Powering An Old Mill 1.5 Kw Lake District Overshot Waterwheel Project Part 5

In this video I got to install an overspeed controller and fix a broken weld on the wheel. the controller is very simple. it reads the speed of the wheel via a proximity sensor and triggers a really if it goes passes a set value. that then drives an actuator that pulls out a pin and shuts the water off.

[snailswrath]

It takes great integrity to show what you're not proud with. Seeing both the good and bad makes these projects far more interesting to follow. Unlike some overproduced, cherry picked fairy-tale that gloss over all the bads just to look good.

[SamsMotors]

Well done for showing your mistakes! Weld fatigue is the cause of a massive percentage of structural failures, so it's always interesting to see another real world case study. The failure is somewhat unsurprising, given that at 1.5kW and around 10rpm, the torque generated is some 1400NM, and probably higher given the efficiency losses of the generation system. Additionally, the diameter of the wheel makes for quite a bit of leverage, so the plate that suffered from the weld fatigue is having to resist any forces acting perpendicular to the rotation of the wheel (e.g. from water landing in the buckets at a bias, or wobbling of the wheel from side to side as it runs.).

On top of that, the weld that failed would be quite a low fatigue class, with the closest match probably being class 36, meaning that it was always susceptible to fatigue failure under cyclic loading.
Given that it's been running for about 2 weeks, at an average of 10RPM, it's only seen around 200, 000 cycles (complete turns). According to the SN curve for a class 36 weld, that would suggest that the direct stress seen by the welded plate is in the region of or above 100 MPa - a number far greater than would be generated by just the torque alone. I'd therefore presume that the main cyclic loading is coming from the wheel "wobbling" from side to side as it runs, causing the welded plate to flex continuously.

In order to alleviate this, I'd suggest some triangulation braces (perhaps 4, one every 90°) running from the outer perimeter of the wheel back down to the hub. Even at quite a shallow angle, these would provide a lot of stiffness to the structure and prevent the hub plate from being flexed as the wheel rotates.

[doubled]

Been missing your videos man! Great to see you back. Can’t wait to see some barn updates.

[NigelMarston]

I am so jealous of this customer - having a river to produce electricity from would be my dream but to take advantage of it with such an amazing waterwheel... well, if ever I buy a property with a river, I'll be calling on Kris to build me one.

[maxtorque]

I like your overspeed failure shut off system!

One useful component for such systems is the cheap electromagnetic door "lock" device normally used to hold doors open or shut. You can get these cheaply in all sort of voltage ranges (AC & DC) and they have huge holding force for tiny amounts of power, and of course, when you remove the current the electromagnet is not a magnet so they are intrinsically fail safe. In this case, the sluice blocking gate could have been held up by such a magnet, and released on either a loss of system power or an overspeed event. This is far simpler mechanically than the chain and pin system so there are less ways it could fail to operate 🙂

[davidbrodie]

I've found this project fascinating and Ive learned a lot, thanks. I like the failsafe that shuts down the water flow, but if it was mine I'm sure birds, squirrels etc would land on the chain that pulls the pin out!

[daveamies]

A 1 year review of the water wheel would be really interesting next January if you can do that 🤞
Great project and great outcome 👍

[deborahdanhauer]

What I love about your water projects is you keep things as simple and straightforward as possible. It seems like so many inventors/makers try to make things as complicated as they can. Then it’s hard to understand and I would imagine, hard to execute. Your solutions are simple, doable, and much more sustainable over time because of that. Truly a pleasure to watch and learn from.❤️🤗🐝

[AndrewTa]

Your level of knowledge and ingenuity is seriously impressive!

[escapetoruralwales]

Hi Kris, I have just moved to a 10.5 acre homestead in wales and I just started a channel. Thanks so much for the inspiration. I have watched your channel for years and it’s because of people like you that I am living my best life 👍

[dfishpool]

Congratulations on achieving a successful outcome on the water wheel - fascinating engineering. Happy New Year, Kris.

[NevReign]

Great job as always Kris. Defo a project to be proud of. All new tech have teething issues, so it takes nothing away from the engineering that's gone into this. Well done mate.

[dudleysdad]

The failure is most likely due to the steel having a heat affected zone (HAZ) in the area of the break possibly micro cracking and brittle fracture, your over plating should work but maybe an idea to read up on how to limit the affect (heat treatment for instance) Also relatively easy and cheap to check using dye penetrant technique. You may already know this of course 🙂Hope it all works out.

[craigcinca]

Very impressive how close you were able to come to the efficiency estimates in your brief. Beautifully engineered and executed!

[william]

I loved this series on the water wheel but i cant hardly wait to see you working on the barn . Its been a long wait but i know it will be worth it. Without a doubt my favorite utube channel. Well done with the water wheel, i wish there was more contractors like you with your work ethics, honor and integrity.

[timsanders]

What a completely honorable tradesman! I bought 3 "Made In China" heavy-duty automotive tools over 4 1/2 yrs. and they are all junk. I now NEVER buy from China, not even casual shoes. The quality of workmanship of any Western European, British or United States manufacturer far exceeds that of China or any Asian country. Kris Harbour is a tradesman of remarkable talent, patience and fortitude. Thanks very much for all 5 episodes which took a ton of time to film and assemble into a remarkable YouTube video.

[afos]

We all get days like you had, and you can not carry everything around with you. Been good to watch and I hope you all celebrate well and raise their glasses to you and your customer. For undertaking this project, well done and keep safe!

[spideybrent]

Hello from Moosomin, Saskatchewan, Canada you have great videos and great at communicating. Thanks for sharing. 😊

[edstraker]

Kudos for the Welsh production. Much more honest and relatable than most of the Hollywood rubbish, where no one makes mistakes. Well done Kris

[drivemenuts]

Great to see the progress. In all of your video's for this water wheel, I only had concern for the thickness of that failed plate, with respect to fatigue failure. However, with 1.5 kW and 30 RPM being pushed through the shaft, I calculate that the plate at the location of failure was experiencing roughly 5 MPa of shear stress. The yeild of the material is roughly 200 MPa. The cyclic stress range would have had to have been 120ish MPa for the failure to occur within a few days. There would need to have been some crazy wobbling cyclic stuff going on that you weren't aware of for that to happen, and then the other side didn't fail. It had to be an issue with the material/welding.