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Machine coordinates reference home question
« on: November 10, 2017, 07:52:51 PM »
Should I " refrence all home " every time I start my mill?

Once my mill completes the refrence all home it automatically rezeros all the axis. I understand that's the machine coordinates 0,0,0

Also known as g53???

Does the program save this when I shut it down or should I redo the home reference next time I start the mill?

Thanks John.

Offline RICH

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Re: Machine coordinates reference home question
« Reply #1 on: November 10, 2017, 09:34:06 PM »
John,
Something could happen when the machine is turned off that would mechanically move the axes. Mach needs to be told where the physical location of the axes are. Referenced, referencing, home, setting home are play on words used over time. Using switches does it automatically per your configuration. If you don't use switches you need to do it manually.
So yes reference the machine each time you start.

G53 is a command to move in Machine Coordinates which are absolute.

There are some options  in general configuration to save current position on exit.

BTW, I don't use switches, need to many of them and just think they are a PITA. But you know what they say about opinions...................., :)

RICH
Re: Machine coordinates reference home question
« Reply #2 on: November 10, 2017, 09:38:40 PM »
Hi John,
unlike Rich I do have home switches and I use them to reference the machine at every start up. With decent home switches and referencing I have
reduced my mistakes by 95%.

Craig
My wife left with my best friend...
     and I miss him!
Re: Machine coordinates reference home question
« Reply #3 on: November 10, 2017, 09:59:28 PM »
Hi,
the last crash I had I was running some code that had a fault in it, I can't remember what it was, but the code would run and at particular point would fault.
The nature of the fault required that I restart Mach and then run from the previous end point. I had done this about four or five times over several hours with
the job near complete before I made a mistake. I had restarted Mach and loaded the Gcode file and pressed <cycle start> BEFORE I had referenced the machine.
It attempted to machine the part, not at my intended work zero as had been established previously but some other location, probably the end point of the last
successful running code. BUGGER!!!!

Having learnt my lesson I re-wrote the <cycle start> button code so that it would not work UNLESS the machine has been referenced. I do have a button that
I can use to override this behavior but seldom do I use it.

Craig
My wife left with my best friend...
     and I miss him!
Re: Machine coordinates reference home question
« Reply #4 on: November 11, 2017, 07:52:56 AM »
Am i correct in saying this?

Machine coordinates are absolute from the home limit switch position?

Any time i reference G53 its from the 0,0,0 in machine coordinates?

thanks, john



Offline RICH

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Re: Machine coordinates reference home question
« Reply #5 on: November 11, 2017, 10:14:23 AM »
john,

Please read 10.7.17 in the mill manual about the G53 command.

Machine Coordinates are absolute coordinates from some 0,0,0 defined datum point.
The defined datum point of 0,0,0 is where some physical point ( controlled point would be a better word) is on the machine. Mach is the controlling software and has an internal 0,0,0 point to work from. Until the machine is referenced it does not know / can't relate the software 0,0,0 to some defined physical location of 0,0,0. Only you can say where the physical point is. So the controller provides  a way to do that since it can't hear, see, what ever, and provides for using switches to electronically and automatically relate the software 0,0,0 to the physical 0,0,0. When that is done it can keep track of the axis coordinates for the current session.

RICH  
Re: Machine coordinates reference home question
« Reply #6 on: November 11, 2017, 10:34:16 AM »
Fortunately my Bridgeport came from the factory as a CNC machine i did not have to install limit switches and home switches they were already there.

I just had to wire and adjust them and they all work fine when i hit the home button

Maybe im over thinking this.

I have been using my mill for a while now but never took the time to set up all that Mach3 can do.

The reason I'm asking is I am  working on the tool change macro now an want to understand the machine coordinates and work offsets better.

And set up the tool offsets automatically.

thanks , john

 

Offline RICH

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Re: Machine coordinates reference home question
« Reply #7 on: November 11, 2017, 10:56:57 AM »
John,

I would suggest you purchase CNC Programming Handbook by Peter Smid.
Read and study it since it's a single source of info that you will refer to for
professional advice / information.

RICH