See no n.g. for adhesives & epoxies, so if there's a better forum for this,
just point me to it.

I need an epoxy that is strong to the point of brittle. I want no flex; it
has to transmit vibration as close to 100% as possible.

Am I looking for a high Shore Hardness value? That's what Devcon uses in its
data sheets to specify hardness.

Is this something that I can achieve by changing the mix of the 2 parts? If
so, what do I lose if I use more hardener?

Any personal experiences with epoxies that you found to be harder than
others?

Thanks.
FBt

On Mar 20, 3:09*pm, Esther & Fester Bestertester
wrote:
See no n.g. for adhesives & epoxies, so if there's a better forum for this,
just point me to it.

I need an epoxy that is strong to the point of brittle. I want no flex; it
has to transmit vibration as close to 100% as possible.

Am I looking for a high Shore Hardness value? That's what Devcon uses in its
data sheets to specify hardness.

Is this something that I can achieve by changing the mix of the 2 parts? If
so, what do I lose if I use more hardener?

Any personal experiences with epoxies that you found to be harder than
others?

Thanks.
FBt

For spacecraft vibration testing we use Dental cement. It's extremely
non-compliant so it is good for transmitting vibration from a
structure to an accelerometer. It is brittle so we remove them by
just taping them with a hammer and breaking them off the surface. We
first put a layer of thin tape on the surface to protect the surface.
the tape does not affect the vibration response.
bob

On Thu, 20 Mar 2008 21:09:14 GMT, in sci.electronics.design Esther &
Fester Bestertester wrote:

See no n.g. for adhesives & epoxies, so if there's a better forum for this,
just point me to it.

I need an epoxy that is strong to the point of brittle. I want no flex; it
has to transmit vibration as close to 100% as possible.

Am I looking for a high Shore Hardness value? That's what Devcon uses in its
data sheets to specify hardness.

Is this something that I can achieve by changing the mix of the 2 parts? If
so, what do I lose if I use more hardener?

Any personal experiences with epoxies that you found to be harder than
others?

Thanks.
FBt
try searching for
sci.engr.chem
or sci.engr.*




martin

Esther & Fester Bestertester wrote:
See no n.g. for adhesives & epoxies, so if there's a better forum for this,
just point me to it.

I need an epoxy that is strong to the point of brittle. I want no flex; it
has to transmit vibration as close to 100% as possible.

Am I looking for a high Shore Hardness value? That's what Devcon uses in its
data sheets to specify hardness.

Is this something that I can achieve by changing the mix of the 2 parts? If
so, what do I lose if I use more hardener?

Any personal experiences with epoxies that you found to be harder than
others?

Filled epoxies (loaded with various mineral and glass bits)
are much more rigid than plain epoxy. But if you start with
a slow cure epoxy (30 minute versus 5 minute) the epoxy,
itself will also be a lot harder. Glass micro spheres are a
good filler if you want to lower the density, and glass
micro beads or aluminum oxide if you want to raise it. Even
adding talcum powder adds to the rigidity, but the gas
bubbles it entrains lowers it (foams are less rigid than
solids of the same material), so vacuum degassing increases
the rigidity.

A very rigid mineral filled epoxy is Hysol 1C:
http://www.gluguru.com/Hysol%20Data%20Sheets/1C.htm

A slighter harder aluminum filled formula is Hysol 9434:
http://www.gluguru.com/Hysol%20Data%20Sheets/9434.htm

But they make lots of variations:
http://www.gluguru.com/HyEpSelecGuide.htm

--
Regards,

John Popelish

Any personal experiences with epoxies that you found to be harder than
others?

I cannot suggest a harder epoxy but you pressed a sensitive button on
me
so here I go.

Many years ago (1991, to be precise) I opted to epoxy-fill my first
5kV
coils I did for my then employer in Cologne, Germany. I used no
multiplier,
straight flyback @ 5kV; about 1000 windings on an RM8 core, winding
and insulation layers being an art of their own. I located some very
liquid
epoxy meant for that purpose, then the whole module went filled, using
vacuum to make sure there were no cavities. Everything worked fine,
the filling
was perfect - I got asked how come the space between the *windinds*
was
not filled (0.05 wire, mylar foil between each layer) by my then
employer...
Some years later I had founded TGI in Bulgaria and did the first HV
source
making the coil more or less the same. However, I used off-the-shelf
epoxy;
it did not get as hard (although it was by far not as liquid before
hardening),
and after some warmup it began to conduct just enough to make the
thing
noisy... I wasted more than one coil (wound with a lot of work) until
I
got what was going on, I spent days if not weeks on that nightmare...
Eventually I learned I needed no filling at all, just a few drops of
melted
silicon at the right spots did the job (still does) quite well.

