Re:Lathe threading

--- In CAD_CAM_EDM_DRO@egroups.com, ballendo@y... wrote:

> Terry, Thank you for the reply.
>
> So you never say so many threads per..
> Its always a 14x2 or 8x1.25 ?

We say Threads per inch or tpi when working imperial as you do from
your reply at the bottom.
When in metric we can't say tpi because there are no inches.
You are also correct in that we say 14 x 2 or 6 x 1
Usually though unless it's a special pitch we just say 14 mill or 6
mill.
As regards sizing the imperial ones we say what you originally said,
something like 3/16 x 24 as we don't use the numbered system here,
only UNF/UNC has this , we always use the bolt size.
To save a lot of head scratching we usually say the size and form,
like 1/4" BSF or 1/4 Whitworth.
One exception to this is BA where they still use the numbered system
but this is fast disapearing to be replaced by small metrics.

All new stuff over here is metric and I would say that in industry
today 90 percent is metric.
I do a lot of repair work and come across all sorts of threads even
the transition ones from imperial to metric where they changed a
shaft size to accept cheaper more popular metric bearings but still
screwcut an imperial thread as that's what the machines of the time
could do easily.
Wadkins the wood working people were very good at this 30 mm x 12 tpi
is not unusual for them.

What determines threads a lot is who owns the companies. During the
60's and 70's when a lot of the car and truck plants were US linked,
Chrysler, Ford, GM all our cars and trucks were UNF/UNC threaded.
Since these companies have become multi-national or let go of the UK
end like GM and Ford they have gone to metric.
With a lot of out imports coming from the far east, India, and the
EEC this has made metric the standard system.

>
> As a young man, I went proudly to the fastener counter at the
> industrial distributor and said, "I'd like some 3/16-24 bolts
> please." The man looked at me and said, "What!". A lot more nervous
> this time I repeated my request. He said, "Son, there's no such
> thing." I said,"Yes there is, I just measured them. They're 3/16
> diameter and 24 threads per inch." The gruffness of his face melted
> and he laughed for EVERYONE in the store to hear. "This poor guy
> doesn't know how to size up a screw!" Red-faced and ashamed, I
> started to leave in humiliation. Then he called out, "Hey wait!

What

> you want is 10-24 and we've got 'em". I went on to buy a LOT of
> fasteners from that store over the years and remember this story
> whenever someone asks me an "uneducated" question. We're all

learning.

>
> Ballendo