I have never heard an explanation of why aliphatic glue creeps.
I have always taken it as gospil.

I have a hard time understanding how a glue that creates a joint
stronger than the wood itself mostly will creep.

Can someone explain to me why this is the case... any one understand the
reason?

--
Jeff

"woodchucker" wrote in message

I have never heard an explanation of why aliphatic glue
creeps. I have always taken it as gospil.

I have a hard time understanding how a glue that creates
a joint stronger than the wood itself mostly will creep.

Can someone explain to me why this is the case... any one
understand the reason?

Same reason that rocks do...they are flexible and time. In the case of rock
strata, LOTS of time. In the case of aliphatic glue, I have never had a
problem.

--

dadiOH
____________________________

Winters getting colder? Tired of the rat race?
Taxes out of hand? Maybe just ready for a change?
Check it out... http://www.floridaloghouse.net

On 10/26/2013 2:37 PM, woodchucker wrote:
I have never heard an explanation of why aliphatic glue creeps.
I have always taken it as gospil.

I have a hard time understanding how a glue that creates a joint
stronger than the wood itself mostly will creep.

Can someone explain to me why this is the case... any one understand the
reason?



I have no scientific evidence, but a sneaking suspicion that it is a
combination of many factors, among others: type of wood and its
dimensional instability due to relative humidity/temperature; cut of
wood and grain (flatsawn moves in width, quartersawn in thickness); type
of glue and amount used; clamping pressure, et al.

IOW just about anything that causes dimensional instability in a glued
up joint, including finish.


--
eWoodShop: www.eWoodShop.com
Wood Shop: www.e-WoodShop.net
https://plus.google.com/114902129577517371552/posts
http://www.custommade.com/by/ewoodshop/
KarlCaillouet@ (the obvious)

On Sat, 26 Oct 2013 15:37:20 -0400, woodchucker wrote:

I have a hard time understanding how a glue that creates a joint
stronger than the wood itself mostly will creep.

Can someone explain to me why this is the case... any one understand the
reason?

I took a look at several websites describing it and they can't even agree
on what it is, let alone what causes it. Some say glue "bumping" out of
the glue line over time is creep. Others talk about two pieces of wood
glued together changing position relative to each other. I didn't find
anyone mentioning both, which is really the case.

But as far as I know, it's caused by the fact that the yellow glue (and
white as well) is "plastic" i.e. a petroleum based polymer. It never
gets really hard so it can deform or squirm under pressure over time.

If you suspect creep could be possibility in a project use hot hide glue
or resourcinol or epoxy. I'm sure there are others but those will do.

Some say that liquid hide glue will creep, others say no - no definitive
answer I could find but I suspect it at least creeps less than PVA glues.
Someone else may have more info on that.

--
This message was for rec.woodworking - if it appears in homeownershub
they ripped it off.

On 10/26/2013 2:37 PM, woodchucker wrote:
I have never heard an explanation of why aliphatic glue creeps.
I have always taken it as gospil.

I have a hard time understanding how a glue that creates a joint
stronger than the wood itself mostly will creep.

Can someone explain to me why this is the case... any one understand the
reason?



I'll throw in my 2 cents, this type glue remains flexible, wood expands
and contracts, no two pieces that form a joint expand or contract
exactly the same.

In article ,
woodchucker wrote:
I have never heard an explanation of why aliphatic glue creeps.
I have always taken it as gospil.

I have a hard time understanding how a glue that creates a joint
stronger than the wood itself mostly will creep.

Can someone explain to me why this is the case... any one understand the
reason?

--
Jeff

The definition of "creep" used in engineering & materials pretty much
expalins it:

"In materials science, creep (sometimes called cold flow) is the
tendency of a solid material to move slowly or deform permanently
under the influence of mechanical stresses. It can occur as a result
of long-term exposure to high levels of stress that are still below
the yield strength of the material."

(wikipedia)

At high enough temperatures, or given enough time, even steel structures
will "creep"


--
Often wrong, never in doubt.

