Edge Joining Plywood
 

Rather than having to buy a whole sheet of plywood just to extend a small piece an inch or so, I decided to edge join fill and sand, before painting, since it the piece will be in a non-load bearing position at the roof of a cabinet.

Can I get recommendations on the best way between the following three pictured examples to go with?

http://i290.photobucket.com/albums/l...ingPlywood.jpg

(I'm trying to keep this simple and fast).

Thanks.

Darren Harris
Staten Island, New York.

Edge Joining Plywood
 

On 11/21/2012 1:56 PM, wrote:
Rather than having to buy a whole sheet of plywood just to extend a small piece an inch or so, I decided to edge join fill and sand, before painting, since it the piece will be in a non-load bearing position at the roof of a cabinet.

Can I get recommendations on the best way between the following three pictured examples to go with?

http://i290.photobucket.com/albums/l...ingPlywood.jpg

(I'm trying to keep this simple and fast).

Thanks.

Darren Harris
Staten Island, New York.


b

a&c probably won't work, unless you use a very extended overlap (like
many inches at least).

Edge Joining Plywood
 

On Wednesday, November 21, 2012 4:00:06 PM UTC-5, chaniarts wrote:
On 11/21/2012 1:56 PM, wrote:

Rather than having to buy a whole sheet of plywood just to extend a small piece an inch or so, I decided to edge join fill and sand, before painting, since it the piece will be in a non-load bearing position at the roof of a cabinet.



Can I get recommendations on the best way between the following three pictured examples to go with?



http://i290.photobucket.com/albums/l...ingPlywood.jpg



(I'm trying to keep this simple and fast).



Thanks.



Darren Harris

Staten Island, New York.





b



a&c probably won't work, unless you use a very extended overlap (like

many inches at least).

I was afraid someone would say that.

Ok. In order to accomplish "B", let's say I grab my 1/4" slot cutting bit and make the slot in the edge of the main piece.

I then slide a 1/4" piece or hardwood into that slot and lay my router on top of the main piece in a position that will allow a 1/2" diameter straight bit (I don't think I have a Rabbeting bit) to rest on the hardwood before tightening it up to get the depth accurate. (And then route and do the same for the bottom).

Would that work?

Thanks.

Darren Harris
Staten Island, New York.

Edge Joining Plywood
 

On 11/21/12 2:56 PM, wrote:
Rather than having to buy a whole sheet of plywood just to extend a
small piece an inch or so, I decided to edge join fill and sand, before
painting, since it the piece will be in a non-load bearing position at
the roof of a cabinet.

Can I get recommendations on the best way between the following
three
pictured examples to go with?

http://i290.photobucket.com/albums/l...ingPlywood.jpg

(I'm trying to keep this simple and fast).

Thanks.

Darren Harris
Staten Island, New York.


None of the above. Just a simple butt joint. You can make the solid wood
piece a bit thicker and then trim it flush with a pattern bit in a
router table.

Or you can cut the pieces the same thickness and used some scrap pieces
with wax paper to keep the edges aligned while clamping. You can also
use pocket holes and screws.

I've done probably a couple hundred feet of this and I've tried all the
fancy bit and edge joints and techniques and biscuits and every other
what-not you see and hear about. What I settled on was simple butt
joints, and flush trimming with the router. It's the fastest, easiest,
and plenty strong enough. The glue is stronger than the plywood.


--

-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

Edge Joining Plywood
 

wrote:
Rather than having to buy a whole sheet of plywood just to extend a
small piece an inch or so, I decided to edge join fill and sand,
before painting, since it the piece will be in a non-load bearing
position at the roof of a cabinet.

Can I get recommendations on the best way between the following three
pictured examples to go with?

http://i290.photobucket.com/albums/l...ingPlywood.jpg

(I'm trying to keep this simple and fast).

For what you want, any will work. Of the three you show, I'd probably do
the first.

Other options: spline, biscuits, "V", butt. A butt joint would do fine
especially if you used thickened epoxy as the glue; no need to clamp even,
just push together and leave alone for a day.


--

dadiOH
____________________________

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

Edge Joining Plywood
 

On 11/21/2012 2:56 PM, wrote:

Can I get recommendations on the best way between the following three pictured examples to go with?

What -MIKE- says, "none of the above" ... glue it up just as you would a
panel, with a butt joint.

The only way I would differ would be to use biscuits, mainly because it
makes it easier to align the faces, thus making it unnecessary to do any
sanding and risk destroying the veneer, and I own a biscuit jointer.

I have made many a plywood panel wider/longer by doing the above simply
by using cutoff's from the same sheet ... and by doing so, most of the
time you can't even see the join in the finished part.

--
www.eWoodShop.com
Last update: 4/15/2010
KarlCaillouet@ (the obvious)
http://gplus.to/eWoodShop

Edge Joining Plywood
 

On Wednesday, November 21, 2012 5:00:50 PM UTC-5, Swingman wrote:
On 11/21/2012 2:56 PM, wrote:



Can I get recommendations on the best way between the following three pictured examples to go with?



