Re: [CAD_CAM_EDM_DRO] First angle & third angle

Hi Peter,

I'm not sure that the fact that one flavour of CAD program does a thing one
way is a good enough reason to abolish all others. I agree that different
drawing systems can lead to confusion if the recipient isn't awake enough to
work out what he is seeing but, without the ability to tailor systems to
suit a particular job, life CAN become quite difficult. This is illustrated
very clearly over here (UK) where screw threads have become 'standardised'
to metric. This is supposedly to make life easier (I can only assume for the
screw stockists and manufacturers!) but what it means for engineers is that
it is now becoming almost impossible to get screws with particular
properties - no coarse Whitworth threads for soft stuff or BSF fine threads
for hard stuff - all you can get is the one 'average' metric thread which is
neither use nor ornament. Imagine the fun trying to get bolts to replace
those in older machinery.
If I had to go with any one drawing projection system I would probably
choose First Angle as I can find it easier to imagine and teach others. For
instance, get a dice, lay it on the table and look down on it. Take a
photograph. Now roll it onto its right side and take another photo,
similarly onto its left side and top. Now merge the photos by directly
overlaying them and what do you have? First angle projections. Simple 'aint
it?

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

----- Original Message -----
From: "Peter Chen" <cadcamcenter@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: 24 March 2001 03:42
Subject: [CAD_CAM_EDM_DRO] First angle & third angle


> Good afternoon :-)
>
> John Stevenson" machines@... wrote:
> I have seen too many mixture of 1st and 3rd angles
> in orthographic projections!!! IMO, 1st angle should
> be abolished. Why?
>
> 1. cause unneccessary confusion
> 2. easier to explain how to get an isometric
> given the orthographic projection in 3rd. angle
> 3. in autocad (what about other CAD's?) one can
> automatically generate views by clicking on
> the side required. For example, if we have a
> front view, clicking on the top will generate