Step 3: Make the lamp base
I used 1/4" thick steel bar stock at 1 1/2" wide. To make a 4" square, you need 2 at 4" and 2 at 3 1/2." Weld these together, grind the welds. (pictures 1-4) Then, because i'm going to pour concrete into the volume, i welded two little pieces of 1/4" bar to keep the hunk of concrete from slipping out someday... (picture 5).
Then drill a 1/4" hole as far to the bottom as possible on one of the sides. This is for the cord.
We won't fill the bottom all the way with concrete so that the cord can come out of the post and out our little hole. So put in a piece of foamcore to the top level of the hole we just drilled. Seal the edges with the glue gun. We'll pour the concrete from the top.
Then glue with the glue gun the threaded rod post onto the foamcore. Make sure it's not off at an angle.
Ok the last two photos are what it looks like when it's dry, top and bottom. Get the idea?
I think the next time I do this, I'll probably forget about floating it above the base. I think a hunk of wood could look nice. This took too long.
Now for our first pour. This will be good practice for the big one. I recommend getting rockite. It's available at a lot of smaller hardware stores. The stuff is awesome. It's like plaster, just a lot stronger. and it has a beautiful smooth finish. Mix it as per instruction so that it's like heavy cream. Or melted ice cream. Not too runny! The more water, the weaker. It's easy to add too much water. Add it slowly.
Pour it in just short of the top of the steel base.
Now, this is the annoying part. I don't think i would do this again this way, but here goes. I wanted the thing to "float" off the base a bit. So i decided to cast in some 1/4" steel bar legs. I welded these little bits of wire on to the legs so that it would adhere well to the concrete. I won't get into the details, because I think it's a bit of a cockamamied way to do this. But you need to make sure the wire won't interfere with the glass for the main pour.
For this step, I'm just setting them into the base about 1/4 inch, so that the shade will seat securely into the base. These will be easy to remove once it's hard, and then I'll cast the legs into the shade. I know, ridiculous.
The trick is you have to somehow hold these little guys in position while the concrete dries. This can be accomplished with small clamps. Or maybe duct tape But have a game plan before you pour. I didn't have one, so this is my improvised half-assed on-the-spot effort. It worked
Rockite dries fast. It's pretty amazing stuff. It will start to set up in about 15 minutes. After an hour you can carve it with a blade. In 24 hours it's wicked hard but you can sand it and shape it a bit. After a week it's rock solid.