Re: A "simple" Hexapod project - Joints

Although I am undecided as to whether or not to build a 3 axis or 5
axis machine I have decided on a vertical slide type set up. This
means no actuators as such to design, just bog standard rails and
leadscrews. See files section "hexapod ideas" if you don't know the
configuration.

This means the mechanics consist of a stiff frame, 6 (for a full
hexapod) or 3 (for a triaglide) linear slides, 3 or 6 leadscrews, 6
fixed struts a table/router mount. And 12 joints.

Carl has used gimbles and these have the advantage that they are
simple to make and decent bearings can mean they have little slop. I
am just wondering what other possibilities there might be, looking at
large machines doesn't seem to help much as the joints are often
covered or are mysterious ball joints that don't seem to be holding
enough ball.

I have just seem some ball joints on the web where the ball is held
by a magnet, the largest was abotu 25mm in diameter and would hold
25kg.

What about universal joints if also allowed to rotate?

Another thing I have noticed is that sometimes joints are combined.
Struts that join at the moving table form a triangle with two pounts
fixed so they can be jointed together and then both put in a ball
joint of some sort.

Ideas appreciated, especially good ones.

Cheers,

Graham