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Mustardbuilder wrote:
> fredfighter@spamcop.net wrote in news:1169496475.404255.84720
> @m58g2000cwm.googlegroups.com:
>
> > ...
> >>
> >> Dunno, that's what I was asking. I have laminated two pieces of ply
> >> together before, just was wondering if it was practical or advisable
> to
> >> do it curved.
> >
> > Laminating a curved piece is, if anything, better than laminating
> > a flat piece, and also better than using a single piece.
>
> Yeah, that's what I reckoned.
> >
> > If you laminate it on the curve before the glue sets the
> > laminated plywood will be pre-stressed to the desired curve.
> >
> > You do not need a mold, you can attach one piece, let it set,
> > then glue the second piece over it.
> >
> > Regarding the veneers, the laminated piece should be symetrical.
> > If the pieces have an A and a B face, they should be laminated
> > ABBA or BAAB, not ABAB or BABA. The grain on the new front
> > and back face should be parallel. I would put the A faces out, ABBA.
>
> Well, the do not really. This stuff is so fine it's beyond belief. For
> instance the 1/4 birch IU have is 12 ply and is one direction on one
> side and the other on the other side, so it doesn't much matter which
> way you put it on.
Aha, I bet that is exactly why they make it that way. Plywood with
the grain on the front and back parallel is 15% stronger (or is it
stiffer, I do not remember) vs bending across that grain. Made as
you describe, it is more omnidirectional in stiffness.
If I were to laminate it for the wing walk, I would do it with the
outer face grain (outside and inside) parallel to the spar
It should curve better that way and be a bit stiffer--like the
way plywood is laid over joists.
> >
> > But I think aircraft and marine plywood is supposed to have A-grade
> > veneers front and back, right?
> >
>
> This stuff has a grade all the way through..
Over on rec.boats some people say they have found marine
ply with voids in the interior plys.
--
FF
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Re: Wing walk ply question.