What -MIKE- says, "none of the above" ... glue it up just as you would a

panel, with a butt joint.



The only way I would differ would be to use biscuits, mainly because it

makes it easier to align the faces, thus making it unnecessary to do any

sanding and risk destroying the veneer, and I own a biscuit jointer.



I have made many a plywood panel wider/longer by doing the above simply

by using cutoff's from the same sheet ... and by doing so, most of the

time you can't even see the join in the finished part.

Thanks everyone.

What was confusing me was the "butt joint". All the butt joints I've seen were with hardwood, and the joint was at a 45° angle.

It sounds like you are saying to just put glue on the edges of both plywood pieces and clamp them together. (No routing necessary).

Darren Harris
Staten Island, New York.

Edge Joining Plywood
 

On 11/21/2012 4:10 PM, wrote:
What was confusing me was the "butt joint". All the butt joints I've seen were with hardwood, and the joint was at a 45° angle.

Technically, what you describe above is generally known as a "scarf" joint.

It sounds like you are saying to just put glue on the edges of both plywood pieces and clamp them together. (No routing necessary).

That's exactly what we're saying. :)

--
www.eWoodShop.com
Last update: 4/15/2010
KarlCaillouet@ (the obvious)
http://gplus.to/eWoodShop

Edge Joining Plywood
 

On 11/21/12 4:10 PM, wrote:
On Wednesday, November 21, 2012 5:00:50 PM UTC-5, Swingman wrote:
On 11/21/2012 2:56 PM, wrote:



Can I get recommendations on the best way between the following three pictured examples to go with?



What -MIKE- says, "none of the above" ... glue it up just as you would a

panel, with a butt joint.



The only way I would differ would be to use biscuits, mainly because it

makes it easier to align the faces, thus making it unnecessary to do any

sanding and risk destroying the veneer, and I own a biscuit jointer.



I have made many a plywood panel wider/longer by doing the above simply

by using cutoff's from the same sheet ... and by doing so, most of the

time you can't even see the join in the finished part.

Thanks everyone.

What was confusing me was the "butt joint". All the butt joints I've seen were with hardwood, and the joint was at a 45° angle.

It sounds like you are saying to just put glue on the edges of both plywood pieces and clamp them together. (No routing necessary).

Darren Harris
Staten Island, New York.


Yes. We like to make rocket science out of this stuff... and the people
selling specialty jig and bit like to, as well. :-)

If you don't have a lot to do and can take your time, you can figure out
a way to help line up and hold the joint so it it perfectly flush. I
have a bunch of harbor freight wide mouth vise-grip clamps that work
great for this. But often it's just a matter of taking the time to make
sure it's flush as you're clamping. The problem with doing it "freehand"
is that your solid wood piece has often warped a bit and won't line up
along the entire length of plywood without some encouragement: clamps.
But it can be done.

Like I wrote, having a router table makes the whole process much faster
and stress free. If you have one, make the pieces thinker than the
plywood and flush cut it with a pattern bit. If not, do your best and
trim by sanding or a VERY sharp plane. -- advanced technique, very easy
to f@C# up. :-)


--

-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

Edge Joining Plywood
 

On 11/21/12 4:14 PM, Swingman wrote:
On 11/21/2012 4:10 PM, wrote:
What was confusing me was the "butt joint". All the butt joints I've
seen were with hardwood, and the joint was at a 45° angle.

Technically, what you describe above is generally known as a "scarf" joint.

It sounds like you are saying to just put glue on the edges of both
plywood pieces and clamp them together. (No routing necessary).

That's exactly what we're saying. :)


You are much more succinct that I.


--

-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

Edge Joining Plywood
 

On 11/21/2012 3:56 PM, wrote:
Rather than having to buy a whole sheet of plywood just to extend a small piece an inch or so, I decided to edge join fill and sand, before painting, since it the piece will be in a non-load bearing position at the roof of a cabinet.

Can I get recommendations on the best way between the following three pictured examples to go with?

http://i290.photobucket.com/albums/l...ingPlywood.jpg

(I'm trying to keep this simple and fast).

Thanks.

Darren Harris
Staten Island, New York.


I would think A would be best.

Edge Joining Plywood
 

On Nov 21, 3:56*pm, wrote:
Rather than having to buy a whole sheet of plywood just to extend a small piece an inch or so, I decided to edge join fill and sand, before painting, since it the piece will be in a non-load bearing position at the roof of a cabinet.

Can I get recommendations on the best way between the following three pictured examples to go with?

http://i290.photobucket.com/albums/l.../Woodworking%2...

(I'm trying to keep this simple and fast).

Biscuits or splines.

