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chris stephens08/03/2010 12:42:03
1049 forum posts
1 photos
Hi Guys,
If one was going to be contentious and provoke a debate, sorry to those who don't like topic diversions, The beauty of the Whitworth systems and the copied, with variation, US system, is that it was designed by an engineer. The Metric system was 'designed' by a committee.  What is that old quip?  "A Camel is a Horse designed by a committee".  
 
To be even more contentious, look what happens when a committee is let loose on boiler testing standards. 
chriStephens 
chris stephens08/03/2010 12:51:10
1049 forum posts
1 photos
Hi Jason, 
better yet to look at the following pages
http://mdmetric.com/tech/thddat3.htm  
http://mdmetric.com/tech/thddat2.htm
chriStephens 
 
 
 
Jeff Dayman08/03/2010 13:13:15
2356 forum posts
47 photos
Does it really matter who invented what system or when?
 
Diverse threading systems are here and likely here to stay for the forseeable future.
 
Much easier to adapt and learn all the systems you can, and tool up as needed.
 
If you come across a drawing with a thread you don't have tooling for, look at the closest diameter and pitch ones you do have and substitute. Common sense really.
 
Much more productive to do that than worry/wring hands or try and start arguments on obscure hobby websites.
chris stephens08/03/2010 13:31:35
1049 forum posts
1 photos
Hi Jeff,
I think you are missing the point slightly. It does not matter who invented whatever system. What does matter is that Mr W. tested various pitches in materials to find ones that stood up best to the job in hand. 
Reasoned debate can provoke knowledge in those new to a subject, or would you disagree?
chriStephens 
JasonB08/03/2010 13:41:46
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25215 forum posts
3105 photos
1 articles
Chris I did say to terry my link would give an "idea of whats available" not the full possibilities that he may not readily be able to get taps & dies for and its not me who wanted to know, maybe your post should have been addressed to terryD, I just gave him a guide as no one else had answered his question.
 
Now can anyone answer mine re the spark plugs?
 
J
Jeff Dayman08/03/2010 14:01:55
2356 forum posts
47 photos
Christephens-
 
Not opposed to reasoned debate at all, but suggest you start a new thread if you want to digress away from thread topic, which is special fine threads on model drawings.
 
Personally I don't care about Whit and early threading history. I am making stuff in the here and now.

Edited By David Clark 1 on 08/03/2010 20:58:26

Circlip08/03/2010 14:49:52
1723 forum posts
Just to illustrate the need for the "Outdated" systems Jeff, consider a slide valve adjusting nut tapped 7BA. What Metric equivalent are you going to replace it with.??
 
  Regards  Ian.
Jeff Dayman08/03/2010 15:33:02
2356 forum posts
47 photos
For the record I am NOT a lover of any particular thread system, or metric, I use what is to hand for models. Professionally I use what is specified if working to others drawings, or what system the client requires for new designs. If I were to put BA thread callouts on new part/product drawings I would expect a big fuss from toolmakers both in Canada/USA and the far east however, so I never do.
 
#2-56 UNC is close to 7BA dia and pitch although a little low on OD ad finer than 7BA, but I do have changewheels taps and dies for it. This would be my first preferred equivalent is making a model that had 7BA specified.
 
#3-56 UNF is also close, but a little larger OD and I don't have taps and dies for it. (although I could get them at low cost from any industrial supply house)
 
finally there is always M2.5 x .45 ANSI coarse metric per B1.13-1983 which is a very close match, but I don't have any taps or dies for it. (I could get probably get them at  an industrial supply house but they will likely ask "what the hell's that for?")
 
All of the above threads can be cut with 60 degree flank single point tools.
 
I have no tooling for 47.5 degree BA threads and get by fine by substituting by comparison as above.
David Clark 108/03/2010 18:29:54
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3357 forum posts
112 photos
10 articles
test
Rob Manley08/03/2010 18:51:39
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71 forum posts
14 photos
I have learnt allot by this thread regarding the UNF system I never would have normally and although it has digressed slightly from the original topic is still relevant.  The whole point of these threads is to provoke discussion for the spread of knowledge surely and everyone has their own views, there is no need to defend your corner to the death.
 
There is no ultimate thread system within the model engineering world.  I do not think I have ever used UNF on a model I have made but if the right situation called for it, why not.  Plus, these are only guidelines as if everyone followed the drawing to the nail there would something wouldn't fit.  In industry it probably matters and a conversion to a wider-used system would be a idea, but as most of our tools are second hand from the 50's-60's.....etc. I doubt it matters very much at all.
 
 Robx32

Edited By David Clark 1 on 08/03/2010 21:00:16

KWIL08/03/2010 19:13:44
3681 forum posts
70 photos
Poor spelling and dialect I can accept but bad language, even in quotes should earn a period of loss of access. Other Forums do this. DC to act?
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