I have read (and followed) instructions that when fitting biscuit
joints, that PVA glue should be used, as this as well as gluing, due
to water content , forces biscuits to swell.
I now tend to use Gorrilla Polyurethane glue on external work rather
than PVA, anybody know if Polyurethane glue is suitable for use with
biscuit jointing ?
On Wed, 3 Dec 2008 21:53:07 +0000, DiggerOp wrote
(in article <[email protected]>):
> According to a textbook I have, edge joining is described as a type
> of butt joint.
My understanding (U.K.) has been that ANY plane surface to plane surface
joint is a butt.. i.e. where one abutts the other, with no mechanical
interpenetration.
I think that "butt" includes nails, screws and/or glue - All strength comes
from the glue or fasteners without which all you have is an "arrangement" not
a "joint."
That's whether end or long grain. It can be a _reinforced_ butt_ by adding
battens or fillets.
I think a biscuit is a sort of a loose tenon of some sort,(Thank you,
Queeeekdraw) but is not "fitted" precisely - it ONLY becomes a joint when
wetted / swollen with glue so, unlike a pure loose tenon, it is still a
(reinforced) butt joint if you follow my logic.
Now a pocket hole....
ARGHHHHHHHHHH !!!
On Thu, 4 Dec 2008 16:41:40 +0000, J. Clarke wrote
(in article <[email protected]>):
> Generally speaking edge grain to edge grain with proper surface prep
> and clamping using any modern glue of the sorts commonly used in
> woodworking will be stronger against intermittent loads than the
> original wood, i.e. the break will be other than in the glue line.
>
> End grain to anything in general the break will be between the glue
> and the end grain and will occur at a much lower level of stress than
> for edge grain to edge grain.
>
> This is why a distinction is made between the two kinds of joint.
>
> Now, for edge grain, biscuits bring two things to the party. The
> first is that if the slots are accurately cut then they serve as
> positioning aids. The second is that under steady shear load many
> glues will creep and fail at a stress level much lower than would be
> the case for a load applied for a short time--the biscuit serves in
> that case to provide a mechanical obstacle to creep.
>
> For end grain they function as small loose tenons and can add
> significantly to the strength of a joint that needs all the help it
> can get.
Well, I'm all for _that_ being the definitive FAQ version.
the garilla glue, even the new low expansion stuff expands so much that I
no longer use it in joints I wish to flush up, sounds strange, but I use J B
weld and or Goop Marine glue
"Osprey" <[email protected]> wrote in message
news:c160aeb0-0028-4c18-a066-5a3000cc749c@x38g2000yqj.googlegroups.com...
>I have read (and followed) instructions that when fitting biscuit
> joints, that PVA glue should be used, as this as well as gluing, due
> to water content , forces biscuits to swell.
>
> I now tend to use Gorrilla Polyurethane glue on external work rather
> than PVA, anybody know if Polyurethane glue is suitable for use with
> biscuit jointing ?
On Dec 2, 8:27=A0pm, "Lew Hodgett" <[email protected]> wrote:
> "SonomaProducts.com" wrote:
> >Regarding Gorilla, if you have ever seen it compared in a lab test as
>
> many of the wood mags have published you will see it is about the
> weakest stuff you can buy for wood. If you need extreme weather
> exposure use expoy. Can't recall the name of that 3M stuff, system 3?
>
> Gorila Glue is IMHO, the most over priced under peckered adhesive on
> the planet.
>
> If TiteBondII doesn't cut it, time for epoxy(Raka, Systems3, West
> Systems, etc)
>
> >Regarding biscuits, I have always used PVA. Regarding the expansion,
> >I
>
> thought it was a myth but then I saw it in real life.
>
> If you use biscuits with epoxy, they become a keying device.
>
> Lew
Lately. I have become a huge fan (again) of Weldbond.
I wouldn't glue a finely crafted mortise and tenon joint with it, but
I find it does what it does better than anything: glue strips of
plywood to the bottom of a solid surface countertop.
On Dec 5, 7:18=A0am, "Swingman" <[email protected]> wrote:
> Agreed ... then try this sequence for the "show me" proof:
>
> http://groups.google.com/group/rec.woodworking/browse_thread/thread/3...
Yeah!
Some pretty smart fellas in the middle of that thread too, eh?
;^)
Robert
"Osprey" <[email protected]> wrote in message
news:c160aeb0-0028-4c18-a066-5a3000cc749c@x38g2000yqj.googlegroups.com...
