Re: Twin motor axis

--- In CAD_CAM_EDM_DRO@yahoogroups.com, Jon Elson <elson@p...> wrote:

> IDA wrote:
>
> >Over on the Geckodrive group, a chap who seems to know what he is

talking about said it is a seriously bad idea to use two motors on a
single axis of a router or plasma table because of the risk of
serious damage to the machine if one motor fails when the other
continues. I am planning a large 2.5m x 3.5m router using 2 motors
on the x axis, and that post reawakened worries. The idea seems
fairly common, so what safeguards can be put in place to alleviate
this risk?

> >
> >
> All the large machines (gantry bed mills, vertical boring mills,

etc.)

> that use tandem axes have bearings on
> the beam that joins the gantry pillars. This allows the paired

slides

> to get out of sync with no harm to the
> machine. One bearing is a conventional bearing, the other is a

sliding

> fit, so it allows the beam to tilt without
> pulling the pillars together. (They probably have estop switches

to

> kill motion if it gets seriously out
> of sync.) This allows the two axis halves to move independently

toward

> the home location, and get sync'ed
> at home. Then, the CNC control is responsible for keeping them

synced.

>
> There are thousands of large machines in industry made this way.
>
> Jon

I think i need a pic to understand this. Do you have any link i
could use.


Wally