I created an inlayed table top by gluing 1/4 stock to a 1/2 piece of
plywood. The problem is that somewhere through the inlay process,
the plywood warped on one side, and now I need to unwarp it.

The table top is 40"x20". Two corners attached to one of the 20"
sides have curled upwards (towards the inlay). The curl is
signifcant (about 1/2" upwards), and seems to be very strong (I can't
bend it back with my hands).

What I was thinking of doing was to score the underside of the plywood
with a circular saw about 3/8 of an inch at 1 inch intervals, and then
forcing it straight with some clamps. I would then glue another sheet
of 1/4" plywood to the bottom of the board once it's forced straight.

Will this work? Does anyone have any suggestions of additional things
I could try, or tips on my proposed method? I've never done this
before, and I don't want to mess up the inlay.

Thanks

John

julvr wrote:

I created an inlayed table top by gluing 1/4 stock to a 1/2 piece of
plywood. The problem is that somewhere through the inlay process,
the plywood warped on one side, and now I need to unwarp it.

The table top is 40"x20". Two corners attached to one of the 20"
sides have curled upwards (towards the inlay). The curl is
signifcant (about 1/2" upwards), and seems to be very strong (I can't
bend it back with my hands).

What I was thinking of doing was to score the underside of the plywood
with a circular saw about 3/8 of an inch at 1 inch intervals, and then
forcing it straight with some clamps. I would then glue another sheet
of 1/4" plywood to the bottom of the board once it's forced straight.

Will this work? Does anyone have any suggestions of additional things
I could try, or tips on my proposed method? I've never done this
before, and I don't want to mess up the inlay.

Thanks

John

always veneer both sides of a substrate, John. that prevents the
curling you experienced.

dave

"David" wrote in message
...
julvr wrote:

I created an inlayed table top by gluing 1/4 stock to a 1/2 piece of
plywood. The problem is that somewhere through the inlay process,
the plywood warped on one side, and now I need to unwarp it.

The table top is 40"x20". Two corners attached to one of the 20"
sides have curled upwards (towards the inlay). The curl is
signifcant (about 1/2" upwards), and seems to be very strong (I can't
bend it back with my hands).

What I was thinking of doing was to score the underside of the plywood
with a circular saw about 3/8 of an inch at 1 inch intervals, and then
forcing it straight with some clamps. I would then glue another sheet
of 1/4" plywood to the bottom of the board once it's forced straight.

Will this work? Does anyone have any suggestions of additional things
I could try, or tips on my proposed method? I've never done this
before, and I don't want to mess up the inlay.

Thanks

John

always veneer both sides of a substrate, John. that prevents the curling
you experienced.

But isn't plywood veneer already? Why would putting more veneer on one side
cause warping?
I am about to try my first veneer project; wouldn't it be adequate to just
varnish the opposite side?

Plywood is a balanced set of veneers. Check the grain orientations in
plywood. That is why there is always an odd number of plies.You are adding
another single sided veneer with different properties and grain orientation.
To help keep the piece from warping, you should do the same thing to both
sides. If you veneer one side, you should veneer the other side with the
same veneer or with something with similar properties. Otherwise, each side
has different wood movement properties. Similarly, if you finish one side of
a piece of plywood, you should put the same finish on the other side to even
moisture gain/loss.

Preston
"Toller" wrote in message
...

"David" wrote in message
...
julvr wrote:

I created an inlayed table top by gluing 1/4 stock to a 1/2 piece of
plywood. The problem is that somewhere through the inlay process,
the plywood warped on one side, and now I need to unwarp it.

The table top is 40"x20". Two corners attached to one of the 20"
sides have curled upwards (towards the inlay). The curl is
signifcant (about 1/2" upwards), and seems to be very strong (I can't
bend it back with my hands).

