Re: Mead screws

From: dwight elvey (dkelvey_at_hotmail.com)
Date: 07/30/04 

Date: 30 Jul 2004 16:13:17 -0700

"Roger Hamlett" <rogerspamignored@ttelmah.demon.co.uk> wrote in message news:<mRuOc.642$9b6.240@newsfe5-gui.ntli.net>...
> "Doug McDonald" <mcdonald@scs.uiuc.edu> wrote in message
> news:cedmd0$t4r$1@news.ks.uiuc.edu...
> > Chris L Peterson wrote:
> >
> > > On Fri, 30 Jul 2004 14:53:42 GMT, "Roger Hamlett"
> > > <rogerspamignored@ttelmah.demon.co.uk> wrote:
> > >
> > >
> > >>Actually, you can get 4-32, it is a special coarse thread for alloy. I
> > >>have the taps and dies for it here. However I think you are right that
> the
> > >>#4's on the back of the OTA bracket are -40. The others on the OTA,
> are
> > >>all -32. I just remmbered the Meade small screws as all being -32, and
> > >>extended this, one screw too small. :-)
> > >
> > >
> > > Of course, this all has to be terribly confusing to somebody used to
> the much
> > > more rational metric thread system.
> > >
> >
> >
> > It's not confusing at all. The problem with the
> > metric screws is that they are rather limited in variety.
> The 'joke', is that I am in a country that uses metric screws, and for
> quite a few projects, have ended up having to get 'custom' dies for
> exactly this reason. The customers 'want' the parts to be metric. Even
> with the old imperial threads, though in parts some ranges 'overlapped',
> the reason in many cases for the large number of types, was that
> materials, and circumstances do differ.
> Metric threads are fine for 'standard' applications.
> I must admit, it gets 'wearing' though, when trying to match a thread on
> an old piece of equipment, and finding it is something that doesn't exist
> in any book, have to hand make the taps....
>
> Best Wishes

Hi
 For anyone that actually has to structurally engineer
something, fractional size hardware makes sense. Metric
makes sense to bean counters. Anyway, I don't recall any
metric hardware on my SCT by Meade.
Dwight