Building a carbon brush/slip-ring assembly for internal tail light wiring

[jclay]

I wanted to create a head tube slip-ring brush assembly, to support internal wiring to the tail light, that could be fabricated by framebuilders having minimal tooling at their disposal. I wrote an article that documents my efforts so that others can accomplish the same results without having to re-plow the same field, or at least as much of it.

It's long and detailed but hopefully worthwhile for those who want to attempt building the device. Since uploading it here didn't work, you can download it from here:

https://groups.google.com/forum/#!to...rs/Q9DxcVCtYgs

[Dmoeny]

that was most excellent! thanks for documenting how you worked it out.

dave

[jclay]

that was most excellent! thanks for documenting how you worked it out.

dave

Happy to do it Dave. Please post pictures and details if you attempt it. I'd be interested in any improvements that others come up with.

[false_aesthetic]

Wow! Thanks so much.

That's super, dooper, rad!

[EricKeller]

if anyone stumbles upon the Hirose youtube video where he makes his version of this, it would be really nice if you would post the link

[Alistair]

if anyone stumbles upon the Hirose youtube video where he makes his version of this, it would be really nice if you would post the link

Here's a video that shows at least one part of the puzzle,

Alistair.

[Ben Hudson]

John, thanks again for a comprehensive guide. I’ve considered the Herse method before but found it too intimidating, and this looks a lot more doable. I assume you use a taillight that grounds to the frame so only one wire has to go via the brush - any issues conducting ground through the headset?

As usual, Hirose’s videos are a goldmine of process information, though a bit more like a haystack for non-Japanese speakers ;) I had a quick look for the coil wrapping video as I’m particularly interested in that bit, but no luck so far.

[EricKeller]

Here's a video that shows at least one part of the puzzle,

Alistair.

thanks, that series skips right over the wiring. How the .... does he get the wire from the seat stay to the downtube? And now I want to make a derailleur. I saw in another build he puts the wiper in the steerer on some bikes.

[duanedr]

I saw in one that he uses a vacuum. He ties a very light thread to the end of the wire, feeds it into the hole at one of the journey and then applies the vacuum to the exit hole of the journey. then it's simply a matter of pulling the wire through. I'm guessing there are a few key considerations like:
- feed in from the small tube to the big tube (or vice versa, I forget which he did in the video I am describing - EDIT: it was a front rack)
- plug off all holes in between,
- have enough of the light thread to reach the full distance
- etc. etc.

Those videos are such an amazing resource. I have spent too much time watching them. Ok, i had to go find it to watch it again. Here's the video:

[EricKeller]

I was trying to figure out what the route was, mostly. I suppose there may be some places where it goes outside the frame.

One of the things that impresses me is that he's not afraid to make anything. e.g. water bottle bosses. Didn't figure out why he didn't just use regular water bottle bosses.

[jclay]

John, thanks again for a comprehensive guide. I’ve considered the Herse method before but found it too intimidating, and this looks a lot more doable. I assume you use a taillight that grounds to the frame so only one wire has to go via the brush - any issues conducting ground through the headset?

As usual, Hirose’s videos are a goldmine of process information, though a bit more like a haystack for non-Japanese speakers ;) I had a quick look for the coil wrapping video as I’m particularly interested in that bit, but no luck so far.

Ben,

You are welcome! One of the things I discovered is that both are conceptually very simple but the devil really is in the details; and the lack of a lathe makes it more-so. That said, from my perspective the Herse method does look a bit more difficult in terms of getting the ring just right. Jan has experience with it, and I don't, but I think you'd want it to be the same ID as that of the lower cup race spigot ID, and snugged as close as possible together while still being insulated; that to prevent the gap from breaking or catching the carbon brush. If somebody engineered and made the part then that hurdle disappears. Jan mentioned to me that model trains use conveniently sized brushes; I hadn't thought of it.

Presumably forks treated with the Herse method haven't failed at the brush hole in the steerer but I feel more comfortable with the smaller hole of the Hirose method and with locating it on the neutral axis (with respect to normal fore/aft stresses) of the steerer.

Making the ring as I did, while fiddly, is absolutely do-able by any careful crafts-person with only a modest tool selection. The brush becomes the sticky wicket but someone is going to discover a way to make it with off the shelf parts and zero machining. I haven't pursued that aspect any further, aside from the general ideas presented in the article. But someone will discover the exact parts to make it happen. The whole assembly will then become feasible for a lot of people who build perfectly good frames but don't have machine tools and I think that will be pretty neat. The democratisation of bicycle slip ring assemblies, I guess.

BTW: I'm selling some framebuilding stuff and vintage bicycle components in the VS classifieds, if anyone is interested.

Best,

[duanedr]

One of the things that impresses me is that he's not afraid to make anything.

Agreed! In one, he makes a chainring spider. is there not a crank out there that has the exact chainrings he wants?! I can only guess the customer wants 'the full monty'. The videos make it look so effortless...

[jclay]

I finished painting the frame and started installing the power wire pull strings.

Brass brush at the DT/HT joint to the tail light boss is easy.
Front DO to the mid-fork exit hole is being fiddly but it will work out in the end.
Into and out of the right rack strut was easy.
The real bear will be coaxing the tail light lead through the crown.

What my preliminary messing around with this has taught me, particularly with the crown portion, is that I'd rather spend time installing conduit for all of the routing in the fork rather than wrestling with string, compressed air and vacuums in an effort to snake the pull strings in. And maybe have the wire exit the fork reinforcing tang rather than routing it through the crown shoulder and into the steerer ID. That's tricky business.

Photo of how the partially assembled frame looks: Flickr

[Ben Hudson]

Here's a video that shows at least one part of the puzzle,

Alistair.

I had high hopes that the semi-mythical wire-winding video would be in this series ('Production of a touring bike'), but I don't think it is. In video 93 (塗装に出す準備 - 'Preparation for paint') he stamps the unpainted fork steerer without any wrapping, and then we never see it again unassembled before the final video 110.


Tantalisingly, from 3.36 in video 6 where he is finishing brazing the fork ( ) we're shown the caption 'Wiring design and ingenuity will be introduced again after the whole system is completed'. And that's the last we hear of it, unless it's tucked away in a different video. The fork steerer has an enormous hole, which is odd since the video linked by Alistair shows him doing the brush assembly the inside-outy way with the brush in the DT, so the hole in the steerer need only be big enough for a wire; as opposed to the Herse way with a big hole in the steerer for the brush to go there.

I got excited by the subseries ダイナモ起倒装置 ('Dynamo lifting device') but this only covers making the parts to remotely raise and lower the bottle dynamo.

I've been giving this a lot of thought and I think I have reached a method that requires no machining and even has the potential to be retrofitted. Normally I'd head right to my lathe and start making chips but taking it all to bits for a rebuild has been a productive creative constraint, forcing me to use off the shelf parts. There are a few inductive leaps in the theory so I'm going to actually try it out for real before I say any more.