I want to cast 18kt white gold, platinum, and palladium (maybe
titnium too but not important).
Just this statement alone decides the question of which machine to
purchase. I can't speak for titanium because it is not a metal in my
repertoire of jewelry use metals. Palladium alloys should not be
"open air melted" (torch melted) because they absorb oxygen and
become porous and brittle. The Ti Research machine is an "open air"
melt machine so shouldn't be used to cast palladium (it is great with
the gold and platinum alloys).
Not knowing th MC-15 machine except from recent advertisements and
their website, I can't say how well it works, but it does have an
induction melt and inert gas atmosphere so it would be preferable
for palladium casting.
Just my thoughts, not associated with either company or any
resellers of their products.
Paul D. Reilly