Is there a way to check plywood to minimize voids?

I would imagine that a good engineering firm with a full set of non
destructive testing equipment could do it for only a few thousand per sheet

;-)

Brian

(Gone Angling) lifted the trapdoor, peered around and
wrote:

Is there a way to check plywood to minimize voids?

Isn't plywood manufactured to certain standards warranted free from major
voids?

The best way is to know your plywood standards and buy the wood that has an
acceptable level of quality. BS1088 is the lowest grade that I know of that
guarantees NO voids. Short of guessing according to what standard applies,
note that you can get a good idea of how many voids are in the wood by
inspecting all 4 cut edges. Look at the whole unit, check the average
quality of the stack, then hand-pick wood that has the smallest and fewest
voids. My experience is that when cutting the wood (so picked) that the
voids you find are no worse than what you see along the edges. Quality
varies a lot by lot (pardon the pun) so be sure to shop several lumber yards
before buying.

Brian

--
My boat project: http://www.advantagecomposites.com/tongass


"Gone Angling" wrote in message
...
Is there a way to check plywood to minimize voids?

"Brian D" ) writes:


.. Quality
varies a lot by lot (pardon the pun) so be sure to shop several lumber yards
before buying.


I'll say. I almost fell over the day I saw a whole skid of
flawless lauan underlayment. No worm holes. No edge voids. No
splits in the face ply. Perfect.

You can run a lamp awith a metal shade tight over the face of thin
plywood like underlayment in a dark room and see the voids as
light streaks. Lauan underlayment voids show up as red streaks.
You can mark the voids with a pencil.

You can fill the voids by putting little pieces of tape over the
pencil line every few inches and drilling a small hole through the
tape and all but the opposite face ply of the wood. Then pump
filler into the holes with a caulking gun unitl it oozes out the
nearest holes. If you drill right through the plywood just put a
piece of tape over the opposet side of the plywood to seal the
hole. For filler I've used ordinary house calk and also the PL
Premium polyurethane glue builders of small boat like.

--
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I have a few other questions. I'm building a simple boat (cajun flat bottom 10
feet) as a starter project.
The points of the bottom are plotted on a piece of plywood. What would i use to
make a smooth curve?

Do you use a hand held jig saw to cut it out?

I want to put a fancy deck on it. Would a hardwood veneer plywood be ok? I'm
not sure if it is rated for exterior use. Other material to use?

1/4 inch ply is that equivalent to 6mm. Is 5.2 mm luan too thin for sides and
deck.

Can i join plywood by a butt joint and a 1x 2 across the joint on the interior.


All my materials are to be bought from a home depot type store.

Thanks

"Gone Angling" wrote in message
...
I have a few other questions. I'm building a simple boat (cajun flat
bottom 10
feet) as a starter project.
The points of the bottom are plotted on a piece of plywood. What would i
use to
make a smooth curve?


A thin wood batten -- piece of pine, 1/4" thick, no knots, will work pretty
well.

Do you use a hand held jig saw to cut it out?

If you're careful. Use a wide blade. Cut a little over and then plane or
belt sand to finish.


I want to put a fancy deck on it. Would a hardwood veneer plywood be ok?
I'm
not sure if it is rated for exterior use. Other material to use?

Plywood veneers, particularly expensive woods like teak, are very thin,
leaving you no room for sanding if you don't keep the varnish in good shape.
There are various ways around this, but all of them are heavy in a ten foot
boat.

Most (maybe all) modern plywood is made with exterior glues, so I wouldn't
worry too much about this for a boat that is not going to take a lot of
abuse -- I assume that the fancy deck means you intend to take good care of
it.



1/4 inch ply is that equivalent to 6mm. Is 5.2 mm luan too thin for sides
and
deck.

1/4" is actually 6.35mm -- normally we ignore the difference, except that
most Home Depot quarter inch ply is actually six millimeter which is a
nuisance if you're using a router for dadoes. So 5.2 is actually 1.15mm
under, or about 20%. Check the drawings and make sure you aren't going both
thinner and weaker. It's probably all right, though, as plywood is pretty
strong, but it will deflect more.

Can i join plywood by a butt joint and a 1x 2 across the joint on the
interior.

Yes, if the drawings call for it. A scarf is better, but requires a couple
of practice tries to figure it out.