And on another occasion I had a guy from a detector repairshop in
Sofia
use the same effect trying to cheat on me... The HPGe gamma detectors
are very sensitive things, the front FET is cooled to -90C or so for
lowest
noise. The bias is a few kV (3.5 in that case), and the HV input is
filtered
through a 1Gohm/0.47uF group. Well, he had had the detector in his
hands
to "check it" for me and had put a stripe of such epoxid along the
resistor
between its pins... (The resistor is a rectangle, say 20x5mm, 1mm
thick).
After some warmup - the preamp consumes not so little, they have not
changed its design for 20 years - the detector begins to behave like
when it needs repair. Well he did not get it for repair because I
looked
and discovered what he had done and cleaned the mess up -and the
detector
worked fine. A few years later he got the same detector in his hands
directly from customers and did the same, this time he had added a
stripe
across the capacitor, though, and had scratched the paint of the
resistor between the pins. Mind you, I had told him I knew what he had
done the first time and he had done it again. I guess the epoxy must
have
had braindamaging effect as well.... (and I had refused to believe
other
people telling me he was sabotaging detectors before I got burned, the
epoxy must have worked on my brain as well - perhaps while dealing
with my coils... :-).

Dimiter

------------------------------------------------------
Dimiter Popoff Transgalactic Instruments

http://www.tgi-sci.com
------------------------------------------------------
http://www.flickr.com/photos/didi_tg...7600228621276/

Esther & Fester Bestertester wrote:
See no n.g. for adhesives & epoxies, so if there's a better forum for this,
just point me to it.

I need an epoxy that is strong to the point of brittle. I want no flex; it
has to transmit vibration as close to 100% as possible.

Am I looking for a high Shore Hardness value? That's what Devcon uses in its
data sheets to specify hardness.

Is this something that I can achieve by changing the mix of the 2 parts? If
so, what do I lose if I use more hardener?

Any personal experiences with epoxies that you found to be harder than
others?

Thanks.
FBt

I need an epoxy that is strong to the point of brittle. I want no flex; it
has to transmit vibration as close to 100% as possible.

Sounds to me as if you're actually looking for stiffness, not
necessarily strength?

I think you'd want to look for (or make) a filled epoxy. A
high-strength epoxy which is loaded up with (e.g.) chopped or milled
fiberglass would be very stiff.

--
Dave Platt 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!

"Esther & Fester Bestertester" wrote in message
obal.net...
See no n.g. for adhesives & epoxies, so if there's a better forum for
this,
just point me to it.

I need an epoxy that is strong to the point of brittle. I want no flex; it
has to transmit vibration as close to 100% as possible.

Am I looking for a high Shore Hardness value? That's what Devcon uses in
its
data sheets to specify hardness.

Is this something that I can achieve by changing the mix of the 2 parts?
If
so, what do I lose if I use more hardener?

Any personal experiences with epoxies that you found to be harder than
others?

Thanks.
FBt

If you can afford it, Araldite 2014. 4-6 hrs grab, 24hr set.It's a grey
paste two part.-

"TT_Man" wrote in message
...

"Esther & Fester Bestertester" wrote in message
obal.net...
See no n.g. for adhesives & epoxies, so if there's a better forum for
this,
just point me to it.

I need an epoxy that is strong to the point of brittle. I want no flex;
it
has to transmit vibration as close to 100% as possible.

Am I looking for a high Shore Hardness value? That's what Devcon uses in
its
data sheets to specify hardness.

Is this something that I can achieve by changing the mix of the 2 parts?
If
so, what do I lose if I use more hardener?

Any personal experiences with epoxies that you found to be harder than
others?

