Tabletop splitting

Snip>
> Glue failure. Your friend is blameless. The heat from his sander
> couldn't soften glue through that much wood, which is a pretty good
> insulator, even if he could afford the sandpaper he'd go through heating
> it hard.
>
> Why did the glue fail? One suggestion given, gaps too big for clamps.
> If the boards were poorly jointed, had snipe, or were squeezed real hard,
> they spring back. Could be only moisture change in the wood, don't know
> where you started or where you are now, but if it's significantly dryer,
> you may have a bit of modest wood failure from contraction, and if you
> starved the joint, might pop. Hard maple is good at that.
I agree. Using too much clamp pressure is the likely culprit. I've seen it
and have done it before myself.
I am really careful now and have switched to 100% K-Bodys, the round handle
limits the clamping pressure. As opposed to crank-type handles. They are
too easy to over-tighten.

Dave



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"Connor Aston" <[email protected]> wrote in message
news:[email protected]...
>
> I have made up a tabletop from planned 1 1/2" maple . The top is made
> from 4 x boards each about 9" wide. I used Titbeond III to glue each edge
> (there was plenty of glue) and spread out along the joint with a brush.
> The problem is after it has been sanded (by a friend of mine on his pad
> sander) at one end the joints have opened up by about a 1/16" running
> down for about 4". I can't really see why this has happened?
> My only guess is that the heat of the sanding has sucked a lot of
> moisture from the Maple? And if the timber has shrunk by sanding it do you
> think it will shrink anymore. I intend to cut the ends and use without a
> breadboard for a more contemporary look.Has anyone else ever had this
> happen. Each rough sawn board had at least
> 4" cut from each end before planning and glueing up.

Glue failure. Your friend is blameless. The heat from his sander couldn't
soften glue through that much wood, which is a pretty good insulator, even
if he could afford the sandpaper he'd go through heating it hard.

Why did the glue fail? One suggestion given, gaps too big for clamps. If
the boards were poorly jointed, had snipe, or were squeezed real hard, they
spring back. Could be only moisture change in the wood, don't know where
you started or where you are now, but if it's significantly dryer, you may
have a bit of modest wood failure from contraction, and if you starved the
joint, might pop. Hard maple is good at that.

"Connor Aston" wrote in message

>So I have learnt another hard woodworkers lesson . . .

First of a two part series that makes us all better wooddorkers ... the
second part is perfecting the "fix" for the first.

Keep it up long enough and we would all become capable of hosting our own TV
shows ... providing our buns fill out the strides nicely and/or our tits
fill the screen, that is.

--
www.e-woodshop.net
Last update: 12/13/05

i wood suggest end coating ( the end grain) with sealer or wax as the
wood dry's faster out the end grain, not a for sure solution but worth a
try. ross

> Ross Hebeisenwrote:
i wood suggest end coating ( the end grain) with sealer or wax as
the
> wood dry's faster out the end grain, not a for sure solution but
worth a
> try. ross


Are the glued joints splitting? or the just random areas of the end
grain splitting?

If your glue joints are splitting, my first thought would be (mainly
since I am only visualizing) that the jointed edges might not have
been perfectly straight.. and if so, maybe you had released your
clamps a bit too soon. Being such thickness, those glue joints would
need absolute dry time, and then some.

There are also other considerations that no one here could posibly
know of, like the age of your glue, the persipitation ratio in your
shop or area you live.. how dry the actual wood was at time of
gluing, etc.. Its almost impossible to really define why you had
this trouble without this knowlege. But those would be a start.

Only real fix, dependng on how severe, would be to rip the joints back
down, and make a fresh joint.

"Connor Aston" <[email protected]> wrote in message
news:[email protected]...
>
> I have made up a tabletop from planned 1 1/2" maple . The top is made
> from 4 x boards each about 9" wide. I used Titbeond III to glue each edge
> (there was plenty of glue) and spread out along the joint with a brush.
> The problem is after it has been sanded (by a friend of mine on his pad
> sander) at one end the joints have opened up by about a 1/16" running
> down for about 4". I can't really see why this has happened?
> My only guess is that the heat of the sanding has sucked a lot of
> moisture from the Maple? And if the timber has shrunk by sanding it do you
> think it will shrink anymore. I intend to cut the ends and use without a
> breadboard for a more contemporary look.Has anyone else ever had this
> happen. Each rough sawn board had at least
> 4" cut from each end before planning and glueing up.

Rather than cut the ends off, unless you planned to any way, simply rip down
the glue joint and reglue.

"Connor Aston" <[email protected]> wrote in message
news:[email protected]...
>
> I have made up a tabletop from planned 1 1/2" maple . The top is made
> from 4 x boards each about 9" wide. I used Titbeond III to glue each edge
> (there was plenty of glue) and spread out along the joint with a brush.
> The problem is after it has been sanded (by a friend of mine on his pad
> sander) at one end the joints have opened up by about a 1/16" running
> down for about 4". I can't really see why this has happened?
> My only guess is that the heat of the sanding has sucked a lot of
> moisture from the Maple? And if the timber has shrunk by sanding it do you
> think it will shrink anymore. I intend to cut the ends and use without a
> breadboard for a more contemporary look.Has anyone else ever had this
> happen. Each rough sawn board had at least
> 4" cut from each end before planning and glueing up.

I assume that you are saying that a glue joint failed, not that the wood
split.

I my best guess is that you didn't do a great job at the jointer. If you
had to use clamps to pull the joint together then that is the answer. My
suggestion is take time to dry fit everything before you glue. If the
joints need more that slight pressure to come together go back to the
jointer and fix the problem.

Having read through all you kind comments I guess it looks like too muc
pressure at clamp time. I had great neat joints before I glued up th
boards. I have 4 clamps with the round wooden handles so to really squez
the hell out of it I borrowed my friends 4 nice orange pipe clamps an
squeezed them really hard. (just to make sure they stayed closed at eac
end). . . So I have learnt another hard woodworkers lesson . . .
don't over tighten boards durning glue up

Althought I still think his sande
http://www.rojekuk.com/industry_padsanders.html could create a lot of heat. My boards had been in th
unheated damp shop for over two months and I dont think it helped
But probably just too much pressure. Thanks everyon

9" is a pretty wide board to begin with and sometimes maple can be a
little brittle; I'm not sure what you mean by "pad sander" but I do't
think normal sanding would produce enough heat fast enough to cause
the cracks you describe. They sound like they are just the kind of
cracks you'd get from using lumber that wasn't dry enough. You
mentioned they were rough cut. Did the mill or lumberyard say what
type of drying they had undergone?


--

Larry Wasserman Baltimore, Maryland
[email protected]