December 14, 2011

Mill Mock Up

Using the plans of the Piney Branch Mill I made a 1/48th scale mock up of the Piney Branch Mill building. I was pleasantly surprised to learn that the building in 1/48th scale is only 8.6 inches long. That will fit in the site nicely.

I tried various placements of the mill. The problem is that this mill has a large wheel and requires quite a bit of vertical drop for the feed water (hydraulic engineers call this head). If I install it as the first mock-up photo below shows, I'll probably have to make the wheel smaller than the prototype to allow for less available head.

Why is the head constrained? Because the water will back up from the dam and pass under the railroad embankment. Water gets to the dam by flowing through the culvert. The higher the dam the bigger the culvert. But, the culvert needs a certain amount of overburden to be realistic. Overburden is the amount of dirt between the top of the culvert arch and the tracks.
View from further back showing culvert in foreground under railroad embankment
Another solution would be to have the dam up stream of the tracks. The water could run to the mill in a race a couple inches up on the bank of Accokeek Creek. It would pass under the railroad tracks in its own small stone culvert. I have seen many mill plans on the HAER site where mill races ran for thousands of feet, so this is not unrealistic. There would be no dam downstream of the railroad tracks. This is my preferred solution at this point. But.....

In this design, the dam is wellupstream of the railroad tracks. The water reaches the mill via a stone and wood race.

Finally, the easiest solution is to reverse the flow of the river and have feed race and dam on the backdrop or hidden by the building. It would be a simpler scene.

I had planned to use this stone culvert on the Virginia Central near Afton built before the civil war as the prototype inspiration for the stone culvert.


  1. Overshot or undershot wheel?

  2. The Piney Branch Mill is an exposed overshot wheel. See the post before with a photo.

  3. OK, so what if you compromised a bit and made it an undershot wheel?

  4. The prototype is an overshot wheel. I can try lowering the stream bed and a few other things to get it all to fit.