Thanks.
FBt

If you can afford it, Araldite 2014. 4-6 hrs grab, 24hr set.It's a grey
paste two part.-

I like Araldite 10, fast cure, 10 minutes to set, 1hr cure. The last time
I ordered it it came as Huntsman 10. You should be able to find a spec.
sheet online.
Huntsman Advanced Materials Americas Inc.
4917 Dawn Ave.
East Lansing Mi. 48823-5691
517-351-5900
Mike

On Thu, 20 Mar 2008 21:09:14 +0000, Esther & Fester Bestertester wrote:

See no n.g. for adhesives & epoxies, so if there's a better forum for
this, just point me to it.

I need an epoxy that is strong to the point of brittle. I want no flex;
it has to transmit vibration as close to 100% as possible.

Am I looking for a high Shore Hardness value? That's what Devcon uses in
its data sheets to specify hardness.

Is this something that I can achieve by changing the mix of the 2 parts?
If so, what do I lose if I use more hardener?

Any personal experiences with epoxies that you found to be harder than
others?

Thanks.
FBt

sci.materials is good.

Al

"Esther & Fester Bestertester" wrote in message
obal.net...
See no n.g. for adhesives & epoxies, so if there's a better forum for
this,
just point me to it.

I need an epoxy that is strong to the point of brittle. I want no flex; it
has to transmit vibration as close to 100% as possible.

Am I looking for a high Shore Hardness value? That's what Devcon uses in
its
data sheets to specify hardness.

Is this something that I can achieve by changing the mix of the 2 parts?
If
so, what do I lose if I use more hardener?

Any personal experiences with epoxies that you found to be harder than
others?

Thanks.
FBt

If you have been letting it cure at room temperature, try about 15 minutes
at 160 F or so. It will get a lot harder.

Tam

If you have been letting it cure at room temperature, try about 15 minutes
at 160 F or so. It will get a lot harder.

Tam

Does it matter when the heat is applied? Right away? Or after it seems to
have cured as much as it is going to at room temp?

"Esther & Fester Bestertester" wrote in message
obal.net...
If you have been letting it cure at room temperature, try about 15
minutes
at 160 F or so. It will get a lot harder.

Tam

Does it matter when the heat is applied? Right away? Or after it seems to
have cured as much as it is going to at room temp?

I have been waiting a few minutes until the epoxy is no longer runny. I turn
the oven on to 200, but turn it off before it reaches temperature. Have also
used a heat gun on something that was part of a large stationary object
(toilet). I haven't bothered, but this information should be available from
the manufacturer.

Tam

hand held hair dryers work fine

let epxy cure to near solid, then heat

else it will reliquify and run with gravity, messy!!

my work once required magnets to be epoxied to core pieces in meter
movements, they went thru ovens after primary cure for abt 15 minutes at 200
deg F

that was before engneering started using cryanoacrylite type adhesives, they
seemed much better and harder with less work time, never had a release
either.

preparation is key to good results

cryo is avail in gel or near gooy form

Loctite corporation has tons of alternatives available


"Tam" wrote in message
. ..

"Esther & Fester Bestertester" wrote in message
obal.net...
If you have been letting it cure at room temperature, try about 15
minutes
at 160 F or so. It will get a lot harder.

Tam

Does it matter when the heat is applied? Right away? Or after it seems
to
have cured as much as it is going to at room temp?

I have been waiting a few minutes until the epoxy is no longer runny. I
turn
the oven on to 200, but turn it off before it reaches temperature. Have
also
used a heat gun on something that was part of a large stationary object
(toilet). I haven't bothered, but this information should be available
from
the manufacturer.

Tam

for epoxies available over the counter ( not commercial specialty) most are
two part resin based, to be mixed like a liquid initially

this appeals to small , unique and one time fixes.

thin applications are ideal, as most ofthese areNOT meant to be filler
types, unless specificcaly stated

thin narrow space between parts creates incredible strength when properly
epoxied, never 'rely' on the epoxy to become strong like the materials you
are joining

except someepoxy may be actualy stronger,, then you just end up breakin the
fixed part in some other place when it is used badly agaon!

filled and putty type epoxies , granted they do not 'run' when applied.
technically diferent formulations

silicone sealants when cured wil offer high strength when used correctly
( thin, well prepared)

acrylic based fillers provide similar opportuinites.

polymers come in many shades of performance and coloration,

dont get hung upon 'the same old thing', the chemists are busy as we sit on
asses typing ...................................


"MakeNoAttemptToAdjustYourSet"
wrote in message ...
On Sun, 23 Mar 2008 20:15:46 GMT, "HapticZ"
wrote:

else it will reliquify and run with gravity, messy!!


