REFLECTOR: Heating and bending

[David Doshay <ddoshay@cisco.com>]

There have been postings about using heat from halogen 
lamps to soften and bend the doors.

I found that my firewall bulkhead has warped and I would like
it to be installed straight. What I have done is to glass it on
one side from the duct up, and of course it is true and plumb
on that side from the duct up. To get the other side true I
need to pull it from the duct cut-out towards the rear about
5/8" while keeping the bulkhead in place at mid-height with
a straight edge across the flanges. The pulling is plenty easy 
to do with some webbing tie-downs that I have. 

I was thinking that I would like to heat about 3/4 of  the
firewall and pull it back, and then let it cool true. My question 
is whether or not I need to pull it beyond true to avoid 
having it spring back. If it is heated and cooled, the transition 
tempurature will rise considerably, and I worry about being 
able to get it that much hotter again if I need to try this more 
than once.

Of course I could just pull it back to true and glass it into
place, (no heat at all) but then this part will be under stress 
and ... well it is hard to know exactly how the airframe will 
move in reaction to that stress. Maybe not at all, maybe it will
twist.

Thoughts?

Thanks,
David