We've received word from Merle in San Diego that, inspired by this blog and the Pump Plans Website, he has built his own pump. I say his own because although Merle's pump shares many components with the pump designed here, he has incorporated so many features and innovations that his pump stands on its' own merits. Of particular interest are the use of a rocking arm instead of cables and pulleys and valve bases of his own design that use rubber from inner tubes as flapper valves.
I built your pump and it works great!!! I haven't gotten all the kinks out of it yet, but against about a 12' head I was pumping 6gpm with an easy cadence. I did a few things differently and have posted the pictures at: http://www.flickr.com/photos/8388399@N04/sets/72157604684368411/ I used 4" abs plastic pipe since Home Depot here only stocks pvc in small diameter pipe. Pvc may be better and smoother, I don't know. Abs bends out flat in the oven like you described, and was easy to work with. I also did flapper valves out of truck inner tube. I don't know if they're better than your ball check valves or not. They do raise the whole affair a couple of inches and require considerable work, but seem rugged and dependable. The rubber works as a gasket and as a valve, but requires more bolts to hold the assembly together. I went to a rocker arm instead of the pulley system. This allowed me to make an adjustable/removable handle. Since portability is an issue, I went ahead and put plywd. wheels and old bike tires on it and used the handle as a tongue. When it's flipped over, the pump and the 10' pipes can easily be pulled back home. I couldn't tell if the pump position was adjustable on your design or not, but I drilled this for 6 different pump positions to allow for different lifts and different operator sizes. I used half inch axle and bolts, and for bearings I used half inch copper pipe, with a slotted and squeezed down half inch copper pipe sleeve. This gave a reasonably snug bearing, and these bearings were epoxied into the wood for all the moveable parts. I used a combination of fir framing lumber, hardwood bearing blocks, and 3/4" plywd. I haven't figured the total cost yet, but am thinking that they will be acceptable.
Readers are encouraged to view Merle's photo set on Flicker Photo Sharing.
Merle is the first reader to send photos of a working pump. This is just the sort of participation and innovation we were hoping for when we started the treadle pump blog. Great work , Merle.