Hello, rbt!

This cog is threaded 1 3/8-24 and was used to drive a generator at 50-100 W as
well as to hop the front fork.

I made two. The lot of two starts at $24.95, which is what I paid for one
spider and cog with nuts. Buy it now for $49.90.

Anyway, the relevance of this post is mostly in the description of the
manufacturing method, not completely discolsed in the auction listing.

I bought a steel spider with nuts and a chrome plated 44 tooth cog already
installed. It had a 110 mm bolt circle. My intent was to adjust the gear ratio
to match the generator output to my average forward speed, providing constant
power on level ground. This I did.

The spider had a 7/8 inch hole in the middle, and a 3/4 inch insert, which came
out easily. I used a Unibit to drill the spider to 1, 1 1/8, and 1 1/4 inches,
which was farly close to the required size for tapping 1 3/4 - 24. This size I
can't remember.

I went ahead with the tapping using a center point in the drill press to hold
the tap over the hole, restraining the cog with a screw in a pattern of jigging
holes in the drill press table. That pattern was drilled on 1 x 1 inch centers
and tapped M6x1 long ago, for use with a cross vise I still use.

I screwed a chrome plated hub into the spider and added a bottom bracket lock
ring, a black one, with the finish sanded down. I'd removed the adjacent spider
paint. I added a spacer of thin derailer cable wire (a single strand) when I
soldered, but the first time through I brazed it in an oven of fire bricks, and
set off my apartment ion detector. (Smoke alarm)

I forget actually how I aligned the threads or whether I soldered and brazed
with the rear hub in place. I really do.

I painted one spider and since the other was less damaged by soldering, left it
as it was.

That's about all.


Yours,
Doug Goncz ( ftp://users.aol.com/DGoncz/incoming )
Student member SAE for one year.
I love: Dona, Jeff, Kim, Mom, Neelix, Tasha, and Teri, alphabetically.
I drive: A double-step Thunderbolt with 657% range.