injector bosses

[Seth]

On Fri, 29 Aug 1997, Garfield wrote:

> On Fri, 29 Aug 1997 14:13:55 -0500, Tom Cloud
> <cloud at peaches.ph.utexas.edu> wrote:
> 
> >A *true* epoxy will cure faster and harder when heat is applied
> >(remember, it's a plastic, so it has an upper limit where it's
> >damaged or destroyed .... I forget, but I think it's near 300 F).
> 
> Ooops, careful there. MOST of the commercial epoxys have transition
> temps Tg below 200deg F, some used in aircraft building are around
> 150degF hence most all the composite planes being painted white!!, so
> the advice someone else gave for trying to locate a higher temp epoxy
> like those used in prepregs is exactamundo spot on. Generally, if the
> epoxy cures at room temps, then it's Tg isn't gonna be more than 100degF
> above that.
> 
> OTOH, it's not THAT hard to find higher temp epoxies. What you want is
> an epoxy you heat to around 200degF to cure, and it will have a Tg
> around 300-350degF. Ciba Adhesives makes a couple; I'll try and track
> down part numbers and suppliers for for the list. OK?
> 
> And as to your surmisals based on plastics/temps of the wiring &
> housings, these are NOT usually epoxies. Trust me, contrary to your
> experiential coffee-pot evidence, generic epoxies are NOT to be relied
> upon in this application, but "high temp epoxy adhesives" especially the
> aluminum-filled varieties, would be ideal. I'll see what I can find and
> report back.
> 
> Garfield
> 
Thanks, Garfield for the clarification.  I have used Permabond, a 
pre-preg aluminum filled adhesive.  I filled it with colloidal silica to 
thicken it into pre-preg bondo. The stuff stilll wont reliably fill a gap 
much over 0.015 inches.  I don't have permabond's address, unfortunately...




Seth