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Jasen Betts
Guest
Mon Jan 23, 2012 9:39 am
On 2012-01-23, Robert Baer <robertbaer_at_localnet.com> wrote:
Quote:
Jim Thompson wrote:
Just used some JB Weld to make a steel-to-steel joint.
Amazing stuff, took overnight to fully harden, but it's so hard now
you can barely scratch it.
Only issue... runny during application. Any fixes for that... maybe
more hardener than 1:1 ??
...Jim Thompson
They have a quickset version that may be less runny.
Never tried it, but have the suspicion that it is not quite as spiffy
in strength.
Wikipedia the source of all ignorance has the same strength figures for
JB-kwik and JB-weld.
--
⚂⚃ 100% natural
--- Posted via
news://freenews.netfront.net/ - Complaints to news_at_netfront.net ---
Jim Yanik
Guest
Mon Jan 23, 2012 5:26 pm
Jim Thompson <To-Email-Use-The-Envelope-Icon_at_On-My-Web-Site.com> wrote in
news:82hoh7dlg4ne9o47s17ckigg20jkv1s9ch_at_4ax.com:
Quote:
Just used some JB Weld to make a steel-to-steel joint.
Amazing stuff, took overnight to fully harden, but it's so hard now
you can barely scratch it.
Only issue... runny during application. Any fixes for that... maybe
more hardener than 1:1 ??
...Jim Thompson
go to
www.systemthree.com and download their Epoxy Book.it's free.
VERY informative about epoxies.
adding more hardener does not make epoxy cure faster or thicker.
it actually makes things worse.
Every epoxy is designed for a specifc resin:hardener ratio.
Epoxy actually takes a week or more to FULLY cure and reach full strength.
You need thixotropic fillers to do make it thicker. Like fumed silica.
Glass or plastic fibers will add strength.
JB Weld already has fillers in it.
--
Jim Yanik
jyanik
at
localnet
dot com
Jim Yanik
Guest
Mon Jan 23, 2012 5:28 pm
Jim Thompson <To-Email-Use-The-Envelope-Icon_at_On-My-Web-Site.com> wrote
in news:v8loh7ledpdisfp4q53v7gneac07jfl475_at_4ax.com:
Quote:
On Sun, 22 Jan 2012 13:13:24 -0500, "Oppie" <Oppie_at_127.0.0.1> wrote:
"Jim Thompson" <To-Email-Use-The-Envelope-Icon_at_On-My-Web-Site.com
wrote in message news:82hoh7dlg4ne9o47s17ckigg20jkv1s9ch_at_4ax.com...
Just used some JB Weld to make a steel-to-steel joint.
Amazing stuff, took overnight to fully harden, but it's so hard now
you can barely scratch it.
Only issue... runny during application. Any fixes for that... maybe
more hardener than 1:1 ??
...Jim Thompson
Been a while since I last used it but I don't recall it being runny.
If you can let it sit for a while before applying - towards the end of
its working time - and then apply, that might be better.
I'll try that... could be because it's _warm_ here ;-)
Some epoxies get weaker if you
don't mix in the specified ratio. Depends on the chemistry.
Yep.
...Jim Thompson
it gets runny because of it's thermal reaction in hardening.
heat makes it cure faster,but makes it thinner and more runny.
--
Jim Yanik
jyanik
at
localnet
dot com
Jim Yanik
Guest
Mon Jan 23, 2012 5:29 pm
Tim Wescott <tim_at_seemywebsite.please> wrote in
news:1vSdnRYZI8kRGIHSnZ2dnUVZ_g6dnZ2d_at_web-ster.com:
Quote:
On Sun, 22 Jan 2012 10:19:43 -0700, Jim Thompson wrote:
Just used some JB Weld to make a steel-to-steel joint.
Amazing stuff, took overnight to fully harden, but it's so hard now
you can barely scratch it.
Only issue... runny during application. Any fixes for that... maybe
more hardener than 1:1 ??
Don't you mess with the epoxy chemistry, Jim. You're an IC designer,
not an industrial chemist.
As pointed out, "hardener" is a misnomer. It's not quite "the other
half of the glue when finished", but it's pretty close. The Wikipedia
entry on epoxy is pretty educational.
Epoxies tend to be runny. They just aren't thixotropic by nature.
Since you want a thin glue layer anyway, the best way to deal with
this issue is to not use too much glue.
actually,too thin a glue joint is not good for epoxies,unlike wood glues.
but too much,and the excess does run.