>I have read (and followed) instructions that when fitting biscuit
> joints, that PVA glue should be used, as this as well as gluing, due
> to water content , forces biscuits to swell.
>
> I now tend to use Gorrilla Polyurethane glue on external work rather
> than PVA, anybody know if Polyurethane glue is suitable for use with
> biscuit jointing ?
The expansion ration of Gorilla would place the biscuit pocket in danger of
splitting throught the face of the board. And, like Mike said, why bother
when PVA is stronger?
"Dan Coby" <[email protected]> wrote in message
news:[email protected]...
> Nova wrote:
>> -MIKE- wrote:
>>> Robatoy wrote:
>>>
>>>> If used PROPERLY, a biscuit will add strength to a butt joint.
>>>>
>>>
>>> Again, not arguing here, I want opinions.....
>>>
>>> How much strength is needed beyond what the glue provides for
>>> the
>>> average linear butt joint? Cabinet door panels for example, or a
>>> table top.
>>>
>>> I understand that each plank of wood wants to warp in the
>>> opposite
>>> direction of the adjacent piece. Is that enough to break a
>>> glue-only joint?
>>>
>>> Keep in mind, my middle name is overkill, so I'm usually the one
>>> using
>>> extra measures that aren't necessarily needed. :-)
>>>
>>
>> A "butt joint" is end grain jointed to long grain. It's not
>> typically used in door panel or table top construction.
>>
>
> What do you call the joint used to connect the edges of two or
> more
> boards to make a table top?
According to a textbook I have, edge joining is described as a type
of butt joint.
On Dec 3, 2:04=A0pm, -MIKE- <[email protected]> wrote:
> > Yes, you can use polyurethane glue with biscuits. =A0I use water-based
> > carpenter's glue with biscuits. =A0The biscuits swell and lock the
> > joint. =A0If the biscuit is too close to the edge, it can swell a bump
> > on the face. =A0There are slight differences between biscuit brands.
>
> Interesting. =A0(not picking a fight)
> I always thought glue locked the joint.
> And biscuits more or less just help you line up the centers of the boards=
.
>
Mike... you like to live dangerously, eh? LOL
If used PROPERLY, a biscuit will add strength to a butt joint.
On Dec 4, 3:54=A0pm, Bored Borg <[email protected]>
wrote:
> Well, I'm all for _that_ being the definitive FAQ version.
Sounds good to me. Count me in!
Robert
Bored Borg wrote:
> On Thu, 4 Dec 2008 16:41:40 +0000, J. Clarke wrote
> (in article <[email protected]>):
>
>> Generally speaking edge grain to edge grain with proper surface prep
>> and clamping using any modern glue of the sorts commonly used in
>> woodworking will be stronger against intermittent loads than the
>> original wood, i.e. the break will be other than in the glue line.
>>
>> End grain to anything in general the break will be between the glue
>> and the end grain and will occur at a much lower level of stress than
>> for edge grain to edge grain.
>>
>> This is why a distinction is made between the two kinds of joint.
>>
>> Now, for edge grain, biscuits bring two things to the party. The
>> first is that if the slots are accurately cut then they serve as
>> positioning aids. The second is that under steady shear load many
>> glues will creep and fail at a stress level much lower than would be
>> the case for a load applied for a short time--the biscuit serves in
>> that case to provide a mechanical obstacle to creep.
>>
>> For end grain they function as small loose tenons and can add
>> significantly to the strength of a joint that needs all the help it
>> can get.
>
> Well, I'm all for _that_ being the definitive FAQ version.
>
Yup. Well put.
On Dec 4, 6:11 am, "Leon" <[email protected]> wrote:
> Try gluing a joint with only glue on the biscuits, that will show you the
> strength of the biscuit.
DOH!
Now why didn't I think of that. What an excellent way to illustrate
to the nay sayers that they do indeed bring a little something to the
party.
>The biscuit does indeed add strength to the joint
> however most anything strong enough to break a joint with out a biscuit will
> break the joint with a biscuit. Biscuits are more helpful for end grain
> gluing and miter joints. They also some what help with alignment providing
> the cutter produces a consistent width slot and the biscuits are of uniform
> thickness. The biggest misconception of the strength of the biscuit is that
> it is often used for the wrong application.
I vote to add Leon's comments to John's in the FAQ. We should just
refer folks to this thread when they start up the annual "biscuits are
only for alignment" stuff.