Wrong. There are plenty of epoxies that stay right where they are put.

Not only that, but capillary attraction will hold most in place.

Also, the extremely high temp a hair dryer or heat gun puts out is too
much. It needs to be in an oven at a known temperature to cure correctly.

On Thu, 20 Mar 2008 21:09:14 GMT, Esther & Fester Bestertester
wrote:

:See no n.g. for adhesives & epoxies, so if there's a better forum for this,
:just point me to it.
:
:I need an epoxy that is strong to the point of brittle. I want no flex; it
:has to transmit vibration as close to 100% as possible.
:
:Am I looking for a high Shore Hardness value? That's what Devcon uses in its
:data sheets to specify hardness.
:
:Is this something that I can achieve by changing the mix of the 2 parts? If
:so, what do I lose if I use more hardener?
:
:Any personal experiences with epoxies that you found to be harder than
thers?
:
:Thanks.
:FBt


Devcon specialise in making epoxy materials for repairs to machinery. For
example their Titanium Putty
http://www.devcon.com/techinfo/124.pdf is specified for repairs to machinery
where the repair requires a machined finish. This must be extremely hard
material when cured.

There are single component epoxies used in IC fabrication which have 94D
hardness ie. ME-430 http://emeigroup.com/pdf/EMHP%20Eng_3.pdf

On Thu, 20 Mar 2008 21:09:14 GMT, Esther & Fester Bestertester
wrote:

See no n.g. for adhesives & epoxies, so if there's a better forum for this,
just point me to it.

I need an epoxy that is strong to the point of brittle. I want no flex; it
has to transmit vibration as close to 100% as possible.

Am I looking for a high Shore Hardness value? That's what Devcon uses in its
data sheets to specify hardness.

Is this something that I can achieve by changing the mix of the 2 parts? If
so, what do I lose if I use more hardener?

Any personal experiences with epoxies that you found to be harder than
others?

Thanks.
FBt

Dunno if it's tough enough but I use GR epoxy glue from Industrial
Formulations.
24 hour cure. (Sometimes a pita.)
Here in BC.
http://www.indform.com/
"We have an epoxy system for almost any project".
Really?? :P

All I know is that GR epoxy has less flex than Lepage 2 page epoxy
(dual syringe) I got from the hardware store.


D from BC
British Columbia
Canada

On Thu, 20 Mar 2008 19:03:05 -0800, wrote:

On Thu, 20 Mar 2008 21:09:14 GMT, Esther & Fester Bestertester
wrote:

See no n.g. for adhesives & epoxies, so if there's a better forum for this,
just point me to it.

I need an epoxy that is strong to the point of brittle. I want no flex; it
has to transmit vibration as close to 100% as possible.

Am I looking for a high Shore Hardness value? That's what Devcon uses in its
data sheets to specify hardness.

Is this something that I can achieve by changing the mix of the 2 parts? If
so, what do I lose if I use more hardener?

Any personal experiences with epoxies that you found to be harder than
others?

Thanks.
FBt

Dunno if it's tough enough but I use GR epoxy glue from Industrial
Formulations.
24 hour cure. (Sometimes a pita.)
Here in BC.
http://www.indform.com/
"We have an epoxy system for almost any project".
Really?? :P

All I know is that GR epoxy has less flex than Lepage 2 page epoxy
(dual syringe) I got from the hardware store.


D from BC
British Columbia
Canada

Nothing to add.. Just checking my usenet client settings.
Ignore this part..


D from BC
British Columbia
Canada

To those who offer help even to the misguided, thank you for the benefit of
your knowledge.

To those who offer directions to the appropriate forum, thanks for the
(index) finger. :-)

FBtf

Esther & Fester Bestertester wrote:
See no n.g. for adhesives & epoxies, so if there's a better forum for this,
just point me to it.

I need an epoxy that is strong to the point of brittle. I want no flex; it
has to transmit vibration as close to 100% as possible.

Am I looking for a high Shore Hardness value? That's what Devcon uses in its
data sheets to specify hardness.

Is this something that I can achieve by changing the mix of the 2 parts? If
so, what do I lose if I use more hardener?

Any personal experiences with epoxies that you found to be harder than
others?

Thanks.
FBt


sci.polymers or sci.materials might be a better bet. There are two
general ways you can make a given epoxy harder: bake it (an hour at 100C
does wonders) or put filler in it.

