Re: Wet test of polyurethane glue
--- Inbolger@yahoogroups.com, "John Bell" <smallboatdesigner@m...>
wrote:
I suspect a couple of things that might be at the root of this
I believe your first choice for the "root of the problem" is
the more important one. It has been both my experience and
observation that so long as there is no glue left in a joint,whether
due to excessive clamping pressure or well driven screws/nails,this
joint can hardly help itself but to fail at some point.
With epoxy,it really doesn't take much to create a glue starved
joint when using a batch of peanut butter.Applied over bare
wood,some of the "liquid" in the peanut butter batch will leach out
and into the wood leaving precious little behind in the peanut
butter. Obviously the remedy for this is as spelled out by
Don,of "OINK" fame.That is,pre-wet the surfaces to be joined with
epoxy,neat, then go at it with the peanut butter batch.
However, my all time favorite,never-let-me-down, I'd-bet-a-
years-salary solution/insurance against glue joint failures is the
not-yet-famous HOLLOW TRICK ! It can be found in the files section
of this group in the Tricks,Tips etc folder
The sketch shown illustrates a timber to plywood joint but
this same method can(should!) be used whenever laminating other
stuff together too,like plywood to plywood. It really doesn't take
much and things go very quickly with a nifty little grinder and some
24 weight Alu-oxide paper.
Timber butt blocks have little end grain exposed and what
little there is can easily be sealed,thus the expansion from water
absorption is not really all that great across the grain and should
not over-come a "hollowed" joint assembly.
Mind you, I am refering to sane hard wood timber blocks and
not some punk wood which has all the properties of a sponge without
any of its usefullness :-)
Sincerely,
Peter Lenihan, big time fan/advocate of the hollow tip,despite being
accused of having way too much hollow above my shoulders, only
trying to encourage sound,long-lived amateur built wood boats for
everyones enjoyment,from along the shores of the St.Lawrence
River............
wrote:
I suspect a couple of things that might be at the root of this
> problem. First is glue starvation. Epoxy needs a thick glue lineto be
> effective. The other issue is that I built the boat as Michalakspecified
> with solid timber butt blocks.Hi John,
I believe your first choice for the "root of the problem" is
the more important one. It has been both my experience and
observation that so long as there is no glue left in a joint,whether
due to excessive clamping pressure or well driven screws/nails,this
joint can hardly help itself but to fail at some point.
With epoxy,it really doesn't take much to create a glue starved
joint when using a batch of peanut butter.Applied over bare
wood,some of the "liquid" in the peanut butter batch will leach out
and into the wood leaving precious little behind in the peanut
butter. Obviously the remedy for this is as spelled out by
Don,of "OINK" fame.That is,pre-wet the surfaces to be joined with
epoxy,neat, then go at it with the peanut butter batch.
However, my all time favorite,never-let-me-down, I'd-bet-a-
years-salary solution/insurance against glue joint failures is the
not-yet-famous HOLLOW TRICK ! It can be found in the files section
of this group in the Tricks,Tips etc folder
The sketch shown illustrates a timber to plywood joint but
this same method can(should!) be used whenever laminating other
stuff together too,like plywood to plywood. It really doesn't take
much and things go very quickly with a nifty little grinder and some
24 weight Alu-oxide paper.
Timber butt blocks have little end grain exposed and what
little there is can easily be sealed,thus the expansion from water
absorption is not really all that great across the grain and should
not over-come a "hollowed" joint assembly.
Mind you, I am refering to sane hard wood timber blocks and
not some punk wood which has all the properties of a sponge without
any of its usefullness :-)
Sincerely,
Peter Lenihan, big time fan/advocate of the hollow tip,despite being
accused of having way too much hollow above my shoulders, only
trying to encourage sound,long-lived amateur built wood boats for
everyones enjoyment,from along the shores of the St.Lawrence
River............
I really suspect the issue was more a problem of gluing the thick solid
timber butt block to thin plywood, with differential expansion being the
main force. I did wet both surfaces prior to applying thickened epoxy, but I
also fear that I may have been too zealous in tightening the screws holding
it all together.
On my AF4, I used plywood butt blocks bedded in 5200 with all being
copiously nailed with ring shanks on 3" centers. The outer seam was
subsequently glassed. That was one tough butt joint.
I've long been suspect of the polyureathanes for structural use after a
series of articles in WB discussing its weakness on wet wood. I'd rather use
something more proven and back it all up with metal fasteners.
timber butt block to thin plywood, with differential expansion being the
main force. I did wet both surfaces prior to applying thickened epoxy, but I
also fear that I may have been too zealous in tightening the screws holding
it all together.
