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Posted: Sat Nov 20, 2010 1:15 am
by Moonbogg
I wouldn't be comfortable using epoxy for a cannon. That may just be me though.

Posted: Sat Nov 20, 2010 1:24 am
by jackssmirkingrevenge
Moonbogg wrote:I wouldn't be comfortable using epoxy for a cannon. That may just be me though.
I was almost hurt by that remark :cry: why would you not feel comfortable?

If the material is used correctly, there's no reason to doubt its strength. It's all down to using it correctly though, my hybrid experimentation is a clear illustration:


Fail at 8x

Win at 17x

Posted: Sat Nov 20, 2010 3:07 am
by Moonbogg
jackssmirkingrevenge wrote:
Moonbogg wrote:I wouldn't be comfortable using epoxy for a cannon. That may just be me though.
I was almost hurt by that remark :cry: why would you not feel comfortable?

If the material is used correctly, there's no reason to doubt its strength. It's all down to using it correctly though, my hybrid experimentation is a clear illustration:


Fail at 8x

Win at 17x
It makes me uncomfortable because in my mind I still see epoxy as "glue" and I consider pressure launchers to be devices that demand strong joints (unless duct tape is used. Duct tape is always acceptable) :wink:

Posted: Mon Nov 22, 2010 12:19 am
by chinnerz
Ok, i went down there today and they have fiber-glass resin.. which i assumed isnt the right stuff.

But there is also this

Image

and this:

Image

will any of these do?

Posted: Mon Nov 22, 2010 12:58 am
by jackssmirkingrevenge
The "casting and embedding resin" might do but it's less likely to be strong enough for high pressure applications as it seems to be designed for aesthetic purposes, in a TLAR sort of world it will probably do but it would not be my first choice.

As to the Newtech stuff, the shop label describes it as "putty" so not much good for casting if that's the case.

I would go with the fibreglass resin.

Posted: Mon Nov 22, 2010 1:38 am
by Selador
jackssmirkingrevenge wrote:As to the Newtech stuff, the shop label describes it as "putty" so not much good for casting if that's the case.
It looks to me like it is epoxy putty. In a can. With separate hardner.

Posted: Mon Nov 22, 2010 1:59 am
by jackssmirkingrevenge
I personally have never used epoxy putty, I imagine for a simple endcap it could suffice but I prefer the idea of pouring liquid because you can be sure it fills every nook and cranny and as such is more likely to seal well and adhere properly. It also means that if your mould has even a small pinhole leak in it, you're screwed, but it's something one learns to live with :roll:

Posted: Mon Nov 22, 2010 3:08 am
by chinnerz
Define "high pressure applications" because i'll be lucky if i can produce 200psi.

I'm only asking because clear would be a bonus as i could use it for other things. :)

Posted: Mon Nov 22, 2010 3:24 am
by jackssmirkingrevenge
chinnerz wrote:Define "high pressure applications" because i'll be lucky if i can produce 200psi.
I would say a thick enough plug would suffice for sub 10 bar applications.
I'm only asking because clear would be a bonus as i could use it for other things. :)
I've used marine epoxy for aesthetic purposes too ;)

Image

Image

Posted: Mon Nov 22, 2010 8:03 pm
by chinnerz
wow, that looks amazing :)

Posted: Mon Nov 22, 2010 11:11 pm
by jackssmirkingrevenge
chinnerz wrote:wow, that looks amazing :)
Shame she wasn't :roll: stick to using it for spudguns ;)

Posted: Tue Nov 23, 2010 1:33 am
by Selador
jackssmirkingrevenge wrote:I personally have never used epoxy putty, I imagine for a simple endcap it could suffice but I prefer the idea of pouring liquid because you can be sure it fills every nook and cranny and as such is more likely to seal well and adhere properly. It also means that if your mould has even a small pinhole leak in it, you're screwed, but it's something one learns to live with :roll:
Waitaminnit, I gotta go check something....


Ok, back.

Whew, I thought the world was collapsing or something. I had to go and make sure my dogs and cats weren't sleeping together, and the sky was still propped up.

You came awful close to dissing some epoxy, there, bro.

;o)

Posted: Tue Nov 23, 2010 1:44 am
by Gippeto
Our buddy TLAR dissing binary adhesives?

Not gonna happen...your world is safe...well...as far as that goes anyway. :wink:

Posted: Tue Nov 23, 2010 2:08 am
by jackssmirkingrevenge
I've been promoting the use of binary adhesives in spudguns for as long as I can remember, because the benefits it has in terms of fleshing out ideas that could not be put together with standard parts for minimal cost. I see lots of good ideas on this forum that are never made because of the lack of material facilities, and that's a damn shame.

The reason it hasn't really caught on is because there are disadvantages to epoxy construction, curing time is one of the factors but when it comes to casting, it's imperative that the mould is spot on, because the slightest leak can result in tragedy forever preserved in the proverbial resin sarcophagus, which can be very disheartening.

I've had my frustrations with the above and decided I can live with it, most people don't seem to be of the same frame of mind.