Post by lynnr on Nov 15, 2015 0:01:19 GMT
Mark the Millwright came out for a preliminary visit to Kirby’s Mill on November 5, 2015.
Mostly he was looking around & measuring.
He wanted to know what we had in mind. I told him the main thing was to get the wheel turning as a focal point for education. Eventually we’d like to hook up a generator. But everything is going to depend on the dam being fixed, RJRD approval, and us being able to raise funds. None of that fazed him. He’s used to working with non-profits.
The Water Wheel
Mark says the metal pieces of the wheel, axle, and mountings all look to be in pretty good shape & should be used in the reconstruction. Some of the old wooden spokes might be OK , but he rest needs re-built. The rims, buckets, and barrel are shot. The square flume box clearly needs replaced.
He recommends white oak for whole thing except the barrel ( the inner ring ) where he would use yellow pine. He says cypress, the type of wood originally used for the buckets, is too brittle. Unless we are sticklers for exact historic specifications, it’s not a good idea.
The current buckets ( the things between the rims that actually catch the water) are constructed with two pieces of 1” thick lumber fitted together with a tongue & groove joint. He recommends making them out of a single piece of 2” lumber. It won’t change any overall dimensions; only the fittings on the inside of the rims.
The Flume ( water conduit )
It is unclear how Kirby brought water from the lake to the wheel. There is evidence of three possibilities:
1. A wooden chute that ran from just below the surface of the lake, along the underside of the slanted ramp that leads down to the swinging bridge, then directly to the flume box. The evidence is the existence of this ramp in line with the water wheel. Kirby did not need to make a slanted ramp. He could have built a level walkway to the bridge if had he wanted. So maybe that ramp is actually the top of a covered flume that went inside the mill house.
2. There is a large valve opening in the dam wall in the mill basement. It is below the level of the flume box. There is nothing attached to it now. But there may have been a pipeline allowing Kirby to draw from deeper in the lake so that when the valve was opened, the pressure could have forced water uphill a short ways to the flume box.
3. The pipe running along the side of the millhouse and bending around the corner, across the front and into the flume box. This is obviously NOT an original pipe. But the pit that it leads from ( under the wooden boards everyone steps on when they go into the workshop ) looks to be old. Inside there is a heavy metal valve that would have allowed water through back in the day. It also looks old. I assumed that the front pipe was a GS addition, but Mark pointed out that the materials look to be roughly the same age as the rest of the mill. After thinking about this, I have to admit that the Girl Scouts were unlikely to have taken the trouble or had the expertise to install an alternative waterflow system for a waterwheel they weren’t really using.
[ I thought about this more in the week following Mark’s visit. Here’s a theory: Even though Kirby had an experienced millwright working with him, his wheel design was unlike any previous water wheel. So maybe the water flow through the original flume turned out to be too much. Maybe the first attempt at correction was installation of an industrial strength valve. And for some reason that didn’t work so he came up with the awkward-looking but usable pit and pipe arrangement. ]
Mark noted that the flume outlet is too short. The edge of the flume where the water drops out is exactly at the top of the wheel. It should be longer so water spills into the buckets on the downstream side & it will turn better. I asked why not make it shorter and have the wheel turn in the other direction. He says it’s possible, but these buckets aren’t designed that way.
Wheel Operation
At the start of a work day, a miller would open a gate which allowed water to fill the flume box. He would release this large volume of water all at once to get the wheel started. Once the wheel began turning and gained momentum, it didn’t need as much flow to keep it going.
HIs wheel at Wolfe creek actually sits in the water, so when it starts up, it runs uneven for a couple hours because the wet side is heavier. Kirby’s wheel sits out of the water, so we won’t have that.
If the only thing we are doing is making the wheel turn just for looks, we can get by with a flow of 10 –15 gallons of water a minute. If we are attaching it to a drive belt to make it do work, it will take more. It takes 800 gallons a minute to turn the stones at Mark’s gristmill.
Once the wheel is operational, we need to consider security. At the very least we should install a brake on it. He does not operate his wheel when the mill is closed because someone needs to be there to watch.
