Re: [CAD_CAM_EDM_DRO] Stewart platform: revisited

> The llnl machine is almost big enough for my purposes. But is it stiff

enough to do steel?

>
> Dave

it should be easy enough to scale it up to the size needed
as for the stiffness?
I've read nothing but good reports on the stiffness of the stewart platform
designs
with all the loads being in almost pure tension or compresion and very
little bending
stress they have what Buckminster Fuller called Tensegrity (tensional
integrety)
the same thing that makes the Geodesic dome one of the strongest structures
for the
weight that you can build
I think the main limits on the stiffness would be the actuators in the
struts
and any lash in the joint bearings ,there are also some areas in the working
volume that are just cant get as much power as others ,has something to do
with the joint angles I think
I've seen some video of a larger machine (still looked like a bunch of
twigs) doing
some die sinking work in steel ,strange beasts to watch ,but I guess you get
used to it

there is another at
http://www.i-way.co.uk/~storrs/lme/LMEHexapodMachine.html
dig around the site and you will find some design drawings to work from
if you wanted to build your own

Brian