Month: May 2019

I like the things I build to have robust connection points. In other projects, I’ve come up with small 3D printable pieces that allow me to “panel mount” Anderson PowerPole connectors as well as 5.5 mm barrel jacks. I reused these concepts here. I use three powerpole connectors for my controller wiring.

In order to give them something solid to be attached to, i framed the foam track with 1/16″ thick 1″ leg angle aluminum. I used Gorilla Glue to attach the aluminum to the foam.

I used a power drill and some files to create the square hole for the barrel jack to protrude through. I also made a little template to make it easy to drill the pair of mounting holes.

I didn’t want the aluminum to be directly in contact with the surface it might be sitting on, so I made 3D printed plastic corner pieces to cover up the corners.

To complete the project, I put a bead of grey caulk around the top edge of the aluminum and foam to fill the gap. I also purchased these variable voltage power supplies from Aliexpress, so it is easy to change the track voltage.

I’m using standard adhesive backed copper tape for the rails. I did order the tape with conductive adhesive, and I can report that indeed this stuff works very well.

The testbed oval track used 1/4″ wide tape. There was a lot of pleating and wrinkling in the turns, even though they were a pretty large radius. I asked some questions on the forums and had a very helpful discussion with Ed “HO RacePro” who suggested going to thinner tape. So, for the proof of concept track, i ordered 1/8″ wide tape.

There were a few difficulties. The tape applying tool I found on thingiverse worked quite well with the 1/4″ tape. It didn’t work as well with the thinner tape. The OD of the retainer was smaller than the OD of the roll itself, so the roll wanted to unspool over the sides. i ended up applying the tape by hand, which was tedious.

This is a still shot from a video I took of a car running. At this point, I just had the rails hooked up to a power supply.

The crossover took a little thinking, and in hindsight i wish I would have planned it a bit better.

I just drilled holes through the foam with a 5/32 drill bit and ran the tape to the underside of the foam to make connections. Most connections are just the tape stuck to itself. I did solder wires onto the tape where i would need to make connections to the power supply and controller.

On the proof of concept oval, I just used flat latex in the slot. This worked fine, and made it easy to judge if any wear was happening, but the roughness of it that is good for tire grip isn’t good for low resistance on the guidepin or flag. If you just pushed the car around the track with your finger you could feel the drag that just isn’t there in a plastic track.

So, I devised the following solution.

1. go ahead and paint the slot and road area grey.

This is necessary to blend the slot in with the road color.

2) Coat the slot and area where the car will run with Smooth-On Epsilon Pro Epoxy.

Repaint just the area where tires will touch, not down in the slot.

Now you have high hardness and some strength only exactly where you need it. And you have traction where you need it.