Re: [bolger] Re: Hmm... scoring ply for a better join?
On the subject of avoiding adhesive-starved
joints/laminations.... I seem to recall reading a
piece advising placing a light mesh cloth- gauze,
cheesecloth, etc. between pieces to be glued together.
While not providing any direct structural
enhancement, the mesh of the cloth served to act as a
sponge to hold in lots of glue/epoxy. Possibly this
came from a Sam Devlin book, a section on using
Resinocol (sp) perhaps? Someone check me on this...
me recollections are rarely dead-on...:-P
-MFX
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joints/laminations.... I seem to recall reading a
piece advising placing a light mesh cloth- gauze,
cheesecloth, etc. between pieces to be glued together.
While not providing any direct structural
enhancement, the mesh of the cloth served to act as a
sponge to hold in lots of glue/epoxy. Possibly this
came from a Sam Devlin book, a section on using
Resinocol (sp) perhaps? Someone check me on this...
me recollections are rarely dead-on...:-P
-MFX
__________________________________________________
Do You Yahoo!?
LAUNCH - Your Yahoo! Music Experience
http://launch.yahoo.com
I think you may be doing "Apples and Oranges" with your question.
The photo you refer to is of a relatively narrow "Stick" that is
being attached to plywood.
In that case, a slight "Hollow" would probably help the joint,
as shown, by allowing more epoxy to stay in the joint, and preventing
some of the "Squeeze out". Less pressure on the same joint, without
the "Hollow" might make a joint that would be almost as strong.
The lesson there is to Not use Too Much pressure when making epoxy
joints. Clamping is good with most wood glue joints, but not with
epoxy. That's the "Apples". The "Oranges" is what you are
wanting to do. Large surface, plywood to plywood, will not have the
same "Squeeze out" problem. It would be difficult to get most of the
epoxy to "Squeeze out" of a big plywood lamination.
"Hollowing", or better your idea of "Roughing", the surface will
probably make a "Stronger" joint, and "Roughing" might be a good
idea, If the surfaces of the plywood were so hard that the epoxy
would not penetrate. The question there is how Much stronger you
want. The epoxy joint, with no additional "Roughing" will be much
stronger than the plywood. Do a simple test, using both methods.
Both will show the joint to be much stronger than the wood.
I did a similar test, as I am using some "Tap Plastics" brand epoxy.
I wanted to check it's performance before I trust it with my boat.
I cut two pieces of 3/8 marine plywood, about 4" wide and 8" long.
I applied epoxy to squares about 4" by 4" on the ends of both pieces.
I put one of the epoxy areas on top of the other, and put a piece of
2x4 on top to lightly hold them together. The next day, after the
epoxy had set, I put the piece spanning a couple pieces of wood and
gave it a good hit in the middle with my hammer. The piece basically
exploded.
About the Only part that remained intact was the Epoxy joint.
So far, I think I will trust my new "Tap" epoxy. It proved to be
Much stronger than the marine plywood I want to put together.
Pat Patteson
Molalla, Oregon
(I hate working with epoxy.)
The photo you refer to is of a relatively narrow "Stick" that is
being attached to plywood.
In that case, a slight "Hollow" would probably help the joint,
as shown, by allowing more epoxy to stay in the joint, and preventing
some of the "Squeeze out". Less pressure on the same joint, without
the "Hollow" might make a joint that would be almost as strong.
The lesson there is to Not use Too Much pressure when making epoxy
joints. Clamping is good with most wood glue joints, but not with
epoxy. That's the "Apples". The "Oranges" is what you are
wanting to do. Large surface, plywood to plywood, will not have the
same "Squeeze out" problem. It would be difficult to get most of the
epoxy to "Squeeze out" of a big plywood lamination.