Larry W. - Baltimore Maryland - lwasserm(a)sdf. lonestar. org

On 10/26/2013 6:32 PM, Larry Blanchard wrote:
On Sat, 26 Oct 2013 15:37:20 -0400, woodchucker wrote:

I have a hard time understanding how a glue that creates a joint
stronger than the wood itself mostly will creep.

Can someone explain to me why this is the case... any one understand the
reason?

I took a look at several websites describing it and they can't even agree
on what it is, let alone what causes it. Some say glue "bumping" out of
the glue line over time is creep. Others talk about two pieces of wood
glued together changing position relative to each other. I didn't find
anyone mentioning both, which is really the case.

But as far as I know, it's caused by the fact that the yellow glue (and
white as well) is "plastic" i.e. a petroleum based polymer. It never
gets really hard so it can deform or squirm under pressure over time.
....

The reason the 'bump' is called creep is that it is really extrusion
under pressure -- plastic deformation. Whether the two jointed pieces
also move relative to each other in net displacement depends on whether
and how well they're constrained and in which direction there are
sufficient forces.

Thinner gluelines are better for minimizing the effect because there's
less bulk material there. Which is why higher clamping pressure is
_a_good_thing_ (tm) besides the empirical observation from testing that
it improves ultimate joint bond strength.

--

Thinner gluelines are better for minimizing the effect because there's
less bulk material there. Which is why higher clamping pressure is
_a_good_thing_ (tm) besides the empirical observation from testing that
it improves ultimate joint bond strength.

--

"Fine Woodworking" magazine did a clamping pressure vs. strength test
some years ago and found that in almost all case, more pressure was
better. Reading that article changed my clamping life and my joints are
much better than they used to be.

On 10/27/2013 10:06 AM, scritch wrote:
Thinner gluelines are better for minimizing the effect because there's
less bulk material there. Which is why higher clamping pressure is
_a_good_thing_ (tm) besides the empirical observation from testing that
it improves ultimate joint bond strength.

....

"Fine Woodworking" magazine did a clamping pressure vs. strength test
some years ago and found that in almost all case, more pressure was
better. Reading that article changed my clamping life and my joints are
much better than they used to be.

I recall it...and it only confirmed what previous work at US Forest
Products Lab and elsewhere has shown...

--

On 10/27/2013 9:02 AM, Larry W wrote:
....

At high enough temperatures, or given enough time, even steel structures
will "creep"

To be observable, it'll still need the loading until temperatures are
quite high...

--

On 10/27/2013 10:02 AM, Larry W wrote:
In article ,
woodchucker wrote:
I have never heard an explanation of why aliphatic glue creeps.
I have always taken it as gospil.

I have a hard time understanding how a glue that creates a joint
stronger than the wood itself mostly will creep.

Can someone explain to me why this is the case... any one understand the
reason?

--
Jeff

The definition of "creep" used in engineering & materials pretty much
expalins it:

"In materials science, creep (sometimes called cold flow) is the
tendency of a solid material to move slowly or deform permanently
under the influence of mechanical stresses. It can occur as a result
of long-term exposure to high levels of stress that are still below
the yield strength of the material."

(wikipedia)

At high enough temperatures, or given enough time, even steel structures
will "creep"



Ok, I understand that.

So how is yellow glue capable of high stresses structurally but not in
bent laminations? I would think the stresses structurally would be
subject to creep to and therefore lower the structural value.

But only bent laminations are devalued.. I understand that bent
laminations are under constant stress, but we don't know what or how the
glue is used structurally. Imagine a bench that someone sits in 16 hours
a day... two shifts... is'nt that under a similar stress?

--
Jeff

On Sun, 27 Oct 2013 09:07:22 -0500, dpb wrote:

Thinner gluelines are better for minimizing the effect because there's
less bulk material there. Which is why higher clamping pressure is
_a_good_thing_

Agreed. I've always wondered about selling dark vs light glues depending
on the color of the wood, because I've never been able to see a glue line
after clamping.

I did once have a few glue bumps on a project - still don't know why and
I've never had it happen again.

--
This message was for rec.woodworking - if it appears in homeownershub
they ripped it off.

On Sun, 27 Oct 2013 13:30:04 -0400, woodchucker wrote:

Imagine a bench that someone sits in 16 hours a day... two shifts...
is'nt that under a similar stress?

