Is SW a drafting program? - Projections

Here is a list of the various classifications of projections per
Bertoline and whether SW can produce them:

Parallel Projection

Orthographic:

Multiview: SW- yes SE- yes
Axonometric
Isometric SW- yes SE- yes
Long Isometric SW-no SE- no
Dimetric SW- yes* SE- yes*
Trimetric SW- yes* SE-yes*
* Both dimetric and trimetric allow variation in some or all angles.
The software does not allow control of this directly.
NOTE: SE allows several isometric options that SW does not have.

Oblique
Cabinet SW-no SE-no
Cavalier SW-no SE-no
General SW-no SE-no
Note: oblique projections were quite common throughout the mechanical
engineering community till CAD became popular. Still used in some
special niches.

============================
Perspective or Central Projection

Linear Perspective
One Point SW-wa SE-wa
Two Point SW-no SE-no
Three Point SW-no SE-no
wa=workaround. A view must be prepared in the part and shown in the
drawing
NOTE: Neither program allows adjustment of the viewpoint(s).

Aerial Perspective SW-wa SE-unknown
wa=workaround Render in PhotoShop with depth effects on one point
perspective. Import image into drawing.

 

Quite often I've had a need to display views that are not easily
available, eg. isometric view of the underside of a part. The only way
I've been able to do this is to update the standard views, to rotate
the part to the correct viewing angle that I want, then create a new
view, and reset the standard views. This is a real pain, and still
does not give me exactly what I want. Maybe there is a macro or add-in
to rotate the triad by degree to obtain the correct view? I'm not very
good with this stuff, but I have noticed that the cursors can be used
to rotate a model by set increments. I'm not sure how large they are,
I think its 15deg.

I think it's becoming obvious that most designers are not drafters, and
they seem to be the push behind CAD development. For myself it has
been years since I used a drawing board, and in some technical colleges
in Australia, they don't teach any manual drafting anymore. Many of
the fundamentals of drafting are not being passed on to future
generations in our schools.

 

Your view orientation settings will allow you to set the increment by which
you rotate with the arrow keys. (default is 15 deg)

With SW2006 and Camera Views you can create anything that can be viewed by
your naked eye. Unfortunately older drafting views were created to show
more information in an easy to create view than is "naked eye" possible.

Photoshop and SolidWorks together can create all the requested views,
however with the ability to "spam" a drawing with 3D views this has become
less of an issue.

Cadguru

 

I'd be curious to know what the common standard is in Australia for
drawings. I am of couse being US-centric simply because that is the way
I have to work most of the time.

As I noted, dimetric and trimetric views cannot be set exactly. Of the
axonometric views, isometric leaves only one choice for orienting the
part. Rotate the part 45 degrees about the vertical axis and then tip
it forward 35 deg 16 minutes. This results in a unit cube having
external edges that make a regular hexagon. A dimetric view is created
by using a tip angle of anything but 35 deg 16 minutes. And a trimetric
view also varies the 45 degrees rotation. It is not clear just what
those other angles are for di & trimetric in SW.

Given the above information, a configuration can be created which two
body move features to give a precise rotation of any part into whatever
axonometric orientation is needed. Thus, a rotation of 45 degrees about
the x axis and then tipping the part forward 35 degrees 16 minutes
would give a long isometric projection when viewed from the front.

 

As a rule, we use ISO standards, Third Angle Projection and Isometric.
However, the company I work for has been purchased by a US firm, so we
are producing some drawings to ASME standards - I think. We are
finding that drawings don't seem to follow any particular standard, and
it relies on the discretion of the team producing our Internal CAD
standard. They approve the format of our drawings, and we follow that
format. A comparison of the ISO or ASME standards with our drawings
would show that many items do not follow either standard particularly
well. This isn't a big problem, as we've found that most of our
suppliers will prepare thier own drawings anyway. It seems that most
companies -small ones at least- here decide what suits them without too
much regard for international standards. Only the schools and colleges
seem to be the ones concerned with getting things correct, and large
companies.

 

Australia and New Zealand use Australian drawing Standards. 3rd Angle
projection metric measurement.

AS 1100.101-1992 TECHNICAL DRAWING PART 101: GENERAL PRINCIPLES
&
AS 1100.201-1992 TECHNICAL DRAWING PART 201: MECHANICAL ENGINEERING DRAWING.

These standards are in compliance with a number of ISO standards.

Most small companies tend to loosely follow the standards, as is the
case for most of the companies I work for. Geometric tolerancing is used
sparingly as a lot of smaller suppliers charge more as soon as they see
them!

I have just completed a job that required drawings to ASME Y14.5M for a
supplier to the North American Military. The biggest pain on this job
was they also required dual dimensions as the product was designed with
mm in mind. Dual dimensions don't really work that well especially with
general drawing block tolerances which is what the client wanted
(rounding errors being the main issue). Geometric tolerancing was also
required, this didn't appear to vary significantly from the ISO standard.

If that ASME job hadn't required me to sign a NDA, I would have asked
and paid someone on here to red-line the drawings for me just for my own
piece of mind. I hadn't had to think about rigorously following
standards since it was required for me to pass exams.


John Layne
www.solidengineering.co.nz

 

TOP,

You mentioned Bertoline, which I assume is referring to the text "
Fundamentals of Graphics Communication and Technical Graphics Communication
".

Is this a good reference for such drawing standards? I'm looking for a
good one to use.

Thanks, -Pat

 

It's a textbook. As such it has parts of standards. For the standards
themselves go to ANSI, ASME or ISO depending on what you need. What
Bertoline does in the book is be thorough and explain. It I became
apparent that there were alot of little things missed or glossed over
in a lot of the CAD packages. There were also some big things like
being able to do all the various projections.

 

Thanks. I'm looking for good, practical text that will gives a clear
explanation of the different types of drawings and the proper way to prepare
them. Bertolines text looked like a good possibility as one by Helsel, et
al, "Engineering Drawing and Design". So I'll probably take a look at both.

Thanks again, -Pat