At the moment I use a OneWay Chuck with #2 tower jaws. In the future I might have custom jaws made, but for now it's sufficient.
This mounts to my old lathe with an adaptor like this:
![Image](http://www.woodcraft.com/Images/products/600/816054.jpg)
This threads on the - obviously threaded - spindle of my super7.
However, the new lathe has a taper spindle, not a threaded one if I'm correct, and I plan on keeping the factory provided 3-jaw chuck mounted to it.
Seeing as Ken Lamb makes a briar chuck made of aluminium which mounts to your 3-jaw with a tenon, I am thinking of making my own adaptor like the above one out of aluminium.
So instead of making a hollow adaptor with threads, I would make it solid with a tenon protruding from the back, so I can mount the OneWay chuck in the 3jaw.
The question is: Would that be safe? Will aluminium do the job, or would it require steel?