Nicely said, Leon.
Robert
"Osprey" <[email protected]> wrote in message
news:c160aeb0-0028-4c18-a066-5a3000cc749c@x38g2000yqj.googlegroups.com...
>I have read (and followed) instructions that when fitting biscuit
> joints, that PVA glue should be used, as this as well as gluing, due
> to water content , forces biscuits to swell.
>
> I now tend to use Gorrilla Polyurethane glue on external work rather
> than PVA, anybody know if Polyurethane glue is suitable for use with
> biscuit jointing ?
Gorilla glue cures on exposure to moisture. It helps to wipe the area with
moist rag before gluing. Not sure what that means for biscuits. Perhaps wet
the biscuits as you insert them, to activate both the compressed wood and
the glue.
On Thu, 04 Dec 2008 11:14:52 -0600, -MIKE- <[email protected]>
wrote:
>Leon wrote:
>> Try gluing a joint with only glue on the biscuits, that will show you the
>> strength of the biscuit. The biscuit does indeed add strength to the joint
>> however most anything strong enough to break a joint with out a biscuit will
>> break the joint with a biscuit.
>
>That was kind of my thinking. They don't seam to add *that much* more
>strength.
>And if I need a *lot* more strength, I'm probably reaching for the
>finger joint bit, no?
Finger joint trumps the biscuit joint. A scarf joint is fairly strong
too, maybe better than the finger joint.
-MIKE- wrote:
> Nova wrote:
>
>> -MIKE- wrote:
>>
>>> Robatoy wrote:
>>>
>>>> If used PROPERLY, a biscuit will add strength to a butt joint.
>>>>
>>>
>>> Again, not arguing here, I want opinions.....
>>>
>>> How much strength is needed beyond what the glue provides for the
>>> average linear butt joint? Cabinet door panels for example, or a
>>> table top.
>>>
>>> I understand that each plank of wood wants to warp in the opposite
>>> direction of the adjacent piece. Is that enough to break a glue-only
>>> joint?
>>>
>>> Keep in mind, my middle name is overkill, so I'm usually the one using
>>> extra measures that aren't necessarily needed. :-)
>>>
>>
>> A "butt joint" is end grain jointed to long grain. It's not typically
>> used in door panel or table top construction.
>>
>
> Ok, replace with "edge" joint.
> Anything to add?
>
>
In a properly prepared edge joint glued with PVA the wood will usually
break before the glue joint fails.
A butt joint joined with just glue is extremely weak and should be
reinforced.
--
Jack Novak
Buffalo, NY - USA
[email protected]
-MIKE- wrote:
> Robatoy wrote:
>
>> If used PROPERLY, a biscuit will add strength to a butt joint.
>>
>
> Again, not arguing here, I want opinions.....
>
> How much strength is needed beyond what the glue provides for the
> average linear butt joint? Cabinet door panels for example, or a table top.
>
> I understand that each plank of wood wants to warp in the opposite
> direction of the adjacent piece. Is that enough to break a glue-only
> joint?
>
> Keep in mind, my middle name is overkill, so I'm usually the one using
> extra measures that aren't necessarily needed. :-)
>
A "butt joint" is end grain jointed to long grain. It's not typically
used in door panel or table top construction.
--
Jack Novak
Buffalo, NY - USA
[email protected]
<[email protected]> wrote in message
news:[email protected]...
> On Dec 4, 6:11 am, "Leon" <[email protected]> wrote:
>
>> Try gluing a joint with only glue on the biscuits, that will show you the
>> strength of the biscuit.
>
> DOH!
>
> Now why didn't I think of that. What an excellent way to illustrate
> to the nay sayers that they do indeed bring a little something to the
> party.
>
>>The biscuit does indeed add strength to the joint
>> however most anything strong enough to break a joint with out a biscuit
>> will
>> break the joint with a biscuit. Biscuits are more helpful for end grain
>> gluing and miter joints. They also some what help with alignment
>> providing
>> the cutter produces a consistent width slot and the biscuits are of
>> uniform
>> thickness. The biggest misconception of the strength of the biscuit is
>> that
>> it is often used for the wrong application.
>
> I vote to add Leon's comments to John's in the FAQ. We should just
> refer folks to this thread when they start up the annual "biscuits are
> only for alignment" stuff.
>
> Nicely said, Leon.
