Let's Make Robots!

What would you call a "Wiper"

I have searching mouser for 1/2 hour now and for the life of me, I can not figure out what to call one of these things. "Wiper" gets me nowhere. I am looking for a small copper contact, sorta springy, that would ride along an exposed trace on a PCB. Specifically, I am trying to transfer power through a rotating joint. This would involve 6 concentric rings etched on a pcb with a 6-pronged "wiper" on the rotating part above.

What is the fancy name for these things?

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I think is the proper term. Anton B used them the wrist joint of his 5 DOF arm. http://letsmakerobots.com/node/18504

Some people use those little gadgets to prevent the phone cord from twisting up or getting entangled. Dont know what you'd call tem. Those things usually only have 4 wires though and with all the phones being cordless, they aren't as easy to come by these days.

http://letsmakerobots.com/node/20319 untanglers..

Also: you can use the brushes from those toy race tracks that are underneath the cars.


This is the term used for strips of springy contact fingers and I have heard of them being used for slipring contacts.

Occasionally had to replace some of those strips if overheated or damaged in 10,000 watt FM transmitters...


sliprings are common in applications such as phonecord detanglers.

i imagine one would get some crackling on the line when it turns, but apparently there are good enuff
for a phone conversation.

in any case i don't see a mechanical way of doing it that doesn't give u lots of noise every time it turns.

we had a big discussion in the shoutbox a few months back about this kinda thing.

i think that the best way to go is to convert the signals to serial data and turn it into
a single line, feed through the joint with infrared like on a remote control, and then decode to parallel on the other end.


Ok, more info and I guess I will just come out with it...

Think of an excavator and the pivot between the tracks assembly and the cab/arm. Battery pack and motors are on the bottom, brains etc are in the cab. I will be transferring motor-level power as well as raw battery power through this guy. Mind you, we are talking about some pretty small motors here, and little current on the data side --maybe a total of 1 amp going through any one contact at any time. Total dia would be around 5cm or so. I should add that, while I appreciate the suggestions of those AWESOME pre-made rotating joints, I am actually just looking for the "fingers" themselves. The link that basile gives is exactly what the disc will look like, with the exception that I will probably etch my own rings. 

You got a good one there, oddbot --I have thought of many ways of trying to use the laser cutter to get this done --Alas, it is just not going to get through metal (even really thin stuff). I can however, coat the copper with a mask and then use the laser to burn off the mask where I want etching to occur. The only issue here is that I have never actually tried to etch all the way through a peice of copper --Well, I have, but not intentionally --only when I forgot the board I was etching and left it in too long!

Thank you for the link to that arm, mint --It is not only beautiful, but it looks like he may have made exactly what I want to do --I will shoot him an email.

I appreciate all your help on this, guys --I just woke up, found all the responses and need to start checking all your links again to see if their paths will lead me to where I need to be.



Have you tried the term rotary union?  These are like slip rings but are not only electrical but also hydraulic and pneumatic.

Mo--om, Phineas and Ferb are making a rotary union!

Hey thanks, one more thing for me to google. Awesome.

Hey I almost forgot about this guys solution to this problem.  If you want to program a PicAxe or something through a rotatry contection try a stereo plug.  Here's the link.  This was posted in July of this year.



Rotary contacts, (slip rings), are also found in phone cord untanglers.

These are in plentiful supply at "dollar stores" here in the states. If you need more than 4 circuits, stack'em.