Edge Joining Plywood
 

On Wednesday, November 21, 2012 5:31:07 PM UTC-5, -MIKE- wrote:
On 11/21/12 4:10 PM, wrote:

On Wednesday, November 21, 2012 5:00:50 PM UTC-5, Swingman wrote:

On 11/21/2012 2:56 PM, wrote:







Can I get recommendations on the best way between the following three pictured examples to go with?







What -MIKE- says, "none of the above" ... glue it up just as you would a



panel, with a butt joint.







The only way I would differ would be to use biscuits, mainly because it



makes it easier to align the faces, thus making it unnecessary to do any



sanding and risk destroying the veneer, and I own a biscuit jointer.







I have made many a plywood panel wider/longer by doing the above simply



by using cutoff's from the same sheet ... and by doing so, most of the



time you can't even see the join in the finished part.



Thanks everyone.



What was confusing me was the "butt joint". All the butt joints I've seen were with hardwood, and the joint was at a 45° angle.



It sounds like you are saying to just put glue on the edges of both plywood pieces and clamp them together. (No routing necessary).



Darren Harris

Staten Island, New York.





Yes. We like to make rocket science out of this stuff... and the people

selling specialty jig and bit like to, as well. :-)



If you don't have a lot to do and can take your time, you can figure out

a way to help line up and hold the joint so it it perfectly flush. I

have a bunch of harbor freight wide mouth vise-grip clamps that work

great for this. But often it's just a matter of taking the time to make

sure it's flush as you're clamping. The problem with doing it "freehand"

is that your solid wood piece has often warped a bit and won't line up

along the entire length of plywood without some encouragement: clamps.

But it can be done.



Like I wrote, having a router table makes the whole process much faster

and stress free. If you have one, make the pieces thinker than the

plywood and flush cut it with a pattern bit. If not, do your best and

trim by sanding or a VERY sharp plane. -- advanced technique, very easy

to f@C# up. :-)

The problem was that you keep using the term "solid wood" which I've always equated to mean *hardwood*, which of course is not what I'm working with.

Thanks.

Darren Harris
Staten Island, New York

Edge Joining Plywood
 

On 11/21/2012 4:46 PM, wrote:
The problem was that you keep using the term "solid wood" which I've always equated to mean*hardwood*, which of course is not what I'm working with.

Although the technique is identical, I think Mike is focusing on what is
akin to "edge banding" plywood with hardwood.

If I understand you correctly, you're just trying to add a bit of length
to some too short plywood, with another piece of plywood.

Basic methodology is the same either way ... a glued "butt" joint.

--
www.eWoodShop.com
Last update: 4/15/2010
KarlCaillouet@ (the obvious)
http://gplus.to/eWoodShop

Edge Joining Plywood
 

wrote in
:

Rather than having to buy a whole sheet of plywood just to
extend a small piece an inch or so, I decided to edge join fill
and sand, before painting, since it the piece will be in a
non-load bearing position at the roof of a cabinet.

Can I get recommendations on the best way between the following
three pictured examples to go with?

http://i290.photobucket.com/albums/l...nder/Woodworki
ng%20Projects/EdgeJoiningPlywood.jpg

I agree with the others who think that neither option A nor C will
work.

If you need to extend it by only "an inch or so", then IMO your
best bet is option B *twice*: add half the extension at each end.
It'll look like you planned it that way.

Edge Joining Plywood
 

On Wed, 21 Nov 2012 13:23:07 -0800 (PST),
wrote:

On Wednesday, November 21, 2012 4:00:06 PM UTC-5, chaniarts wrote:
On 11/21/2012 1:56 PM, wrote:

Rather than having to buy a whole sheet of plywood just to extend a small piece an inch or so, I decided to edge join fill and sand, before painting, since it the piece will be in a non-load bearing position at the roof of a cabinet.



Can I get recommendations on the best way between the following three pictured examples to go with?



http://i290.photobucket.com/albums/l...ingPlywood.jpg



(I'm trying to keep this simple and fast).



Thanks.



Darren Harris

Staten Island, New York.





b



a&c probably won't work, unless you use a very extended overlap (like

many inches at least).

I was afraid someone would say that.

Ok. In order to accomplish "B", let's say I grab my 1/4" slot cutting bit and make the slot in the edge of the main piece.

I then slide a 1/4" piece or hardwood into that slot and lay my router on top of the main piece in a position that will allow a 1/2" diameter straight bit (I don't think I have a Rabbeting bit) to rest on the hardwood before tightening it up to get the depth accurate. (And then route and do the same for the bottom).

Would that work?

Thanks.

Darren Harris
Staten Island, New York.
If you got the slot cutter, why not slot both pieces and make a
spline? No fussy set-up for the router for a second cut and plenty
strong enough.