Agreed ... then try this sequence for the "show me" proof:
http://groups.google.com/group/rec.woodworking/browse_thread/thread/3f4a18d3ed666b23?q=#93dd922478c6b5da
--
www.e-woodshop.net
Last update: 10/22/08
KarlC@ (the obvious)
In article <[email protected]>,
[email protected] says...
> Nova wrote:
> > -MIKE- wrote:
> >> Robatoy wrote:
> >>
> >>> If used PROPERLY, a biscuit will add strength to a butt joint.
> >>>
> >>
> >> Again, not arguing here, I want opinions.....
> >>
> >> How much strength is needed beyond what the glue provides for the
> >> average linear butt joint? Cabinet door panels for example, or a table
> >> top.
> >>
> >> I understand that each plank of wood wants to warp in the opposite
> >> direction of the adjacent piece. Is that enough to break a glue-only
> >> joint?
> >>
> >> Keep in mind, my middle name is overkill, so I'm usually the one using
> >> extra measures that aren't necessarily needed. :-)
> >>
> >
> > A "butt joint" is end grain jointed to long grain. It's not typically
> > used in door panel or table top construction.
> >
>
> What do you call the joint used to connect the edges of two or more
> boards to make a table top?
Are you talking about laminating?
Nova wrote:
> -MIKE- wrote:
>> Robatoy wrote:
>>
>>> If used PROPERLY, a biscuit will add strength to a butt joint.
>>>
>>
>> Again, not arguing here, I want opinions.....
>>
>> How much strength is needed beyond what the glue provides for the
>> average linear butt joint? Cabinet door panels for example, or a table
>> top.
>>
>> I understand that each plank of wood wants to warp in the opposite
>> direction of the adjacent piece. Is that enough to break a glue-only
>> joint?
>>
>> Keep in mind, my middle name is overkill, so I'm usually the one using
>> extra measures that aren't necessarily needed. :-)
>>
>
> A "butt joint" is end grain jointed to long grain. It's not typically
> used in door panel or table top construction.
>
What do you call the joint used to connect the edges of two or more
boards to make a table top?
Chuck Olson wrote:
>
> I'm really new to woodworking, but I recently saw a TV ad for Kreg Pocket
> Hole Joinery. It looked like it might be better than biscuit joinery. Any
> opinions?
>
Sure! I use both.
I use biscuits to align panels. They work well for this and are hidden
on all sides.
I prefer pocket screws for face frame assembly, plywood drawer box
assembly, case assembly where I don't use dados and glue and one side is
hidden, on the baseboard radiator covers I build that move a lot with
temperature changes.
It's very difficult to hide pocket holes in visible spots.
I don't use either of them on fine furniture where joinery like mortise
and tenon, sliding dovetail, or dovetails are more appropriate. I also
prefer M&T or cope and stick on doors.
"Robatoy" wrote:
>Lately. I have become a huge fan (again) of Weldbond.
I wouldn't glue a finely crafted mortise and tenon joint with it, but
I find it does what it does better than anything: glue strips of
plywood to the bottom of a solid surface countertop.
SFWIW:
Ran some test years ago using some Corian samples, 12mmn CDX, and
epoxy.
The epoxy joint didn't fail.
Lew
"J. Clarke" wrote
> Generally speaking edge grain to edge grain with proper surface prep
> and clamping using any modern glue of the sorts commonly used in
> woodworking will be stronger against intermittent loads than the
> original wood, i.e. the break will be other than in the glue line.
>
> End grain to anything in general the break will be between the glue
> and the end grain and will occur at a much lower level of stress than
> for edge grain to edge grain.
>
> This is why a distinction is made between the two kinds of joint.
>
> Now, for edge grain, biscuits bring two things to the party. The
> first is that if the slots are accurately cut then they serve as
> positioning aids. The second is that under steady shear load many
> glues will creep and fail at a stress level much lower than would be
> the case for a load applied for a short time--the biscuit serves in
> that case to provide a mechanical obstacle to creep.
>
> For end grain they function as small loose tenons and can add
> significantly to the strength of a joint that needs all the help it
> can get.
Well said!
--
www.e-woodshop.net
Last update: 10/22/08
KarlC@ (the obvious)
"SonomaProducts.com" wrote:
>Regarding Gorilla, if you have ever seen it compared in a lab test as
many of the wood mags have published you will see it is about the
weakest stuff you can buy for wood. If you need extreme weather
exposure use expoy. Can't recall the name of that 3M stuff, system 3?
