[TheForge] metallurgy question

[Jerry Frost]

Terry: One thing I've noticed about you and possibly one of your greatest 
failings is your tendency to try reinventing the wheel to avoid paying the 
established manufacturers. This is a perfect example, as deep water cameras 
are commonly available for the price. Heck, my 35 year old Nikonis is good 
for 300 fathoms and only cost about $600 in the day. Think Cusler or the 
other guys make their own cameras?

A couple of my old coffee shop buddies from when I lived in Anchorage were 
airplane salvers and one used ROVs, Sidescan sonar and other cool stuff he 
developed as he went. He didn't design and build the components he assembled 
them in configurations he needed at the time. ALL his cameras, electronics, 
sonars, motors, actuators, etc. etc. ETC. were off the shelf. One of the 
guys even had a manned submersible though he avoided using it if possible. 
Both guys did salt and fresh water salvage and let the boats, barges, etc, 
go to the insurance companies preferred heavy lift salvers.

The only way a camera or other deep dive component will suffer decompresson 
expansion woes is if it leaks. The only reason you have to worry about this 
kind of thing is if you're designing your own, the commercial guys figured 
this stuff out a long time ago.

Jer
----- Original Message ----- 
From: "terry l. ridder" <terrylr at blauedonau.com>
To: "theforge e-mail list" <theforge at mailman.qth.net>
Sent: Friday, May 27, 2011 7:12 PM
Subject: [TheForge] metallurgy question


> hello;
>
> i have a metallurgy question.
>
> a camera housing on one of the deep submergence rov needs to be
> re-engineered. the housing is subjected to compression and expansion
> cycling on every trip it makes. the current housing made of aircraft
> aluminium alloy is showing definite stress fractures and microfissures.
> the lense assembly is fine. would like to use something other than
> indium for the lense seals but they hold up the best.
>
> the current camera housing is a cylinder open on one end for the fused
> quartz lens assembly.
>
> the current cameras are being replaced with HD cameras. having a camera
> crushed at depth really defeats the purpose of the rov and the HD
> cameras.
>
> the camera assemblies are not allowed to free-flood while every
> other feature of the deep submergence rov is allowed to free-flood.
>
> not only are the camera housings subjected to extreme pressure but
> temperature differentials. Lake Superior is roughly just above freezing
> at 1,000 ft. Lake Michigan is approximately the same at 900 ft.
>
> the pressure at 1,000 ft is 459 psia. (pounds per square inch absolute)
>
> would anyone have suggestions for an alloy that would take the
> mechanical stress and thermal cycling that the camera housing must
> experience?
>
> -- 
> terry l. ridder ><>