If you're bonding hard materials, you might want to use a glass bead
filler. When you squeeze the bondline down, the spheres contact the
surface, and as the epoxy shrinks (1% or so), it applies a preload to
the glass/substrate interfaces. That's a pretty stiff joint.

If you're trying to do something in shear, e.g. attach a strain gauge,
glue is not your friend at all. You might be better off using solder or
indium bonding or something like that.

Cheers,

Phil Hobbs

On Mar 20, 1:09*pm, Esther & Fester Bestertester
wrote:
See no n.g. for adhesives & epoxies, so if there's a better forum for this,
just point me to it.

I need an epoxy that is strong to the point of brittle. I want no flex; it
has to transmit vibration as close to 100% as possible.

Am I looking for a high Shore Hardness value? That's what Devcon uses in its
data sheets to specify hardness.

Is this something that I can achieve by changing the mix of the 2 parts? If
so, what do I lose if I use more hardener?

Any personal experiences with epoxies that you found to be harder than
others?

Thanks.
FBt

Rubinno cement made by Singer Kearfott in the 70's was used on
guidance systems for the Sram missile, PC3, and A7 navey fighter
jets. It is the best there is.

Rubinno cement

Google turns up zero hits. Is the correct spelling? Any web references you
can give?

Thanks,
FBt

On Mar 21, 10:36*am, Esther & Fester Bestertester
wrote:
Rubinno cement

Google turns up zero hits. Is the correct spelling? Any web references you
can give?

Thanks,
FBt

Try:
Kearfott Guidance & Navigation Corporation
1150 McBride Avenue
Little Falls, New Jersey 07424-2500, USA

It is probably $50 a quart. Minimum.

But that doesn't help me know *where*.

FBt

Gerald Newton wrote:

On Mar 20, 1:09 pm, Esther & Fester Bestertester
wrote:
See no n.g. for adhesives & epoxies, so if there's a better forum for this,
just point me to it.

I need an epoxy that is strong to the point of brittle. I want no flex; it
has to transmit vibration as close to 100% as possible.

Am I looking for a high Shore Hardness value? That's what Devcon uses in its
data sheets to specify hardness.

Is this something that I can achieve by changing the mix of the 2 parts? If
so, what do I lose if I use more hardener?

Any personal experiences with epoxies that you found to be harder than
others?

Thanks.
FBt

Rubinno cement made by Singer Kearfott in the 70's was used on
guidance systems for the Sram missile, PC3, and A7 navey fighter
jets. It is the best there is.

What exactly was it used for? For securing components in a high
vibration environment, that might damp the vibrations that the OP wants
to transmit.

--
Paul Hovnanian
------------------------------------------------------------------
During the next two hours, the system will be going up and down several
times, often with lin~po_~{po ~poz~ppo\~{ o n~po_~{o[po ~y oodsou#w4ko

Look on the web for, Aluma Lead.I used to use Aluma Lead for doing auto
body repair work.Also, J B Weld might work for you. www.jbweld.com
cuhulin

Esther & Fester Bestertester wrote:

See no n.g. for adhesives & epoxies, so if there's a better forum for this,
just point me to it.

I need an epoxy that is strong to the point of brittle. I want no flex; it
has to transmit vibration as close to 100% as possible.

Am I looking for a high Shore Hardness value? That's what Devcon uses in its
data sheets to specify hardness.

I believe that (Shore) is a measure of resistance to indentation. In
other words, pressure. You might need something else, depending on which
direction the vibration is acting with respect to the surface. A
pressure wave will result in both pressure and tensile stresses on the
adhesive. A shear wave will result in (duh) shear stresses.

In addition, you need to define what you mean by 'transmit vibration'.
I'm not a mechanical guy, but I'd be willing to bet that the problem of
maximizing mechanical energy transmission is analogous to that of
maximizing electromagnetic energy transmission. That is: It is optimal
when the impedance (modulus of elasticity?) is closely matched and
energy reflection is minimized.

The strength of the adhesive only becomes important if the amplitude of
the vibration approaches the strength limit of the bond.

This appears to be the sort of problems that people designing sonar
transducers have to deal with.

--
Paul Hovnanian
------------------------------------------------------------------
What if no one ever asked a hypothetical question?