"Hollowing", or better your idea of "Roughing", the surface will
probably make a "Stronger" joint, and "Roughing" might be a good
idea, If the surfaces of the plywood were so hard that the epoxy
would not penetrate. The question there is how Much stronger you
want. The epoxy joint, with no additional "Roughing" will be much
stronger than the plywood. Do a simple test, using both methods.
Both will show the joint to be much stronger than the wood.
I did a similar test, as I am using some "Tap Plastics" brand epoxy.
I wanted to check it's performance before I trust it with my boat.
I cut two pieces of 3/8 marine plywood, about 4" wide and 8" long.
I applied epoxy to squares about 4" by 4" on the ends of both pieces.
I put one of the epoxy areas on top of the other, and put a piece of
2x4 on top to lightly hold them together. The next day, after the
epoxy had set, I put the piece spanning a couple pieces of wood and
gave it a good hit in the middle with my hammer. The piece basically
exploded.
About the Only part that remained intact was the Epoxy joint.
So far, I think I will trust my new "Tap" epoxy. It proved to be
Much stronger than the marine plywood I want to put together.
Pat Patteson
Molalla, Oregon
(I hate working with epoxy.)
--- In bolger@y..., "timothyennuinet" <timothy@e...> wrote:
> I was looking at this picture:
>
> http://groups.yahoo.com/group/Bolger2/files/building%
20tips/Hollow1.JPG
>
> ..and I thought.. gee, if the epoxy needs a slight hollow to grip
even
> better than it does with a flat surface, then when doing ply upon
ply
> (for building up 1.5" sides, hulls with 1/2" ply) why not scuff up
one
> side with a circular sander? This would create, admittedly random,
> hollows in which the glue could settle a bit and perhaps bond the
two
> surfaces better, and with less waste.
>
> What do you all think? Perhaps not a random scuffing.. perhaps a
> careful pattern of lines, scoring entirely down the length or
breadth
> of a sheet?
>
> Heck, I could look at the plains of Nazca for artistic
inspiration. :)
>
> And for that matter, when joining ply edgewise, perhaps the butt
could
> be scored on one side as well..
>
> --T
Thanks for that URL,
Very good site I think.
Jules
Very good site I think.
Jules
Interesting:
http://www.epoxyproducts.com/25points4u.html
Takes several days for epoxy to cure completely, so they are saying you can
get a chemical bond within 48 hours.
Incidentaly, I've been able to make Raka blush. By having it rained on with
48 hours!
http://www.epoxyproducts.com/25points4u.html
Takes several days for epoxy to cure completely, so they are saying you can
get a chemical bond within 48 hours.
Incidentaly, I've been able to make Raka blush. By having it rained on with
48 hours!
----- Original Message -----
From: "Jeff Blunck" <boatbuilding@...>
To: <bolger@yahoogroups.com>
Sent: Thursday, May 09, 2002 1:58 PM
Subject: Re: [bolger] Hmm... scoring ply for a better join?
> > I am no chemist, Jeff, but my understanding is that
> > secondary bonds with epoxy are both chemical and
> > mechanical (where mechanical structures exist).
> > Plyester joints may be essentialy mechanical only, I
> > am not sure, but the are weak secondary bonds, but
> > epoxy is much stronger.
>
> Once epoxy sets up and is hard enough to sand without clogging paper I
don't
> see anything but mechanical bonding if you put more epoxy on top. If you
> can still dent it with you finger nail, you would surely get both, but
once
> set up hard, I can't see it as anything but mechanical. Most solovents
> won't hurt epoxy. I've heard the MTBE in the gasoline can make it
dissolve
> but not much else short of extreme acids or alkalais.
>
> Maybe epoxy can dissolve or soften itself to get back to a chemical
> connection. Like you though, I'm no chemical engineer so any thing is
> certainly possible.
>
> Jeff
>
>
>
> Bolger rules!!!