Not really, the boards of the top are not stressed in reference to each
other.

Now if the legs were bolted to the floor and braced and the top glued to
those legs, you'd see sag over time. How much would be creep of the top
vs the legs and how much wood fibers elongating is beyond me.

--
This message was for rec.woodworking - if it appears in homeownershub
they ripped it off.

On 10/27/2013 12:30 PM, woodchucker wrote:
....

So how is yellow glue capable of high stresses structurally but not in
bent laminations? I would think the stresses structurally would be
subject to creep to and therefore lower the structural value.

But only bent laminations are devalued.. I understand that bent
laminations are under constant stress, but we don't know what or how the
glue is used structurally. Imagine a bench that someone sits in 16 hours
a day... two shifts... is'nt that under a similar stress?

The difference is that in the bent lamination example there's residual
stress (and quite a lot) of the bent material trying to return to it's
original shape. This is constant and unrelenting; hence over time the
plasticity begins to show.

In the bench there's some intermittent loading but there really isn't a
comparable load between the glue joints that is continuous nor in the
tangential direction that is there as the difference in lengths in the
curved lamination.

--

dpb wrote:
On 10/27/2013 10:06 AM, scritch wrote:
Thinner gluelines are better for minimizing the effect because
there's less bulk material there. Which is why higher clamping
pressure is _a_good_thing_ (tm) besides the empirical observation
from testing that it improves ultimate joint bond strength.

...

"Fine Woodworking" magazine did a clamping pressure vs. strength test
some years ago and found that in almost all case, more pressure was
better. Reading that article changed my clamping life and my joints
are much better than they used to be.

I recall it...and it only confirmed what previous work at US Forest
Products Lab and elsewhere has shown...

Only to a point though... correct? Everything I've ever heard was that
there is a point where too much pressure will squeeze out too much glue
which will result in a weakened joint. Maybe that has been proven not to be
true, but based on that, I generally clamp until I begin to get squeeze out
and maybe give it a little more tweak for good measure, but stop at that
point. That said, I spread my glue and try to avoid excess glue on the
surface prior to clamping. This is one area where I do not agree with
things I've seen Brian do in his videos. He likes to lay on the glue!

--

-Mike-

On 10/27/2013 2:26 PM, Mike Marlow wrote:
....

Only to a point though... correct? Everything I've ever heard was that
there is a point where too much pressure will squeeze out too much glue
which will result in a weakened joint. Maybe that has been proven not to be
true, ...

Basically, research has shown that there really is no such thing as
being able to "starve" a joint by excess pressure with anything
approaching a practical application of clamps and cauls that one would
use for normal glue-ups. Hmmm....I can't seem to find the link just
offhand and don't want to take the time to really look now, but the
kinds of clamping pressures that were used are in the _way_on_up_there_
(tm) ranges--actually in the incredible kinds of numbers compared to
what we normally think of as clamping pressures.

--

dpb wrote:
On 10/27/2013 2:26 PM, Mike Marlow wrote:
...

Only to a point though... correct? Everything I've ever heard was
that there is a point where too much pressure will squeeze out too
much glue which will result in a weakened joint. Maybe that has
been proven not to be true, ...

Basically, research has shown that there really is no such thing as
being able to "starve" a joint by excess pressure with anything
approaching a practical application of clamps and cauls that one would
use for normal glue-ups. Hmmm....I can't seem to find the link just
offhand and don't want to take the time to really look now, but the
kinds of clamping pressures that were used are in the
_way_on_up_there_ (tm) ranges--actually in the incredible kinds of
numbers compared to what we normally think of as clamping pressures.

Very good. I did read a long time ago that only a very small amount of glue
has to survive the clamps in order to make a good bond and that in fact too
much glue might be counterproductive, so what you say above makes sense.

--

-Mike-

On 10/27/2013 4:15 PM, Mike Marlow wrote:
dpb wrote:
On 10/27/2013 2:26 PM, Mike Marlow wrote:
...

Only to a point though... correct? Everything I've ever heard was
that there is a point where too much pressure will squeeze out too
much glue which will result in a weakened joint. Maybe that has
been proven not to be true, ...

