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[JasonBModerator @jasonb]

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 DaymanParticipant @jeffdayman43397]

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

[CirclipParticipant @circlip]

Just to illustrate the need for the “Outdated” systems Jeff, consider a slide valve adjusting nut tapped 7BA.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 DaymanParticipant @jeffdayman43397]

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 13Participant @davidclark13]

test

[Rob ManleyParticipant @robmanley79788]

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

[KWILParticipant @kwil]

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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