K-9’s Ears completed
As you can see, I finished K-9’s ears over the July 4th weekend. (Click on the picture for a larger image.) I actually figured out the soldering last weekend. Solder with an acid core – and some time invested in developing a workable technique – will get brass tubes (3/32 inch diameter) to stick to stainless steel mesh. I’m not going to win any awards for my craftsmanship… but considering this was my first time soldering anything… I think I did ok.
With the ear stalk attached to the mesh, the next challenge was constructing the outer ear rims. At first, I attempted to use spline from a window screen repair kit. It’s essentially a hollow, rubber, 1/8 inch thick tube and is available at most hardware stores. Unfortunately it was the same grey color as K-9’s body and proved unpaintable. My next brainstorm was to use the PVC casing from some 12-gauge speaker wire I had lying around. I took an exacto knife, sliced the cable down the middle and removed the wire inside. I applied a little hot glue to one end of the casing (where it met the stalk) and fit the casing over the edges of the mesh. (Be sure to check the hot glue gun temp. It doesn’t take much to melt the casing.) I left the other end of the casing long enough to wrap around the mesh, cover the stalk and overlap with the casing on the other side. I cut the casing such that I could fit it around the stalk and glue it in place. It looks more or less seamless this way. A little silver metalic spray paint and the ears themselves were done.
Lastly, I needed to create the ear base. If you look at the picture above (or any image of K-9), you’ll see that the ears don’t come directly out of his head. Instead they sit on small rounded protrusions. Following pjwadelaide’s lead (see my previous post), I used the front ends of two pens. The opening, where the ink tip comes out, is usually removable, about the right height and sufficiently curved for our purposes. In my case, I found a pen/pencil freebie set from some trade show that had metal ends. I used a Dremel to widen the openings to ~1/8 of an inch. Next, I drilled 1/8th inch holes in K-9’s head where I wanted the ears to be (the exact spacing will depend on the size of your ears). I filled the inside of the pen tips with hot glue and inserted a 1/8th inch aluminum tube, making sure it was aligned with the opening in the tip. (It’s only aluminum b/c I had them around from my previous ear experiments.) Before the glue could dry, I quickly slid the aluminum tube through the holes in K-9’s head until the pen ends made contact. The 3/32 inch ear stalks slide nicely into the 1/8th tube. Note that the 1/8th inch tube was only ~2 inches long while the ear stalks continued for 2-3 inches beyond that inside the head. This will allow me to attach gears and motors at a later date to rotate the ears.
I didn’t use the aluminum tube initially and tried to hot glue the ear bases directly to his head. They easily popped off. The tube, encased in solidified hot glue, helps provide a little structural integrity to the ears as a whole.
Next up… the control panel!