I have made a very simple chuck, of the bell type, this consist of a piece of tube welded to a face plate and two rows of four off m8 screws drilled and tapped into the side of the tube. so this acts like a four jaw chuck. simple but effective.
for a three jaw chuck you will need a self centering scroll with a bevel gear on the other side for the operation of the jaws to move in and out.
for the jaws you will need to drill and tap into the centre of a bar. Then machine the bar into a cross section with the thread at it's middle, after this carefully hacksaw through the thin wall of thread that will be left and you will have your chuck jaws.
of course the size of these jaws will depend on how big you intend to make the chuck.
I hope this will give you some ideas for your chuck. Good luck.
Thanks and yess something like that. I did know about this spider idea, but it is not something i had in mind to youse my self.
I need ideas for 4-6" 3-4 jaws lathe type, self centering or manual centering mounting on a faceplate. But people more ideas pleas.