What I was thinking of doing was to score the underside of the plywood
with a circular saw about 3/8 of an inch at 1 inch intervals, and then
forcing it straight with some clamps. I would then glue another sheet
of 1/4" plywood to the bottom of the board once it's forced straight.

Will this work? Does anyone have any suggestions of additional things
I could try, or tips on my proposed method? I've never done this
before, and I don't want to mess up the inlay.

Thanks

John

always veneer both sides of a substrate, John. that prevents the
curling
you experienced.

But isn't plywood veneer already? Why would putting more veneer on one
side
cause warping?
I am about to try my first veneer project; wouldn't it be adequate to just
varnish the opposite side?

Toller wrote:

"David" wrote in message
...

julvr wrote:


I created an inlayed table top by gluing 1/4 stock to a 1/2 piece of
plywood. The problem is that somewhere through the inlay process,
the plywood warped on one side, and now I need to unwarp it.

The table top is 40"x20". Two corners attached to one of the 20"
sides have curled upwards (towards the inlay). The curl is
signifcant (about 1/2" upwards), and seems to be very strong (I can't
bend it back with my hands).

What I was thinking of doing was to score the underside of the plywood
with a circular saw about 3/8 of an inch at 1 inch intervals, and then
forcing it straight with some clamps. I would then glue another sheet
of 1/4" plywood to the bottom of the board once it's forced straight.

Will this work? Does anyone have any suggestions of additional things
I could try, or tips on my proposed method? I've never done this
before, and I don't want to mess up the inlay.

Thanks

John


always veneer both sides of a substrate, John. that prevents the curling
you experienced.


But isn't plywood veneer already? Why would putting more veneer on one side
cause warping?
I am about to try my first veneer project; wouldn't it be adequate to just
varnish the opposite side?


Look at the problems that the OP had with veneering one side. g

dave

Toller wrote:
"David" wrote in message
...

julvr wrote:


I created an inlayed table top by gluing 1/4 stock to a 1/2 piece of
plywood. The problem is that somewhere through the inlay process,
the plywood warped on one side, and now I need to unwarp it.

The table top is 40"x20". Two corners attached to one of the 20"
sides have curled upwards (towards the inlay). The curl is
signifcant (about 1/2" upwards), and seems to be very strong (I can't
bend it back with my hands).

What I was thinking of doing was to score the underside of the plywood
with a circular saw about 3/8 of an inch at 1 inch intervals, and then
forcing it straight with some clamps. I would then glue another sheet
of 1/4" plywood to the bottom of the board once it's forced straight.

Will this work? Does anyone have any suggestions of additional things
I could try, or tips on my proposed method? I've never done this
before, and I don't want to mess up the inlay.

Thanks

John


always veneer both sides of a substrate, John. that prevents the curling
you experienced.


But isn't plywood veneer already? Why would putting more veneer on one side
cause warping?
I am about to try my first veneer project; wouldn't it be adequate to just
varnish the opposite side?

My understanding is that you want to have the same amount of veneer on
either side of the core. Isn't plywood always an odd # of plys ?

On Sun, 27 Nov 2005 00:01:16 GMT, lid (julvr) wrote:

I created an inlayed table top by gluing 1/4 stock to a 1/2 piece of
plywood. The problem is that somewhere through the inlay process,
the plywood warped on one side, and now I need to unwarp it.
The table top is 40"x20". Two corners attached to one of the 20"
sides have curled upwards (towards the inlay).

My guess would be that the inlay has shrunk at a different rate than
the plywood and has pulled the plywood up.

What I was thinking of doing was to score the underside of the plywood
with a circular saw about 3/8 of an inch at 1 inch intervals, and then
forcing it straight with some clamps. I would then glue another sheet
of 1/4" plywood to the bottom of the board once it's forced straight.
Will this work?

If what I suspect has happened is indeed the case the same thing could
happen again but this time with the 1/4". The 1/4" isn't really going
to add any strength.

