"Pete C." wrote:

Karl Townsend wrote:

"Pete C." wrote in message
ster.com...

Karl Townsend wrote:

...
You rapid travel in the home direction until you hit the decel switch
about an inch out from the limit switch. When you hit the decel switch
you drop from rapid to slow until you hit the limit switch. When you
hit
the limit switch you drops to creep for ~ 1/2 rev until you reach the
index signal at which point you stop and zero/home the axis.

The home procedure with a galil card is different. First it homes off
only a
home switch and an encoder index pulse on each axis

1. rapid till NC home switch opens.
2. reverse slow till home switch closes
3. creep till index pulse made.

This is occurring on all axis simultaneously. If you shut down anywhere
near
home it only takes a few seconds.

Karl

That's a similar process really. It's basically using a decel switch as
the home switch, and needs to have enough travel after that decel/home
switch to avoid crashing into the limit when rapiding in to home. One
presumes that this setup also includes a home offset, so that axis zero
is just off the limit and not +1" out at the decel/home switch.

The X axis home on lathes is nowhere near a limit. You don't want to go
clear to the back of the lathe to home it.

Yes, it makes no difference where along the axis you home, as long as
you know where that point is.

I should add that if your home point is not at the end of an axis
travel, your homing routine needs to have the intelligence to reverse
and search for home in the other direction if it encounters a limit
switch instead of a home switch.



At least on my machines decel switches aren't used. Instead softlimits are
used to prevent motion out-of-bounds. They allow for a barrier in the work
zone like a lathe chuck. Just more than one way to skin a cat.

Softlimits don't work when you are not sure of your position, such as
when you are homing.