On my AF4, I used plywood butt blocks bedded in 5200 with all being
copiously nailed with ring shanks on 3" centers. The outer seam was
subsequently glassed. That was one tough butt joint.
I've long been suspect of the polyureathanes for structural use after a
series of articles in WB discussing its weakness on wet wood. I'd rather use
something more proven and back it all up with metal fasteners.
----- Original Message -----
From: "dbaldnz" <oink@...>
To: <bolger@yahoogroups.com>
Sent: Sunday, August 29, 2004 4:04 PM
Subject: [bolger] Re: Wet test of polyurethane glue
| I feel with epoxy it is VERY important to wet both surfaces to be
| glued with an unthinned coat of epoxy, and while still wet, apply the
| thickened glue.
| After 2 failures using polyurethane under ideal dampened conditions, I
| just don't think it's worth the risk, and costs as much as epoxy when
| you have to throw away a half used container after a few months,
| DonB
|
I feel with epoxy it is VERY important to wet both surfaces to be
glued with an unthinned coat of epoxy, and while still wet, apply the
thickened glue.
After 2 failures using polyurethane under ideal dampened conditions, I
just don't think it's worth the risk, and costs as much as epoxy when
you have to throw away a half used container after a few months,
DonB
glued with an unthinned coat of epoxy, and while still wet, apply the
thickened glue.
After 2 failures using polyurethane under ideal dampened conditions, I
just don't think it's worth the risk, and costs as much as epoxy when
you have to throw away a half used container after a few months,
DonB
> As the 'experienced builder' in question, this is distressing. The buttmodified
> blocks on Bruce's boat were in fact glued with epoxy. The epoxy was
> with the addition of microfibers and the butt blocks were screwed on asspecified
> well. I suspect a couple of things that might be at the root of this
> problem. First is glue starvation. Epoxy needs a thick glue line to be
> effective. The other issue is that I built the boat as Michalak
> with solid timber butt blocks. I would not use this method again,FWIW. I've
> observed that solid timber moves a lot more than plywood with changes inmore so
> moisture. This movement puts a lot of stress on glue lines, and even
> if the joint is glue starved. If I had to do it again, I'd useplywood for
> butt joints or make a taped joint or even scarf the sheets togetherinstead
> of screwing a length of 1x4 to a piece of plywood.posts
>
> Sorry for the problem, Bruce.
>
> Best,
>
> JB
>
> ----- Original Message -----
> From: "Bruce Hector" <bruce_hector@h...>
> To: <bolger@yahoogroups.com>
> Sent: Sunday, August 29, 2004 9:02 AM
> Subject: [bolger] Re: Wet test of polyurethane glue
>
>
> | I'm suspicious of all these glues also. I had a failure of a stressed
> | joint on the Tims bow module last summer, which I chalked up to
> | starvation. But I wasn't sure.
> |
> | Now the butt blocks in my Michalak sport dory have separated. Not
> | sure what glue was used, but I doubt it was epoxy. I bought this one
> | from an experienced builder.
> |
> | I spread them a little wider and piped in some thicked epoxy. That'll
> | hold them.
> |
> | I'm coming to the conclusion that its silly to save $50 bucks on glue
> | in something your life may depend on, like a boat.
> |
> | Bruce Hector
> |http://www.brucesboats.com
> |
> |
> |
> |
> | Bolger rules!!!
> | - no cursing, flaming, trolling, spamming, or flogging dead horses
> | - stay on topic, stay on thread, punctuate, no 'Ed, thanks, Fred'
> | - Pls add your comments at the TOP, SIGN your posts, and snip away01930, Fax:
> | - Plans: Mr. Philip C. Bolger, P.O. Box 1209, Gloucester, MA,
> (978) 282-1349
> | - Unsubscribe:bolger-unsubscribe@yahoogroups.com
> | - Open discussion:bolger_coffee_lounge-subscribe@yahoogroups.com
> | Yahoo! Groups Links
> |
> |
> |
> |
> |
John,
Do you have an easy way to do the scarf on a sheet of plywood? I am going to
need to make a scarf in a white cedar board that is 8� wide and the type of
jig I have used in the past does not lend itself to this width of wood.
All the best,
Robert Gainer
Do you have an easy way to do the scarf on a sheet of plywood? I am going to
need to make a scarf in a white cedar board that is 8� wide and the type of
jig I have used in the past does not lend itself to this width of wood.
