[modeleng] Re: unknown thread
- From: "Tim Rickard" <the_viffer@xxxxxxxxxxx>
- To: modeleng@xxxxxxxxxxxxx
- Date: Fri, 15 Oct 2004 09:35:39 +0000
Peter the BA thread s a totally metric thread. There is a mathematical
relationship involving non integer powers that lets you calculate the
dimensions of any BA thread starting from 0BA which is 6mm diameter and as I
recall 1mm pitch. There are details in Tubal Cain's Workshop Handbook but
I'm glad to copy it out and either post it here or sent it to individuals if
there is any demand. I dread to think how they set up a lathe to cut them
the first time.
There was some sympathy in parts of Victorian Britain for both metrication
such as the BA thread and for decimalisation eg the florin aka two shilling,
1/10 pound or as we now know it 10p which was introduced in Victorian days
for just that purpose.
>From: peter.chadwick@xxxxxxxxxxx
>
> >in accordance with our Imperialist traditions we
> >stole the Thury thread off the French Swiss
>Could well be - the BA is basically a metric thread - the BS with its
>dimensions in imperial was relatively recent, I believe early 1950s - my
>1927 Machinery's Handbook (I'm much too mean to buy a newer copy!) has its
>dimensions in metric.
>
>Peter Chadwick
>
>MODEL ENGINEERING DISCUSSION LIST.
>
>
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