Gorila Glue is IMHO, the most over priced under peckered adhesive on
the planet.
If TiteBondII doesn't cut it, time for epoxy(Raka, Systems3, West
Systems, etc)
>Regarding biscuits, I have always used PVA. Regarding the expansion,
>I
thought it was a myth but then I saw it in real life.
If you use biscuits with epoxy, they become a keying device.
Lew
On Dec 3, 12:09=A0am, "Lew Hodgett" <[email protected]> wrote:
> "Robatoy" wrote:
> >Lately. I have become a huge fan (again) of Weldbond.
>
> I wouldn't glue a finely crafted mortise and tenon joint with it, but
> I find it does what it does better than anything: glue strips of
> plywood to the bottom of a solid surface countertop.
>
> SFWIW:
>
> Ran some test years ago using some Corian samples, 12mmn CDX, and
> epoxy.
>
> The epoxy joint didn't fail.
>
> Lew
The Weldbond doesn't fail either.
Regarding Gorilla, if you have ever seen it compared in a lab test as
many of the wood mags have published you will see it is about the
weakest stuff you can buy for wood. If you need extreme weather
exposure use expoy. Can't recall the name of that 3M stuff, system 3?
Regarding biscuits, I have always used PVA. Regarding the expansion, I
thought it was a myth but then I saw it in real life. If you use
biscuits for a panel, let them dry for many days before you flatten
the panel. Becuase they swell the wood and if you flatten too soon
then the swelling will subside later and you have some nice biscuit
shaped depressions along the joint... really nice. I didn't notice it
until the lacquer was laid down.
On Dec 2, 2:38=A0am, Osprey <[email protected]> wrote:
> I =A0have read (and followed) instructions that when fitting biscuit
> joints, that PVA glue should be used, as this as well as gluing, due
> to water content , forces biscuits to swell.
>
> I now tend to use Gorrilla Polyurethane glue on external work rather
> than PVA, anybody know if Polyurethane glue is suitable for use with
> biscuit jointing ?
Osprey wrote:
> I have read (and followed) instructions that when fitting biscuit
> joints, that PVA glue should be used, as this as well as gluing, due
> to water content , forces biscuits to swell.
>
> I now tend to use Gorrilla Polyurethane glue on external work rather
> than PVA, anybody know if Polyurethane glue is suitable for use with
> biscuit jointing ?
Polyurethane glue isn't necessary for that joint.
Poly is good for situations in which you need a waterproof connection,
gap filling, or connecting odd materials together.
And Poly isn't not nearly as strong as PVA, either.
--
-MIKE-
"Playing is not something I do at night, it's my function in life"
--Elvin Jones (1927-2004)
--
http://mikedrums.com
[email protected]
---remove "DOT" ^^^^ to reply
> Yes, you can use polyurethane glue with biscuits. I use water-based
> carpenter's glue with biscuits. The biscuits swell and lock the
> joint. If the biscuit is too close to the edge, it can swell a bump
> on the face. There are slight differences between biscuit brands.
Interesting. (not picking a fight)
I always thought glue locked the joint.
And biscuits more or less just help you line up the centers of the boards.
--
-MIKE-
"Playing is not something I do at night, it's my function in life"
--Elvin Jones (1927-2004)
--
http://mikedrums.com
[email protected]
---remove "DOT" ^^^^ to reply
Robatoy wrote:
> On Dec 3, 2:04 pm, -MIKE- <[email protected]> wrote:
>>> Yes, you can use polyurethane glue with biscuits. I use water-based
>>> carpenter's glue with biscuits. The biscuits swell and lock the
>>> joint. If the biscuit is too close to the edge, it can swell a bump
>>> on the face. There are slight differences between biscuit brands.
>> Interesting. (not picking a fight)
>> I always thought glue locked the joint.
>> And biscuits more or less just help you line up the centers of the boards.
>>
> Mike... you like to live dangerously, eh? LOL
>
> If used PROPERLY, a biscuit will add strength to a butt joint.
>
Again, not arguing here, I want opinions.....
How much strength is needed beyond what the glue provides for the
average linear butt joint? Cabinet door panels for example, or a table top.
I understand that each plank of wood wants to warp in the opposite
direction of the adjacent piece. Is that enough to break a glue-only joint?
