Steam era freight cars used radial roof designs as part of their construction. Modeling a radial roof can be challenging if you are trying to accurately match the proper radius of the prototype. Learning how to build these roof designs will open up new opportunities for you as a modeler. I have published a technique for building up the radial shape using .010″ styrene sheets. The technique is like making a sheet of plywood. The binder to hold the layers together is a combination of CA and MEK or Testors (if you like in Cali like me).
Creating a consistent radius is the trick. You can make a wood form to a special shape or find a piece of wood molding as I did. The trim piece happen to match the radius of Southern Pacific wood cabooses. The radius that I tried to match 18′ 2″ of the prototype.
The key to using this lamination technique is to use double-sided tape to hold the first sheet tight to the form. Start the lamination by bonding the edge of the sheet with MEK. Flow a small amount of CA between the layers. Press the top sheet down starting at the edge and moving to the non-bonded edge. Continue to add sheets until you have the required thickness. Clean up any CA that might flow out as you press sheets together. Sell the edge with MEK. Let the assembly cure overnight or so.
The picture above shows how I added a clamp to hold down the lamination as it cures. The roof mold was modified to create a slightly different radius. The approach was not successful. The basswood overlay did not maintain a constant radius so the roof failed to conform to the desired radius. I will try a different approach in a couple of weeks.
The next post will cover the construction of the cupola.