- Lynn
Mostly he was looking around & measuring.
He wanted to know what we had in mind. I told him the main thing was to get the wheel turning as a focal point for education. Eventually we’d like to hook up a generator. But everything is going to depend on the dam being fixed, RJRD approval, and us being able to raise funds. None of that fazed him. He’s used to working with non-profits.
The Water Wheel
Mark says the metal pieces of the wheel, axle, and mountings all look to be in pretty good shape & should be used in the reconstruction. Some of the old wooden spokes might be OK , but he rest needs re-built. The rims, buckets, and barrel are shot. The square flume box clearly needs replaced.
He recommends white oak for whole thing except the barrel ( the inner ring ) where he would use yellow pine. He says cypress, the type of wood originally used for the buckets, is too brittle. Unless we are sticklers for exact historic specifications, it’s not a good idea.
The current buckets ( the things between the rims that actually catch the water) are constructed with two pieces of 1” thick lumber fitted together with a tongue & groove joint. He recommends making them out of a single piece of 2” lumber. It won’t change any overall dimensions; only the fittings on the inside of the rims.
The Flume ( water conduit )
It is unclear how Kirby brought water from the lake to the wheel. There is evidence of three possibilities:
1. A wooden chute that ran from just below the surface of the lake, along the underside of the slanted ramp that leads down to the swinging bridge, then directly to the flume box. The evidence is the existence of this ramp in line with the water wheel. Kirby did not need to make a slanted ramp. He could have built a level walkway to the bridge if had he wanted. So maybe that ramp is actually the top of a covered flume that went inside the mill house.
2. There is a large valve opening in the dam wall in the mill basement. It is below the level of the flume box. There is nothing attached to it now. But there may have been a pipeline allowing Kirby to draw from deeper in the lake so that when the valve was opened, the pressure could have forced water uphill a short ways to the flume box.
3. The pipe running along the side of the millhouse and bending around the corner, across the front and into the flume box. This is obviously NOT an original pipe. But the pit that it leads from ( under the wooden boards everyone steps on when they go into the workshop ) looks to be old. Inside there is a heavy metal valve that would have allowed water through back in the day. It also looks old. I assumed that the front pipe was a GS addition, but Mark pointed out that the materials look to be roughly the same age as the rest of the mill. After thinking about this, I have to admit that the Girl Scouts were unlikely to have taken the trouble or had the expertise to install an alternative waterflow system for a waterwheel they weren’t really using.
[ I thought about this more in the week following Mark’s visit. Here’s a theory: Even though Kirby had an experienced millwright working with him, his wheel design was unlike any previous water wheel. So maybe the water flow through the original flume turned out to be too much. Maybe the first attempt at correction was installation of an industrial strength valve. And for some reason that didn’t work so he came up with the awkward-looking but usable pit and pipe arrangement. ]
Mark noted that the flume outlet is too short. The edge of the flume where the water drops out is exactly at the top of the wheel. It should be longer so water spills into the buckets on the downstream side & it will turn better. I asked why not make it shorter and have the wheel turn in the other direction. He says it’s possible, but these buckets aren’t designed that way.
Wheel Operation
At the start of a work day, a miller would open a gate which allowed water to fill the flume box. He would release this large volume of water all at once to get the wheel started. Once the wheel began turning and gained momentum, it didn’t need as much flow to keep it going.
HIs wheel at Wolfe creek actually sits in the water, so when it starts up, it runs uneven for a couple hours because the wet side is heavier. Kirby’s wheel sits out of the water, so we won’t have that.
If the only thing we are doing is making the wheel turn just for looks, we can get by with a flow of 10 –15 gallons of water a minute. If we are attaching it to a drive belt to make it do work, it will take more. It takes 800 gallons a minute to turn the stones at Mark’s gristmill.
Once the wheel is operational, we need to consider security. At the very least we should install a brake on it. He does not operate his wheel when the mill is closed because someone needs to be there to watch.
- Lynn