Hmm, this is a good point so it bears checking on. I currently use
a clothes iron and press it by hand and use about 5 inches square of
the sole plate at any one time. I weigh about 225 pounds these days
and am pushing down on the iron with a fair amount of force - lets
say half my weight 112 pounds - which I am sure is more than I am
pushing down.
5 x 5 = 25 sqaure inches of surface area
112 / 25 = 4.48 pounds per square inch
This has worked very good for me so far (although I suspect I have
beginners luck). So, a 12" x 12" board would require
12 x 12 = 144 square inches x 4.48 pounds per square inch = 645
pounds of presure on that plate for a large circuit board. This
would be pretty hard to achieve without some form of mechanical
advantage (unless I keep putting on weight since I quit smoking!)
Chris
--- In Homebrew_PCBs@yahoogroups.com, Alan King <alan@n...> wrote:
>
> Steve wrote:
>
> >--- In Homebrew_PCBs@yahoogroups.com, "Stefan Trethan"
> ><stefan_trethan@g...> wrote:
> >...
> >
> >
> >>The thing is, pressure, as in force per area, depends, well,
like on
> >>
> >>
> >area.
> >
> >
> >>In a fuser/laminator you only have a "line" thus 1-dimensional
> >>relationship between boardsize and pressure. In a press you
have that
> >>squared, which could be another problem.
> >>
> >>
> >
> >Very good point. I doubt an electric griddle could stand up to
much
> >pressure, too.
> >
> >Steve Greenfield
> >
> >
> >
> >
>
> A ton or two may be closer than you'd think off hand, remember
the
> rollers flatten out a bit and create a contact patch. Not sure
extreme
> pressure is really important, with correct heat the toner should
flow
> without that much pressure. Reinforcing a plate is easy enough,
and
> actually had thought of using a levered hand roller like in the
manual
> tile cutter I used last week. But probably too much work to keep
the
> board and print aligned that way.. Just worth investigating a
bit,
> since the griddle is useful on it's own for SMT reflow anyway. If
it
> can be made to work it'd be great, if not there is no real loss
either..
>
> Alan
>