It's funny how statements which you make come back with a vengeance and bite you again! The last photo on my May 9th post showed a banner which was a tongue in cheek version of John F Kennedy's speech about going to the moon. The banner read "We do this not because it was easy, but because we thought it would be easy". This certainly applied to a recent activity!
Our 11 year old granddaughter Georgia started intermediate school this year. She's a smart cookie and is in an accelerated class where the work is set up to challenge them. Each student was recently asked to come up with a project, implement it and report the results. Georgia had seen something on power generation using a waterwheel and thought it would be cool to see how power output changed with water flow and gearing. All this because they have a small stream passing through their property! She asked her dad Kerryn (our youngest son) what he knew about the subject and the answer was very little. As the lead time for completing the project was only a couple of weeks or thereabouts, he was straight on to me to see what I knew about the topic. The answer was Sweet Fanny Adams, apart from understanding the physics and engineering principles. The short time deadline was going to be quite a challenge.
A brief discussion was had over the phone with Kerryn, with the thought that the 3 generations could work together as well as Georgia conducting the experiments and writing the report. Wherever possible, everyday recycled materials could be used. How hard could it be? And then the catch.... would Nana and Granddad mind doing the 400 km round trip this coming weekend to help make it all happen? Immediate thoughts went back to the first paragraph of this post - no pressure then!
The best part of day one after the phone call was spent on YouTube and other sources learning about different types of waterwheel and it became quickly apparent that an undershot wheel was the only practical option because their stream was relatively shallow. Next step was to see what resources we already had which might be useful for constructing a waterwheel.
Jennie had an old bicycle which had been unloved and not ridden for 3 or 4 decades. That might be a useful source of big sprockets and maybe a chain. I had an alloy bike rim which we inherited with the house decades ago and a quick bit of dismantling got underway. I also dug out some threaded bar, stainless tube and other bits and pieces which Jennie previously referred to as hoarded junk, sigh... I also requisitioned one of Jennie's nylon chopping boards to make thrust washers for new axles. It wasn't strictly theft as it had been re-purposed some time ago as a fishing bait board for the boat!
Next step was to head to the village transfer station and see if there were any old bikes with sprockets of various sizes. One was spotted under sheets of corrugated iron in a pool of disgusting water. Quite a job pulling it out in those unsanitary conditions. Good value for a couple of bucks! A quick bit of hacksaw work to get the sprocket and chain off, followed by soaking the chain in kerosene to loosen up the rust.
Sunday dawned with the main goal of hooking up the generator. It was spun up at various rpm using an electric drill to obtain voltage output characteristics, particularly at speeds that the waterwheel would rotate at. A good confidence boost as it worked just fine. A mount for the generator was made, using clamps for chain alignment and tensioning. With time being a precious commodity, a rudimentary coupling was made to mount the generator sprocket. Not a perfect solution but adequate for the experiments to be run.
With time getting on, Jennie and I had to make the 3 hour trip home whilst Georgia and her parents headed for the stream again to test how the completed rig worked. Very much in our thoughts on the way home and a hope that I hadn't lost any engineering mojo with that dodgy coupling!
Got a message soon after we arrived home, complete with videos and photos - an outstanding success in every respect, apart from the chain periodically jumping off the sprockets.
Georgia has to complete her report and submit it this week. Her parents and grandparents might be a teensy bit biased but when it's finally assessed, it's hard to imagine that the outcome will be a poor one!