Does anyone have any suggestions of additional things
I could try, or tips on my proposed method? I've never done this
before, and I don't want to mess up the inlay.

The first thing I would try would be to clamp the top down on
something flat to see if I'm going to ruin the inlay anyway when I
straighten it. If the inlay survives that, could you put an apron
around the bottom of the top to hold it flat?

Mike O.

"julvr" wrote in message
. ..
I created an inlayed table top by gluing 1/4 stock to a 1/2 piece of
plywood. The problem is that somewhere through the inlay process,
the plywood warped on one side, and now I need to unwarp it.

Was the 1/4in stock well dried?


The table top is 40"x20". Two corners attached to one of the 20"
sides have curled upwards (towards the inlay). The curl is
signifcant (about 1/2" upwards), and seems to be very strong (I can't
bend it back with my hands).

That's a lot of bend for the size of the piece. Why don't you provide more
information on the 1/4" stock that you used to make the inlay. Type of
wood, length of pieces, width, etc. Type of glue? Glue application
details? How long did it take for the plywood to curl? Was the plywood wet
(been laying around outside or something)? What is the orientation of the
inlay stock relative to the dimensions of the plywood?

I'm having a hard time believing that the 1/4" stock pulled the plywood like
you're describing the movement. Not to say it couldn't, but I'm imagining a
project that you just completed, using "normal" lumber pieces - stuff you'd
get from the BORG. This just does not seem to be a simple case of putting a
veneer on one side of a substrate and suffering problems with unequal
moisture absorbtion.


What I was thinking of doing was to score the underside of the plywood
with a circular saw about 3/8 of an inch at 1 inch intervals, and then
forcing it straight with some clamps. I would then glue another sheet
of 1/4" plywood to the bottom of the board once it's forced straight.


If it is a moisture related problem, you can moisten the underside of the
plywood and try to clamp it back to flat. I'd try that before I scored the
piece.


--

-Mike-

Whatever you do to the top you have to do to the bottem otherwise it will
twist. Sorry.
Dave
"Mike Marlow" wrote in message
...

"julvr" wrote in message
. ..
I created an inlayed table top by gluing 1/4 stock to a 1/2 piece of
plywood. The problem is that somewhere through the inlay process,
the plywood warped on one side, and now I need to unwarp it.

Was the 1/4in stock well dried?


The table top is 40"x20". Two corners attached to one of the 20"
sides have curled upwards (towards the inlay). The curl is
signifcant (about 1/2" upwards), and seems to be very strong (I can't
bend it back with my hands).

That's a lot of bend for the size of the piece. Why don't you provide
more
information on the 1/4" stock that you used to make the inlay. Type of
wood, length of pieces, width, etc. Type of glue? Glue application
details? How long did it take for the plywood to curl? Was the plywood
wet
(been laying around outside or something)? What is the orientation of the
inlay stock relative to the dimensions of the plywood?

I'm having a hard time believing that the 1/4" stock pulled the plywood
like
you're describing the movement. Not to say it couldn't, but I'm imagining
a
project that you just completed, using "normal" lumber pieces - stuff
you'd
get from the BORG. This just does not seem to be a simple case of putting
a
veneer on one side of a substrate and suffering problems with unequal
moisture absorbtion.


What I was thinking of doing was to score the underside of the plywood
with a circular saw about 3/8 of an inch at 1 inch intervals, and then
forcing it straight with some clamps. I would then glue another sheet
of 1/4" plywood to the bottom of the board once it's forced straight.


If it is a moisture related problem, you can moisten the underside of the
plywood and try to clamp it back to flat. I'd try that before I scored
the
piece.


--

-Mike-

"Dave W" wrote in message
...
Whatever you do to the top you have to do to the bottem otherwise it will
twist. Sorry.

I understand that but his project seems to have warped immediately and that
is not characteristic of the type of thing you're speaking of. I could well
be missing something here Dave, but I don't see any way his project could
have absorbed enough moisture to have moved 1/2" ply 1/2" overnight. I
suppose you could suggest that the glue did it, but I've never seen glue do
that before and I've glued up a lot of wood.

