Glueing query

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Richard Edwards - 16 Feb 2010 17:18 GMT

I need to glue a stack of 40+ brass and steel pieces. They will be
pulled together with three tie bars. They are a bit finicky to get
lined up so I need a reasonably long wet time. I also need a "thin"
adhesive as I do not want a tolerance build up.
At the moment I am considering an anerobic like Loctite 290 (which I
have plenty of) but even that goes off relatively quickly once the
stack comes together. The adhesive is just "braces" hopefully the tie
bars will be the "belt".

Any ideas?

Richard

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Dudley Simons - 16 Feb 2010 17:20 GMT

> I need to glue a stack of 40+ brass and steel pieces. They will be
> pulled together with three tie bars. They are a bit finicky to get
[quoted text clipped - 8 lines]
>
> Richard

glue up small batches and then once they have gone off glue the 'clumps'
together?

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David Littlewood - 16 Feb 2010 19:06 GMT

>I need to glue a stack of 40+ brass and steel pieces. They will be
>pulled together with three tie bars. They are a bit finicky to get
[quoted text clipped - 4 lines]
>stack comes together. The adhesive is just "braces" hopefully the tie
>bars will be the "belt".

Araldite, preferably the 24 hour setting type. Spread very thinly and
squeeze together hard. Alternatively, if you feel Araldite would be too
thick, what about varnish?

David

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David Littlewood

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Dragon - 16 Feb 2010 20:54 GMT

>>I need to glue a stack of 40+ brass and steel pieces. They will be
>>pulled together with three tie bars. They are a bit finicky to get
[quoted text clipped - 8 lines]
> squeeze together hard. Alternatively, if you feel Araldite would be too
> thick, what about varnish?

There are many epoxies that are thinner than Araldite.
Try your nearest model/hobby shop.

Henry

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Peter Fairbrother - 16 Feb 2010 22:06 GMT

>>> I need to glue a stack of 40+ brass and steel pieces. They will be
>>> pulled together with three tie bars. They are a bit finicky to get
[quoted text clipped - 11 lines]
> There are many epoxies that are thinner than Araldite.
> Try your nearest model/hobby shop.

Yes.

The usual Araldite you buy in shops is rubbish, mostly because it's old
and has been lying around in the shop for years, but also because the
domestic variety just plain isn't very good (though Araldite do make
some good industrial glues).

A solution may be to thin an available epoxy, preferably not shop
Araldite, with isopropanol (aka IPA, Iso-Propyl Alcohol, propan-2-ol, etc).

This tends to slow down the setting time of epoxies quite a lot,
especially if more than about 4% isopropanol is used as thinner. Test
first though.

For the DHP (the manufacturer) epoxy I normally use for gluing, 10% or
more IPA will slow the 30-minute version down to about 12-24 hours,
depending on temperature.

If polyester glue is suitable, thinning it with styrene will probably
give a better result than a thinned epoxy in constrained conditions, as
the styrene thinner will chemically combine with the glue, whereas IPA
in epoxy will have to evaporate eventually somehow.

It depends on how big and thick the pieces are though, and the required gap.

-- Peter Fairbrother

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David Littlewood - 16 Feb 2010 23:51 GMT

>The usual Araldite you buy in shops is rubbish, mostly because it's old
>and has been lying around in the shop for years, but also because the
>domestic variety just plain isn't very good (though Araldite do make
>some good industrial glues).

I have some Araldite (24hr) that must be over 10 years old, and it still
works fine. Maybe takes a little longer to go fully hard. Most of the
Araldite I have binned (about two lots over 30 years) is because I
couldn't get the caps off.

>A solution may be to thin an available epoxy, preferably not shop
>Araldite, with isopropanol (aka IPA, Iso-Propyl Alcohol, propan-2-ol,
[quoted text clipped - 7 lines]
>more IPA will slow the 30-minute version down to about 12-24 hours,
>depending on temperature.

This is a most useful tip, thanks.

>If polyester glue is suitable, thinning it with styrene will probably
>give a better result than a thinned epoxy in constrained conditions, as
>the styrene thinner will chemically combine with the glue, whereas IPA
>in epoxy will have to evaporate eventually somehow.

Not that easy to get hold of styrene (and as I recall, it stinks).

David

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David Littlewood

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Peter Fairbrother - 17 Feb 2010 17:24 GMT

>> The usual Araldite you buy in shops is rubbish, mostly because it's
>> old and has been lying around in the shop for years, but also because
[quoted text clipped - 5 lines]
> Araldite I have binned (about two lots over 30 years) is because I
> couldn't get the caps off.

I can only suggest you try a good fresh epoxy and see the difference. As
I said, I mostly use NHP 30 minute which is about a tenner for 8 ounces,
but there are other similar types.

It's like chalk and cheese, really it is, and you will most likely start
using epoxy for things you previously thought epoxy couldn't do.

