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Quoting Vik Olliver <[log in to unmask]>:


> Fair enough. While sitting outside on the back porch with a glass of
> brandy in hand, listening to the post-Easter Egg Hunt chaos, I started
> thinking about moulding processes and began experimenting with some HDPE
> and PET bottles lying around. It occurred to me that these might make a
> cheap source of raw material for at least some parts of the fabricator,
> and demonstrate its immediate usefulness to Environmentalists.
>
> I was concerned about the rigidity, but thicker parts such as PET bottle
> mouths and HDPE bottle handles seemed to be sufficiently robust. I'll
> quantify that later.

Yes - one of the things I really want to do is to make the machine work with
thermoplastic granules, as supplied in bulk by ICI, DuPont etc.  And, as you
imply, also as supplied by the recycling industry.  All RP machines that use
thermoplastic that I know of need it in highly refined and controlled form
(usually a spool of filament).

> Experimentation with a low-cost glue gun and thermocouple revealed that
> neither material would readily melt at 130C, and an "improved" glue gun
> with stacked heating elements will be constructed when I next go to the
> "Two Dollar Store".
>
> I aim to extrude stacked layers of the materials manually, and if the
> results are promising I'll knock something up out of Meccano to produce
> pipe and lathed shapes. Anyone remember the "meccanograph"? A mechanical
> spirograph that produced quite complex shapes. Might be a useful
> low-tech approach for making test structures.

Brill!  I look forward to the JPEGs...

Yours

Adrian

http://staff.bath.ac.uk/ensab