All my materials are to be bought from a home depot type store.

You have my sympathy. I find Home Despot very convenient, but often
frustrating.


--
Jim Woodward
www.mvFintry.com


..

"Gone Angling" writes:

I have a few other questions. I'm building a simple boat (cajun flat
bottom 10
feet) as a starter project.
The points of the bottom are plotted on a piece of plywood. What would i
use to
make a smooth curve?

A batten.

Buy a 3/4" x 3/4" x 1/16" x 96" extruded aluminum angle and use the back
edge.

You can pick up spots that are out by as little as 1/32" this way.

I faired out a 55 ft boat using this method.

HTH


--
Lew

S/A: Challenge, The Bullet Proof Boat, (Under Construction in the Southland)
Visit: http://home.earthlink.net/~lewhodgett for Pictures

We show pictures of the method at our tech. support web site:
http://bateau2.com/modules.php?name=...ticles&secid=1

See "Camber and other curves . . "

I like to cut smooth curves with a circular saw, they come out much nicer
than with a jig saw. The limit is 3/8" plywood but since you work with 1/4",
it will work.

Lauan? That is another matter. I have seen some very nice one on some very
bad. It's probably good enough for a practice boat if you coat it with
epoxy.
--
Jacques
http://www.bateau.com


"Gone Angling" wrote in message
...
I have a few other questions. I'm building a simple boat (cajun flat
bottom 10
feet) as a starter project.
The points of the bottom are plotted on a piece of plywood. What would i
use to
make a smooth curve?

Do you use a hand held jig saw to cut it out?

I want to put a fancy deck on it. Would a hardwood veneer plywood be ok?
I'm
not sure if it is rated for exterior use. Other material to use?

1/4 inch ply is that equivalent to 6mm. Is 5.2 mm luan too thin for sides
and
deck.

Can i join plywood by a butt joint and a 1x 2 across the joint on the
interior.


All my materials are to be bought from a home depot type store.

Thanks

Gone Angling ) writes:
I have a few other questions. I'm building a simple boat (cajun flat bottom 10
feet) as a starter project.
The points of the bottom are plotted on a piece of plywood. What would i use to
make a smooth curve?

plastic electrical conduit is good. comes in 10 ft lengths at "Home Depot
type stores". cheap and no need to rip a thin piece of wood which probably
won't come out even anyway.


Do you use a hand held jig saw to cut it out?

yes but a jig saw wobbles more than a circular saw. I use a jig saw for
cutting tight curves and small pieces.


I want to put a fancy deck on it. Would a hardwood veneer plywood be ok? I'm
not sure if it is rated for exterior use. Other material to use?

decorative wall panels are not waterproof. I'd only use it above the
waterline on a boat kept under cover when not in use.


1/4 inch ply is that equivalent to 6mm. Is 5.2 mm luan too thin for sides and
deck.

5.22 mm lauan is 1/5 inch.


Can i join plywood by a butt joint and a 1x 2 across the joint on the interior.

two separate things. 1x2 is a framing. you can fasten panels so they end on
a frame. a 4" wide piece of the same plywood is a good butt. fasten with glue
and "clinched" (bent over and back in) little nails.

people often butt join plywood with fibreglass tape soaked in resin. most
people recommend epoxy resin but I've used cheaper polyester.



All my materials are to be bought from a home depot type store.

builders of small cheap boats use polyurethane cosntruction adhesive in a
tube available from these types of stores. Bulldog PL Premium is the one
most often mentioned. I use it.

there are photos of my cheap plywood boats on my website (see below). its
common for amateurs to build this way for themselves, not expecting a boat
they can pass on to their grandchildren's grandchildren. Of my boats the
Dogskiff and Loonie are lauan underlayment. The Delta is virola
underlayment. I left the virola boat outside last winter and the plys were
comming apart at the edge. Had to cut some off one end. I brought it in
this winter. Otherwise the virola boat stays outside. I don't expect it to
last long. The lauan boats are kept inside. (They hang on pegs on the
garage wall.) They are holding up very well. The Dogskiff has been used 4
summers now and is in great shape. TF Jones had a lauan underlayment kayak
9 years, kept inside when not in use, and it was still in fine shape when
he cut it up because he got tired of it and wanted to make a different
boat. No great loss.

good luck

--
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