help ID bicycle spoke threads?

Woops, I meant 22 or 23 threads per 10mm, sorry ..

"I've got this silly idea for a design using bicycle spokes. I can't measure this thread and I don't know metric threads very well at all. I do have a real cheapo shadowgraph style optical comparator, and was able to get what I believe is a usable picture. The scale shown is millimeters, and it appears there are either 20 or 21 threads per 10mm, don't know which to count as #1. The spoke threads mic at .078" which is real close to 2mm. Not that I have a die this size, but can anyone ID this thread and explain how to do it?"

See the image:

Grant Erwin Kirkland, Washington

2-56

You want a thread roller. I suspect you have a 2mmX.5 thread. You can not effectively cut threads that small on a wire spoke, but a rolled thread is simple, and a lot stronger. A good motorcycle shop should be able to do the job for you - sounds a bit heavier than the standard bicycle spoke.

I would guess 56 tpi. Your shadowgraph picture supports that, and it is a standard spoke thread.

Note that spoke threads are rolled rather than cut; the threaded diameter is larger than the unthreaded body diameter.

Bingo! Should have thought of that. I did in fact have a 2-56 die, and I was able to extend the thread like I needed to. Wow, that was quick.

Some time ago I saw a design for a tool to center a punchmarked piece in the

4-jaw on a lathe. The guy made a shank which clamped a piece of rubber sheet vertically in his toolpost, exposed on both sides. There was a tiny hole in the sheet and through this he inserted a bicycle spoke with a spoke nipple threaded way on, flange towards the rubber. Then another spoke nipple threaded onto the end sticking through the rubber, and another spoke threaded into the second nipple. The effect was to suspend two spokes roughly in alignment with the lathe axis, mounted on a rubber sheet. He cut down the spoke towards the headstock to about 1", and sharpened it, and the other spoke he cut off at about 10", and he sharpened it too. To use it, you catch the short end in your punchmark, spin the lathe, and adjust your 4-jaw until the far end ran true, pointing right at a center in the tailstock. There's a 10-1 magnification factor. Sounded real easy to make, but I never knew anything about bicycle spokes. Until today, that is. It's a piece of cake to thread 2 spokes and 2 spoke nipples together so the flanges meet, and it would be real easy to tighten this over a piece of innertube about the size of a postage stamp.

I'm going to make this, and I'll post pix when I'm done. Might be soon, might be

5 years from now (my queue is l-o-o-o-n-g) but I'll get to it, hopefully before I need it.

Toughest part's going to be straightening the spokes, which aren't particularly straight.

Anyone remember the exact source for this design? I'm sure it was either HSM or PIM but I can't find it.

GWE

These were more common when I was younger, but "tailor made" ones are still available new:

But if it was me, I'd also make my own and save 30 bux plus shipping. More fun and satisfaction that way, and little chance of screwing it up. :-)

Jeff

Wouldn't it be easier to use (and maybe to make) if you drilled out a block sized to fit in your toolpost, and glued the wiggler (centered) inside the hole with a little RTV silicone?

You don't need heaps of flexibility, since the wiggler ordinarily wouldn't make excursions of more than a couple of degrees. The mounting system would be conducive to quick setup and teardown, and could be adjusted to near-center easily and quickly with no more tools than it takes to mount a cutting tool.

LLoyd

2-56 has a nominal diameter of 0.086" (0.060+2x0.013).

Ted

Cycle threads are rolled; the unthreaded spoke diameter could well be .078.

My spokes have a rolled thread. They are 2mm x 56 tpi which is a hybrid thread, but I was able to use a 2-56 die to increase the thread length on one spoke which was all I needed to do.

GWE