All the best,
Robert Gainer
>From: "John Bell" <smallboatdesigner@...>
>Reply-To:bolger@yahoogroups.com
>To: <bolger@yahoogroups.com>
>Subject: Re: [bolger] Re: Wet test of polyurethane glue
>Date: Sun, 29 Aug 2004 13:33:26 -0400
>
>Hmmm....
>
>As the 'experienced builder' in question, this is distressing. The butt
>blocks on Bruce's boat were in fact glued with epoxy. The epoxy was
>modified
>with the addition of microfibers and the butt blocks were screwed on as
>well. I suspect a couple of things that might be at the root of this
>problem. First is glue starvation. Epoxy needs a thick glue line to be
>effective. The other issue is that I built the boat as Michalak specified
>with solid timber butt blocks. I would not use this method again, FWIW.
>I've
>observed that solid timber moves a lot more than plywood with changes in
>moisture. This movement puts a lot of stress on glue lines, and even more
>so
>if the joint is glue starved. If I had to do it again, I'd use plywood for
>butt joints or make a taped joint or even scarf the sheets together instead
>of screwing a length of 1x4 to a piece of plywood.
>
>Sorry for the problem, Bruce.
>
>Best,
>
>JB
>
>----- Original Message -----
>From: "Bruce Hector" <bruce_hector@...>
>To: <bolger@yahoogroups.com>
>Sent: Sunday, August 29, 2004 9:02 AM
>Subject: [bolger] Re: Wet test of polyurethane glue
>
>
>| I'm suspicious of all these glues also. I had a failure of a stressed
>| joint on the Tims bow module last summer, which I chalked up to
>| starvation. But I wasn't sure.
>|
>| Now the butt blocks in my Michalak sport dory have separated. Not
>| sure what glue was used, but I doubt it was epoxy. I bought this one
>| from an experienced builder.
>|
>| I spread them a little wider and piped in some thicked epoxy. That'll
>| hold them.
>|
>| I'm coming to the conclusion that its silly to save $50 bucks on glue
>| in something your life may depend on, like a boat.
>|
>| Bruce Hector
>|http://www.brucesboats.com
>|
>|
>|
>|
>| Bolger rules!!!
>| - no cursing, flaming, trolling, spamming, or flogging dead horses
>| - stay on topic, stay on thread, punctuate, no 'Ed, thanks, Fred' posts
>| - Pls add your comments at the TOP, SIGN your posts, and snip away
>| - Plans: Mr. Philip C. Bolger, P.O. Box 1209, Gloucester, MA, 01930, Fax:
>(978) 282-1349
>| - Unsubscribe:bolger-unsubscribe@yahoogroups.com
>| - Open discussion:bolger_coffee_lounge-subscribe@yahoogroups.com
>| Yahoo! Groups Links
>|
>|
>|
>|
>|
>
Hmmm....
As the 'experienced builder' in question, this is distressing. The butt
blocks on Bruce's boat were in fact glued with epoxy. The epoxy was modified
with the addition of microfibers and the butt blocks were screwed on as
well. I suspect a couple of things that might be at the root of this
problem. First is glue starvation. Epoxy needs a thick glue line to be
effective. The other issue is that I built the boat as Michalak specified
with solid timber butt blocks. I would not use this method again, FWIW. I've
observed that solid timber moves a lot more than plywood with changes in
moisture. This movement puts a lot of stress on glue lines, and even more so
if the joint is glue starved. If I had to do it again, I'd use plywood for
butt joints or make a taped joint or even scarf the sheets together instead
of screwing a length of 1x4 to a piece of plywood.
Sorry for the problem, Bruce.
Best,
JB
As the 'experienced builder' in question, this is distressing. The butt
blocks on Bruce's boat were in fact glued with epoxy. The epoxy was modified
with the addition of microfibers and the butt blocks were screwed on as
well. I suspect a couple of things that might be at the root of this
problem. First is glue starvation. Epoxy needs a thick glue line to be
effective. The other issue is that I built the boat as Michalak specified
with solid timber butt blocks. I would not use this method again, FWIW. I've
observed that solid timber moves a lot more than plywood with changes in
moisture. This movement puts a lot of stress on glue lines, and even more so
if the joint is glue starved. If I had to do it again, I'd use plywood for
butt joints or make a taped joint or even scarf the sheets together instead
of screwing a length of 1x4 to a piece of plywood.
Sorry for the problem, Bruce.