Basically, research has shown that there really is no such thing as
being able to "starve" a joint by excess pressure with anything
approaching a practical application of clamps and cauls that one would
use for normal glue-ups. Hmmm....I can't seem to find the link just
offhand and don't want to take the time to really look now, but the
kinds of clamping pressures that were used are in the
_way_on_up_there_ (tm) ranges--actually in the incredible kinds of
numbers compared to what we normally think of as clamping pressures.

Very good. I did read a long time ago that only a very small amount of glue
has to survive the clamps in order to make a good bond and that in fact too
much glue might be counterproductive, so what you say above makes sense.


Squeezing out too much glue does not cause a weak joint. The tighter
you squeeze the better, the thinner the glue line the better.

Glue starvation is the situation when there simply is not enough glue to
cover all of the surfaces being joined to begin with.

Glue starvation is a condition when not enough glue was applied to cover
the surfaces, not squeezing down to a thin layer.

"Mike Marlow" wrote in message ...

dpb wrote:
On 10/27/2013 10:06 AM, scritch wrote:
Thinner gluelines are better for minimizing the effect because
there's less bulk material there. Which is why higher clamping
pressure is _a_good_thing_ (tm) besides the empirical observation
from testing that it improves ultimate joint bond strength.

...

"Fine Woodworking" magazine did a clamping pressure vs. strength test
some years ago and found that in almost all case, more pressure was
better. Reading that article changed my clamping life and my joints
are much better than they used to be.

I recall it...and it only confirmed what previous work at US Forest
Products Lab and elsewhere has shown...

Only to a point though... correct? Everything I've ever heard was that
there is a point where too much pressure will squeeze out too much glue
which will result in a weakened joint. Maybe that has been proven not to be
true, but based on that, I generally clamp until I begin to get squeeze out
and maybe give it a little more tweak for good measure, but stop at that
point. That said, I spread my glue and try to avoid excess glue on the
surface prior to clamping. This is one area where I do not agree with
things I've seen Brian do in his videos. He likes to lay on the glue!
================================================== ======================================
The Titebond website says clamping pressure up to 250 PSI should be used. I
don't think home woodworkers have to be concerned about over clamping.

"Leon" wrote in message
...

On 10/26/2013 2:37 PM, woodchucker wrote:
I have never heard an explanation of why aliphatic glue creeps.
I have always taken it as gospil.

I have a hard time understanding how a glue that creates a joint
stronger than the wood itself mostly will creep.

Can someone explain to me why this is the case... any one understand the
reason?



I'll throw in my 2 cents, this type glue remains flexible, wood expands
and contracts, no two pieces that form a joint expand or contract
exactly the same.
================================================== ==========================================
Not saying that glue creep doesnt happen but I've never seen it. I have a
few pieces that my father built in Japan in the mid 70s. They went from
there (very humid) to the desert (bone dry) then to Seattle (humid) and have
seen no creep at all.

On 10/27/13 4:31 PM, Leon wrote:
On 10/27/2013 4:15 PM, Mike Marlow wrote:
dpb wrote:
On 10/27/2013 2:26 PM, Mike Marlow wrote:
...

Only to a point though... correct? Everything I've ever heard was
that there is a point where too much pressure will squeeze out too
much glue which will result in a weakened joint. Maybe that has
been proven not to be true, ...

Basically, research has shown that there really is no such thing as
being able to "starve" a joint by excess pressure with anything
approaching a practical application of clamps and cauls that one would
use for normal glue-ups. Hmmm....I can't seem to find the link just
offhand and don't want to take the time to really look now, but the
kinds of clamping pressures that were used are in the
_way_on_up_there_ (tm) ranges--actually in the incredible kinds of
numbers compared to what we normally think of as clamping pressures.

Very good. I did read a long time ago that only a very small amount
of glue
has to survive the clamps in order to make a good bond and that in
fact too
much glue might be counterproductive, so what you say above makes sense.


Squeezing out too much glue does not cause a weak joint. The tighter
you squeeze the better, the thinner the glue line the better.