Keep in mind, my middle name is overkill, so I'm usually the one using
extra measures that aren't necessarily needed. :-)
--
-MIKE-
"Playing is not something I do at night, it's my function in life"
--Elvin Jones (1927-2004)
--
http://mikedrums.com
[email protected]
---remove "DOT" ^^^^ to reply
Nova wrote:
> -MIKE- wrote:
>> Robatoy wrote:
>>
>>> If used PROPERLY, a biscuit will add strength to a butt joint.
>>>
>>
>> Again, not arguing here, I want opinions.....
>>
>> How much strength is needed beyond what the glue provides for the
>> average linear butt joint? Cabinet door panels for example, or a table
>> top.
>>
>> I understand that each plank of wood wants to warp in the opposite
>> direction of the adjacent piece. Is that enough to break a glue-only
>> joint?
>>
>> Keep in mind, my middle name is overkill, so I'm usually the one using
>> extra measures that aren't necessarily needed. :-)
>>
>
> A "butt joint" is end grain jointed to long grain. It's not typically
> used in door panel or table top construction.
>
Ok, replace with "edge" joint.
Anything to add?
--
-MIKE-
"Playing is not something I do at night, it's my function in life"
--Elvin Jones (1927-2004)
--
http://mikedrums.com
[email protected]
---remove "DOT" ^^^^ to reply
"Paul Fisher" <[email protected]> wrote in message
news:[email protected]...
> the garilla glue, even the new low expansion stuff expands so much that I
> no longer use it in joints I wish to flush up, sounds strange, but I use J
> B weld and or Goop Marine glue
> "Osprey" <[email protected]> wrote in message
> news:c160aeb0-0028-4c18-a066-5a3000cc749c@x38g2000yqj.googlegroups.com...
>>I have read (and followed) instructions that when fitting biscuit
>> joints, that PVA glue should be used, as this as well as gluing, due
>> to water content , forces biscuits to swell.
>>
>> I now tend to use Gorrilla Polyurethane glue on external work rather
>> than PVA, anybody know if Polyurethane glue is suitable for use with
>> biscuit jointing ?
>
>
I'm really new to woodworking, but I recently saw a TV ad for Kreg Pocket
Hole Joinery. It looked like it might be better than biscuit joinery. Any
opinions?
> I'm really new to woodworking, but I recently saw a TV ad for Kreg Pocket
> Hole Joinery. It looked like it might be better than biscuit joinery. Any
> opinions?
>
Pocket holes are great and pretty darn strong, but leave holes behind.
You can plug the holes, but there's nothing to plug or hide with biscuits.
Whichever works best for your application.
--
-MIKE-
"Playing is not something I do at night, it's my function in life"
--Elvin Jones (1927-2004)
--
http://mikedrums.com
[email protected]
---remove "DOT" ^^^^ to reply
Bored Borg wrote:
> On Wed, 3 Dec 2008 21:53:07 +0000, DiggerOp wrote
> (in article
> <[email protected]>):
>
>> According to a textbook I have, edge joining is described as a type
>> of butt joint.
>
> My understanding (U.K.) has been that ANY plane surface to plane
> surface joint is a butt.. i.e. where one abutts the other, with no
> mechanical interpenetration.
>
> I think that "butt" includes nails, screws and/or glue - All
> strength
> comes from the glue or fasteners without which all you have is an
> "arrangement" not a "joint."
> That's whether end or long grain. It can be a _reinforced_ butt_ by
> adding battens or fillets.
>
> I think a biscuit is a sort of a loose tenon of some sort,(Thank
> you,
> Queeeekdraw) but is not "fitted" precisely - it ONLY becomes a joint
> when wetted / swollen with glue so, unlike a pure loose tenon, it is
> still a (reinforced) butt joint if you follow my logic.
>
> Now a pocket hole....
>
>
>
> ARGHHHHHHHHHH !!!
Generally speaking edge grain to edge grain with proper surface prep
and clamping using any modern glue of the sorts commonly used in
woodworking will be stronger against intermittent loads than the
original wood, i.e. the break will be other than in the glue line.
End grain to anything in general the break will be between the glue
and the end grain and will occur at a much lower level of stress than
for edge grain to edge grain.
This is why a distinction is made between the two kinds of joint.
Now, for edge grain, biscuits bring two things to the party. The
first is that if the slots are accurately cut then they serve as
positioning aids. The second is that under steady shear load many
glues will creep and fail at a stress level much lower than would be
the case for a load applied for a short time--the biscuit serves in
that case to provide a mechanical obstacle to creep.
For end grain they function as small loose tenons and can add
significantly to the strength of a joint that needs all the help it
can get.
