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Shear strength of epoxy putty

Post about things you have launched or thought about launching. Also post about various materials used for building cannons. No posts about explosive projectiles!
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Unread postAuthor: theBOOM » Tue Jul 06, 2010 1:44 am

I find that heating the epoxy before mixing it in the correct ratios will give me a more "liquid-like" epoxy, which makes mixing and pouring a bit simpler. To make the final product stronger and ensure proper curing you should heat the cast for about 2 hours at about 250*F.

JSR do you use medical syringes to mix your epoxy? I bought about 8 of them and I seem to be running out already...
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Unread postAuthor: jackssmirkingrevenge » Tue Jul 06, 2010 2:50 am

theBOOM wrote:JSR do you use medical syringes to mix your epoxy? I bought about 8 of them and I seem to be running out already...


I run the laboratory I work in so I have a practically endless "free" supply ;)

What I do many times though is take say a 10mL syringe, remove the plunger, plug the nozzle with a screw and use it a small measuring cylinder.
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Unread postAuthor: btrettel » Tue Jul 06, 2010 10:47 pm

Thanks for all the help.

I suppose I'll heat the epoxy to reduce the viscosity.

My main worry is residual stress from the cooling. As a material cools, it contracts a bit. This will make the epoxy be in a state of tension when the chamber is unpressurized. Devcon was smart enough to provide the coefficient of thermal expansion though, so I should be able to figure out how much stress is created and factor it into my calculations. :)
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