Paul Hovnanian P.E. wrote:
The strength of the adhesive only becomes important if
the amplitude of the vibration approaches the strength limit of the bond.

This appears to be the sort of problems
that people designing sonar transducers have to deal with.

I saw something on Blue Whales the other day
that mentioned they are the loudest creature.
I looked it up and the figure is 188dB (like being next to a rocket)
....and there is great controversy about SONAR use
because it is thought (due to weird behavior
like healthy-appearing specimens beaching themselves)
that it is so loud that it damages the hearing of whales.

On 3ÔÂ21ÈÕ, ÉÏÎç5ʱ09·Ö, Esther & Fester Bestertester
wrote:
See no n.g. for adhesives & epoxies, so if there's a better forum for this,
just point me to it.

I need an epoxy that is strong to the point of brittle. I want no flex; it
has to transmit vibration as close to 100% as possible.

Am I looking for a high Shore Hardness value? That's what Devcon uses in its
data sheets to specify hardness.

Is this something that I can achieve by changing the mix of the 2 parts? If
so, what do I lose if I use more hardener?

Any personal experiences with epoxies that you found to be harder than
others?

Thanks.
FBt



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On 3ÔÂ21ÈÕ, ÉÏÎç5ʱ09·Ö, Esther & Fester Bestertester
wrote:
See no n.g. for adhesives & epoxies, so if there's a better forum for this,
just point me to it.

I need an epoxy that is strong to the point of brittle. I want no flex; it
has to transmit vibration as close to 100% as possible.

Am I looking for a high Shore Hardness value? That's what Devcon uses in its
data sheets to specify hardness.

Is this something that I can achieve by changing the mix of the 2 parts? If
so, what do I lose if I use more hardener?

Any personal experiences with epoxies that you found to be harder than
others?

Thanks.
FBt



Do you want access to China's massive pool of electronic
manufacturers... but lack the time to contact suppliers, negotiate
contracts, arrange shipping or monitor product quality? Don't worry -
Let seriouswholesale deal with all that for you.

*Check out the huge range of Gadgets, MP3 / MP4 Players, Car DVD /
Audio, and Computer Accessories now by visiting the online wholesale
catalog at seriouswholesale. com You'll have peace of mind thanks to
the seriouswholesale Quality Control, 12-month Warranty on all
products, and easy secure payment by credit card through Paypal.

Selling on eBay or your own online store? Send products direct from
our warehouse to your customers using our unique drop-shipping
service. You can profit by selling hundreds of different products,
without holding any of your own inventory! Any questions you have will
be answered by the seriouswholesale English-speaking customer support
team... Their aim is to make your China electronics importing business
easier to run than ever before.

Welcome to http://www.seriouswholesale.com.

seriouswholesale - Buy from the source, profit without the hassle.

- 12 Months Warranty - No minimum order restrictions - Drop-shipping
with no additional fee - Pay by safely by PayPal seriouswholesale
Wholesale Co., Ltd.: Chinas original and best online electronics
wholesaler & drop-shipper: seriouswholesale. com

"The Last Mimsy" wrote in message
...
Which, would oddly meat your needs.

Don't let your meat loaf ;-)

Tim

--
Deep Fryer: A very philosophical monk.
Website @ http://webpages.charter.net/dawill/tmoranwms

On Thu, 20 Mar 2008 16:19:07 -0700, The Last Mimsy wrote:
On Thu, 20 Mar 2008 21:09:14 GMT, Esther & Fester Bestertester

See no n.g. for adhesives & epoxies, so if there's a better forum for this,
just point me to it.

I need an epoxy that is strong to the point of brittle. I want no flex; it
has to transmit vibration as close to 100% as possible.

Am I looking for a high Shore Hardness value? That's what Devcon uses in its
data sheets to specify hardness.

Is this something that I can achieve by changing the mix of the 2 parts? If
so, what do I lose if I use more hardener?

Any personal experiences with epoxies that you found to be harder than
others?

With the way you worded this, it would seem that a technical response
would go right over your head.

Epoxy mix ratios are NEVER meant to be altered. You need to find an
epoxy that matches your needs. The only time I ever saw mix ratio ranges
to alter behavior, it was with an epoxy branded as "stycast". Which,
would oddly meat your needs.

It will not likely be cheap, however.

Just FYI, when I was a kid, my Dad (RIP) got a two-bottle set of one of
the first epoxies, and its instructions gave one ratio for a rigid bond,
and another for "flexible".