Edge Joining Plywood
 

On 11/21/12 4:46 PM, wrote:
On Wednesday, November 21, 2012 5:31:07 PM UTC-5, -MIKE- wrote:
On 11/21/12 4:10 PM, wrote:

On Wednesday, November 21, 2012 5:00:50 PM UTC-5, Swingman wrote:

On 11/21/2012 2:56 PM, wrote:







Can I get recommendations on the best way between the following three pictured examples to go with?







What -MIKE- says, "none of the above" ... glue it up just as you would a



panel, with a butt joint.







The only way I would differ would be to use biscuits, mainly because it



makes it easier to align the faces, thus making it unnecessary to do any



sanding and risk destroying the veneer, and I own a biscuit jointer.







I have made many a plywood panel wider/longer by doing the above simply



by using cutoff's from the same sheet ... and by doing so, most of the



time you can't even see the join in the finished part.



Thanks everyone.



What was confusing me was the "butt joint". All the butt joints I've seen were with hardwood, and the joint was at a 45° angle.



It sounds like you are saying to just put glue on the edges of both plywood pieces and clamp them together. (No routing necessary).



Darren Harris

Staten Island, New York.





Yes. We like to make rocket science out of this stuff... and the people

selling specialty jig and bit like to, as well. :-)



If you don't have a lot to do and can take your time, you can figure out

a way to help line up and hold the joint so it it perfectly flush. I

have a bunch of harbor freight wide mouth vise-grip clamps that work

great for this. But often it's just a matter of taking the time to make

sure it's flush as you're clamping. The problem with doing it "freehand"

is that your solid wood piece has often warped a bit and won't line up

along the entire length of plywood without some encouragement: clamps.

But it can be done.



Like I wrote, having a router table makes the whole process much faster

and stress free. If you have one, make the pieces thinker than the

plywood and flush cut it with a pattern bit. If not, do your best and

trim by sanding or a VERY sharp plane. -- advanced technique, very easy

to f@C# up. :-)

The problem was that you keep using the term "solid wood" which I've always equated to mean *hardwood*, which of course is not what I'm working with.

Thanks.

Darren Harris
Staten Island, New York


So, you now realize that everything I've been describing does just as
well with any and all woods, correct?


--

-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

Edge Joining Plywood
 

On 11/21/12 4:53 PM, Swingman wrote:
On 11/21/2012 4:46 PM, wrote:
The problem was that you keep using the term "solid wood" which I've
always equated to mean*hardwood*, which of course is not what I'm
working with.

Although the technique is identical, I think Mike is focusing on what is
akin to "edge banding" plywood with hardwood.

If I understand you correctly, you're just trying to add a bit of length
to some too short plywood, with another piece of plywood.

Basic methodology is the same either way ... a glued "butt" joint.


Oh, OK. I must've glanced over the part about doing a plywood to
plywood joint.

In that case, I reiterate everything I wrote? :-) A butted glue joint,
plywood to plywood, will be even stronger than to solid wood, because
the expansion rates will be equal.


--

-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

Edge Joining Plywood
 

On 11/21/2012 8:43 PM, -MIKE- wrote:
On 11/21/12 4:53 PM, Swingman wrote:
On 11/21/2012 4:46 PM, wrote:
The problem was that you keep using the term "solid wood" which I've
always equated to mean*hardwood*, which of course is not what I'm
working with.

Although the technique is identical, I think Mike is focusing on what is
akin to "edge banding" plywood with hardwood.

If I understand you correctly, you're just trying to add a bit of length
to some too short plywood, with another piece of plywood.

Basic methodology is the same either way ... a glued "butt" joint.


Oh, OK. I must've glanced over the part about doing a plywood to plywood
joint.

In that case, I reiterate everything I wrote? :-) A butted glue joint,
plywood to plywood, will be even stronger than to solid wood, because
the expansion rates will be equal.



Nonsense.

A scarfed joint maybe.
But a butt joint?
No way.

Edge Joining Plywood
 

On 11/21/12 11:02 PM, Richard wrote:
On 11/21/2012 8:43 PM, -MIKE- wrote:
On 11/21/12 4:53 PM, Swingman wrote:
On 11/21/2012 4:46 PM, wrote:
The problem was that you keep using the term "solid wood" which I've
always equated to mean*hardwood*, which of course is not what I'm
working with.

Although the technique is identical, I think Mike is focusing on what is
akin to "edge banding" plywood with hardwood.

If I understand you correctly, you're just trying to add a bit of length
to some too short plywood, with another piece of plywood.

Basic methodology is the same either way ... a glued "butt" joint.


Oh, OK. I must've glanced over the part about doing a plywood to plywood
joint.

In that case, I reiterate everything I wrote? :-) A butted glue joint,
plywood to plywood, will be even stronger than to solid wood, because
the expansion rates will be equal.



Nonsense.

A scarfed joint maybe.
But a butt joint?
No way.

Are you going to back this up with any facts or just run away?
Spouting off an opinion without backing it up is what is nonsense.

