Re: [CAD_CAM_EDM_DRO] Low cost limit switch suggestions

Robert Allen & Marsha Camp wrote:

> Hi,
> I'm putting servos w/gekko 320s on the x and y axes of a
> older ball screw equipped mill and am going to use CNC PRO.
>
> In talking to Mariss of gekkodrives he recommended that the
> limits kill the power to the drives because if a drive fails
> there is a good chance that the output transistors will
> short and the motor will travel at top speed until it blows
> the fuse or hits the end of the ballscrew (not good).
>
> This means I used up the original limits that are on the
> machine.
>
> So here are the questions, does any one have a suggestion
> for limit switches that are inexpensive, rugged, accurate,
> and relatively small (I want it all). Also it would be nice
> if I could only have to install one per axis which brings up
> the second question,
>
> If I already have max. travel limits do I need any thing but
> a home switch?

Probably not. EMC, at least, has software limits that are referenced
from the home switch position. The software-sensed limit switches
would be pretty redundant.

> What are the reasons for having limits the computer can see?

Reall not much use. About the only time they might be tripped under
normal use is when a home search goes the wrong way. You could
probably come up with a way that the limit switches could both
give individual signals to the computer and provide an E-stop
signal too. That is really an or-gate type function.

Jon