Large Steam Era Flywheels

Overview
I was challenged by someone .. I believe it was Russ Greene of New England Brownstone, to create some flywheels. The kind of flywheels that were used with steam engines c. 1900 let’s say. I wanted to try this with using WS&F .. White, Strong & Flexible .. one of the materials from Shapeways. This is a sintered Nylon .. meaning they use a laser to melt Nylon powder to create the model. This is quite strong but has a noticeable roughness. To me this looks much like rough cast iron in O scale.
The Design
I looked around for examples using both Google images and one of my favorite resources, Google Books. I came up with four different versions (or sizes) of flywheels.

The flywheels are approximately 10′, 9′, 8′ and 7′ in diameter. Clicking the image to the left will open a larger version where you can see all the dimensions. This graphic was generated directly in Sketchup so you are seeing the actual Sketchup models with applied dimensions .. that is why you get all of the decimals.

Spokes
To create the spokes I used a plugin called ‘Curviloft‘. You can create two shapes .. such as the thin oval where the spokes meet the inside of the rim and the fatter oval that forms the center and ‘loft’ along the path between them. I then used the ‘Rotate Tool’ to array 9 copies around the center.
Rendered in Kerkythea
I used the open source Kerkythea rending engine to make a ‘pretty picture’. Happy with the results I uploaded the mesh to Shapeways for printing.
Printed
They came out really well. MUCH stronger than if I had done them in FUD .. and cheaper. The current cost of WS&F on the Materials page at Shapeways is as follows:

$1.50/part
$0.28/material cm3
$0.21/machine cm3

To break that down ..

  • There are 4 flywheels in this mesh so you get charged $1.50 each for a total of $6. These flywheels were printed before Shapeways started the “per part” charge. To save $4.50 I would have to sprue all 4 flywheels into one.
  • The $0.28 material charge is the actual cost of the plastic per cm3
  • The $0.21 machine charge is the volume the object takes up if enclosed in a box.
Painted
I brush painted the flywheel with acrylics and then came back with weathering powder. If you click the image to get the full size version you will see just how well the rough sintered surface looks like cast iron. That rough surface wouldn’t have been right for the smooth rim where the belt runs so I used red automotive spot putty to fill in the rough surface, sanded with fine sandpaper, painted silver and then used a silver rub-n-buff.

I was happy with the result. They would be expensive to order in quantity but would make excellent candidates to use as a master for a RTV mold to be cast in resin.