The glue will be stronger than the plywood. More surface area would be
unnecessarily redundant. He already said it is non load bearing, so even
more reason to do the simplest technique. However, even if it was load
bearing, the glue joint would be stronger than the plywood.


--

-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

Edge Joining Plywood
 

On Wed, 21 Nov 2012 23:35:09 -0600, -MIKE-
The glue will be stronger than the plywood. More surface area would be
unnecessarily redundant. He already said it is non load bearing, so even
more reason to do the simplest technique. However, even if it was load
bearing, the glue joint would be stronger than the plywood.

Yeah, but it's plywood which has a tendency to separate when force is
applied to the slices ~ as compared to most any hardwood which does
not.

I'm not going to label it nonsense, but I am highly dubious of glued
butt joined plywood being able to withstand most any flexing or
shearing force.

Edge Joining Plywood
 

Dave wrote:

I'm not going to label it nonsense, but I am highly dubious of glued
butt joined plywood being able to withstand most any flexing or
shearing force.

Problem is that those expressing doubt are not speaking from any experience
for the application.

Try it as I stated, with biscuits (or spline or domino) and your
dubiousness will evaporate, most particularly when considering the OP's
very clearly stated intended use ... a guaranteed fix for that
circumstance.

Have simply done it too many times myself ...

--
www.ewoodshop.com (Mobile)

Edge Joining Plywood
 

On Thu, 22 Nov 2012 07:41:48 -0600, Swingman wrote:
Problem is that those expressing doubt are not speaking from any experience
for the application.

Ok, I hadn't read the OP's original message.

Edge Joining Plywood
 

On 11/22/2012 3:11 AM, Dave wrote:
On Wed, 21 Nov 2012 23:35:09 -0600,
The glue will be stronger than the plywood. More surface area would be
unnecessarily redundant. He already said it is non load bearing, so even
more reason to do the simplest technique. However, even if it was load
bearing, the glue joint would be stronger than the plywood.

Yeah, but it's plywood which has a tendency to separate when force is
applied to the slices ~ as compared to most any hardwood which does
not.

I'm not going to label it nonsense, but I am highly dubious of glued
butt joined plywood being able to withstand most any flexing or
shearing force.

It'll have about half the strength of the same thickness of solid
lumber--essentially forget about the end grain plies and only consider
the plies w/ long grain as being the effective thickness of the material.

That's not exact because there is some plus from the endgrain section
but there's also a counter effect that the small sections of edge grain
aren't connected. I've seen some test data from like Purdue or the
Forest Products Lab or somesuch place but a quick search didn't locate
it this morning...

But, for the OPs purpose it'll work perfectly well...

--

Edge Joining Plywood
 

On Thu, 22 Nov 2012 08:40:33 -0600, dpb wrote:
It'll have about half the strength of the same thickness of solid
lumber--essentially forget about the end grain plies and only consider
the plies w/ long grain as being the effective thickness of the material.

Ok, I hadn't read the original message. I'll concede the intended
attachment of such a thin piece should be ok, whatever method you use
to attach it.

Edge Joining Plywood
 

On 11/22/2012 8:44 AM, Dave wrote:
On Thu, 22 Nov 2012 08:40:33 -0600, dpb wrote:
It'll have about half the strength of the same thickness of solid
lumber--essentially forget about the end grain plies and only consider
the plies w/ long grain as being the effective thickness of the material.

Ok, I hadn't read the original message. I'll concede the intended
attachment of such a thin piece should be ok, whatever method you use
to attach it.

It does not necessarily have to be "thin". There is generally more
strength in a glued plywood butt joint than most would suspect, even
plywood to plywood, as was under discussion.

The overriding requirement is that there be sufficient strength to stand
the test of time _for the purpose intended_ ... much like using pocket
hole joinery for face frames - just the right amount of strength for the
task at hand

Were there not usable strength to be had from an edge glued plywood
joint because of the orientation of the plys, plywood would be much less
useful for any number of uses that are routinely considered practical.

IOW, joints such as this, or any framing of plywood with other material,
that are considered entirely practical, would not be so:

http://e-woodshop.net/images/StackedTansu4.JPG

That said, I would not expect to butt joint/glue two 3/4 x 48 x 48
panels of plywood and expect that join to be in the middle of an
unsupported span to be as strong as a single 4 x 8 sheet.

However, reinforce that same span, with even minnimal support
perpendicular to the plywood to plywood butt jointed join, and for all
practical purposes the fact the plywood is made from two butt jointed
panels becomes of much less concern.

I have saved many a not-wide/long-enough end panel/cabinet part from the
scrap pile by butt joining plywood where any downside from a weaker part
is of absolutely no concern ... just as the OP pondered.

