1 more "Hip Hip" for Lim "StepOffs"

A while back there was a short discussion on Limit "Step Offs", An
adjustable "distance" the machine moves in the positive direction after
finding the Limit Switches during a "homing" sequence. Some controllers
allow you to modify this distance, others do not. I personally find it a
necessary option. ALL controls being developed today should have this
option, or it will fall behind the curve.

Properly set up, a controller should allow one to "step off" from the
switches a distance that is uniquely particular to the machines design
(read-adjustable). That final location then becomes in effect Machine
Zero ( this may be based on fence locations or fixture point(s)).

I had many reasons why I liked the option based on simple head changes
and tool offsets alone, that are more simply handled in this fashion
than by any other means. But, one more important reason was in regards
open loop machines ( and there will continue to be many of those in the
years to come so please don't turn this into Servo is better than
Stepper, BOTH have their place ).

IF, and I say IF, the machine is NOT where it is supposed to be after
running a file, And, When using a Rewind command, or a command that
tells the machine to Go to Machine Zero after the job, You have a far
better chance of a successful event IF there is some "clearance" or
leeway, rather than having the machine smash into your limits at Rapid
rates. With the Proggy I use, I have a command in the last line of the
code that ALWAYS re-homes the machine after a Job. I am usually not
standing there. When I do come back, I will know if it was within my
preset Guidelines or not in a "gentle fashion" rather than finding out I
had a clamp in the way, lost a few steps and Smashed my Limits, losing
position.

As many find out as they are setting up a machine for the first time, or
as they are trying out a new "version" of someones release, or if they
are avid Beta testers..... Admit it, They have at one time or another (
I've done it quite a bit :-) ) driven that machine *hard* into a
limit/mechanical stop device. Not all machines have been designed to
allow mechanical space "behind" the "Trip Zone" of the switch (though
all should be).

**Even then, If a machine overtravels when heading back to the Machine
Zero location, any deviation in the actual location of the hardware
will Force a reset as Limits generally cause all Positional information
to be lost. In most programs I have used, Only a homing routine can be
allowed to not reset if desired.

I don't suppose this matters much to those who only run a tops of 50ipm
or so..... But running anywhere between 250ipm, 500ipm and beyond can
make a big mess in a really big hurry.

Being an avid beta tester, I can attest that The Limit Step Off distance
adjustability has indeed saved more than just a little wear and tear on
my stuff. I will not run a software without it, nor recommend one until
it has it in it.

Chris L