The core pies are welded so they are connected electrically, but the completed structure is not physically strong. In order to prevent it falling apart, I need to use an external brace. Here are those reinforcement pieces before clamping them around the core. At first, I thought I could use that wooden insert as both a winding key and to hold the core together when the long bolts of the external brace are removed during the winding process.
Here is the problem:
Note that once the long bolts are in place, they prevent the copper from winding around the core and must be removed. So I abandoned the wood insert and made a metal one which grips the clamping bars much more tightly.
The square rod sitting alongside is what will make the whole unit turn.
In order to provide a constant space between the strands in which to place high temperature insulating cement, I wound the copper with string alongside it. Once a layer was completed, I removed the string and filled the space it left with cement.
As each layer needed to dry before I started the next one, this turned out to be a long project.
To make what I’m doing more clear, this is a cut-away drawing of how the windings wrap around the core and are insulated from one another.
There are 12 layers of windings, but I only drew two in this picture of the core’s top half because I’m lazy. Insulation shown in this picture is for electricity, not so much for heat.