IOW, it's all in the application ... :)

--
www.eWoodShop.com
Last update: 4/15/2010
KarlCaillouet@ (the obvious)
http://gplus.to/eWoodShop

Edge Joining Plywood
 

-MIKE- wrote:
On 11/21/12 4:10 PM, wrote:
On Wednesday, November 21, 2012 5:00:50 PM UTC-5, Swingman wrote:
On 11/21/2012 2:56 PM, wrote:



Can I get recommendations on the best way between the following
three pictured examples to go with?



What -MIKE- says, "none of the above" ... glue it up just as you
would a panel, with a butt joint.



The only way I would differ would be to use biscuits, mainly
because it makes it easier to align the faces, thus making it
unnecessary to
do any sanding and risk destroying the veneer, and I own a biscuit
jointer.



I have made many a plywood panel wider/longer by doing the above
simply by using cutoff's from the same sheet ... and by doing so, most
of
the time you can't even see the join in the finished part.

Thanks everyone.

What was confusing me was the "butt joint". All the butt joints I've
seen were with hardwood, and the joint was at a 45° angle. It sounds like
you are saying to just put glue on the edges of both
plywood pieces and clamp them together. (No routing necessary). Darren
Harris
Staten Island, New York.


Yes. We like to make rocket science out of this stuff... and the
people selling specialty jig and bit like to, as well. :-)

If you don't have a lot to do and can take your time, you can figure
out a way to help line up and hold the joint so it it perfectly
flush.

Simple and easy way is to clamp thin, narrow boards or ply along one piece
along the edge where you are going to put the other, apply glue, slide piece
#2 between the clamped on guides.

--

dadiOH
____________________________

Winters getting colder? Tired of the rat race?
Maybe just ready for a change? Check it out...
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Edge Joining Plywood
 

On 11/21/2012 8:43 PM, -MIKE- wrote:
....

... A butted glue joint,
plywood to plywood, will be even stronger than to solid wood, because
the expansion rates will be equal.

Not so fast...

Assuming the same material in the same orientation so the plies match
up, there is (roughly) half the material that is edge grain to edge
grain and thereby an effective glue surface.

On the other half, you have end-grain facing end grain and it will have
essentially no strength from the glue joint (normal gluing practices,
yellow pva, etc., etc., ...).

So, in essence, if you start w/ a 3/4" ply, your end result is (again
roughly) as if the actual material were more like 3/8" in thickness.
That ain't too bad, and will suffice for many applications as in OP's
and as Swing notes he's done (and I'd think virtually all who have done
any significant amount of cabinet work will have at some point--it's
just too common a problem of having need for that smidge more material
that doesn't justify the cost of a whole sheet for the purpose).

You're right that if you were to do the classic joint test on the result
w/ a test specimen you would find that most of the fractures will be of
the long grain breaking rather than the glue joint itself separating.
But, what you're not accounting for is that there isn't that much long
grain...so even if the joint that is glued is as strong, it's putting
the 90-lb weakling in the same ring as the weight lifter when it gets
down to the actual strength--that smaller glue joint area and material
just can't support what twice the material can/would.

As noted down thread a little earlier (I hadn't seen this part before
that seemed worthy of direct comment), I have seen such test data altho
I don't recall precisely where (and on T-day I'm not spending any more
time looking for it again). In that, study abicr the result was
generally slightly less than that of the equivalent long-grain plies and
was attributed to the two or three plies of solid material not being
physically together as one solid section.

I don't recall it being in that study, but I'd expect w/ proper
preparation such as sizing the end grain plies and using epoxies one
could manage to increase the bond strength a fair amount but I would
still doubt one could achieve the same strength as an equivalent of same
thickness of solid material.

--

Edge Joining Plywood
 

On 11/22/2012 10:46 AM, dpb wrote:
On 11/21/2012 8:43 PM, -MIKE- wrote:
...

... A butted glue joint,
plywood to plywood, will be even stronger than to solid wood, because
the expansion rates will be equal.

Not so fast...

Assuming the same material in the same orientation so the plies match
up, there is (roughly) half the material that is edge grain to edge
grain and thereby an effective glue surface.


One would probably presume that you would not change outer veneer grain
direction. If the outer veneer grain is run in the same direction the
inner ply's should be running in the same direction also.

Edge Joining Plywood
 

On 11/22/2012 10:46 AM, dpb wrote:

Your point is valid and should not be ignored in deciding upon the
suitability of this method for an intended purpose.

--
www.eWoodShop.com
Last update: 4/15/2010
KarlCaillouet@ (the obvious)
http://gplus.to/eWoodShop

Edge Joining Plywood
 

On 11/22/2012 10:52 AM, Leon wrote:
....

One would probably presume that you would not change outer veneer grain
direction. If the outer veneer grain is run in the same direction the
inner ply's should be running in the same direction also.
....

If it's from the same piece and same face up, of course. But, not
_necessarily_ so in general. Some isn't symmetric from face to rear,
for example. And two panels of same species veneer but different
manufacturers might not coincide even if a decent match of the face
grain is possible.

