I'm having a hell of time getting my head around this. I have gone over the manual like a rash but I still cannot get my Machine to behave. Firstly, I am assuming that DRO means the Digital Position of my X, Y & Z axis, and that the digits I ought to be using as Safe Limits are the Machine Coordinates Y/N ??

For arguments sake my Z Machine Coordinates that I want to set as Safe Limits are -5 and -63 I enter tham into the Max an Min Motor Home/Soft Limits Dialogue box then close the box. On testing the Z sails straight past both safe limits completely ignoring them on either end of the travel.

My questions are is there something disabling the Safe Limits? A check box perhaps ? Secondly, am I setting this up right? Taking -63 to be lower in value than -5

Finally, What are the other options in the  Motor Home/Soft Limits Dialogue box ? Home Off, Home Neg and Auto Zero What do they do 

Z max would normally be set as zero and Z min as the extent of your travel as a negative value.
If you use -5 as Z max then you will have to turn off Soft Limits when homing.
You may not have noticed the Soft Limits button and thus dont have it active.

Home Off is a value you enter to tell Mach how far away the axis is from its negative extent, for example X axis zero is normally defined as tool furthest left on that axis. If however you homed fully right then you could set a Home Off value equal to the distance your home is away from fully left. What would then happen is when you home, the DRO for Machine Coords would display the value you have set in Home Off and Mach would know that X0 is that amount away in the negative direction.

Auto Zero needs to be chosen as it will set the machine coords zero (or the Home Off value if other than zero)

Home Neg just tells the axis which direction to move whilst homing.

Hood

Thanks again old friend... I'm away to my bed know, I try it in the morning.

well Mr Hood, thank you ever so much for the help, I am now a NEWBIE SMART A#$E EXPERT at soft limits, one hell of a learning curve, but I have fiddled on all day and not hit the hardware limits or heard the sickening crunch of the Gantry hitting bed once!! Weee, chuffed to ribbons!!!

Okay next question. Is it possible to program Mach3 to move to a preset position when I need to do a tool change? i.e. my home positions are Z15, Y15 and x15 but I would like to have it go to X260, Y300 to change the tool.

Ther is also an Auto Tool Zero, how does that work?

 

 

You can alter the M6 macro to do whatever you wish, my Chiron one has something similar in it.
I have never used Aulto Tool Zero as I do my toolsetting via an integrated height checker which links to the tooltable in Mach. There are a few macros floating about however so if you do a serch you should find some.
Hood

"I have never used Aulto Tool Zero as I do my toolsetting via an integrated height checker which links to the tooltable in Mach"

Oh... That looks interesting... How do you do that

BTW thanks for the M6 Macro help. Gonna be a busy chappie adding all these goodies to my "Modified" Chinese Wonder

You can see one of them here, http://www.machsupport.com/forum/index.php/topic,10331.msg93511.html#msg93511
Not sure if I detail the code  in the buttons but of not I can let you know later if you want.
I have one at each mill (Beaver Knee Mill and Chiron VMC)

Hood