Glue starvation is the situation when there simply is not enough glue to
cover all of the surfaces being joined to begin with.

Glue starvation is a condition when not enough glue was applied to cover
the surfaces, not squeezing down to a thin layer.

I agree with this and it's been my experience. As long as there is some
glue and the entire surface is covered on both pieces, lets it all
squeeze out. The science of glue dictates that there need not be any
excess glue on the actual surface of the wood, but only what has been
absorbed into the fibers.


--

-MIKE-

"Playing is not something I do at night, it's my function in life"
--Elvin Jones (1927-2004)
--
http://mikedrums.com

---remove "DOT" ^^^^ to reply

On Sun, 27 Oct 2013 15:09:38 -0700, CW wrote:

Not saying that glue creep doesnt happen but I've never seen it. I have
a few pieces that my father built in Japan in the mid 70s.

I have no idea what kind of glue your father used. It doesn't make any
difference unless the conditions we've been talking about here exist.
That's a situation where the pieces of wood are under strain in reference
to each other and the glue is the only restraint.

Any of that furniture have bent laminations in it?

--
This message was for rec.woodworking - if it appears in homeownershub
they ripped it off.

-MIKE- wrote:


I agree with this and it's been my experience. As long as there is
some glue and the entire surface is covered on both pieces, lets it
all squeeze out. The science of glue dictates that there need not be
any excess glue on the actual surface of the wood, but only what has
been absorbed into the fibers.

I am not disagreeing with you at all Mike, but I am going to raise a
question that is relevant to conversations in this group. We suffer lots of
people talking about "science' when in fact there is no science behind the
claims they make. Not accusing you of that but I would ask you what the
science is you make reference to.

--

-Mike-

On 10/27/13 8:56 PM, Mike Marlow wrote:
-MIKE- wrote:


I agree with this and it's been my experience. As long as there is
some glue and the entire surface is covered on both pieces, lets it
all squeeze out. The science of glue dictates that there need not be
any excess glue on the actual surface of the wood, but only what has
been absorbed into the fibers.

I am not disagreeing with you at all Mike, but I am going to raise a
question that is relevant to conversations in this group. We suffer lots of
people talking about "science' when in fact there is no science behind the
claims they make. Not accusing you of that but I would ask you what the
science is you make reference to.


I completely understand, Mike. It's a tough order and I'll see what I
can come up with.
This was something I read in print years ago (in school, perhaps) and
not on the internet. But I'll look around a see what I can find.

As a further explanation, I'll try to paraphrase. The glue, itself, is
not what has the strength. It's the way the glue acts in concert with
the wood fibers that is the key to the strength.

For example, lets say you had a glue joint that contained a section of
cured glue between the wood that prevented the wood fibers from
touching. To exaggerate, lets say it was 1/8" strip of cured glue. That
joint would be much weaker than a [quote] glue-starved [end-quote] joint
in which the glue was fully applied to both surfaces but all excess glue
was squeezed out by very tight clamping.

The wood fibers grabbing each other (for lack of better words) and being
cured together with the glue is what gives the strength to the joint.

Now, I'm quite certain the textbook or article i read that explained
this did a much better job than I just did and I'll do what I can to
look it up in the web.


--

-MIKE-

"Playing is not something I do at night, it's my function in life"
--Elvin Jones (1927-2004)
--
http://mikedrums.com

---remove "DOT" ^^^^ to reply

On 10/27/2013 5:52 PM, CW wrote:
"Mike Marlow" wrote in message ...

dpb wrote:
On 10/27/2013 10:06 AM, scritch wrote:
Thinner gluelines are better for minimizing the effect because
there's less bulk material there. Which is why higher clamping
pressure is _a_good_thing_ (tm) besides the empirical observation
from testing that it improves ultimate joint bond strength.

...

"Fine Woodworking" magazine did a clamping pressure vs. strength test
some years ago and found that in almost all case, more pressure was
better. Reading that article changed my clamping life and my joints
are much better than they used to be.

I recall it...and it only confirmed what previous work at US Forest
Products Lab and elsewhere has shown...