Simply included for preciseness of description...

One other thing...lumber-core ply does act in this regard much like
solid lumber--not surprising since, in fact, it is mostly a solid core.
Of course, the core ply in solid core is rarely glued (if ever; won't
say it hasn't been done but I've never seen a sheet that was nor recall
a spec for it) the strength along the length isn't nearly what a regular
piece of ply of the same thickness will bear...

--

Edge Joining Plywood
 

On 11/22/2012 10:32 AM, dadiOH wrote:
....

Simple and easy way is to clamp thin, narrow boards or ply along one piece
along the edge where you are going to put the other, apply glue, slide piece
#2 between the clamped on guides.

Be sure pieces are either finished or use wax paper or blue tape or some
other method to not glue them to the finished work from the squeeze out...

--

Edge Joining Plywood
 

On 11/22/12 10:32 AM, dadiOH wrote:
Yes. We like to make rocket science out of this stuff... and the
people selling specialty jig and bit like to, as well. :-)

If you don't have a lot to do and can take your time, you can figure
out a way to help line up and hold the joint so it it perfectly
flush.

Simple and easy way is to clamp thin, narrow boards or ply along one piece
along the edge where you are going to put the other, apply glue, slide piece
#2 between the clamped on guides.


Excellent.
Hopefully, remove clamped on guides before glue sets is the next step.
Ask me how I know. :-)


--

-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

Edge Joining Plywood
 

On 11/22/2012 7:41 AM, Swingman wrote:
wrote:

I'm not going to label it nonsense, but I am highly dubious of glued
butt joined plywood being able to withstand most any flexing or
shearing force.

Problem is that those expressing doubt are not speaking from any experience
for the application.

Try it as I stated, with biscuits (or spline or domino) and your
dubiousness will evaporate, most particularly when considering the OP's
very clearly stated intended use ... a guaranteed fix for that
circumstance.

Have simply done it too many times myself ...


Agreed.

Either of those increase the contact and gluing area.

Edge glued plywood has minimal of both.
Also, plywood is not solid (well duh!).
I'm not had a lot of luck edge gluing air to air.

I'd expect the seam to open up from temperature cycling.
Even though the expansion rates of the plywood match, the glue doesn't.

Edge Joining Plywood
 

On 11/22/12 10:46 AM, dpb wrote:
On 11/21/2012 8:43 PM, -MIKE- wrote:
...

... A butted glue joint,
plywood to plywood, will be even stronger than to solid wood, because
the expansion rates will be equal.

Not so fast...

Assuming the same material in the same orientation so the plies match
up, there is (roughly) half the material that is edge grain to edge
grain and thereby an effective glue surface.

On the other half, you have end-grain facing end grain and it will have
essentially no strength from the glue joint (normal gluing practices,
yellow pva, etc., etc., ...).

So, in essence, if you start w/ a 3/4" ply, your end result is (again
roughly) as if the actual material were more like 3/8" in thickness.
That ain't too bad, and will suffice for many applications as in OP's
and as Swing notes he's done (and I'd think virtually all who have done
any significant amount of cabinet work will have at some point--it's
just too common a problem of having need for that smidge more material
that doesn't justify the cost of a whole sheet for the purpose).

You're right that if you were to do the classic joint test on the result
w/ a test specimen you would find that most of the fractures will be of
the long grain breaking rather than the glue joint itself separating.
But, what you're not accounting for is that there isn't that much long
grain...so even if the joint that is glued is as strong, it's putting
the 90-lb weakling in the same ring as the weight lifter when it gets
down to the actual strength--that smaller glue joint area and material
just can't support what twice the material can/would.

As noted down thread a little earlier (I hadn't seen this part before
that seemed worthy of direct comment), I have seen such test data altho
I don't recall precisely where (and on T-day I'm not spending any more
time looking for it again). In that, study abicr the result was
generally slightly less than that of the equivalent long-grain plies and
was attributed to the two or three plies of solid material not being
physically together as one solid section.

I don't recall it being in that study, but I'd expect w/ proper
preparation such as sizing the end grain plies and using epoxies one
could manage to increase the bond strength a fair amount but I would
still doubt one could achieve the same strength as an equivalent of same
thickness of solid material.

--

Like I said.... rocket science. :-p
Happy Thanksgiving!


--

-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

Edge Joining Plywood
 

Richard wrote:
On 11/22/2012 7:41 AM, Swingman wrote:
wrote:

I'm not going to label it nonsense, but I am highly dubious of glued
butt joined plywood being able to withstand most any flexing or
shearing force.

Problem is that those expressing doubt are not speaking from any
experience for the application.

Try it as I stated, with biscuits (or spline or domino) and your
dubiousness will evaporate, most particularly when considering the
OP's very clearly stated intended use ... a guaranteed fix for that
circumstance.

Have simply done it too many times myself ...


Agreed.

Either of those increase the contact and gluing area.