> - no cursing, flaming, trolling, spamming, or flogging dead horses
> - pls take "personals" off-list, stay on topic, and punctuate
> - add your comments at the TOP and SIGN your posts, snip all you like
> - To order plans: Mr. Philip C. Bolger, P.O. Box 1209, Gloucester, MA,
01930, Fax: (978) 282-1349
> - Unsubscribe:bolger-unsubscribe@yahoogroups.com
>
> Your use of Yahoo! Groups is subject tohttp://docs.yahoo.com/info/terms/
>
>
>
> I am no chemist, Jeff, but my understanding is thatOnce epoxy sets up and is hard enough to sand without clogging paper I don't
> secondary bonds with epoxy are both chemical and
> mechanical (where mechanical structures exist).
> Plyester joints may be essentialy mechanical only, I
> am not sure, but the are weak secondary bonds, but
> epoxy is much stronger.
see anything but mechanical bonding if you put more epoxy on top. If you
can still dent it with you finger nail, you would surely get both, but once
set up hard, I can't see it as anything but mechanical. Most solovents
won't hurt epoxy. I've heard the MTBE in the gasoline can make it dissolve
but not much else short of extreme acids or alkalais.
Maybe epoxy can dissolve or soften itself to get back to a chemical
connection. Like you though, I'm no chemical engineer so any thing is
certainly possible.
Jeff
Letting epoxy cure and sanding makes a strong joint
but making the joint all<BR>
at once and letting it cure makes a chemical bond
rather than mechanical.<BR>
I am no chemist, Jeff, but my understanding is that
secondary bonds with epoxy are both chemical and
mechanical (where mechanical structures exist).
Plyester joints may be essentialy mechanical only, I
am not sure, but the are weak secondary bonds, but
epoxy is much stronger.
I would have to say that long before I signed up to do
some of the list of stuff that is being recomended
here, I would scarph and bag the bottom. It really is
easy. With Half inch ply you could probably bicuit
join it rather than scarph it. You need to do
something to get the edges held down. If you have a
scarpher jig scarfing the whole bottom would make
sense, but mine is only 4' long.
______________________________________________________________________
Games, Movies, Music & Sports!http://entertainment.yahoo.ca
but making the joint all<BR>
at once and letting it cure makes a chemical bond
rather than mechanical.<BR>
I am no chemist, Jeff, but my understanding is that
secondary bonds with epoxy are both chemical and
mechanical (where mechanical structures exist).
Plyester joints may be essentialy mechanical only, I
am not sure, but the are weak secondary bonds, but
epoxy is much stronger.
I would have to say that long before I signed up to do
some of the list of stuff that is being recomended
here, I would scarph and bag the bottom. It really is
easy. With Half inch ply you could probably bicuit
join it rather than scarph it. You need to do
something to get the edges held down. If you have a
scarpher jig scarfing the whole bottom would make
sense, but mine is only 4' long.
______________________________________________________________________
Games, Movies, Music & Sports!http://entertainment.yahoo.ca
Even with bagging, I have never starved a joint in ply, either
scarphing or laminating. There was some talk of this about 10 years
ago, concern VB created too much pressure for laminating wood with
epoxy, but i have never seen it in practice. I think Linehan's
detail is nice, but it scared me at the first time he posted it
because it actualy increases the squeezeout at the edges of the
joint. I don't doubt he can control it satisfactorily, but if one is
going to exercise skill, it can be exercised with simpler arangemnts
also. One of the purposes of moderate amounts of milled fiber, or
glass ballons is that they retain space, even in a tight joint, for
glue. On laminated sheets that are VBagged I have used clear with
complete success. On nailed surfaces I prefer thicker stuff and a
notched trowel.
scarphing or laminating. There was some talk of this about 10 years
ago, concern VB created too much pressure for laminating wood with
epoxy, but i have never seen it in practice. I think Linehan's
detail is nice, but it scared me at the first time he posted it
because it actualy increases the squeezeout at the edges of the
joint. I don't doubt he can control it satisfactorily, but if one is
going to exercise skill, it can be exercised with simpler arangemnts
also. One of the purposes of moderate amounts of milled fiber, or
glass ballons is that they retain space, even in a tight joint, for
glue. On laminated sheets that are VBagged I have used clear with
complete success. On nailed surfaces I prefer thicker stuff and a
notched trowel.
