We have owned a J-2r for 6 years now and it is a excellent machine.
once you use it you'll wonder why anybody would spin cast anything.
As with most things it has its pros & cons but the biggest advantage
is the ability to cast at an exact temprature. We notice changes in
castings with as little as +/- 10 degrees. It works really well if
you plan to use it for light - medium production. the only downsides
are it uses a TON of nitrogen and the crucibles and sealing rods dont
last long. But those are offset by less casting rejects.
We have noticed that the quality of alloy makes a huge difference in
the way it casts, We have tired what seems to be hundreds of
different alloys from many different suppliers and found that United
Precious Metals alloys are far superior for resistance casting.