I vaguely recall seeing a project somewhere that drew on a wall with an=20
ink jet cartridge suspended by two cables.
Once upon a time I considered a plotter that was a small car that ran=20
around the paper raising and lowering a pen to produce the drawing.=20
Think Turtle Graphics.
I have not ruled out an XY mechanism for my PCB drill project that=20
implements two, crossed 1/4-20 lead screws (0.05 inches per rev) from=20
the hardware store.

On 5/21/2013 4:03 AM, alan.b.pearce@stfc.ac.uk wrote:
>> But, to get back on topic, my curiosity is piqued about why so many stud=
ents would
>> more readily choose an LCD over a motor.
>> The answer might or might not be as obvious as I think
> The problem is that anything to do with motors requires a reasonable amou=
nt of mechanics to do something useful, which is probably beyond time and a=
vailable effort in a classroom.
>
> If you could provide the basics of an X-Y mechanism that could hold a pen=
 (I am thinking ordinary ballpoint or pencil here), along with some means o=
f raising/lowering the pen, then the classroom project becomes a programmin=
g one instead of a mechanical one, which is probably a lot more do-able. Yo=
u would need to provide some failsafe drive electronics for the motors, so =
that incorrect programming doesn't pop the drive transistors.
>
> Then I suspect you would get some interest in using motors.

--=20
John Ferrell W8CCW
That which can be destroyed by the truth should be.
P.C. HODGELL
  =20


--=20
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