Henry, et alia:
I use ultra fine grain isomolded graphite.
I concur with Dr. McCreary’s view that the product of machining graphite is
filth and I send those parts out to specialists who are fully set up for
that work. I strongly recommend same...my lungs have had their fill of
filth from those ancient times when I mistakenly thought that doing it
myself was cheaper, just sayin’....
In hybrids particularly using a graphite throat insert is problematic
during that portion of the burn when the O/F ratio runs lean, for reasons I
assume to be obvious.....
Bill
On Fri, Jul 17, 2020 at 4:04 PM Henry Spencer <hspencer@xxxxxxxxxxxxx>
wrote:
On Fri, 17 Jul 2020, Jack Hanna wrote:
I've heard graphite as a nozzle is effective, however it's also
extremely porous, and I'm hesitant to use it as a unibody design for the
main combustion chamber and injector...
I can't advise specifically on hybrid issues, but more generally...
Graphite is porous, or not, depending on what type you get -- there are
*many* different flavors of graphite, it's not a single well-defined
material with a single set of properties.
Machining graphite tends to generate huge amounts of fine dust, which is a
mild lung irritant and, being electrically conductive, needs to be kept
out of electric motors and such (as in, it can cause electrical fires in
your tools!). The usual recommendation is a shop-vac with a HEPA filter,
with its nozzle as close as possible to the cutting edge(s). And best to
have a respirator and a fire extinguisher handy.
Some types of graphite can be very hard on cutting tools, even carbide.
Henry