Only to a point though... correct? Everything I've ever heard was that
there is a point where too much pressure will squeeze out too much glue
which will result in a weakened joint. Maybe that has been proven not
to be
true, but based on that, I generally clamp until I begin to get squeeze out
and maybe give it a little more tweak for good measure, but stop at that
point. That said, I spread my glue and try to avoid excess glue on the
surface prior to clamping. This is one area where I do not agree with
things I've seen Brian do in his videos. He likes to lay on the glue!
================================================== ======================================

The Titebond website says clamping pressure up to 250 PSI should be
used. I don't think home woodworkers have to be concerned about over
clamping.



I put as much pressure as I can into the joint. The glue will go into
the wood as well. the more squeeze out the thinner the amount of glue in
the joint.. And that's perfect.

--
Jeff

On 10/27/2013 8:56 PM, Mike Marlow wrote:
-MIKE- wrote:


I agree with this and it's been my experience. As long as there is
some glue and the entire surface is covered on both pieces, lets it
all squeeze out. The science of glue dictates that there need not be
any excess glue on the actual surface of the wood, but only what has
been absorbed into the fibers.

I am not disagreeing with you at all Mike, but I am going to raise a
question that is relevant to conversations in this group. We suffer lots of
people talking about "science' when in fact there is no science behind the
claims they make. Not accusing you of that but I would ask you what the
science is you make reference to.



Many years ago, in shop class we never used premixed glue, we used
WeldWood. We clamped the bujeezus out of every thing we glued up.
Almost with out fail there was a popping sound when unclamping the wood.

With the more modern wood glues that we use today I have not witnessed
this popping sound when unclamping.

I have to think that the popping sound was a spot that might have not
been properly covered with glue and or a portion of the glue that was
improperly mixed. Nothing ever came apart what ever the case.

Either way, with the modern glues and for the past 35 years I have not
had a joint fail because of it being clamped too tightly. That is not
scientific but is a result of countless gallons of glue having been used
on hundreds of projects.

I look at squeeze out as collateral damage. It is wasted glue but a
good indicator that the joint was properly closed and I apply pressure
until I see squeeze out, and most often more than that. ;~)

woodchucker wrote in
:

I put as much pressure as I can into the joint. The glue will go into
the wood as well. the more squeeze out the thinner the amount of glue
in the joint.. And that's perfect.


Sometimes I get boards that want to lift in the middle during a glue-up.
That tends to limit the amount of pressure I can apply. What can I do to
keep this from happening as I tighten the clamps?

Puckdropper
--
Make it to fit, don't make it fit.

On 10/27/13 10:41 PM, Puckdropper wrote:
woodchucker wrote in
:

I put as much pressure as I can into the joint. The glue will go into
the wood as well. the more squeeze out the thinner the amount of glue
in the joint.. And that's perfect.


Sometimes I get boards that want to lift in the middle during a glue-up.
That tends to limit the amount of pressure I can apply. What can I do to
keep this from happening as I tighten the clamps?

Puckdropper


Some guys will use cauls across the board to help with alignment. Those
would keep that from happening. I usually just find a decent sized tool
box or something similar to set on top of the boards.

This system would prevent it, as well.
http://www.woodcraft.com/product/2000321/1858/woodriver-clamping-system.aspx


--

-MIKE-

"Playing is not something I do at night, it's my function in life"
--Elvin Jones (1927-2004)
--
http://mikedrums.com

---remove "DOT" ^^^^ to reply

On 10/27/2013 8:56 PM, Mike Marlow wrote:
....

I am not disagreeing with you at all Mike, but I am going to raise a
question that is relevant to conversations in this group. We suffer lots of
people talking about "science' when in fact there is no science behind the
claims they make. Not accusing you of that but I would ask you what the
science is you make reference to.

There's a whole field of adhesives science for wood as well as for
everything else -- read at US Forest Products Laboratory a little for
just some as well as at many of the universities with forest products
research areas. Then, of course, the manufacturers do research and
development on their own as well.

You just missed an international conference ...

http://www.forestprod.org/woodadhesives/index-2a.html

Or, take a look at a search at amazon...

http://books.google.com/books/about/Wood_Adhesives.html?id=y443r1zAnH8C

There's plenty of science involved as well as empirical testing.

