Before doing the casting, there was a little more work to do to prepare the cap. I welded an electrical conduit pivot on the handle and built up the forge shelf rest to improve strength and improve visual appeal. The pivot will fit into a sleeve attached to the bottom to allow the cap to slide up and down, and swing out-of-the-way.
To keep the refractory from sliding out of the cap, sheet metal screws go through the metal ring and into the interior. Additional support screws are located at various points along the surface. The refractory will surround the screws and the weight will be distributed to multiple points to stay in place and keep from pulling out.
2000 degree F paint was added to the area around the ports.
Foam forms for the open areas were created from computer packing materials. Crescents form the vents to the top, the bar goes all the way through from one forge port to the other, and the center is a cylinder->dome that matches the inner diameter of the main heating chamber below.
The forms initially were missing the forge bar, so the aluminum tape was needed to join the vents to the dome and give it structure. Now it’s an artifact that I don’t feel like removing. When we burn out the foam it will be easily removed.
Two inches of Inswool was added to the top strip and rubber-cemented into place until the refractory can surround it and protect it from the most extreme heat. The form is inserted into the forge ports, and the whole cap installed onto a flat, water-impervious, surface and taped to make sure there are no leaks.
Now we mix the refractory + extra insulation in a 2:1 ratio as we discussed before and start pouring it in. Now we wait for it to cure.
24 hours later, I cut out the foam and patch places that didn’t fill in quite fully. Also, I generally make a “wash” of water run over the refractory to drizzel over the top to fully seal it in and cut down on the crumbly stuff.
Not bad at all… I have my forging ports run horizontally with a refractory arch backed up by inswool over top. To either side I have the vents that run up to the top. I’m going to need to drill/dremel out the top of the vents still because the castable got between the form and the table top. I’ll wait for it to dry though so it’s a little more solid.