Shoddy Hardware (Was: Re: WW fixtures (was Re: "New" PDP-8))

From: Merle K. Peirce <at258_at_osfn.org>
Date: Sat Apr 6 07:00:41 2002

Thank you Peter, it was the pitch that interested me. I once used an
Acme threaded spring hanger for a writing assignment. While it sounds
very simple, describing one of the little buggers makes you stop and think.

On Sat, 6 Apr 2002, Pete Turnbull wrote:

> On Apr 5, 19:54, Merle K. Peirce wrote:
> > Peter, could you address how Acme threads fit into these schemes? I
> > should expect that they are always relatively coarse.
>
> In a sense, they don't. They're not normally used for fasteners, which is
> what the others are for (arguably with the exception of BSP) :-)
>
> Yes, they're usually fairly coarse, and used for things like leadscrews on
> machine tools and vise jaws. For leadscrews, they're usually made to some
> specific pitch that equates to some nice decimal number of turns per inch,
> or millimetres per turn. They're also unusual in having large flats on
> both the crests and troughs (most other threads are rounded on one or the
> other); in fact they're almost square -- the thread depth is 0.5 x the
> pitch, and the walls slope at only 14.5 degrees, so the included angle is
> 29 degree, much less than most threads which are typically either 55 or 60
> degrees. And the clearance between screw and nut is very small, typically
> 0.001".
>
> --
> Pete Peter Turnbull
> Network Manager
> University of York
>

M. K. Peirce

Rhode Island Computer Museum, Inc.
Shady Lea, Rhode Island

"Casta est quam nemo rogavit."
              
              - Ovid
Received on Sat Apr 06 2002 - 07:00:41 BST