[TheForge] Nuts

Fri Dec 12 11:59:01 2003

Square threads and acme threads are often mistaken for each other as 
well. Square threads do have a propensity to seize as I recall.  Acme 
threads were developed to lessen the chance of seizing.  Many jacks and 
vises will use a square thread since they are slightly stronger than an 
Acme thread (also as I recall).

Charles

Dan Tull wrote:

>"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" <[email protected]>
>To: <[email protected]>
>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
>>    
>>
>
>
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