Athearn Radio Controlled Crane

Ok, bigger is better. Also note that I had to grind down the screws sticking thorough the bottom that holds the D-shaft plate to the bottom.

This is the chemical part of trying to make the power ring. The stuff in the plastic box is ferric chloride etchant. It's very corrosive and will cause burns on your skin. Wear rubber gloves, old clothes and face protection when working with an acid. etchant can be bought from Jemaco. Here's a link to there page. Jemaco
Use a pair of plastic tweezers or make some from pieces of wood. Using any type of metal tongs or tweezers with destroy them. I put the ring in and kept checking every few minuets. It takes a while to dissolve the copper. I used a Sharpie as a etchant resist. The results were not pretty.

And here are the not to pretty results. The ink in the Sharpie didn't quite keep the etchant for eating away on the part I didn't want etched.

I tried three different products for a resist on a test board. From left to right, nail polish, Floquil paint and a product made for circuit boards when silk screening them for PC boards.

Here are the results. The nail polish worked great. It's the first time I ever used that. The Floquil paint didn't fair so well. It got under etched. When I wiped the board off the paint came right off. The control resist paint naturally came out good since that's what it was designed for.

Next up, the mechanical way to make two power tracks.

Clock makers use a method that incorporates what is known as a pot chuck, or one version of it. Take a piece of ferrous material, brass, aluminum, steel and face it flat in the lathe. Then add concentric circles a couple thousands deep. These grooves will hold the excess ACC glue that will be used to glue the copper disk to the chuck. I've blued it up for a better visual appearance.

To center it I used a home made center with a very sharp point to hold the board in the center of the chuck. I already turned a few circles to cut through the copper cladding. This electrically separates the two rings.

Once the ACC glue had dried I cut out the center for the motor to fit into. Unfortunately there is an angle on the inner most ring do to the way the tool is set up which needed to be filed out.

Not to good a job of filing, but the motor fits.

Now that I had the power ring made it was time to figure out a mounting procedure to bring the power from the ring into the shell. I like Geoff's idea of the pogo sticks. Being that died in the wool DYI'er I had to make my own. I started by taking the contact point from a relay and soldered it to the end of a piece of 1/16" square tubing.

Next I soldered a piece of 3/32" square tubing to the winch plate. The 1/16" square tubing rides inside the 3/32" tubing. Next is to make a spring that will hold the power pickup pin down firmly.