19th  February 2012
Revision
ISOMETRIC DRAWINGS
Views use 30 degrees for lines showing
 ‘horizontals’ of the object:

This is the most widely used drawing convention and you should be very confident that you know what the term Isometricmeans.  
It can sometimes be seen described as a ‘pictorial’ view.     Examination questions asking for a ‘pictorial view’ mean an ‘isometric
This convention can be exceptionally useful as the drawing is ‘built-up’ from an actual plan.  If a ground floor map of a room is completed and all the walls are shown as flat panels – vertical to the first ‘view’ – then a PLANOMETRIC view has been started.  One big advantage of this drawing style is that all circles still appear as circles on the finished sketch,
~ Isometric, Planometric & Axonometric ~
Isometric Projection
X-axis  ~ 30 degrees to the horizontal
Y-axis  ~ 30 degrees to the horizontal
Z- axis ~ vertical
The same scale is used on all three axes
PLANOMETRIC DRAWINGS
Planometric

X-axis ~30 degrees to the horizontal
Y-axis ~ 60 degrees to the horizontal
Z- axis ~ vertical
The same scale is used on all three axes
This small line illustration should show  how a ‘plan-view’ becomes an  axonometric or a planometric  dependent on the angle used to  represent the horizontal lines.    
Axonometric
(45 degree angle)
Planometric
              (60/30 degree angles)
Check out the DESIGN-CYCLE section
http://en.wikipedia.org/wiki/Axonometric_projection
2 - Design & Technology On The Web - Orthographic Drawings - 1st and 3rd angle drawings explained
4 - Design & Technology On The Web - 1 point, 2-point and 3-point Perspective Drawings - Mr Richmond Help - DTOTW - DTOTW Bill
2 - Design & Technology On The Web - Orthographic Drawings - 1st and 3rd angle drawings explained
4 - Design & Technology On The Web - 1 point, 2-point and 3-point Perspective Drawings - Mr Richmond Help - DTOTW - DTOTW Bill
IF IN DOUBT ASK !
 whereas on an isometric they will appear squashed.  If measurements need to be taken straight from the drawing, it is obviously easier as you can simply measure everything on the paper and then use the scale.
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