Plum Geek Forum

Just curious:
Did you ever experiment in your pro typing with having some sort of small tip on the motor shaft to increase friction a bit?
I ask because I find that Ringo will spin out on some seemingly flat surfaces or get hung up on a joint in a wooden floor.

I have found the same thing.

I have considered [but haven't yet tried] putting a short piece of heat-shrink tubing on the end of each motor shaft.

How much slack is there in the wire from board to motor? I haven't got my Ringo yet but I'm just wondering about the potential for a 3d-printed add-on which is a little clip clipped onto the ringo body, allowing me to have the motors flat for a standard wheeled setup too for surfaces that arent so uniform. Not that it matters, i could replace the motors but I'd rather not modify ringo itself at all. just reposition and clip on some wheels

The motor shafts are very thin ( 0.8mm) , so not sure if attaching a wheel will be successful. let us know if you can make it work!

i would use a nano-quadcopter propeller as the actual attachment, which is designed to pop on the end of these exact motors. then all that's needed is to 3d print a cylinder that the ends of the propeller clip into the inside of, and we've got a wheel with treads if need be -- It's not high on my to-do though. just thinking it's fun thing to work with the gyro on, see if i can get it to balance itself.

Hey guys. Sorry I've been away for a while.

One thing to check is the height of the motors in the clips. If they press too far up, it'll allow more weight to be supported by the felt pads which reduces traction. You want enough room that the robot rocks front and back a bit. You can also make sure the pads are clean. We once ran it on a white board to trace a line, but the dry erase ink got on the pad which turned out to be fairly tacky, so that caused a breaking action as it went around a smooth surface.

One quick warning about press-fitting something to the end of the shaft.... when you press it onto the shaft, be sure to give equal pressure to the rear black cap on top of the motor where the wires come out. When you press inward axially on the shaft, all the pressure ends up on this back cap, which itself is press fit into the motor. It is possible to pop this off and re-seating it can mess up the commutator contacts and ruin the motor.

To really get better traction...

I would suggest adding some really thin heat shrink to the shafts. We were going to do this from the start, but what we realized is that over time, the heat shrink would always start to release from the shaft so the shaft would spin inside the shrink and you wouldn't get movement. We figured it was best to send them with bare shafts than to have lots of people running into this trouble.

If you go the shrink route, it's important to get the end perfectly round otherwise it'll "bump" as it rotates. A trick we used was to set the motor to run at high speed, then lightly touch the running end to a hot soldering iron - this tends to kind of "lathe" the end of the shrink to make it round.

We also tried putting a dab of rubber potting material, but this too always came loose.

Another possible solution the next time we need motors is to see if they can stamp some sort of grooves into the shaft. This may allow better placement of some sort of traction material.

-Kevin