--- In
Homebrew_PCBs@yahoogroups.com, Adam Seychell
<adam_seychell@y...> wrote:
> This weekend I played around with my hot air welder again, trying
> to get better practice. I bought three types or welding rod, and
> small and large triangle type and a 3 mm round, each type comes
> in 50 rods per pack. I found triangle is the best. For 4.5mm
> sheet I use the larger triangle, for 3 mm sheet I use the small
> triangle rods. Practice on lots of scrap pieces and then try and
> break the weld when cooled. A ∗really∗ good weld will not break
> at the weld, but rather the sheet its self will break. The trick
> is to get the right temperature setting and nozzle distance from
> the work piece. There is a fine line between burning the plastic
> and not heating it enough to properly fuse. If the temperature is
> too low then it takes too long to melt the plastic and so too
> much heat transfers to the bulk of the material, which makes
> everything deform and then you cannot push hard of the rod. If
> the heat is too hot then it very easy to burns the plastic which
> contaminates it with carbon and produces a weak weld.
>
> Adam
Hi Adam
The trick that I use is the hot air welding gun itself. It's
temperature is automatically controlled and it is having a digital
display showing the temperature which also can be used to set the
temperature requested. It then takes the gun probably 10 seconds or
so to reach a new temeparature level and it then stays there. This
really helps a lot in getting consistent good results.
Markus