It depends on the precise formulation, and it's different for epoxies
where the catalyst is in a much smaller bottle, but in general a good
epoxy will begin to lose a noticeable amount of adhesion after about 6
months, and will start taking noticeably longer to harden after about a
year.

There is a trade-off the manufacturers make about life and properties -
some of the very best high-tech epoxies have a shelf life of only a
month, and three months is common.

For the epoxies I mentioned, the shelf life is in between - a very short
shelf life is too restricting. NHP and West Systems epoxies will still
be okay after couple of years (West catalyst goes off after about a
year, but the resin itself lasts longer) - though both are still best
when fresh.

It's not essential, but if you keep epoxy in the bottom of a fridge it
will last longer. Don't freeze it though, and warm to room temperature
before use.

> Not that easy to get hold of styrene (and as I recall, it stinks).

It's straightforward to get hold of styrene. Most of the people who
supply boatbuilding (as opposed to boat repair) polyester resins also
supply it, and you can simply buy it on ebay. Eg:

http://www.cfsnet.co.uk/cgi-local/sh000001.pl?REFPAGE=http%3a%2f%2fwww%2ecfsnet%
2eco%2euk%2facatalog%2fCFS_Catalogue__POLYESTER_RESINS_1%2ehtml&WD=styrene&PN=CF
S_Catalogue__Styrene_279%2ehtml%23aCSTSTY_2d001#aCSTSTY_2d001
http://thefibreglassshop.co.uk/shop/article_35/Styrene---1L..html?shop_param=cid
%3D135%26aid%3D35%26
http://cgi.ebay.co.uk/1-Litre-Styrene-Additive-Thinning-Resin-GRP-Work_W0QQitemZ
220499732908QQcmdZViewItemQQptZUK_Crafts_Other_Crafts_EH?hash=item3356cee9ac

It's slightly nasty stuff, be careful when using it - most important is
to avoid breathing it.

And yes, it stinks.

-- Peter Fairbrother

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Drawfiler - 16 Feb 2010 21:21 GMT

On Feb 16, 5:18 pm, Richard Edwards <poundea...@blueyonder.co.uk>
wrote:

> I need to glue a stack of 40+ brass and steel pieces. They will be
> pulled together with three tie bars. They are a bit finicky to get
[quoted text clipped - 8 lines]
>
> Richard

I think it depends on the application but you could try good old
shelac and paint each one inturn then clam up and gently heat, the
shelac will melt and fuse giving a thin joint. If you go for araldite
24 hour, raise the tempreature and it will thin and set quickly as
well as giving a thin joint, but not as thin as shelac.
Peter

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Richard Edwards - 16 Feb 2010 23:45 GMT

>I need to glue a stack of 40+ brass and steel pieces. They will be
>pulled together with three tie bars. They are a bit finicky to get
[quoted text clipped - 8 lines]
>
>Richard

Gentlemen,

Very many thanks for your prompt and interesting suggestions.

I am looking for a maximum glue thickness of .03mm or thereabouts so
"thin" is of the essence.

Based on the suggestions I think I will pursue the IPA thinned epoxy
option and the Shellac option. I feel that I should have some shellac
flakes on the shelf anyway. I see some experimenting coming on <G>

Peter, you mention DHP, I have searched and searched but probably
cannot see the wood for the trees <G> Can you give me a better pointer
to the product or manufacturer?

Richard

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Peter Fairbrother - 17 Feb 2010 00:57 GMT

> Peter, you mention DHP, I have searched and searched but probably
> cannot see the wood for the trees <G> Can you give me a better pointer
> to the product or manufacturer?

My bad - should be NHP. Sorry about that.

Should be readily available, and much favoured by rocketeers. 14,400
worldwide and 538 UK-only google links today.

I'm not recommending them - well actually I am a bit - just saying that
that's what I use for gluing and similar jobs.

For composite layup I use West Systems epoxies. Composite layup epoxies
are usually thinner than gluing epoxies, which may be of interest to
you, though a small-but-useful pack of NHP at around a tenner is about
1/3 the price of a small-but-useful pack of West Systems at about £30.

NHP adheres better than West for gluing purposes.

If you possibly can, buy fresh epoxies from someone with a large
turnover. After a few months in stock they begin to stop working as well
as fresh ones, the difference is quite noticeable.

There are better-performing epoxies than these available, but all the
ones I have tried were ouch! expensive.

YMMV, but probably not by that much.

For another perhaps unexpected but possibly quite apt suggestion see:

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=320186922795&ssPageName=STR
K:MEWAX:IT

for 1 mil (?=0.025 mm?) FEP film. Just be be careful not to overheat it
too much, if it gets really hot it can give of dangerous fumes above
about 300 C. Melts at 260 C, in theory.

But you can safely put it in eg a hot domestic electric oven. I'd
recommend at say 230-250 C when compressed, if your oven goes that high
and if SWMBO will let you...

Again, do a trial run first if at all possible. Using sheet glue is a
different technique, and things have to be very clean,

-- Peter

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Model Forum / General / Models / February 2010

Glueing query