--

dpb wrote:
On 10/27/2013 8:56 PM, Mike Marlow wrote:
...

I am not disagreeing with you at all Mike, but I am going to raise a
question that is relevant to conversations in this group. We suffer
lots of people talking about "science' when in fact there is no
science behind the claims they make. Not accusing you of that but I
would ask you what the science is you make reference to.

There's a whole field of adhesives science for wood as well as for
everything else -- read at US Forest Products Laboratory a little for
just some as well as at many of the universities with forest products
research areas. Then, of course, the manufacturers do research and
development on their own as well.

You just missed an international conference ...

http://www.forestprod.org/woodadhesives/index-2a.html

Or, take a look at a search at amazon...

http://books.google.com/books/about/Wood_Adhesives.html?id=y443r1zAnH8C

There's plenty of science involved as well as empirical testing.

Oh - no doubt there is a great deal of science behind the development of
wood glues. That was not my question to -Mike-.

--

-Mike-

"Puckdropper" wrote:

Sometimes I get boards that want to lift in the middle during a
glue-up.
That tends to limit the amount of pressure I can apply. What can I
do to
keep this from happening as I tighten the clamps?

--------------------------------------------
Sounds like cauls would solve your problem.

Lew

On 10/27/2013 11:55 PM, Mike Marlow wrote:
....

Oh - no doubt there is a great deal of science behind the development of
wood glues. That was not my question to -Mike-.

Oh, I missed what caught your attention...I don't think that's quite
what the article/text he read probably said, exactly...

Here's a link to a pretty good exposition from US FPL. I _know_ I've
seen a report there that had extensive lab test data on ultimate bond
strength vs clamping pressures but I can't seem to find it at the
moment. This author doesn't include such data and does comment that
starving a joint is possible but he's mostly worried about the porosity
"sucking up" too much and moving it away from the joint internally
rather than squeeze-out if there's insufficient available.

But, it does have excellent discussion of the chemistry/mechanical
bonding processes...

http://www.fpl.fs.fed.us/documnts/pdf1991/river91a.pdf

If you've not spent some time poking around the US FPL website, it's
well worth a few afternoons on otherwise dull days for anybody...the
Handbook is invaluable to at least know of its existence.

--

On 10/27/2013 10:41 PM, Puckdropper wrote:
woodchucker wrote in
:

I put as much pressure as I can into the joint. The glue will go into
the wood as well. the more squeeze out the thinner the amount of glue
in the joint.. And that's perfect.


Sometimes I get boards that want to lift in the middle during a glue-up.
That tends to limit the amount of pressure I can apply. What can I do to
keep this from happening as I tighten the clamps?

Puckdropper


If the pieces are flat to begin with and you have a problem with the
pieces slipping when pressure is applied you can shoot pins or brads
through a piece of card board into one edge. the slight protruding pin
or brad sill engage the mating piece and not let the pieces slide during
clamping.

"Puckdropper" puckdropper(at)yahoo(dot)com wrote in
message

Sometimes I get boards that want to lift in the middle
during a glue-up. That tends to limit the amount of
pressure I can apply. What can I do to keep this from
happening as I tighten the clamps?

One reason for that is that the clamps aren't centered on the edges; i.e.,
they are - in your example - set so they are applying pressure toward the
bottoms of the edges. Try being careful as to where the pressure is on the
edge. Despite that care, they may still want to buckle especially if the
edges are less than perfect 90 degree angls to the faces.

A general cure is to apply clamps across both faces, i.e., to both top and
bottom and tighten differentially while checking the faces with a straight
edge.



--

dadiOH
____________________________

Winters getting colder? Tired of the rat race?
Taxes out of hand? Maybe just ready for a change?
Check it out... http://www.floridaloghouse.net

On 10/27/2013 10:41 PM, Puckdropper wrote:

Sometimes I get boards that want to lift in the middle during a glue-up.
That tends to limit the amount of pressure I can apply. What can I do to
keep this from happening as I tighten the clamps?

