’ it out before gifting it away. If you want to add a chain ‘handle’, read on.
7) With a chain breaker, break the chain down into a length of 6 or 7 links (about 12 half links) or use your judgement on length. Now is a good time to clean the chain, if you haven’t already. Make sure you leave an outer plate on each end with the pin still in. Now for the unorthodox part, remove two bushings from the inner links (the little cylinders that the chain pivots on). You should be able to pry apart inner links with a flat blade screwdriver.
8 ) You won’t be able to use a chain tool to reassemble the chain, you will need to use a vice or channel lock pliers. Line up the parts in this order: outer plate, sprocket, bushing, outer plate. The sprocket should approximately take up the space of the missing inner plates. Using the vice, push the pin through. Now, for a stronger connection, use a socket like in the pic to push the pin slightly past flush. I believe I used an 8 or 9 mm socket.
That’s it. You just made an eco-friendly (reused parts) handmade gift. Go have a beer.