Edge glued plywood has minimal of both.
Also, plywood is not solid (well duh!).
I'm not had a lot of luck edge gluing air to air.

I'd expect the seam to open up from temperature cycling.
Even though the expansion rates of the plywood match, the glue
doesn't.

Bet you don't think you can edge glue veneer either, huh? Edge glue into
one large sheet before laying it, I mean.


--

dadiOH
____________________________

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

Edge Joining Plywood
 

dpb wrote:

I don't recall it being in that study, but I'd expect w/ proper
preparation such as sizing the end grain plies and using epoxies one
could manage to increase the bond strength a fair amount but I would
still doubt one could achieve the same strength as an equivalent of
same thickness of solid material.

I guarantee you that one can glue two pieces of ply together edge to edge
with epoxy and that the ply will break before the glue joint.

--

dadiOH
____________________________

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

Edge Joining Plywood
 

dpb wrote:
On 11/22/2012 10:32 AM, dadiOH wrote:
...

Simple and easy way is to clamp thin, narrow boards or ply along one
piece along the edge where you are going to put the other, apply
glue, slide piece #2 between the clamped on guides.

Be sure pieces are either finished or use wax paper or blue tape or
some other method to not glue them to the finished work from the
squeeze out...

No need, once the joint has been glued and clamped just remove the guide
pieces.

--

dadiOH
____________________________

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

Edge Joining Plywood
 

On Thursday, November 22, 2012 2:29:06 PM UTC-5, dadiOH wrote:
dpb wrote:

On 11/22/2012 10:32 AM, dadiOH wrote:

...



Simple and easy way is to clamp thin, narrow boards or ply along one

piece along the edge where you are going to put the other, apply

glue, slide piece #2 between the clamped on guides.



Be sure pieces are either finished or use wax paper or blue tape or

some other method to not glue them to the finished work from the

squeeze out...



No need, once the joint has been glued and clamped just remove the guide

pieces.

I certainly didn't get the consensus I was expecting. The answers have been all over the place. :-)

The only real surprise to me was the recommendation to just glue the plywood edges to each other without any special routing. (All the more easier, I say).

I try to keep things simple, but just to show *exactly* what I'm doing here, I'm replacing the top of a game cabinet like this:

http://i290.photobucket.com/albums/l...PositionII.jpg

The 22-1/2" x 6" piece above the marquee is vinyl covered particle board and it slopes down at 15°:
http://i290.photobucket.com/albums/l...arqueeRoof.jpg

Here's a shot of the cabinet without it:
http://i290.photobucket.com/albums/l...eRoof-less.jpg

I will make the 5" wide piece I have wider to match this original 6" wide piece, which has a 15° bezel on the front and rear:
http://i290.photobucket.com/albums/l...ueeRoofTop.jpg

I will then glue/screw the two 3/4" blocks taken from the bottom original piece onto the ends of the new piece:
http://i290.photobucket.com/albums/l...RoofBottom.jpg

Those two blocks will also be glued back to the inside of the cabinet.

Thanks everyone.

Darren Harris
Staten Island, New York.

Edge Joining Plywood
 

I certainly didn't get the consensus I was expecting. The answers have been all over the place. :-)

The only real surprise to me was the recommendation to just glue the plywood edges to each other without any special routing. (All the more easier, I say).

I try to keep things simple, but just to show *exactly* what I'm doing here, I'm replacing the top of a game cabinet like this:

http://i290.photobucket.com/albums/l...PositionII.jpg

The 22-1/2" x 6" piece above the marquee is vinyl covered particle board and it slopes down at 15°:
http://i290.photobucket.com/albums/l...arqueeRoof.jpg

Here's a shot of the cabinet without it:
http://i290.photobucket.com/albums/l...eRoof-less.jpg

I will make the 5" wide piece I have wider to match this original 6" wide piece, which has a 15° bezel on the front and rear:
http://i290.photobucket.com/albums/l...ueeRoofTop.jpg

I will then glue/screw the two 3/4" blocks taken from the bottom original piece onto the ends of the new piece:
http://i290.photobucket.com/albums/l...RoofBottom.jpg

Those two blocks will also be glued back to the inside of the cabinet.

Thanks everyone.

Darren Harris
Staten Island, New York.



The reasons the answers were all over the place are...
a. speculation from woodworkers... woodworkers are prone to overdoing
things.
b. many, including me, didn't read your entire post... or they jumped
into the discussion without reading your OP.

However, if you weed through the posts to get to the information coming
from those of us who have actually done what you're trying to do, you'll
see a consensus to use the KISS rule and do the simplest joint in the
simplest way.

After looking at you pictures, I'm puzzled why you are even attempting
to extend a piece of plywood and not just cut another crap the correct
size, or go to the lumber yard and get a 24x48 pre-cut piece of MDF for
like 5 bucks and cut it exact.


--

-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