--
--
--John
to email, dial "usenet" and validate
(was jclarke at eye bee em dot net)
Leon wrote:
> Try gluing a joint with only glue on the biscuits, that will show you the
> strength of the biscuit. The biscuit does indeed add strength to the joint
> however most anything strong enough to break a joint with out a biscuit will
> break the joint with a biscuit.
That was kind of my thinking. They don't seam to add *that much* more
strength.
And if I need a *lot* more strength, I'm probably reaching for the
finger joint bit, no?
--
-MIKE-
"Playing is not something I do at night, it's my function in life"
--Elvin Jones (1927-2004)
--
http://mikedrums.com
[email protected]
---remove "DOT" ^^^^ to reply
J. Clarke wrote:
> Generally speaking edge grain to edge grain with proper surface prep
> and clamping using any modern glue of the sorts commonly used in
> woodworking will be stronger against intermittent loads than the
> original wood, i.e. the break will be other than in the glue line.
>
> End grain to anything in general the break will be between the glue
> and the end grain and will occur at a much lower level of stress than
> for edge grain to edge grain.
>
> This is why a distinction is made between the two kinds of joint.
>
> Now, for edge grain, biscuits bring two things to the party. The
> first is that if the slots are accurately cut then they serve as
> positioning aids. The second is that under steady shear load many
> glues will creep and fail at a stress level much lower than would be
> the case for a load applied for a short time--the biscuit serves in
> that case to provide a mechanical obstacle to creep.
>
> For end grain they function as small loose tenons and can add
> significantly to the strength of a joint that needs all the help it
> can get.
>
There ya go.
--
-MIKE-
"Playing is not something I do at night, it's my function in life"
--Elvin Jones (1927-2004)
--
http://mikedrums.com
[email protected]
---remove "DOT" ^^^^ to reply
> Now why didn't I think of that. What an excellent way to illustrate
> to the nay sayers that they do indeed bring a little something to the
> party.
>
>
> Robert
I couldn't have said it better myself.
They help "a little" on edge joints. :-)
--
-MIKE-
"Playing is not something I do at night, it's my function in life"
--Elvin Jones (1927-2004)
--
http://mikedrums.com
[email protected]
---remove "DOT" ^^^^ to reply
"-MIKE-" <[email protected]> wrote in message
news:[email protected]...
>> Yes, you can use polyurethane glue with biscuits. I use water-based
>> carpenter's glue with biscuits. The biscuits swell and lock the
>> joint. If the biscuit is too close to the edge, it can swell a bump
>> on the face. There are slight differences between biscuit brands.
>
> Interesting. (not picking a fight)
> I always thought glue locked the joint.
> And biscuits more or less just help you line up the centers of the boards.
Try gluing a joint with only glue on the biscuits, that will show you the
strength of the biscuit. The biscuit does indeed add strength to the joint
however most anything strong enough to break a joint with out a biscuit will
break the joint with a biscuit. Biscuits are more helpful for end grain
gluing and miter joints. They also some what help with alignment providing
the cutter produces a consistent width slot and the biscuits are of uniform
thickness. The biggest misconception of the strength of the biscuit is that
it is often used for the wrong application.
"Osprey" <[email protected]> wrote in message
news:c160aeb0-0028-4c18-a066-5a3000cc749c@x38g2000yqj.googlegroups.com...
>I have read (and followed) instructions that when fitting biscuit
> joints, that PVA glue should be used, as this as well as gluing, due
> to water content , forces biscuits to swell.
>
> I now tend to use Gorrilla Polyurethane glue on external work rather
> than PVA, anybody know if Polyurethane glue is suitable for use with
> biscuit jointing ?
I use yellow carpenters glue. No problems up to now.
Dan
On Tue, 2 Dec 2008 02:38:16 -0800 (PST), Osprey
<[email protected]> wrote:
>I have read (and followed) instructions that when fitting biscuit
>joints, that PVA glue should be used, as this as well as gluing, due
>to water content , forces biscuits to swell.
>
>I now tend to use Gorrilla Polyurethane glue on external work rather
>than PVA, anybody know if Polyurethane glue is suitable for use with
>biscuit jointing ?
Yes, you can use polyurethane glue with biscuits. I use water-based
carpenter's glue with biscuits. The biscuits swell and lock the
joint. If the biscuit is too close to the edge, it can swell a bump
on the face. There are slight differences between biscuit brands.