Re: CNC robotic welding arms

These would seem in theory to be ideal for plasma or laser cutting.
Realising that calculating the movement coordinates can be pretty
straightforwards set me thinking about these robot arms in the first
place. Just generate G Code that contains all rotational coordinates,
and most any controller would work in the same way that many folks
use their controller's Y-axis to rotate a rotary table.
However, how the controller handles the velocity calculations is
another matter when you start using rotational axes, as the
controller really needs to know the distance it's moving to calculate
the velocity. ie. many controllers have problems with a large
rotational move combined with a very small linear move.
Can anyone shed some light as to how high-end controller handle this
problem ?

Rab

--- In CAD_CAM_EDM_DRO@y..., "Mark Ehle" <ehlem@c...> wrote:
> A while back I had entertained the idea of building a CNC plasma
torch
> that used rotary joints rather than linear stuff. I reasoned that
this
> would be a lot cheaper way to go if a person could work out the
math to
> use polar coordinates and translate this into step/direction.
> I have since found a cheap source of linear bearnings/ways (the junk
> yard) and have abandoned the rotary idea, but still think that this
has
> merit for a cheap way to go. Anybody else doing this? Does EMC
handle
> polar joints?
>
> Later -
>
> Mark Ehle
>
> Dowliing, MI
>