Phil Lee, Squid wrote:
> [email protected] wrote:
> > A cool 10 minute video clip showing how your basic errand bike is put
> > together, including seeing a wheel-building machine in action:
> >
> > http://www.youtube.com/watch?v=fQXxDMfpyuw
>
> Anyone know the process for making those handlebar bulges?
It's hard to tell, isn't it? It's at 4:30 to 4:55 or so in the video.
Bulging of tubes is often done by having a female die with space for
the bulge, then forcing the tube radially into the die by use of an
elastomer plug which is axially compressed. The elastomer applies
pressure to the inside of the tube, bulging it into the die. (Some is
done by using a liquid to apply that pressure, but that's not what this
looked like.) I think the yellow on the end of those steel rods is the
elastomer.
I was confused by the brightness of the yellow part, thinking at first
that it might be hot; but I now think it appears bright just because it
was brightly lit for the video. I note that the newly-formed bulges
appear cold.
Cool video! I plan to use this in class.
- Frank Krygowski
