A moving waterwheel

outward facing corners made with plasticardMy exhibition layout will feature a mill with turning waterwheel. This article explains the simple electrics behind this.

The mill house and waterwheel I’m building are from Wills Kit CK22 with added plastic card sheets for the wooden flooring, internal walls and secondary building on the side. The waterwheel was also modified, using parts from a second wheel to increase the number of paddles although this isn’t shown here.

For power to the waterwheel, I initially considered an Arduino-controlled motor that could vary the timing and speed but in the end went for something much simpler, a basic DC motor controlled by a simple on/off switch at the rear of the layout.

The problem was that most DC motors – 9v or 12v – have rotation speeds that are far too fast. Water wheels turn slowly and certainly not at the thousands of RPM that typical DC motors spin at.

>This post is part of a series on the construction of a lifelike model railway for exhibitions. To read other posts in the series covering its development, track work, scenery and model building making, see building an exhibition model railway.

I tried various DIY gearing assembles but couldn’t get these to fit in the OO /  1:76.2 scale building that will house it. Especially as I want it to have two floors and I couldn’t get the motor unit and my clunky collection of assorted gears to fit in the available space available under the plasti-card first floor ceiling.

Instead, I went with this geared motor.. It’s got the DC motor and gearbox built into a small form factor box that just fitted between the base of the model and the first floor.

Running this at 3v – using a switchable power supply – gave roughly the speed I wanted. As seen below.

geared down DC motor for model railway animation

A hole with the diameter of the waterwheel axel was carefully drilled through the mill house wall and the motor was glued to the base of the model so the shaft from the motor aligned with the hole. Given the vibration that comes off the motor, the usual Poly cement wasn’t strong enough to hold the motor in place so I used a two-part epoxy glue.

[The axel was positioned at a height so that the wheel reaches below the base of the model as it will sit “in the river” and therefore will need to be lower than the building].

The water wheel axel was then pushed through the hole and twisted into the hollow end of the motor shaft. The other end of the axle will rest on a wall in the river so it needs to protrude out further than expected. Once I had this distance measured, I then glued the axel into the shaft again using two-part epoxy glue.

After a bit of further sanding of the axel, the wheel itself was pushed on, some further work was done to the building and it was all tested. Here’s it as it stands, still a lot to do on the mill itself but the water wheel works.

model railway animation water wheel

The two leads from the motor are a bit short by default so these need extending to reach to under the baseboard for connection to the DC accessory bus wiring and control switch but this is straightforward enough with a bit of soldering.

Next up add some furniture and other mill house objects to the first floor that will be visible through the windows and at some point I’ll add the fake water for the river.

> A final, personal, note: I spend a huge amount of time testing, photographing, writing and researching techniques for these articles and pay for all the running costs of MRE out of my own pocket. If you found this article useful you can support me by making a donation on my fund-raising page. Thanks and happy modelling, Andy. Affiliate notice: If you plan to buy the products on this page or similiar, please use the links here. These will take you to carefully selected businesses, including Hornby, Rapid Online, Amazon, eBay, Scale Model Scenery and Element Games, through which you can buy products mentioned. These links are made under their affiliate schemes which means that although the price to you does not change I receive a small commission on the orders you place which helps me maintain this site and allows me to create more articles like this. Please see my disclaimer for more information. Thank you for your support, Andy.


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