--

-Mike-

The finished product will have an apron, but it doesn't help me in the
short term. The problem is if I try to use clamps to straigthen the
edge, I start to hear cracking noises, which is the glue giving way.
The other problem is that I need to straighten it before I run it
through a thickness sander (I'm planning on taking 3/32" off the top
layer), and I can't run it through with the apron on.


The wood I used on the top is mostly 1/4 oak. I glued several 1/4"x
2" strips together, so there are 10 pieces of oak glued together on
the warped side. When Gluing the pieces, I did each peice
individually, and I clamped the peice beside it, waited for the glue
to dry and repeated the process. One of the pieces might have been a
fraction to small, which might have pulled the top in...

As for other details, the glue I used was LePage Carpenters glue.

The plywood was cheap borg plywood, so it has a soft center, and had
only one vaneered side (which I placed at the bottom -- I glued the
oak to the unfinished side). I just checked and it has only four
layers.

John

"julvr" wrote in message
...
The finished product will have an apron, but it doesn't help me in the
short term. The problem is if I try to use clamps to straigthen the
edge, I start to hear cracking noises, which is the glue giving way.
The other problem is that I need to straighten it before I run it
through a thickness sander (I'm planning on taking 3/32" off the top
layer), and I can't run it through with the apron on.


The wood I used on the top is mostly 1/4 oak. I glued several 1/4"x
2" strips together, so there are 10 pieces of oak glued together on
the warped side. When Gluing the pieces, I did each peice
individually, and I clamped the peice beside it, waited for the glue
to dry and repeated the process. One of the pieces might have been a
fraction to small, which might have pulled the top in...

This is weird. Even if movement due to moisture absorbtion were the cause,
I would not expect this degree of movement from the wood you used. You just
don't get 1/2" of shrinkage out of a 2" piece of oak. One piece being too
small would likewise not produce the pull you've described. If you simply
glued the individual pieces down, and did not have to clamp them
aggressively to get a good piece to piece fit, then I don't understand the
problem. Moisture problems as mentioned in other posts, which result from
not veneering both sides of a substrate take time to show up, and I just
can't see them being the culprit with a 1/4" piece of oak for an inlay. I
don't know - maybe I'm wrong on this one.


As for other details, the glue I used was LePage Carpenters glue.

The plywood was cheap borg plywood, so it has a soft center, and had
only one vaneered side (which I placed at the bottom -- I glued the
oak to the unfinished side). I just checked and it has only four
layers.


I think what I would try is to construct a tent out of plastic and apply
some moisture inside the tent, while all the time exerting clamp pressure on
the assembly. I'd increase the clamp pressure over intervals until I could
get it flat again. How long of an interval would be a process of
experimentation. I think I'd let it absorb some moisture for a day or two
and then try increasing clamp pressure every few hours and see how that
goes.

This one is intriguing to me. Keep this thread alive, and post your
results, regardless of the method(s) you choose.

--

-Mike-

Fixed it!

What I did was I set my circular saw to a depth of 1/2", and scored
the plywood everywhere there was a seem in the inlay above. I then
built a steam-tent, steamed it up, and using some clamps, straigtened
out the board over the course of an hour. Once straight, I let it
dry for a few days, and then glued a piece of 1/4" handy pannel to
the back, using lots of glue to fill the scores I made in the
plywood. I then got it trimmed on a table saw to ensure the edges
were straight.

It worked quite well, and it's perfectly straight except a 1/16"
deflection in one corner, which will dissappear once it's run through
a thickness sander (see my next post...)

I still don't know what caused the warp, but I'm glad it could be
fixed. Once I attach the drop-down border it shouldn't be able to
warp any more. For now, I'm keeping it clamped to a straight board
just in case...

John