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Epoxy question

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
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Epoxy question

Unread postAuthor: Demon » Tue Mar 30, 2010 11:01 am

Here is a question that might make a certain know member get out of is cave :roll:

Here is some info : as you all know, i am working on a 6 mm carbine wich is done now ( i only need to make a stock ) ...

But ...

Epoxy just failed on me.
I explain : in the trigger mech, the 'bolt catch arm support' , wich was held by epoxy, just falled when i was holding the gun ... It is put under approx 10 lbs of stress and it popped off. (the said part is held in sandwich between to sheets of aluminium and is itself made of aluminium)

My question is :

Is metal epoxy made to bind two metals and if yes, why did it failed (Was there grease to be cleaned out or something) ? Or else, should i try Krazyglue to repair it ?

I need your help dudes
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Unread postAuthor: jrrdw » Tue Mar 30, 2010 11:22 am

Not all epoxies stick to all metals. Read the documentation that came with it and more importantly the directions. You'd be surprised...
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Unread postAuthor: Demon » Tue Mar 30, 2010 12:55 pm

So then what, should i use crazy glue with a solvant use before ?
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Unread postAuthor: Gippeto » Tue Mar 30, 2010 1:35 pm

Bonding aluminum might present some problems.

Almost immediately after you rough up the surface, a layer of aluminum oxide begins to form....not sure if epoxy bonds to aluminum oxide or not.

Aluminum has a rather high coefficient of expansion...which could cause the epoxy bond to fail. This would require large changes in temperature though.

Proper mixing of the two parts to achieve rated strength.

Proper curing. (Eh what Jack? :wink: ) Likely not the case here given the amount of time it's been together.

Pictures showing the failure might be in order.
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Unread postAuthor: jrrdw » Tue Mar 30, 2010 1:52 pm

Going on how your discription sounds to me, I would screw the two parts together to sandwitch the bolt handle in there. Pictures of the pieces apart, then together would help.
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Unread postAuthor: Demon » Tue Mar 30, 2010 3:19 pm

Here are the two pics, before and after failure

Would crazy glue with a proper solvant cleaning do the job?
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Unread postAuthor: saefroch » Tue Mar 30, 2010 3:38 pm

The only thing I can think of is to weld that together, it is possible that if you scrub the aluminium very well, then epoxy it again that it will hold. As mentioned before, epoxy is not a one-type-glues-all.
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Unread postAuthor: Demon » Tue Mar 30, 2010 3:55 pm

So krazy glue OK or not ?

it worked very well when i was making metal figurines back in time ...
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Unread postAuthor: Hawkeye » Tue Mar 30, 2010 5:34 pm

You have to etch aluminum with a two part system to make it work.
No other treatment will work in a lasting manner.
The closest you can get is aggressively scoring and drilling small recesses in the parts you want to glue, applying a layer of Epoxy and then 'wet sanding' the epoxy into the roughened surfaces.
An Epoxy specifically designed for aluminum is always a wise idea.
Guys who routinely glue Aluminum with Epoxy will tell you that even good surface preparation that is not an etch system will always eventually fail.
Honestly, Aluminum etch is really not something you want to be around too much.

It looks like you could adapt the piece a bit and screw or bolt it in position instead.
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Unread postAuthor: jrrdw » Tue Mar 30, 2010 6:15 pm

Demon wrote:So krazy glue OK or not ?

it worked very well when i was making metal figurines back in time ...


Try it......
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Unread postAuthor: Demon » Wed Mar 31, 2010 8:36 am

Demon wrote:
So krazy glue OK or not ?

it worked very well when i was making metal figurines back in time ...



Try it......


Thank you very much, you are of a very wise help ...

It looks like you could adapt the piece a bit and screw or bolt it in position instead.


I tried but as i dont have a press drill, i failed. (it needs to be very tight, so gluing is the best option)
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Unread postAuthor: qwerty » Wed Mar 31, 2010 10:43 am

Just use this stuff-http://www.diy.com/diy/jsp/bq/nav.jsp?action=detail&fh_secondid=9726445&ecamp=trf-005&CAWELAID=266888200

* Suitable for steel, cast iron, copper, aluminium, brass, concrete, bricks, ceramics and marble
* 2 component power epoxy adhesive, sets in 5 minutes, super strong - up to 130kg/cm2
* Also bonds metal/stone to other surfaces such as wood, leather, glass, ceramics, and most plastics
* Sets Metallic Grey, Gap filling, Interior or Exterior
* Sandable, drillable and paintable water resistant
* Oil and common solvent resistant, heat resistant to 150c, cold resistant to -30c
* No shrinking or expansion on curing, withstands rough handling
(from the site)
It's brilliant stuff and very hard to crack.
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Unread postAuthor: Demon » Wed Mar 31, 2010 11:20 am

Just use this stuff-http://www.diy.com/diy/jsp/bq/nav.jsp?action=detail&fh_secondid= 9726445&ecamp=trf-005&CAWELAID=266888200

* Suitable for steel, cast iron, copper, aluminium, brass, concrete, bricks, ceramics and marble
* 2 component power epoxy adhesive, sets in 5 minutes, super strong - up to 130kg/cm2
* Also bonds metal/stone to other surfaces such as wood, leather, glass, ceramics, and most plastics
* Sets Metallic Grey, Gap filling, Interior or Exterior
* Sandable, drillable and paintable water resistant
* Oil and common solvent resistant, heat resistant to 150c, cold resistant to -30c
* No shrinking or expansion on curing, withstands rough handling
(from the site)
It's brilliant stuff and very hard to crack.


It looks like exactly what i need, but it is not disponible.
I will try Crazyglue
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Unread postAuthor: Coodude26 » Wed Mar 31, 2010 1:23 pm

Crazy Glue (Cyanoacrylate adhesive) is just a thin layer of acrylic AKA plastic. It can not withstand most any kind of torque, and its main redeeming characteristic is that it can hold 2 pieces together. To do this effectively it needs to 'grab' the material by soaking into it. It will not soak into aluminum, rather it will likely just form a thin layer of hard plastic on top, but you're welcome to give it a try.


Also for future reference, when someone on the site says "just try it", we are not trying to insult you. Usually it means that we don't know how it will do and trying it can't possibly hurt (ie this situation)
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Unread postAuthor: Demon » Wed Mar 31, 2010 2:00 pm

I maybe found something ...

I could try to make grooves on the 4 aluminium surfaces wich are in contact and fill those grooves with epoxy.
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