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Topic Date User

Victorian gear testing volunteers needed 6-May-2011 At 3:44:08 PM cruze

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On 6/05/2011 Jim Titt wrote:
>I can help you with the heat question. We were trying to develop a way
>of pulling old glue-ins by heating the epoxy so it softened so I glued
>a bolt in a granite block and then cut the block open so we could measure
>the temperature down the bolt.
>Even with the bolt glowing dull red and flaming epoxy everywhere we couldn´t
>get melting more than a third of the way down and at the bottom of the
>bolt we only got a rise of around 10°C. The poor conductivity of the stainless
>was just too much for the heat input we could get in the bolt eye even
>with an 1800°C torch.
>This was with a normal filled epoxy adhesive, using another mix with less
>filler powder but more colloidal silica that we made ourselves we managed
>to get enough softening to pull the bolt but this was after about 15 minutes
>of keeping the bolt eye glowing.

Might also have something to do with epoxy adhesives being thermoset rather than thermoplastic and typically decompose before melting...