[cyclestart]

I'm building a toy and don't want to spend much cash, Picture a linear stage that swings around like a crane/boom for unlimited rotations. Stepper motor hanging off the end.

What's needed is a rotary connector like a Leslie speaker or a radar dish. Problem: the ones I've found cost big $$. Home-made idea #1 was a deep groove bearing design but rotating one of these bearings showed resistance all over the map. Idea #2 is a cobbled together slip ring device, maybe salvaged from a couple of scrap car alternators or similar.

Doomed to failure ? Other ideas ?

[bharbour]

Both of your ideas are a lot like what I have considered for the same problem. Years ago, I bought a rotary connector. I got to see the inside of it and it was little round double sided circuit boards with a couple of gold plated wires rubbing on each side. There were 4 stacked up as I remember. It was seriously expensive to buy.

I have been thinking about building a slip-ring for a piece I am working on. Alternator brush holders were the model I had in mind.

If the current requirements are low and noise tolerance high, you might try copper rings on a plastic central support with spring steel wires pushing against either side of the ring.

Good Luck,
Bob

[cyclestart]

If the current requirements are low and noise tolerance high, you might try copper rings on a plastic central support with spring steel wires pushing against either side of the ring.

Well that's the thing, my grasp of electricity is poor. I've learned the hard way what happens when power to the stepper motors is disrupted. Not sure if the spring/brush connection is going to cause problems as well.

Another automotive use of slip rings can be found in some steering columns for cruise or radio controls. I'm not ready to rip apart steering columns at the scrap yard, although I might if I knew which one is a likely donor

Good Luck

Thanks Bob, the luck will be needed.

[daedalus]

do you need infinite rotation, or just multiple turns? If its just multiple turns, a really cheap and easy way round this is to have a coiled cable. You can count rotations in electronics to limit overwinding.

[vger]

cyclestart,

I know where there are several rotary connectors (brand new) that I can probably get for very little ($20 or so). They have 12 leads with 4 wipers per lead. The leads look like about 14 guage wire. They are about 10 to 12 inches in diameter (running on memory) and about 8 inches thick.

Would these fit your need ? I'll try to get a pic today and post it....

Steve

[cyclestart]

Would these fit your need ? I'll try to get a pic today and post it....

$20 ?? Yes, I'm interested. 10x8 is large but there's plenty of room so not a problem. 14 gauge wire suggests it can easily handle the current..

[vger]

Finally got pics... Diameter is 9" and overall length (thickness) is 4 1/4" including the housing. There are 16 circuits and each wiper has 2 contacts riding on the slide rings. The wires are 16 guage all numbered A1 - A8 and B1 - B8. Insulation seems to be polyethelyne.

First pic is bottom (business end) showing the center flange that rotates continuously.

Second pic is top side with cover on.

Third pic is with cover removed.

These have never been used. And I was right about the $20 price. If you can handle an additional $5 for my trouble, and the shipping cost, I'll send you one.

Shoot me a private message...

Steve