Years ago when I was a young boy, my friend and I would go on adventures walking through the woods following creeks and brooks (they call them rivers in Connecticut) where we’d stumble across ruins of old mills. To us it felt like we were the first archaeologist finding an ancient tomb or some long lost artifact, but in reality, they were pretty well documented. We’d find pipes and gears and other bits and pieces half buried in the dirt and at one mill site a draft tube from an ancient turbine stuck out of the mud.
I always wondered about that pipe and how it fit into the scheme of making power for the mill. The only thing I remembered from school was that mills had water wheels on the outside and looked like the typical grist mill we normally associate with water power.
Fast forward 40 years
After moving back up to New England from a stint living down in Louisiana I once again became interested in water power. However, this time I had a better understanding, a car, a digital camera and the internet in my armamentarium of essential tools. This has (almost ?) become an obsession and to this day my wife rolls her eyes when I slam on the brakes when I see a mill dam, or other water power related device. I’ve amassed a collection of pictures of anything and everything dealing with the harnessing of water. Pictures from the net, my own pictures, catalogs, everything I could get my grubby little hands on.
Since they were of no use sitting on my hard drive, I put them together on my old Dam Page. Once I started using the blog I shut down the old site, along with The Dam Page. The blog has offered a better way to put pictures up on line. Clickity zip! Seriously, beating them up there in HTML was a real bummer. WordPress makes it so much easier. So now that I have a way to put oodles of pictures up on the site, you will get to see oodles of pictures I took over the years. Feel free to copy and use them for your own enjoyment or education, or both.
Most of this page and associated galleries are geared more toward hydro-turbines and their associated machinery, for modeling purposes. I touch on typical water wheels, but this page is directed more towards the modern hydro-turbine and its use in supplying power to mills both tiny and large. This is not a complete treatise on the subject, nor is it my intention to supply engineering formulas since there are books and plenty of other resources on the internet for such needs, but to offer a visual insight to the historical workings of a mill’s hydro turbine and following power train. That being said, some basic understanding of the physics behind hydro turbines and how they are set up is necessary to convey real life situations into a scale model.
Or, putting it another way, I’m gonna upload up a butt load of pictures I’ve taken or found and try to explain them in layman’s terms so you can build a super cool scene and impress visitors with awesome background information.
Believe me, I’m no expert on the subject. I try to be accurate, however if you see something I missed or quoted wrongly you are welcomed to correct me. I’m not an engineer, but if you need a hydro engineer I can hook you up. Now, on with the show…
NOTE: Clicking on most pictures will bring you to a gallery of more examples of whatever you clicked on.
When we think of water power from years ago the first thing that comes to our minds is the old grist mill with a creaking water wheel on the side. Granted, these are neat eye catchers, but most mill owners had converted to hydro turbines by 1900. Any new mill after 1870’s was built with a turbine in mind. It is simply much better at converting water flow into power and any mill owner in their right mind would have specified a turbine. The old over, under and breast wheels were outdated once the Francis or Boyden turbines came on the market. However, the water wheel carried on well into the 20th century at some locations as evident by small mills still having their wheels and manufacturers offered steel wheels to replace the tired wooden ones. You can see one here at the Sudbury Grist Mill gallery. Here’s a nice page on small water powered mills and their placement.
The earliest method of transferring the weight of water into useful power was the water-wheel, but it still took thousands of years before the water-wheel was transformed into the modern hydro-turbine. Once the turbine became the vogue power source most mills realized an immediate increase in power simply due to the turbines improved efficiency over the old water wheels. The true modern day hydro turbine came to life in 1848 when James B. Francis and Uriah A. Boyden out of Lowell, MA created what is now called the Francis design. Mr. Francis met Mr. Boyden at a demonstration of one of Mr. Boyden’s turbines in Lowell. Mr. Francis was the Manager of Locks and Canals in Lowell and took an immediate interest in Mr. Boyden and they began to work together improving the design and thus created the turbine which now bears the name of Mr. Francis. They improved it so much that it was 90% more efficient than Mr. Boyden’s previous design.
From the water-wheel, or turbine, the power was transmitted through gears, line-shafts, leather belts and pulleys to the intended piece of equipment. There are inherent inefficiencies in all of those mechanical drive components and a lot of energy is lost. After the electric generator and motor where invented most mills eliminated the mechanical drive from the wheel pit and replace it with a generator and mounted a motor “upstairs” that would drive the line shafting and the following machinery. This increased the efficiency between the turbine and the upper line-shafts because generating and transferring the electricity to a motor is much more efficient than trying to do it through multiple gear, belts and pulleys. An added plus was that it was easier to maintain.
The mill still needed the line-shafting throughout the building simply because smaller electrical motors for individual machines hadn’t been offered and most machines were built to be driven off of a line-shaft.
The change over to all electric didn’t happen overnight. It twas gradual and in some cases it didn’t happen until the 1960s and maybe even later. Some of the machinery that was being powered by overhead line-shafting never needed replacing. It was built to last and it did. Replace a worn bushing or re-Babbitt a pillow block and you’re good to go for another 20yrs. No use in replacing or upgrading the whole machine if it’s working fine. However, once a machine was scheduled for replacement, that’s when the conversion was done. It just wasn’t cost effective to retrofit the whole mill with electric motors.
