[Exerpted from http://llpots.com/leachwheel]
Leach Treadle Wheel History
There is surprisingly little written about the Leach Treadle Wheel design and functionality. Bernard Leach was a larger man (6'5" or 197cm tall). He adapted a treadle wheel that potters had been using in England at the time, re-sized it and made some mechanical changes. This design has been used an the gold-standard of treadle driven pottery wheels since the middle of the last century. In working on designing a treadle wheel of my own. Discussing materials to use, and how to construct the joints, I have heard more than half a dozen times "If you change it too much then you won't have a TRUE Treadle Wheel". I don't want to discount the power of myth or the mystique of the Leach Treadle Wheel, but I am not so much a Purist as to hold to the statement that the Leach Treadle Wheel is the only TRUE Treadle Wheel.
The Meriram Webster Dictionary defines Treadle as a noun from the Middle English treadle step of a stair and from Old English, from tredan: "a swiveling or lever device pressed by the foot to drive a machine". I have seen and used many different styles of treadle action pottery wheels. From a standing model, to an all metal one about 2/3 scale that was very similar to the Leach Treadle Wheel.
You can find published plans for a Leach Style Treadle Wheel in the book The Self Reliant Potter, by Andrew Holden. Unfortunately the book is out of print and is nearly impossible to get a hold of. I have two copies and am willing to share the information as long as no copyright infringements are perceived. You can also find downloadable instructions on Simon Leach's website here.
There are a few, rare, wheels that were imported from England mostly during the 60s and 70s in conjunction with Warren Mackenzie and his students at the University of Minnesota. The wheels that I have seen are generally still in great working order and are wonderful to look and and use. In speaking with Warren a few years back he told me about how the gentleman from Waves Of Grain came to his studio when Warren had a spare Leach Wheel for him to disassemble the entire unit and take measurements for creating beautiful working Leach Style Treadle Wheels.
Also, Doug Gates has been making Leach Style treadle wheels for the last number of years that are second to none in quality and craftsmanship. It was rumored that he had stopped making his fine wheels in order to go to medical school. I have gotten email from him and he intends to continue making them as long as there is demand. His contact information is located on my Treadle Resources page..
Using a Leach Treadle Wheel
There is a surprisingly large group of people using, and loving, Leach Style Treadle Wheels. Many people ask "WHY?!". Usually these people want a logical explanation as to why you would manually pump on a Treadle arm when in this marvelous age of technology you could just have a motor turn your wheelhead for you! That is exactly the reason for using the treadle wheel! By having a machine do the work for you, you are removing your "touch" one more step from the creation process. And actually, the amount of effort required to operate a treadle wheel is actually quite minimal.
You do have to adopt a different mindset to use it though. You will not be able to whack down 100 pounds of clay and try and muscle through centering that on a treadle wheel. In fact, there is almost no muscling through anything on a treadle wheel. Things are done much slower than on an electric or kick wheel. You may need to wait a revolution or two as you are learning the nuances of the wheel before exerting at the right point to bring the clay back to center. You will find that this waiting time will either frustrate the heck out of you or allow you to take more time with your work, and become more efficient and deliberate with your movements.
One of the best qualities of throwing on the treadle wheel is that you're body is directly connected to the speed of the wheel. As you get more used to throwing with it you will speed up and slow down the wheel as second nature and you will never accidentally hit the pedal and have you're 60# bowl flatten out after getting the shape just right. Don't think that you cannot throw large work on a treadle however! I regularly throw up to 30# bowls and occasionally throw a piece in many parts and end up with a much larger piece than that!
Learning to throw on a Treadle is a very humbling and wonderful experience. In my learning process, I found it frustrating to throw work on an electric wheel. Sure, I could throw a perfectly round bowl, with a shape that was just so, but I always felt that it was lacking something... some character. On a treadle wheel. INSTANT CHARACTER! My pieces were wobbly, wonky and just great! Still beginner pieces, but I felt it liberating to be freed from the perfectly round bowl and began to be able to look at the many other qualities that make for enjoyable pottery.