--
Jim Yanik
jyanik
at
localnet
dot com
Jim Yanik
Guest
Mon Jan 23, 2012 5:31 pm
Robert Baer <robertbaer_at_localnet.com> wrote in
news:_e2dnR7LeqHmc4HSnZ2dnUVZ_gadnZ2d_at_posted.localnet:
Quote:
Tim Wescott wrote:
On Sun, 22 Jan 2012 10:19:43 -0700, Jim Thompson wrote:
Just used some JB Weld to make a steel-to-steel joint.
Amazing stuff, took overnight to fully harden, but it's so hard now
you can barely scratch it.
Only issue... runny during application. Any fixes for that... maybe
more hardener than 1:1 ??
Don't you mess with the epoxy chemistry, Jim. You're an IC designer,
not an industrial chemist.
As pointed out, "hardener" is a misnomer. It's not quite "the other
half of the glue when finished", but it's pretty close. The
Wikipedia entry on epoxy is pretty educational.
Epoxies tend to be runny. They just aren't thixotropic by nature.
Since you want a thin glue layer anyway, the best way to deal with
this issue is to not use too much glue.
Epoxies do not tend to be runny; there is a brand called CantSag if
i
remember correctly, and that is but one of three i found without
looking too hard.
you've never seen a boat-building epoxy then.
most epoxies -used as glues- have fillers added,and some of those fillers
make it less runny.
But temperature is a big factor.
--
Jim Yanik
jyanik
at
localnet
dot com
Andy Bartlett
Guest
Mon Jan 23, 2012 6:15 pm
"Jasen Betts" <jasen_at_xnet.co.nz> wrote in message
news:jfj6c4$cfc$1_at_reversiblemaps.ath.cx...
Quote:
On 2012-01-23, Robert Baer <robertbaer_at_localnet.com> wrote:
Jim Thompson wrote:
Just used some JB Weld to make a steel-to-steel joint.
Amazing stuff, took overnight to fully harden, but it's so hard now
you can barely scratch it.
Only issue... runny during application. Any fixes for that... maybe
more hardener than 1:1 ??
...Jim Thompson
They have a quickset version that may be less runny.
Never tried it, but have the suspicion that it is not quite as spiffy
in strength.
Wikipedia the source of all ignorance has the same strength figures for
JB-kwik and JB-weld.
The original is good for 600 deg F which for some applications is a must (I
repaired a rust hole in an elbow in my boiler chimney several years ago -
the repair is still rock solid)
I think the kwik stuff is only good for 250 deg F or so ....
Dave Platt
Guest
Mon Jan 23, 2012 8:46 pm
In article <_e2dnR7LeqHmc4HSnZ2dnUVZ_gadnZ2d_at_posted.localnet>,
Robert Baer <robertbaer_at_localnet.com> wrote:
Quote:
Epoxies tend to be runny. They just aren't thixotropic by nature. Since
you want a thin glue layer anyway, the best way to deal with this issue
is to not use too much glue.
Epoxies do not tend to be runny; there is a brand called CantSag if i
remember correctly, and that is but one of three i found without looking
too hard.
I think it depends entirely on the specifics of the epoxy... the
resins and hardeners used, and any fillers or additives.
TAP Plastics makes a nice range of "marine-grade" epoxies... one
resin, three different hardeners. The mixed epoxies have significantly
different viscosities, wetting abilities, and hardening times. The
one I prefer as my "general utility infielder" bulk-mix epoxy is the
low-viscosity variety, and if I don't add any fillers it's *quite*
runny.
TAP sells a number of fillers that can be added to their epoxies, to
modify the characteristics. One which might be of interest is
"Cab-o-Sil", a very fine "fumed" silica that can make a liquid epoxy
into a non-runny thixotropic gel, or a peanut-butter or petroleum-
jelly-like paste.
Possibly, adding a few percent of a filler like this to JB Weld might
reduce its tendency to be runny during cure, without affecting its
strength and ruggedness. I would certainly want to try this
experimentally before depending on the result!
See
http://www.tapplastics.com/uploads/pdf/pb14.pdf for details on
their various fillers.
--
Dave Platt <dplatt_at_radagast.org> AE6EO
Friends of Jade Warrior home page:
http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!
flipper
Guest
Mon Jan 23, 2012 11:35 pm
On Mon, 23 Jan 2012 11:46:19 -0800, dplatt_at_radagast.org (Dave Platt)
wrote:
Quote:
In article <_e2dnR7LeqHmc4HSnZ2dnUVZ_gadnZ2d_at_posted.localnet>,
Robert Baer <robertbaer_at_localnet.com> wrote:
Epoxies tend to be runny. They just aren't thixotropic by nature. Since
you want a thin glue layer anyway, the best way to deal with this issue
is to not use too much glue.
