Graham. wrote:

On Sat, 11 Aug 2012 17:02:25 +0100, (Steve Firth)
wrote:


http://www.youtube.com/watch?v=IEoOrWaMH9M&NR=1

The graphic has two identical and impossible Möbius loops intended to
illustrate two different motions.

It was actually difficult to pick the mistakes or to prioritise them. As
you say the diagram is impossible, if it's just taken as oscillating
backwads and forwards as I suspect it was intended to be, it's still
wrong that's not the motion of an orbital sander which is, as the name
suggests, orbital and the motion of any point on the surface of the
sanding sheet moves in an orbit (epicycle and deferent) like this:

http://upload.wikimedia.org/wikipedi...le_et_deferent.
png

Then there's mixing electricity and water in a rather unsafe manner and
the fact that he doesn't seem to have noticed that the orbital sander is
one of those with a vaccuum extract that uses the cooling fan on the
motor to suck air through holes in the sanding sheet. Fortunately for
him the sheet he is using doesn't have holes but if it developed one I
suspect the end result would be "crispy Italian". I'm sure that there
are many other mistakes in that very short video clip.