Best,
JB
----- Original Message -----
From: "Bruce Hector" <bruce_hector@...>
To: <bolger@yahoogroups.com>
Sent: Sunday, August 29, 2004 9:02 AM
Subject: [bolger] Re: Wet test of polyurethane glue
| I'm suspicious of all these glues also. I had a failure of a stressed
| joint on the Tims bow module last summer, which I chalked up to
| starvation. But I wasn't sure.
|
| Now the butt blocks in my Michalak sport dory have separated. Not
| sure what glue was used, but I doubt it was epoxy. I bought this one
| from an experienced builder.
|
| I spread them a little wider and piped in some thicked epoxy. That'll
| hold them.
|
| I'm coming to the conclusion that its silly to save $50 bucks on glue
| in something your life may depend on, like a boat.
|
| Bruce Hector
|http://www.brucesboats.com
|
|
|
|
| Bolger rules!!!
| - no cursing, flaming, trolling, spamming, or flogging dead horses
| - stay on topic, stay on thread, punctuate, no 'Ed, thanks, Fred' posts
| - Pls add your comments at the TOP, SIGN your posts, and snip away
| - Plans: Mr. Philip C. Bolger, P.O. Box 1209, Gloucester, MA, 01930, Fax:
(978) 282-1349
| - Unsubscribe:bolger-unsubscribe@yahoogroups.com
| - Open discussion:bolger_coffee_lounge-subscribe@yahoogroups.com
| Yahoo! Groups Links
|
|
|
|
|
--- Inbolger@yahoogroups.com, "Bruce Hector" <bruce_hector@h...>
wrote:
A lot of builders used Weldwood powdered glue at one time. If the
joint was tight and it was clamped until it dried, it was pretty
strong and waterproof. I made an entire set of camping cookout
kitchen boxes using weldwood, ring nails and porch paint. Most of the
joints were lapped so there was no fully exposed edge grain. It
worked great.
Nels
wrote:
>> I'm coming to the conclusion that its silly to save $50 bucks onglue
> in something your life may depend on, like a boat.Sort of like buying cheap tires for your 50 K pick-up.
>
> Bruce Hector
>http://www.brucesboats.com
A lot of builders used Weldwood powdered glue at one time. If the
joint was tight and it was clamped until it dried, it was pretty
strong and waterproof. I made an entire set of camping cookout
kitchen boxes using weldwood, ring nails and porch paint. Most of the
joints were lapped so there was no fully exposed edge grain. It
worked great.
Nels
I'm suspicious of all these glues also. I had a failure of a stressed
joint on the Tims bow module last summer, which I chalked up to
starvation. But I wasn't sure.
Now the butt blocks in my Michalak sport dory have separated. Not
sure what glue was used, but I doubt it was epoxy. I bought this one
from an experienced builder.
I spread them a little wider and piped in some thicked epoxy. That'll
hold them.
I'm coming to the conclusion that its silly to save $50 bucks on glue
in something your life may depend on, like a boat.
Bruce Hector
http://www.brucesboats.com
joint on the Tims bow module last summer, which I chalked up to
starvation. But I wasn't sure.
Now the butt blocks in my Michalak sport dory have separated. Not
sure what glue was used, but I doubt it was epoxy. I bought this one
from an experienced builder.
I spread them a little wider and piped in some thicked epoxy. That'll
hold them.
I'm coming to the conclusion that its silly to save $50 bucks on glue
in something your life may depend on, like a boat.
Bruce Hector
http://www.brucesboats.com
the joint was clamped and wetted properly,cured then immersed and
failed.
Ive gone back over the container and found further info like;
strong and waterproof
Ideal for marine applications
Not for below waterline use
. I emailed the company for clarrifications ,their email adress
doesnt work. their website gives lots of info on ALL their glue
products, but not this one . Perhaps it is too new.
.
I tested the regular non water resistant AQUADHERE and the dry test
has shown it to be at least as strong. Afew more days will tell the
wet results.
I suspect that once this tube of glue is used up It wont be replaced.
Cheers Paul
failed.
Ive gone back over the container and found further info like;
strong and waterproof
Ideal for marine applications
Not for below waterline use
. I emailed the company for clarrifications ,their email adress
doesnt work. their website gives lots of info on ALL their glue
products, but not this one . Perhaps it is too new.
.
I tested the regular non water resistant AQUADHERE and the dry test
has shown it to be at least as strong. Afew more days will tell the
wet results.
I suspect that once this tube of glue is used up It wont be replaced.
Cheers Paul