Epoxies do not tend to be runny; there is a brand called CantSag if i
remember correctly, and that is but one of three i found without looking
too hard.
I think it depends entirely on the specifics of the epoxy... the
resins and hardeners used, and any fillers or additives.
Here's a nice, concise, page on the MasterBond epoxy range with a
common frame of reference. (I.E. the table showing viscosity for
common things).
http://www.masterbond.com/techtips/optimizing-viscosity-epoxy-adhesives-potting-compounds-and-sealants
Their epoxy range is 200 cps to 1,500,000 cps.
Quote:
TAP Plastics makes a nice range of "marine-grade" epoxies... one
resin, three different hardeners. The mixed epoxies have significantly
different viscosities, wetting abilities, and hardening times. The
one I prefer as my "general utility infielder" bulk-mix epoxy is the
low-viscosity variety, and if I don't add any fillers it's *quite*
runny.
TAP sells a number of fillers that can be added to their epoxies, to
modify the characteristics. One which might be of interest is
"Cab-o-Sil", a very fine "fumed" silica that can make a liquid epoxy
into a non-runny thixotropic gel, or a peanut-butter or petroleum-
jelly-like paste.
Possibly, adding a few percent of a filler like this to JB Weld might
reduce its tendency to be runny during cure, without affecting its
strength and ruggedness. I would certainly want to try this
experimentally before depending on the result!
See
http://www.tapplastics.com/uploads/pdf/pb14.pdf for details on
their various fillers.
Jim Yanik
Guest
Tue Jan 24, 2012 7:59 pm
flipper <flipper_at_fish.net> wrote in
news:vanrh71omm9bbv7svv64lc8e8ab7qtbde5_at_4ax.com:
Quote:
On Mon, 23 Jan 2012 11:46:19 -0800, dplatt_at_radagast.org (Dave Platt)
wrote:
In article <_e2dnR7LeqHmc4HSnZ2dnUVZ_gadnZ2d_at_posted.localnet>,
Robert Baer <robertbaer_at_localnet.com> wrote:
Epoxies tend to be runny. They just aren't thixotropic by nature.
Since you want a thin glue layer anyway, the best way to deal with
this issue is to not use too much glue.
Epoxies do not tend to be runny; there is a brand called CantSag
if i
remember correctly, and that is but one of three i found without
looking too hard.
I think it depends entirely on the specifics of the epoxy... the
resins and hardeners used, and any fillers or additives.
Here's a nice, concise, page on the MasterBond epoxy range with a
common frame of reference. (I.E. the table showing viscosity for
common things).
http://www.masterbond.com/techtips/optimizing-viscosity-epoxy-adhesives
-potting-compounds-and-sealants
Their epoxy range is 200 cps to 1,500,000 cps.
TAP Plastics makes a nice range of "marine-grade" epoxies... one
resin, three different hardeners. The mixed epoxies have
significantly different viscosities, wetting abilities, and hardening
times. The one I prefer as my "general utility infielder" bulk-mix
epoxy is the low-viscosity variety, and if I don't add any fillers
it's *quite* runny.
TAP sells a number of fillers that can be added to their epoxies, to
modify the characteristics. One which might be of interest is
"Cab-o-Sil", a very fine "fumed" silica that can make a liquid epoxy
into a non-runny thixotropic gel, or a peanut-butter or petroleum-
jelly-like paste.
Possibly, adding a few percent of a filler like this to JB Weld might
reduce its tendency to be runny during cure, without affecting its
strength and ruggedness. I would certainly want to try this
experimentally before depending on the result!
See
http://www.tapplastics.com/uploads/pdf/pb14.pdf for details on
their various fillers.
FYI,you can get West System epoxies and fillers at many marine boat
stores,and also fiberglass cloth and mat for projects.
That's where I bought my fumed silica;boat store.
One more FYI;
www.systemthree.com offers a Trial kit for very low cost;
it includes IIRC,8oz epoxy,fast and slow hardener,several fillers including
fumed silica,phenolic microballoons,plastic chopped fiber and wood flour,a
spreader,a small piece of glass cloth,a couple of mixing cups,and their
Epoxy Book.
It was $10 PPD several years ago when I bought one,I don't know what it's
at now.
I have no financial connection to them.
--
Jim Yanik
jyanik
at
localnet
dot com
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