--- In bolger@y..., "timothyennuinet" <timothy@e...> wrote:
> I was looking at this picture:
>
> http://groups.yahoo.com/group/Bolger2/files/building%
20tips/Hollow1.JPG
>
> ..and I thought.. gee, if the epoxy needs a slight hollow to grip
even
> better than it does with a flat surface, then when doing ply upon
ply
> (for building up 1.5" sides, hulls with 1/2" ply) why not scuff up
one
> side with a circular sander? This would create, admittedly random,
> hollows in which the glue could settle a bit and perhaps bond the
two
> surfaces better, and with less waste.
>
> What do you all think? Perhaps not a random scuffing.. perhaps a
> careful pattern of lines, scoring entirely down the length or
breadth
> of a sheet?
>
> Heck, I could look at the plains of Nazca for artistic
inspiration. :)
>
> And for that matter, when joining ply edgewise, perhaps the butt
could
> be scored on one side as well..
>
> --T
Best way I can figure is to pretreat the surface(s) with straight epoxy or
maybe even slightly thinned first. Let it soak in for 10 or 15 minutes,
re-apply if necessary, then some slightly thickened epoxy and nail it
together. Pretreating prevents the possiblility of getting a dry joint due
to the wood wicking epoxy out of the joint.
Letting epoxy cure and sanding makes a strong joint but making the joint all
at once and letting it cure makes a chemical bond rather than mechanical.
I'm really not sure if it makes a difference since it's still stronger than
the plywood.
Jeff
maybe even slightly thinned first. Let it soak in for 10 or 15 minutes,
re-apply if necessary, then some slightly thickened epoxy and nail it
together. Pretreating prevents the possiblility of getting a dry joint due
to the wood wicking epoxy out of the joint.
Letting epoxy cure and sanding makes a strong joint but making the joint all
at once and letting it cure makes a chemical bond rather than mechanical.
I'm really not sure if it makes a difference since it's still stronger than
the plywood.
Jeff
A brief sanding with rough sandpaper might help some, but unless you are
vacuum bagging, you are not reall going to squish your epoxy out from
between sheets of plywood. And probably not even then.
vacuum bagging, you are not reall going to squish your epoxy out from
between sheets of plywood. And probably not even then.
----- Original Message -----
From: "timothyennuinet" <timothy@...>
To: <bolger@yahoogroups.com>
Sent: Thursday, May 09, 2002 11:13 AM
Subject: [bolger] Hmm... scoring ply for a better join?
> I was looking at this picture:
>
>http://groups.yahoo.com/group/Bolger2/files/building%20tips/Hollow1.JPG
>
> ..and I thought.. gee, if the epoxy needs a slight hollow to grip even
> better than it does with a flat surface, then when doing ply upon ply
> (for building up 1.5" sides, hulls with 1/2" ply) why not scuff up one
> side with a circular sander? This would create, admittedly random,
> hollows in which the glue could settle a bit and perhaps bond the two
> surfaces better, and with less waste.
>
> What do you all think? Perhaps not a random scuffing.. perhaps a
> careful pattern of lines, scoring entirely down the length or breadth
> of a sheet?
>
> Heck, I could look at the plains of Nazca for artistic inspiration. :)
>
> And for that matter, when joining ply edgewise, perhaps the butt could
> be scored on one side as well..
>
> --T
>
>
>
>
> Bolger rules!!!
