donald gillies wrote:
> Re: (This is borderline on-topic, my apologies if it isn't) :
>
> http://ebay.com/
>
> in particular:
>
> http://img1.iwascoding.de/
>
> Is TREK the only company to make investment-cast (IC) head-tubes? Can
> someone comment on the quality (either the weight, or durability) of
> TREK IC head-tubes? Has anyone ever had a failure with one of these?
> How did TREK deal with the 'orange-peel' from the sand casting process?
>
> This innovation was developed in about 1983 or 1984. It saved a lot
> of time and cost in the manufacture of the lower-end TREKs, as no lugs
> had to be brazed onto the head tubes, and they probably didn't need to
> mitre the top or downtubes on these bikes. Any idea how many hours of
> work it saved in assembling a frame?
I don't have any figures on how mush time they saved, but the cast head lugs were implemented to facilitate Trek's short-lived induction brazing method of frame building, where instead of a flame, electromagnetic induction was used to heat the parts to brazing temperature. You are correct that the tubes were not mitered; instead they were straight-cut at a specific angle which mated with an internal shoulder in the socket.
They were heavy as sin, though, and I was not sorry to see them go. I never saw one fail (I was Trek's warranty inspector at the time these were being used). "Orange peel" was not an issue; the company responsible for the casting (Signicast in Milwaukee) did a very good job. They also did Trek's cast BB shells, seat lugs, fork crowns, and dropouts, as well as the internal lugs used on Trek's first aluminum frame bike. There was, as I recall, a coarse grind mark on the back of the head lug where the molten metal was introduced that needed a little polishing with a Dynafile, but that's about it.
--
John Thompson (john@os2.dhs.org)
Appleton WI USA