Re: [CR]British bike building techniques


Example: Humor

Date: Mon, 21 May 2001 17:47:14 +0100
Subject: Re: [CR]British bike building techniques
From: "Hilary Stone" <Hilary.Stone@Tesco.net>
To: dave bohm <davebohm@home.com>, OROBOYZ@aol.com, Classicrendezvous@bikelist.org


Yes Mercian still use open hearth brazing as do Whitcomb. Pashley also use it on their roadster models and on their traditional Post Office bikes which are soon to be superseded by a new model. Open hearth brazing was the only method practiced by British framebuilders for many years both large and small. Very few used anything else in pre-war days. With the open hearth method torches were still used but almost always fired with coal gas ­ these days Natural gas would be the equivalent though I think both Mercian and Whitcomb actually now use oxy-acetylene. I don't think there's reducing effect in the open hearth methgod.

Regards Hilary Stone

----------

>From: "dave bohm" <davebohm@home.com>

>To: <OROBOYZ@aol.com>, <Classicrendezvous@bikelist.org>

>Subject: Re: [CR]British bike building techniques

>Date: Mon, May 21, 2001, 4:36 pm

>


>

> That also raises the question in my mind if anyone still uses the open
hearth

> "coal gas" method? Is it correct tom assume that the open hearth method was

> used by larger concerns doing higher production, and that the small, one man

> or so shops used hand held torchs? I have heard that Mercian is the last

> practitioner of the open hearth approach. Anyone know if that is still the

> case?

>

>

> Just some observations for the few interested, I looked up "Coal Gas"

> here is a link:

> http://www.zetatalk.com/energy/tengy11a.htm

>

> looks like its a hydrogen/oxygen mix. This has relatively low heating

> potential compared to oxy/acetylene which must necessitate the fire brick

> hearth to retain heat.

>

> One more interesting thing, at least to me is that often, when brazing

> silver or gold a brick of charcoal can be used to position the piece. This

> charcoal produces a reducing atmosphere during brazing, reducing the need

> for flux and or giving a better result. Might the charcoal fire hearth

> technique accomplished a similar thing?

>

> Dave Bohm

> Bohemian