> - no cursing, flaming, trolling, spamming, or flogging dead horses
> - pls take "personals" off-list, stay on topic, and punctuate
> - add your comments at the TOP and SIGN your posts, snip all you like
> - To order plans: Mr. Philip C. Bolger, P.O. Box 1209, Gloucester, MA,
01930, Fax: (978) 282-1349
> - Unsubscribe:bolger-unsubscribe@yahoogroups.com
>
> Your use of Yahoo! Groups is subject tohttp://docs.yahoo.com/info/terms/
>
>
>
Hi Timothy, My reaction to your scuffing or scoring scheme is that you
would just be using more epoxy and doing a lot of not very useful
work. Peter Lenihens sketch illustrates a method of getting tight
joints that will not be gluestarved. It is not a method for laminating
panels. For laminating my inclination is to join surfaces that are in
the best condition feasible. Voids filled with epoxy are probably not
going to give you a better bond. The bond is between epoxy and wood
fibers. You just need ENOUGH epoxy. If you really want to be
scrupulous, precoat the panels, wash them, sand them and then laminate
them.
Bob Chamberland
would just be using more epoxy and doing a lot of not very useful
work. Peter Lenihens sketch illustrates a method of getting tight
joints that will not be gluestarved. It is not a method for laminating
panels. For laminating my inclination is to join surfaces that are in
the best condition feasible. Voids filled with epoxy are probably not
going to give you a better bond. The bond is between epoxy and wood
fibers. You just need ENOUGH epoxy. If you really want to be
scrupulous, precoat the panels, wash them, sand them and then laminate
them.
Bob Chamberland
--- In bolger@y..., "timothyennuinet" <timothy@e...> wrote:
> I was looking at this picture:
>
>http://groups.yahoo.com/group/Bolger2/files/building%20tips/Hollow1.JPG
>
> ..and I thought.. gee, if the epoxy needs a slight hollow to grip even
> better than it does with a flat surface, then when doing ply upon ply
> (for building up 1.5" sides, hulls with 1/2" ply) why not scuff up one
> side with a circular sander? This would create, admittedly random,
> hollows in which the glue could settle a bit and perhaps bond the two
> surfaces better, and with less waste.
>
> What do you all think? Perhaps not a random scuffing.. perhaps a
> careful pattern of lines, scoring entirely down the length or breadth
> of a sheet?
>
> Heck, I could look at the plains of Nazca for artistic inspiration. :)
>
> And for that matter, when joining ply edgewise, perhaps the butt could
> be scored on one side as well..
>
> --T
I was looking at this picture:
http://groups.yahoo.com/group/Bolger2/files/building%20tips/Hollow1.JPG
..and I thought.. gee, if the epoxy needs a slight hollow to grip even
better than it does with a flat surface, then when doing ply upon ply
(for building up 1.5" sides, hulls with 1/2" ply) why not scuff up one
side with a circular sander? This would create, admittedly random,
hollows in which the glue could settle a bit and perhaps bond the two
surfaces better, and with less waste.
What do you all think? Perhaps not a random scuffing.. perhaps a
careful pattern of lines, scoring entirely down the length or breadth
of a sheet?
Heck, I could look at the plains of Nazca for artistic inspiration. :)
And for that matter, when joining ply edgewise, perhaps the butt could
be scored on one side as well..
--T
http://groups.yahoo.com/group/Bolger2/files/building%20tips/Hollow1.JPG
..and I thought.. gee, if the epoxy needs a slight hollow to grip even
better than it does with a flat surface, then when doing ply upon ply
(for building up 1.5" sides, hulls with 1/2" ply) why not scuff up one
side with a circular sander? This would create, admittedly random,
hollows in which the glue could settle a bit and perhaps bond the two
surfaces better, and with less waste.
What do you all think? Perhaps not a random scuffing.. perhaps a
careful pattern of lines, scoring entirely down the length or breadth
of a sheet?
Heck, I could look at the plains of Nazca for artistic inspiration. :)
And for that matter, when joining ply edgewise, perhaps the butt could
be scored on one side as well..
--T