I haven't seen anything like that lately, probably because so few
people would have the right measuring stuff. :-)

Thanks,
Rich

On Mon, 24 Mar 2008 19:27:09 -0700, The Last Mimsy
wrote:

On Tue, 25 Mar 2008 01:40:00 GMT, Rich Grise wrote:

On Thu, 20 Mar 2008 16:19:07 -0700, The Last Mimsy wrote:
On Thu, 20 Mar 2008 21:09:14 GMT, Esther & Fester Bestertester

See no n.g. for adhesives & epoxies, so if there's a better forum for this,
just point me to it.

I need an epoxy that is strong to the point of brittle. I want no flex; it
has to transmit vibration as close to 100% as possible.

Am I looking for a high Shore Hardness value? That's what Devcon uses in its
data sheets to specify hardness.

Is this something that I can achieve by changing the mix of the 2 parts? If
so, what do I lose if I use more hardener?

Any personal experiences with epoxies that you found to be harder than
others?

With the way you worded this, it would seem that a technical response
would go right over your head.

Epoxy mix ratios are NEVER meant to be altered. You need to find an
epoxy that matches your needs. The only time I ever saw mix ratio ranges
to alter behavior, it was with an epoxy branded as "stycast". Which,
would oddly meat your needs.

It will not likely be cheap, however.

Just FYI, when I was a kid, my Dad (RIP) got a two-bottle set of one of
the first epoxies, and its instructions gave one ratio for a rigid bond,
and another for "flexible".

I haven't seen anything like that lately, probably because so few
people would have the right measuring stuff. :-)

Thanks,
Rich


There are some epoxies that give different characteristics with a
different mix ratio, but not many, and NONE of those that do not should
be manipulated in such a way.

Curious, I have been using epoxies for more than 40 years and have
read many articles on epoxies in for instance Adhesives and Sealants
magazine, and I have never once seen or heard of any epoxy whose
properties do not depend on mix ratio; although in many cases exact
mix ratio is not critical.

The "stycast" I mentioned has about four different hardening schedules,
and uses about three different hardening medias. All yield differing
results for heat resistance, high temp softening after cure, etc.

When it is several grams of base media, and a few drops of "hardener",
I call it barely qualified to be called epoxy.

When the mix is closer to 50 50, one will find it is more stringently
adhered to as both constituents are critical to the finished medium.

Some mixes have to be accurate to within 0.1 grams or 0.1%.

"Epoxy" is not an adhesive, it is a family of adhesives that includes
many different specific chemistries. All high strength epoxies are
multi-functional, that is, they are a blend of two or more of the
basic epoxy chemistries. In any critical application it is foolish
not to discuss your specific requirements with one or more epoxy
formulators to obtain a blend closely optimized to your needs, and
then to qualify the materials and application process with testing.
Master Bond is one supplier of specialty epoxies with good tech
support.

On the other hand, for hobby applications, you can get good variation
in hardness with mix ratio with any nominally 5:1 ratio marine epoxy.
These epoxies are normally available with slow or fast hardeners in
order to allow reasonable working time in cool (use fast hardener) to
hot (use slow hardener) conditions. More hardener results in more
flexibility with lower strength and hardness. I mostly use "The West
System" with pump dispensers for easy measurement - one stroke of each
is 5:1, for small amounts I count drops. With the addition of fumed
silica (available from the same marine suppliers as the epoxy) it can
be thickened into a non-running paste very easily, or with the
addition of fine wood dust as a filler you can make epoxy foam.

BTW, by far the most common reason for lower than normal strength
epoxy is inadequate mixing, especially in the filled, pasty
formulations. It is best to consider the point where the epoxy
appears to be completely mixed to be the half way point in mixing. If
you actually measure the strength or hardness of the cured epoxy the
additional mixing will almost always result in better and more
consistent properties.

"The Last Mimsy" wrote in message
...
On Tue, 25 Mar 2008 15:49:55 GMT, Glen Walpert wrote:

All high strength epoxies are
multi-functional, that is, they are a blend of two or more of the
basic epoxy chemistries.


Two. Epoxy, by definition is a two part mix.

You're talking about different things. Epoxy is a two part mix when you buy
it, but that doesn't mean that each part is not made of multiple compounds
mixed inmanufacture.