Introduction: Water Mill From Tree Branches

About: I may be an electrical engineer by trade but that won't stop me from tinkering in the domain of mechanical engineers and artists:P

When I was young, I used to go hiking with my grandparents and cousins a lot. One thing almost all trips had in common was water. Why? The answer is watermills. The easiest way to convince us to go hiking was a promise of building a watermill. No matter if we were close to a river or a creek, we built dams to direct water and placed mills into the stream.

Back then we weren't allowed to make the watermills ourselves because we were "too young to use knives" but some 10 years after our last trip I am writing this Instructable to share my skills with you. All you will need is a knife (a pocket knife with a saw is even better), the rest can be found in nature.

Enough intro, here is how you make one:

Step 1: Making the Shaft

You will need to cut about 25 cm (10") piece of branch around 1.5 cm (3/8") thick. Make sure to find a piece that is as straight as possible as that will enable your watermill to spin more smoothly. Branch has to be fresh.

Now cut all the way through the branch in the middle (images 2 and 3). You can do that by carefully wiggling knife up and down or, as I did, tap the back of your knife with a rock (or a piece of wood). You might want to ask a friend to hold the stick steady while you tap the knife (be careful not to cut his fingers off accidentally!). No matter what you do don't try doing this step in your lap . Find yourself a tree stump or do it on the dirt. Once you cut through, you need to twist your knife to open up the crack. You want it to be 2 to 3 times as wide as your paddles.

Now you need to repeat the process two more times so that paddles will be spaced evenly (eyeball it to 60°).

Make sure you cut through the centre. Cutting off centre will make your watermill's paddles stand crooked.

Last step is to peel the bark where you want your mill to be supported. This reduces friction and lets your watermill to spin faster. Scoring the bark with a knife will help you get straight lines.

Step 2: Preparing Wood for Paddles

If you are building your mill near populated areas, you are likely to find some old broken planks. If so, I recommend you to make the paddles out of them. Otherwise you will need to find find a branch (preferably dry as it splits more easily), around 5 cm (2") in diameter and saw off a chunk 10 to 15 cm (4 to 6") long. Split it twice across it's center and proceed to cut slabs from outside inwards (image 3). Once you assess that slabs are becoming too narrow, proceed to splitting next quarter. Slabs should be 1 to 2 mm (3 to 5/64") thick.

You can try cutting slabs from another direction but I have found that cutting slabs from quarters yields best results (fewest ruined slabs).

Don't think splitting dried wood will be as easy as simply pressing on it with a sharp knife. You will have to help yourself with a rock or a reasonably sized branch, if you are afraid of damaging your knife. Start the cut by tapping back of your knife above the wood and once you sink your blade entirely inside the wood, proceed by tapping next to the wood.

One tiny trick to speed this step up is to prepare paddles in advance. Making paddles at home with a bandsaw could also be considered safer alternative to fiddling with a knife.

Step 3: Cut to Length

You will find that a lot of your paddles are different in length and/or go thin towards the end. For use in a watermill that is a problem and therefore you need to cut them to length. Determine the shortest (usable) paddle and tidy it up, then use it as a reference to cut the others to length.

Once all paddles are cut to length, you have to thin them on one side to make it easier to insert the paddles into the shaft (image 3) and that's it!

Step 4: Time to Assamble

Insert paddles with the sharpened side forward in notches in shaft. If you are having trouble sticking them in, you can insert knife in the notch near it's end and twist it gently. This should open up the notch and let you insert the paddle more easily.

Step 5: Support Structure

The last thing you need is two pieces of Y branches for your mill to rest on, as seen in the photo above. They can be fresh or dried - whichever you happen to come across first. In my experience, stripping bark from fresh twigs makes the watermill spin slower. Not entirely sure why, but if you are using fresh Y branches with smooth bark, you don't have to do anything, while you will want to strip bark from dried up branches.

Now comes the time to use your imagination.

Place your mill in water and try to get it to spin as fast as possible. You can place it under a waterfall or improvise a dam. Make sure to place it perpendicular to water flow or it will drift to one side and either fall off support structure or just get stuck.

Step 6: The More the Merrier

One watermill is cute but a bunch of them really catches the eye.

If you prepare the paddles in advance, making a watermill should take you less than 10 minutes. That said, I highly encourage you to build your own. I look froward to your feedback and "I made it!" photos!

One last note: please be mindful of other nature goers and don't harvest materials for your watermills from first tree or bush you see, but stray off the path a little to leave nature pretty for others.

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