[TheForge] Nuts

[Dan Tull]

"ask an engineer what time it is , and he will tell you how to build a
watch"....but,

a good answer.  I couldn't figure out why they said it would bind ( as I had
no problem w/ it ),
but they seemed to know what they were talking about,, is why I asked the
question.
Now we know they had different tolerance threads.
Thanks Dave.

dan tull
georgia
abba, afc, S.C. psba, obg,sofa
----- Original Message ----- 
From: "David E. Smucker" <davesmucker@hotmail.com>
To: <theforge@mailman.qth.net>
Sent: Friday, December 12, 2003 11:14 AM
Subject: Re: [TheForge] Nuts


> Ralph makes a really good point -- and may bring us to understand the
> jamming problem Dan Tull talked about.  There are two classes of ACME
> treads -- General Purpose and Centralizing.  Each class having a series of
> tolerance divisions that set the fit of nut to thread.  For General
Purpose
> common use includes 2G, 3G and 4G -- with 2G being the preferred choice
(it
> has the most clearance) while 3G and 4G have less backlash in each case.
>
> Likewise the Centralizing class has a series of tolerance that are in
common
> use 2C, 3C and 4C.  What is centralizing?  In the centralizing form the
flat
> crest of the tread is design such that it will hit the flat root of the
> thread before both tapered sides of the thread will mate and prevent
wedging
> of the taper sides of the thread -- which could result in jamming.  In
other
> words the major diameter of the tread insure that only one taper face of
the
> tread can be in contact.  All of the power treads I work with in jacks,
> mills etc where of the centralizing type.
>
> You can find detailed information on this in Machinery's Handbook, just
look
> under ACME threads.
>
> I have no idea if Dave Brown's ACME thread are General Purpose or
> Centralizing -- might make a difference in how they would work in a vise,
> clamps etc.
>
> Dave Smucker