Head is the measure of the height difference between the water in the river/pond and the tailwater level. If there is a 14 foot difference between the two, then it is said to have 14ft of head. If you multiply .438 by the head height you get the pressure of the water that will push against the blades of the turbine. i.e. 14ft x .438 = 6.132 PSI. Which doesn’t sound like much but it you add up all the square inches on a blade and multiply it by the number of blades, then the pounds of force rises dramatically. Low head heights turbines turn relatively slow, but generate enormous amounts of torque, where a high head turbine is usually built for speed with lower torque ratings. Low head turbines usually had to be up-geared to spin the shafts of machinery like looms and machine tools, where high head turbines were geared down, unless the machine they were driving happened to need the same speed as the turbine. Each site capability and requirements can be totally different from another, so all of this has to be considered in the design and thus, no two sites are identical.
More head, more power.
In many cases when a dam was built it was designed for a set power range. Over time most mills outgrew their earlier power requirements and would add a set of flashboards to the top of the dam which increased the head height and therefore the power potential. If the mill exceeded the dam and flash-board capability then a dam might be built farther and higher up the river to supply more pressure. A race (canal) or penstock (pipe) would then transmit the water to the mill.
The volume of water moving over a particular distance over a particular time period. If there isn’t enough flow, then you can’t keep the turbine filled with water and won’t generate enough power for your mill. To increase flow, you needed to dam the river to hold enough water back to last for the workday, or build your mill next to a larger river. Any small river over 10 feet wide (other than a bayou) could potentially run a small mill. That’s basically a brook, so you really don’t need to build “super dam”. Obviously, if you want to power a bigger mill, you need a bigger river, but most raceways to the mills never exceeded 30 feet and that’s only 4-5 inches in HO scale. 2″ race way in HO scale would power a decent sized mill. Don’t worry, I have plenty of pictures for you to use as reference.
Dams come in all sizes. From the tiny to monstrous. Building a model of the Hoover Dam would be ridiculous in any of the model railroad scales as it would simply be too large and would most likely take up the size of a house. But, lucky for us, there are plenty of examples of small dams that would fit on any layout quite nicely and still give the impression of harnessing power.
Gates and Gate Hoists
Gate hoists are some of the coolest contraptions I have ever come across while searching for dam stuff. The most interesting thing about them is that there are so many different designs. Not only did you have the big manufactures making their designs, but you had the local foundry and machine shops building their own for the guy down the road, or in some cases, for their own use. Everyone had their idea of what was the best design.
Races, Flumes and Penstocks
Very seldom will anyone see a turbine since most are buried deep in the bowels of the mills they powered, so for modeling purposes, a race, flume or penstock would be the first place to start to to give the impression that the mill was water powered. All of these are pretty easy to model and only need to run up to the mill, or underneath it. A small arched opening on the downside of the mill to indicate a tailwater discharge and you are ready to go. Really no need to model the turbine, or the dam for that matter. The dam can be farther up river around a corner totally out of the scene. Of course, everyone loves a dam and falling water.
As mentioned earlier, the turbine replaced the water wheel as the dominant water to power converter. The earliest turbines were were called tub-wheels and were usually built out of wood. These wheels were compact and at best a bit better than a typical water-wheel power-wise. You can see one in operation at the Carding Mill at Old Sturbridge Village in Sturbridge, MA
Another unexpected find. Based on Mr Macaulay’s book, too. Excellent video. Enjoy. Mills
The Francis Turbine
The Francis design, by which most turbines are related, hasn’t changed in design except for individual company “perfections”. The runners or the moving part connected to the drive shaft are in most cases identical with the variations in designs being in the method of flow control. It is normally used in low head high flow situations where the head height can range from 10ft on up to 100ft. I’m sure there are higher head examples of the Francis, but in those cases a Pelton wheel might be a better candidate.
The Appleton Turbine
Sometimes just by luck I come across bits like this. Enjoy
Mill Retreat Turbine renewal
I just happened to come across this site and had to put some links to their pictures of renewing a turbine. This is a typical set up.
The Old Stone Mill
I grew up in the Vernon/Rockville area and could see this building from the library of my old 6th grade school. It was last used by the Amerbelle Co until 2012 when the company shut their doors for good due to overseas manufacturing.
Modeling a Water Powered Mill
I feel that one of the more fascinating things about model building is research and is why I put this page up. Like I said, it’s more of a visual asset than any technical treatise on the subject, but touches on the technical side to give you an idea of how these turbines were utilized in order for you to create a realistic and accurate scene. As for modeling, how far you want to go is up to you. An old grist mill with a wheel on the side is pretty self explanatory. A larger textile mill, not so much. Most visitors will see just that, a big brick mill. But, toss in a canal on one side and an arched opening on the river side with water coming out and it changes the whole thing. You can leave it at that, with an occasional explanation to some visitors, and you’ve increased the model’s intrigue without too much work. If you want to model the turbine you do have some options that are totally realistic and would make very interesting scenes.
One thing to remember is that you don’t need to model the whole system to indicate that a mill is water powered. Unless the mill is built right next to the dam and is small in design will you ever see everything. As mentioned before, some dams are built farther up the river out of sight. Penstocks are often buried. Buildings themselves can physically block a view, which happens too often in real life. And of course, the turbine is tucked away in the basement. However, with every rule there are exceptions. See below.
I want to thank French River Land Co. for allowing me to use their photos. They were green before green was cool. There is a lot more info on their website that delves deeper into the engineering side of hydro power, so if you are truly interested in installing a power plant, or need to have your dam repaired and updated to code, then these are the people to talk to.