Something like these "clamp assists" I made are helpful and easy to make:

https://picasaweb.google.com/1113554...19809590270898

Or, whatever it takes:

https://picasaweb.google.com/1113554...19809463542642


--
eWoodShop: www.eWoodShop.com
Wood Shop: www.e-WoodShop.net
https://plus.google.com/114902129577517371552/posts
http://www.custommade.com/by/ewoodshop/
KarlCaillouet@ (the obvious)

On 10/28/2013 9:59 AM, Swingman wrote:
On 10/27/2013 10:41 PM, Puckdropper wrote:

Sometimes I get boards that want to lift in the middle during a glue-up.
That tends to limit the amount of pressure I can apply. What can I
do to
keep this from happening as I tighten the clamps?

Something like these "clamp assists" I made are helpful and easy to make:

https://picasaweb.google.com/1113554...19809590270898


Or, whatever it takes:

https://picasaweb.google.com/1113554...19809463542642

**** Google and their damned redirects to what they want you to see:

https://picasaweb.google.com/lh/phot...t=d irectlink

https://picasaweb.google.com/lh/phot...t=d irectlink

--
eWoodShop: www.eWoodShop.com
Wood Shop: www.e-WoodShop.net
https://plus.google.com/114902129577517371552/posts
http://www.custommade.com/by/ewoodshop/
KarlCaillouet@ (the obvious)

On 10/28/2013 8:28 AM, dpb wrote:
....

... I've
seen a report there that had extensive lab test data on ultimate bond
strength vs clamping pressures but I can't seem to find it at the
moment. This author doesn't include such data ...

BTW, these data are/were prepared for the purposes of commercial
production purposes, _NOT_ one-of-a-kind manual glue-ups as is normally
thought of/practiced here. Consequently what are "high" pressures are
well beyond what is achieved by the application of a few bar clamps and
manual tightening.

And, of course, don't forget when looking at numbers that the
denominator in 'psi' is in inches and so has a multiplicative effect for
thickness under an inch -- it takes a 4/3-inch in length to counteract
3/4" thickness so that force when converted to psi ends up with higher
numerical values than one might expect will be quite easily if don't
actually think thru the numbers.


--

On 10/27/2013 10:41 PM, Puckdropper wrote:
wrote in
:

I put as much pressure as I can into the joint. The glue will go into
the wood as well. the more squeeze out the thinner the amount of glue
in the joint.. And that's perfect.


Sometimes I get boards that want to lift in the middle during a glue-up.
That tends to limit the amount of pressure I can apply. What can I do to
keep this from happening as I tighten the clamps?

Which is where for longer pieces running them over a glue joint profile
is really the cat's meow--not only does it give the alignment firmly it
adds to the surface joint area...

--

dpb wrote:
On 10/27/2013 11:55 PM, Mike Marlow wrote:
...

Oh - no doubt there is a great deal of science behind the
development of wood glues. That was not my question to -Mike-.

Oh, I missed what caught your attention...I don't think that's quite
what the article/text he read probably said, exactly...

It happens in newsgroups...


Here's a link to a pretty good exposition from US FPL. I _know_ I've
seen a report there that had extensive lab test data on ultimate bond
strength vs clamping pressures but I can't seem to find it at the
moment. This author doesn't include such data and does comment that
starving a joint is possible but he's mostly worried about the
porosity "sucking up" too much and moving it away from the joint
internally rather than squeeze-out if there's insufficient available.

But, it does have excellent discussion of the chemistry/mechanical
bonding processes...

http://www.fpl.fs.fed.us/documnts/pdf1991/river91a.pdf

If you've not spent some time poking around the US FPL website, it's
well worth a few afternoons on otherwise dull days for anybody...the
Handbook is invaluable to at least know of its existence.

Just what I need - another interesting distraction! You really had to go
and do that didn't you? You just know where I'll be tonight...


--

-Mike-

Swingman wrote:


**** Google and their damned redirects to what they want you to see:

Agreed!


https://picasaweb.google.com/lh/phot...t=d irectlink

****-hot, Karl - I like that idea! Clever. Simple, Obvious. Well, maybe
not so obvious or I would have know about it long ago. I'm stealing that
idea from you brotha.



--

-Mike-