Re: [CAD_CAM_EDM_DRO] First angle and Third angle

----- Original Message -----
From: "Peter Chen" <cadcamcenter@...>
>
> How about creating new metric standard for use or
> ornament? Regarding older machineries, isn't that the
> reason those stubborn Americans are still sticking to
> their Imperial inches and gallons. Don't we have to
> start somewhere, sometime, or do we still continue
> postponing the inevitable and prolong the pain (the

What is the point of creating yet more 'standards' when perfectly good ones
exist already? It will only add to the confusion as metric threads have. If
you look back at the history of screw threads you will see that each one was
designed very carefully for specific jobs and great thought was put into
working out the strongest thread angle and tapping forces for different
types of material. OK, in those days they didn't have the stong tool steels
we have today and so they had to design things to be kind to their tools as
well as doing the job efficiently - now we just seem to have reverted to a
mindset of using brute force and ignorance to achieve our goals, that's if
we can't just program a machine and set it going to do the job while we go
off and have our lunch. The biggest problem though is that, when
standardization is allowed to take over, the jobs that do require anything
non-standard become much more difficult. Coincidentally, I have just had an
email from the senior engineer at Sodastream asking me if I could help him
identify the thread on the C02 bottles they use in their machines - its
something like 7/16" British Standard Brass. This reminded me about the BSB
threads - all 19 t.p.i. so that you can screw a spacer nipple into a big
hole and onto a small pipe both at the same time - try doing that with
metric threads!!

Ian

p.s. My description of the dice was not a typo, perhaps not described
clearly enough. What I intended to say was that side which is uppermost as
you look down on the dice would be the front. Roll the dice to the right
and, looking down, you get the left side view positioned to the right of the
front etc.

--
Ian W. Wright
Sheffield UK
www.iw63.freeserve.co.uk